Loxoconcha eichwaldi Livent., L. ex gr. temperata Olteanu. 4. The layer with Dreissena sp., Pontalmyra (?) sp., Pseudoca- tillus pseudocatillus (Barb.) ...
Georgian National Museum Research Institute of Paleoanthropology and Paleobiology
I. Taktakishvili, M. Vekua, L. Maissuradze, I. Shatilova
The paleobiological characteristic of the Late Neogene of Western Georgia (Molluska, Ostracoda, Foraminifera, Pollen data)
Tbilisi 2018
საქართველოს ეროვნული მუზეუმი პალეოანთროპოლოგიისა და პალეობიოლოგიის კვლევითი ინსტიტუტი
ი. თაქთაქიშვილი, მ. ვეკუა, ლ. მაისურაძე, ი. შატილოვა
დასავლეთ საქართველოს გვიანნეოგენურის პალეობიოლოგიური დახასიათება (მოლუსკები, ოსტრაკოდები, ფორამინიფერები, პალინომორფები)
თბილისი 2018
wigni eZRvneba Cveni Zvirfasი megobrebis i. TaqTaqiSvilsa da m. vekuas xsovnas, romelTa xelnaweri safuZvlad daedo am naSroms This book is dedicated to the memory of our dear friends I. Taktakishvili and M. Vekua, whose manuscripts are the basis of the present work.
The present work is the result of many years of common field investigations, carried on by the authors on the territory of Western Georgia. The work consists of three parts devoted to the Pontian, Kimmerian and Kujalnician stages. Each of them begins with a description of outcrops, followed by brief data about the history of fauna development. The results of pollen analysis of same outcrops are presented separately. The work also encloses: the stratigraphical scheme of the Upper Neogene of the Eastern Paratethys, the map of studied sites of the Pontian, Kimmerian and Kujalnician and pollen diagrams of the described outcrops. We hope that the present work will be of interest to specialists as well as students, who continue the geological and paleontological investigations in Western Georgia, the stratotypical region of the Eastern Paratethys.
Editor: I. Kokolashvili Reviewer: T. Lominadze
Introduction The appearance of Western Georgia as a separate region coincides with the end of the Middle Sarmatian, a turning-point in the geological history of the Caucasus. As a consequence of the crustal movements the Transcaucasian intermountain depression, covered by sea in the Early and Middle Miocene was transformed into a dry land split into two sections by the Dzirula massif. The western part was linked with the Black Sea basin, the so-called Rioni bay, where marine deposits continued to accumulate until the end of the Pleistocene. The territory adjoining the Rionian bay hemmed in by high mountains, became isolated from the rest of the South Caucasus. Warm and humid climate prevailed there preserving rich forest vegetation. Thus, from the end of the Middle Sarmatian the Kolkhida refuge was formed. By the way, many Tertiary species have survived there till now. The Kura Bay emerged eastward of the Dzirula massif and in the Late Sarmatian the territory of Georgia adjoining this bay eventually became dry land with the landscape typical of the continental climate. Thus, from the Middle Sarmatian onwards the organic world of Western and Eastern Georgia developed along independent lines influenced a quite divergent natural conditions. According to the stratigraphical scheme (Fig. 1), elaborated for the Black Sea region, the composition of the Upper Neogene continued through stages beginning from the Pontian and lasting till the Kujalnician (Popov et al. 2013). On the territory of Western Georgia this stretch of geological time contains full spectrum of the strtatigraphical unites, represented by full series of deposits dated by marine fauna. So, the biostratigraphical scheme of the Upper Neoge-
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ne of Western Georgia is very detailed contrary to the other parts of the Eastern Paratethys.
Fig. 1. The correlation of standard chronostratigraphy units and the Eastern Paratethys regional stages for Miocene-Quaternary. Standard chronostratigraphy is based on the International Stratigraphic Chart, 2016\12 (ICS). Regional stages of the Eastern Paratethys are modified after Popov et al. (2013)
The Upper Neogene deposits are widely distributed on the territory of Western Georgia (Fig.2).They occupy comparatively narrow zone and are represented by clays, sands, conglomerates and coquina. All these deposits accumulated in the brackish Rionian Bay. 6
Fig. 2. Studied sites of the Upper Neogene deposits in Western Georgia
The facts mentioned above, wight lead to the conclusion that Western Georgia is a unique region from both the geological and botanical points of view. On one hand it is the stratotypical region of the Eastern Paratethys and on the other it is the refuge of Tertiary floras elements. The faunistical assemblages of Upper Neogene deposits of Western Georgia
The Pontian stage We begin the description of sections from Abkhazia, where the most northern outcrops of the Pontian deposits of Transcaucasian intermountain depression are represented. Here in the upper part of thick conglomerates (about 2000 m) with interlayer of marl the Upper Pontian fauna was found: Dreissena anisoconcha Andrus., Lim7
nocardium (Tauricardium) petersi (M. Hoern), Paradacna abichi (R. Hoern). The thickness of Upper Pontian is 200 m and it is interbedded between Meotian and Kimmerian (Ebersin 1947). In region of Bzibi river the outcrops of Pontian are connected to conglomerates of Pitsunda, which thickness is about some thousand miters. The thickness of Pontian is about 2000 m. The layers are crushed in folds forming small synclines and anticlines. Toward eastern the conglomerates are changed by argillo-arenaceous rocks, with Upper Pontian fauna: Phyllocardium planum (Desh.), Pontalmyra planicostata (Desh.), Paradacna abichi (R. Hoern.). The Pontian deposits are widely distributed near v. Mukhudzyrkhva forming clayey bench about 40m high. In this locality the Pontian is represented by three parts which is confirmed also by fauna of Ostracoda (Vekua 1975). In Lower Pontian the following mollusks were determined: Congeria digitifera Andrus., Paradacna abichi (R. Hoern.), Valensiennius sp., Dreissena simplex Barb., Dr. tenuissima Sinz., Pseudocatillus pseudocatillus (Barb.), Parvivenus widhalmi Sinz. (Ebersin, 1934, 1935; Chelidze, 1974). On the left bank of Jijikvara river the small locality of Middle Pontian layers (about 2m), with complex of mollusks typical for Subrhomboidal horizon is situated: Congeria subrhomboidea Andrus., Cong. turgida Brus., Pontalmyra subincerta Andrus., Caladacna steindachneri (Brus.), Plagiodacna carinata (Desh.). Westward of Jijikvara river the Subrhomboidal horizon is overlapped by the deposits of Upper Pontian with following fauna: Dreissena rostriformis Desh., Dr. anisoconcha Andrus., Phyllocardium planum (Desh.), Paradacna abichi (R. Hoern.) and Valensiennius cf. reussi Neum. (Ebersin, 1934, 1935; Chelidze, 1974; Taktakishvili, 1984).
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On the territory of t. Sukhumi and further till t. Gulripsh the Pontian deposits are connected with conglomerates (thicknes about 1000 m). The fauna is preserved mainly in the argillo-arenaceous deposits (Ebersin, 1934, 1935; Chelidze, 1974). The deposits near v. Bogovesht are of great interest. Here for a distance of 1.0 km is exposed the thick strata of conglomerates, dipping on south with fauna transitional between Upper Pontian and Lower Kimmerian: Dreissena anisoconcha Andrus., Dr. rostriformis (Desh.), Dr. aff. iniquivalvis (Desh.), Dr. theodori Andrus., Pontalmyra planicostata (Desh.), Pont. cf. crassatellata (Desh.), Prosodacna aff. leptopsamatha Dav., Paradacna abichi (R. Hoern.), Par. abichi latior Andrus., Par. deformis Ebers., Valensiennius aff. annulatus Rouss. At first this layers were dated as Lower Kimmerian (Djashi, Taktakishvili, 1978). By opinion of Alpaidze (Alpaidze, Shengelia, 1988) the layers of whole Pontian and lower part of Kimmerian between which is the gradual transition, are represented here. The whole character of Pontian deposits is not changed till r. Kodori, where appears a new facies, later named the “Flexuosian layers”. The deposits are represented by conglomerates, sandstones and bluish-gray clays with fauna: Congeria flexuosa Takt., Dreissena sp., Limnocardium (Euxinicardium) seninskii Andrus., Pseudocatillus pseudocatillus larga Takt., Paradacna abichi (R. Hoern.), Chartoconcha sp. On the basis of this fauna the layers are dated as lower part of Bosforian (Taktakishvili, 1967). On the territory of southern Abkhazia the Pontian is widely distributed. The outcrop on r. Otapi is of great interest, where the lowest part of Pontian stage, the Eupatorian layers were discovered (Taktakishvili, 1975, 1978; 1984, Maissuradze et al., 2013). At first this stratigraphical unit on Crimea peninsula was described by Davitashvili (1933, 1937). The description of Otapi section is given below:
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Mt 2 1. Gray argillo-arenaceous rocks with fauna: Congeria novorossica (Sinz.), C. navicula Andrus., C. panticapaea Andrus., Hydrobia sp., Neritina sp. ………………..……...….. 40 m Pn 1 2. The same deposits with interbeds of yellowish sandstone and lens of argillo-arenaceous rocks with mollusks: Congeria novorossica (Sinz.), C. panticapaea Andrus., Prosodacna littoralis (Eichw.), Lythoglyphus (?) sp. ..….………… 4 m 3. Yellowish-gray coquina, formed by Prosodacna littoralis (Eichw.), Congeria novorossica (Sinz.), C. navicula Andrus., C. panticapaea Andrus., Hydrobia sp., Neritina sp., Micromelania sp. ……………………………………. 10 m The following foraminifera were determined in layers 2 and 3: Quinqueloculina seminulum maeotica Gerke, Elphidium macellum maeotica Gerke, E. ex gr. pontica Dolgopol. et Pauli, Protelphidium ex gr. subgranosus (Egger), Ammonia beccarii Linne. (Maissuradze, 1980, 1988). The assemblage of Ostracoda is richer: Caspiolla acronasuta (Livent.), C.venusta (Zal.), Caspiocypris labiata (Zal.), Candona sp., Cypria tocorjescui Hanganu, Pontoniella acuminata (Zal.), P. loczyi (Zal.), Cyprideis torosa Jones, C. punctilata pliocenica Rosjeva, Leptocythere goitensis (Suz.), L. crebra (Suz.), L. ex gr. gutata (Suz.), L. praebacuana Livent., L. pontica (Suz.), L. microlata (Livent.), Loxoconcha eichwaldi Livent., L. ex gr. temperata Olteanu. 4. The layer with Dreissena sp., Pontalmyra (?) sp., Pseudocatillus pseudocatillus (Barb.), Prosodacna littoralis (Eichw.), Parvivenus widhalmi Sinz., Abra tellinoides (Sinz.), Lythoglyphus (?) sp. ……………………….. 20 m Interruption in deposition ………….……………...... 70 m 5. Bluish-gray clays. In the lower part of layer are determined: Paradacna abichi (R. Hoern.), Congeria novorossica (Sinz.), Prosodacna littoralis (Eichw.) and Hydrobia sp. In upper part were seen: Dreissena tenuissima Andrus., Pseu-
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Pn 2
docatillus pseudocatillus (Barb.), Prosodacna littoralis (Eichw.), Parvivenus widhalmi Sinz., Hydrobia sp. ... 50 m The following foraminifera are presented in layers 4, 5: Quinqueloculina seminulum maeotica Gerke, Ammonia beccarii (Linne). Among Ostracoda: Pontoniella acuminata (Zal.), P. loczyi (Zal.), Bakunella dorsoarcuata (Zal.), Caspiolla balcanica (Zal.), Caspiocypris labiata (Zal.), Cypria tocoriesqui Hanganu, Leptocythere andrussovi Livent., L. multituberculata Livent., L. praebacuana Livent., L. naca (Mehes.), L. bosqueti (Livent.), L. cellula Livent., Pontoleberis pontica Stanč., Loxoconcha djaffarovi Schneid., Loxoconcha sp., Xestoleberis sp. ………….……….... 50 m 6. The layer of conglomerates with broken shells ..…..… 0,5 m 7. Bluish-gray argillo-arenaceous rocks with numerous Congeria novorossica (Sinz.), C. turgida Brus., C. flexuosa Takt., Dreissena rimestiensis Font., Dr. tenuissima Andrus., Dr. rostriformis rumana Sabba, Dr. rostriformis corniculata Sabba, Dr. polymorpha levis Takt., Limnocardium (Euxinicardium) seninskii Andrus., Pontalmyra subincerta Andrus., P. sulcatina (Desh.), Pseudocatillus pseudocatillus (Barb.), Prosodacna fisheri Dav., Pr. littoralis (Eichw.), Plagiodacna carinata (Desh.), Unio sp., Viviparus achatinoides Desh., Bithynia sp., Melanopsis sp., Micromelania sp., Neritina sp., Hydrobia sp., Planorbis sp., Pyrgula sp. ……………………………...…..….. 1.5-2.0 m 8. Yellowish-gray clays with bad preserved Dreissena rimestiensis Font., Limnocardium (Euxinicardium) seninskii Andrus., Pontalmyra sp., Chartoconcha sp. …………….. 1 m 9. Yellowish-gray clays without fauna …..…..….…..… 4.5 m 10. Yellowish-gray clays with Congeria turgida Brus., Dreissena rimestiensis Font., Dr. rostriformis corniculata Sabba, Dr. rostriformis rumana Sabba, Pontalmyra sulcatina 11
(Desh.), P. subincerta Andrus., P. repens Takt., Didacnomya corbuloides (Desh.), Pseudocatillus pseudocatillus (Barb.), Ps. medius Eber., Prosodacna fisheri Dav., Pr. littoralis (Eichw.), Chartoconcha sp. Plagiodacna carinata (Desh.), Viviparus achatinoides Desh. .....……... 2 m Pn 3 11. Bluish-gray argillo-arenaceous rocks without fauna..….12 m Interruption in deposition …………....……………… 20 m 12. Bluish-gray argillo-arenaceous rocks with interbeds of coquina. ..…………………………….………………….. 35 m The layers 11 and 12 contain the similar assemblage of mollusks: Congeria turgida Brus., Dreissena rimestiensis Font., Dr. rostriformis corniculata Sabba, Dr. palymorpha levis Takt., Limnocardium (Tauriardium) petersi (M. Hoern), L. (Euxinicardium) seninskii Andrus., Pontalmyra sulcatina (Desh.), P. incerta verrucosicostata (Sen.), Prosodacna littoralis (Eichw.), Pros. fisheri Dav., Paradacna abichi (R. Hoern), P. cf. retowskii Andrus. The age of layer 1 is Upper Meotian. The layers 2-5 belong to Lower Pontian. The layers 2 and 3 contain the fauna of Eupatorian horizon and layers 4 and 5 belong to Odessian horizon. Beginning from layer 7 the composition of mollusks become richer and the character of fauna is not changed till layer 10. So, the layers 7-10 can be dated as Middle Pontian, in spite of absence of Congeria subrhomboidea. But at the same time in layer 7 are presented such species as Congeria flexuosa Takt. and other mollusks typical for Flexuosian layers. The layers 11 and 12 are dated as Upper Pontian. On the territory of Abkhazia the Pontian deposits are distributed also in the basin of r. Galidzga. Here more interesting are the outcrops near v.v. Pokveshi and Gupi, where Pontian deposits are represented in other facies than on r. Otapi and contain somewhat peculiar complex of mollusks. The outcrop begins by conglomerate (2 m), which is overlapped by sandstones (10 m) with fauna: Congeria subcarinata Desh., Dreissena tenuissima Andrus., Dr. rostrifo12
rmis rumana Sabba, Limnocardium (Euxin.) seninskii Andrus., Pontalmyra incerta verrucosicostata Sen., Pseudocatillus cf. pseudocatillus (Barb.), Prosodacna fischeri Dav., Pr. littoralis (Eichw.), Paradacna abichi (R. Hoern.), Anodonta sp. Upper are represented the sandy-argillaceous rocks of subrhomoidal horizon (about 0,8 m) with rich fauna: Congeria subrhomboidea Andrus., C. turgida Brus., C. flexuosa Takt., Dreissena rimestiensis Font., Dr. rostriformis corniculata Sabba, Dreissenomya aperta (Desh.), Phyllocardium planum (Desh.), Limnocardium (Tauric.) petersi (M. Hoern.), Pontalmyra subincerta (Andrus.), P. megrelica (Takt.), P. sulcatina (Desh.), Didacnomya corbuloides (Desh.), Paradacna abichi (R. Hoern.), Par. omnivaga Papaian., Caladacna steindachneri (Brus.), Plagiodacna carinata (Desh.). Above is disposed the thick strata of gray clays with following mollusks: Congeria cf. turgidopsis Andrus., Cong. flexuosa Takt., Dreissena rimestiensis Font., Dr. rostriformis rumana Sabba, Dr. polymorpha levis Takt., Dr. mobilis Takt., Phyllocardium planum (Desh.), Limnocardium (Tauric.) petersi (M. Hoern.), Pontalmyra incerta verrucosicostata (Sen.), Prosodacna fisheri Dav. The thickness of Pontian is 50-60 m. Probably, the analogy of Lower Flexsuosian layers, Middle and Upper Pontian are presented here. The second locality of Eupatorian horizon is known on the territory of Samegrelo, near v. Urta (region of Zugdidi), where the following layers are exposed: Mt2 1. Gray-bluish sandy clays with Congeria subnovorossica Osaul, Hydrobia sp., Congeria panticapaea Andrus., Abra tellinoides Siniz., Nassa sp., Cyprideis littoralis (Brady). .... 20 m Pn1 Eup 2. Yellowish-gray sandstone without mollusks. The foraminifera are represented by Ammonia beccarii (L.), Porosononion sp., Elphidium ex. gr. macellum (F. et M.), Nonion ex gr. bogdanowiczi Volosh. Ostracoda: Caspiolla acronasuta (Livent.), Caspiocypris labiata (Zal.), Bakunella dorsoar13
cuata (Zal.), Pontoniella accuminata (Zal.), P. loszyi (Zal.), Hemicythera marinescui Olteanu, Urocytheris (Drobetiella) ex gr. mirabilis Olteanu, Cyprideis littoralis (Brady) ………………………………………………………… 4 m Pn1 Od 3. Bluish-gray clays with badly preserved mollusks…... 15 m On the basis of fauna, the age of layer 1 is dated as Upper Meotian (Chelidze, 1971, 1974; Popkhadze, 1978). The mixed character of microfauna, the presence of Upper Meotian species alongside the species typical for Pontian and the presence of foraminifera peculiar for Late Meotian brackish basins allows to date the layer 2 as Eupatorian (Vekua, 1975). The age of layer 3 is determined as Odessian. It contains the microfaunistical assemblage, in which the foraminifera and Meotian species of Ostracoda are absent. At whole the assemblage is poor and monotonous. Generally the Pontian deposits of Samegrelo are of great interest as they are represented in quite peculiar facies. Espesially must be noted the sections on r. r. Djumi and Kulistskali. The description of section Kulistskhali, where the length of Pontian deposits is about 1.5 km is given below: Mt 2 1. Bluish-gray clays with Congeria novorossica (Sinz.) and Mactra superstes Dav. By data of Badzoshvili (1979) here also are Congeria navicula Andrus.,C. panticapaea Andrus., Caspiohydrobia starobogatovi Iljina, C. tamanensis Iljina ………….…………………………………...... 2-3 m Interruption in deposition ……..…………...…….. 20-25 m Pn 2 2. Gray-bluish clays with Congeria flexuosa Takt. and Prosodacna sp. ……………......………...……….…………... 0.2 m Interruption in deposition ……….…………………... 15 m 3. Gray-bluish clays with Congeria turgida Brus., numerous C. flexuosa Takt., Dreissena rimestiensis Font., Dr. rostriformis corniculata Sabba, Dr. rostriformis rumana Sabba, 14
Dr. palymorpha levis Takt., Limnocardium (Euxin.) seninskii Andrus., Pontalmyra subincerta Andrus., P. megrelica (Takt.), P. repens (Takt.), Didacnomya corbuloides tenera Takt., Pseudocatillus cf.subdentatus (Desh.), Prosodacna fisheri Dav., Pr. littoralis (Eichw.), Paradacna abichi (R. Hoern.), Caladacna steindachneri (Brus.), Chartoconcha sp., Plagiodacna carinata (Desh.), Unio sp., Viviparus achatinoides Desh. Bithynia sp., Zagrabica reticulate Sab. ….................................................................................. 25 m Interruption in deposition ...………….…………….. 250 m 4. The same layer with Dreissena sp., Dr. rostriformis corniculata Sabba, Limnocardium (Euxinicardium) seninskii Andrus., Pseudocatillus sp., Prosodacna sp., Plagiodacna carinata (Desh.), Bithynia sp., Zagrabica sp. …….... 3 m Interruption in deposition …….……………………. 350 m 5. Yellowish-gray clays with bad preserved mollusks….... 4 m 6. Gray-bluish clays with lenses of mollusks ………..…... 4 m Interruption in deposition …………………….……. 400 m 7. Gray-bluish clays with numerous mollusks: Congeria subrhomboidea Andrus., Congeria novorossica (Sinz.), C. turgida Brus., C. flexuosa Takt., Dreissena rostriformis corniculata Sabba, Dr. palymorpha levis Takt., Limnocardium (Euxinicardium) seninskii Andrus., Pontalmyra subincerta Andrus., P. megrelica (Takt.), P. repens (Takt.), Didacnomya corbuloides tenera Takt., Prosodacna littoralis (Eichw.), Paradacna omnivaga Papaian., P. cf. blandita Papaian., Caladacna steindachneri (Brus.), Chartoconcha sp., Plagiodacna carinata (Desh.), Viviparus achatinoides Desh., Bithynia sp., Zagrabica sp., Melanopsis sp., Neritina sp., Micromelania sp., Planorbis sp. …………..... 10 m Interruption in deposition ……………..…………… 150 m 8. The same layer with Congeria subrhomboidea Andrus...8 m 15
9. Gray-bluish clays with interbeds of conglomerates and numerous mollusks: Congeria turgida Brus., C. flexuosa Takt., Dreissena rostriformis corniculata Sabba, Dr. polymorpha levis Takt., Limnocardium (Euxinicardium) seninskii Andrus., Pontalmyra (?) cf. sulcatina (Desh.), Pseudocatillus sp., Prosodacna fisheri Dav., Caladacna steindachneri (Brus.), Bithynia sp., Neritina sp., Planorbis sp. … ………………………………………………………. 2.5 m Interruption in deposition ……………………….…. 150 m Pn 3 10. Gray-bluish clays with Paradacna abichi (R. Hoem.) ... 2 m Interruption in deposition …………….……………. 200 m 11. Gray-bluish clays with Paradacna abichi (R. Hoem.) .. 2m The layer 1 is Upper Meotian. The layers 2-6 contain the fauna of Flexuosian horizon; the layers 7, 8 belong to the Subrhomboidal horizon and layer 9 again belongs to Flexuosian horizon. The layers with Paradacna abichi are the deposits of Upper Pontian. In the outcrop Kulistskhali, in spite of absence of visible interruption or unconformity between layers of Meotian and Pontian, it is possible to suppose the presence of great hiatus, which embrace whole Lower Pontian. By opinion of Taktakishvili (1984) only the deposits of Middle (layers 2-9) and Upper Pontian are presented here (layers 10-11). So, we can conclude that the Flexuosian horizon occupies two levels: below the Subrhomboidal horizon and above it, as it was supposed by Chelidze (1974). By our opinion (Taktakishvili 1984) Lower flexuosian horizon is distributed above Novorossian substage forming the Middle Pontian together with Subrhomboidal and Upper Flexuosian horizons. The section near v. Bia is the single in Black Sea region outcrop of Rhomboidal layer (Taktakishvili, 1984): Mt 2 1. Gray argillo-arenaceous rocks, with fauna: Congeria subnovorossica Osaul., Hydrobia sp., Congeria panticapaea And-
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Pn
Pn
1
2
rus., Abra tellinoides (Sinz.), Nassa sp., Cyprideis littoralis Bradly ……………………………………………. 17 m 2. Yellowish-gray sandstone with foraminifera: Ammonia beccarii (Linne), Elphidium ex gr. macellum (F. et M.), Protelphidium sp., Nonion ex gr. bogdanowiczi Vol. Much richer is the assemblage of Ostracoda: Caspiolla acronasuta (Livent.), Caspiocypris labiata (Zal.), Bacunella dorsoarcuata (Zal.), Pontoniella acuminata (Zal.), P. loszyi (Zal.), Hemicyteria marinescui Olteanu, Urocytereis (Drobetiella) ex. gr. mirabilis Olteanu, Cyprideis littoralis (Brady) …………………………………...……… 10-15 m 3. Gray clays with bad preserved mollusks ………...……. 3 m 4. Gray argillo-arenaceous rocks with bad preserved mollusks, among which are determined: Pontalmyra cf. subincerta Andrus., Paradacna ex gr. retowskii Andrus. …….… 20 m 5. Yellowish sandstone rich in fauna: Congeria turgida Brus., C. rumana Sabba, Dreissena rostriformis corniculata Sabba, Dr. aperta (Desh.), Phyllocardium planum (Desh.), Limnocardium (Tauricardium) petersi (M. Hoern.), L. (Bosphoricardium) emarginatum (Desh.), L. (Euxinicardium) sp., L. (E.) seninski Andrus., Pontalmyra subincerta Andrus., P. ex gr. planicostata (Desh.), Didacnomya (?) cf. corbuloides (Desh.), Prosodacna (?) sp., Caladacna steindachneri (Brus.), Plagiodacna carinata (Desh.), Bithynia sp. ………………………………………….…………. 1 m 6. Ferruginous sandstone with fauna: Congeria rhomboidea M. Hoern., C. rumana Sabba, Dreissena rostriformis (Desh.), Dr. rostriformis corniculata Sabba, Dr. simplex (Barb.), Dreissenomya aperta (Desh.), Phyllocardium planum (Desh.), Phyll. cf. complanatum (Fuchs.), Limnocardium. decorum (Fuchs.), L. aff. apertum (Muens.), L. (Tauricardium) petersi (M. Hoern.), L. (Euxinicardium) subode17
ssae (Sinz.), L. (Arpadicardium) peregrinum Ebers., L. (Bosphoricardium) emarginatum (Desh.), Pontalmyra subincerta Andrus., otiophora (Brus.), P. cf. georgiana (Ebers.), Didacnomya sp., Pseudocatillus pseudocatillus (Barb.), Ps. cf. simplex (Fuchs.), Paradacna andrussovi Ebers., P. retowskii ossoinae Stev., P. cf. radiata Stev., P. cf. okrugici (Brus.), Parvidacna planicostata Stev., Caladacna steindachneri (Brus.), Plagiodacna carinata (Desh.), Pisidium krambergeri Brus., Viviparus achatinoides Desh., Bithynia sp., Zagrabica sp., Z. naticina Brus., Melania sp., Micromelania cf. laevis (Fuchs), Planorbis sp. ..……………………………………………….. 3-5 m Pn3 7. Yellowish-gray clays with Paradacna abichi (R. Hoem.)..1 m The layer 1 is dated as Upper Meotian. The layers 2 and 3 belong to Lower Pontian (Taktakishvili 1971). By data of microfauna (Vekua, 1979) the Eupatorian and Odessian horizons are represented here. The layers 4-6 can be refer to Middle Pontian, the upper part of which contains the fauna of Rhomboidal layers. The layer 7 belongs to Upper Pontian. By data of Chelidze (1971, 1973, 1974; Chelidze, Popkhadze, 1971) in outcrop Bia the Lower Pontian (layers 2, 3) is absent and the Middle Pontian is unconformity bedded on Upper Meotian. On the basis of microfauna the Lower Pontian is presented here by both horizons: Eupatorian and Odessian (Vekua, 1979). The mixed character of microfauna, in which composition together with Pontian species are Meotian taxa of Ostracoda and foraminifera typical for fresh water basins of Late Meotian, allows to refer the lower part of outcrop Bia to Eupatorian horizon. In assemblages of upper part of Lower Pontian the foraminifera and Meotian Ostracoda are fully absent. The composition of Ostracoda is poor and is devoid of species, richly presented in corresponding layers of section with
18
Middle Pontian fauna of mollusks. Respectively the upper part of Lower Pontian of outcrop Bia is dated as Odessian. The Pontian is widely distributed in Guria, represented by full series of deposits belonging both to shallow and deep-sea facies. The description of outcrop near v. Gogoreti is given below. Here lengthwise from v. Konchkati to v. Meria are exsposed: Mt1 1. Gray clays with Abra tellinoides (Sinz.) ……..…… 30-40 m Pn1 2. Yellowish-gray sandstone without fauna ………....…. 5-6 m 3. Conglomerates without fauna …………………...… 15-20 m 4. The alternation of sandstones and yellowish marls with fauna: Congeria digitifera Andrus., Paradacna abichi (R. Hoem.), Valenciennius gurianius Bog. …….…….…. 60-70 m Interruption in deposition ……………..…….……….. 10 m Pn2 5. Bluish-gray marls, rich in fauna: Congeria subrhomboidea Andrus., C. turgida Brus., C. digitifera Andrus., C. subcarinata Desh., C. aff. turgidopsis Andrus., C. aff. mirabilis Sen., Dreissena rostriformis corniculata Sabba, Dr. rostriformis rumana Sabba, Dr. rimestiensis Font., Dr. polymorpha levis Takt., Dr. tenuissima Sinz., Dr. cf. pseudomirabilis Tschel., Phyllocardium planum (Desh.), Pontalmyra subincerta Andrus., Didacnomya sp., Pseudocatillus sp., Paradacna abichi (R. Hoem.), Caladacna steindachneri (Brus.), Chartoconcha sp., Plagiodacna carinata (Desh.), Limnea sp., Valenciennius gurianus Bog. Bithynia sp., Micromelania sp. …………………………………….…. 1.5 m Pn3 6. Bluish-gray marls, with C. digitifera Andrus., …………. 60 m 7. Bluish-gray clays with Valenciennius gurianus Bog. and Paradacna abichi (R. Hoem.) ………..……………. 150 m Further there is the hiatus in deposition, after which the Egrissian (Kujalnician) deposits are exposed. So, in this outcrop the Kimmerian is fully absent.
19
The layer 1 is the Lower Meotian. The layers 2-4 belong to Lower Pontian and the layer 5 to Middle Pontian or Subrhomboidal horizon. The layers 6, 7 are of Upper Pontian age. In outcrop Gogoreti the Pontian is represented by three parts and has transgressive character. It can be considered as a typical Pontian section, although the Middle Pontian is represented by more shallow facies, than in other regions of Black Sea basin. The Pontian deposits, distributed near v. Japareuli are of different character. They are represented mainly by bluish-gray clays with poor fauna: Congeria digitifera Andrus., Dreissena anisoconcha Andrus., Paradacna abichi (R. Hoern.), Valenciennius gurianus Bog., Valenciennius sp. The sediments of section Japareuli are very rich in pollen and spores. The deposits along r. Bjuja-Achistskali are somewhat differrent, where Upper Pontian is overlapped by Lower Kimmerian. The thickness of Pontian is about 20-30 m and contains the rich assemblages of fauna: Dreissena anisoconcha Andrus., Dr. rostriformis (Desh.), Dr. aff. angusta (Rouss.), Dreissenomya aperta (Desh.), Phyllocardium planum (Desh.), Oraphocardium alatoplanum (Andrus.), Limnocardium (Tauricardium) petersi (M. Hoern.), L. (Bosphoricardium) emarginatum (Desh.), Pontalmyra subcrenulata (M. Hoern.), P. planicostata (Desh.), P. sulcatina (Desh.), P. perfecta (Tschel.), P. annosa (Tschel.), P. crassatelata (Desh.), Paradacna abichi (R. Hoern.), P. retowskii (Andrus.), Caladacna steindachneri (Brus.), Plagiodacna carinata (Desh.), Stenodacna praeangusticostata Eber. By Ebersin (Ebersin, Dsvelaya, 1962) the layers of section Bjuja-Achitskali are the analogue of Bosforian substage of Kerch peninsula. The division of Pliocene deposits on stages and horizons is based mainly on the data of bivalved mollusks. Significant role also played the microorganisms, especially Ostracoda, with the help of which the presence of Eupatorian layers in outcrops Otapi, Urta was 20
confirmed and determined their level in outcrop Bia. The main criterion underlying these conclusions (Vekua, Suladze, 1976) is the mixed Meotian-Pontian composition of assemblages characteristic for the Eupatorian deposits of stratotypical section in Crimea. By macrofaunal data the deposits of Eupatorian are characterized by impoverished assemblage of brackish mollusks. According to Ebersin (1959) in the Black Sea-Caspian region the representative of the genera Eupatoria, Dreissena, Prosodacna, Monodaca at first appeared in Eupatorian. But more important is the fact of origin of several Prosodacna from the group "littoralis". In Ponto-Caspian basins the expansion of brackish Cardiidae began by these taxa. In the Meotian foraminifera are predominate fossils in composition of microfauna. The Ostracoda are represented by single tests. The picture is changed in Eupatorian, when the number of Ostracoda increased. The assemblage has a mixed Meotian-Pontian composition. At first the genera Pontoniella and Bakunella appeared. The genera Leptocythere and Loxoconcha are represented by numerous species. The number of foraminifera and their specific composition is small. The assemblage composed from euryhaline species, which morphologically differ from taxa widely distributed in the Late Meotian. So, we can say, that in the Eupatorian the assemblages of macro- and microfauna are of mixed Meotian-Pontian composition. In Odessian time (Lower Pontian) besides the species of genera Pontoniella and Bakunella, the representatives of genera Caspiocypris, Lineocypris, some Leptocythere, Loxoconcha djaffarovi Schneid. and Cytherura perata Schneid. penetrated into Rioni Bay from the several basins of Paratethys. The Meotian relicts disappeared fully, but at whole the assemblages of Ostracoda became richer (Imnadze, 1974; Djanelidze et al., 1985). The ecological conditions of desalted Odessian Sea were fatal for foraminifera and in deposits of the Upper Meotian their assemblage is represented by the following species: Quinqueloculina semi21
nulum maeotica Gerke, Cycloforina gracilis Karrer, Sinuloculina ex. gr. consobrina (d'Orb.), Miliolinella ex gr. circularis (Born.), Elphidium macellum maeotica Gerke, E. feodorovi Bogd., Ammonia becarii (L.). The species, similar to the Mediterranean stenobiontic forms were not seen. The gradually changes of bionomical conditions was the main reason of disappearance of foraminifera in Late Neogene basins of Paratethys (Djanelidze et al., 1985; Maissuradze, 1988). Their extinction began in the Late Meotian and finished in the Middle Pontian. The decrease of salinity was the main factor, which influenced on this process, which is confirmed by abundance of Ostracoda typical for freshwater basins and by distribution of brackish and freshwater mollusks (Davitashvili, 1933, 1937; Ebersin, 1967; Imnadze, 1974; Taktakishvili, 1978; Popkhadze 1978; Suladze, 1984; Djanelidze et al., 1985, Nevesskaya et al., 2003; Maissuradze, Koiava, 2011). The salinity of water in basins of the Late Meotian and Pontian was 5 ‰ that was pernicious for foraminifera, but favorable for Osracoda. According to the above mentioned data it is possible to conclude, that in the history of microfauna the Eupatorian was the turning-point, after which the foraminifera, the predominate group in the Miocene basins of Eastern Paratethys nearly fully disappeared and the prevail position was occupied by Ostracoda. The significant changes in composition of macrofauna were also connected with Eupatorian, when in Black Sea - Caspian region the genera Didacna, Monodacna and Prosodacna appeared at first. In Western Georgia some unusual for Euxinic basin facies of Middle Pontian are represented: the Rhomboidal layers, with Congeria rhoboidea M. Hoern. and Lower and Upper Flexuosian layers with Congeria flexuosa Takt. The first is widely distributed in Pannonian and Dacian basins, the second is known only in Georgia. It is represented by gray argillo-arenaceous rocks, with numerous Congeria flexuosa, Dreissena, fresh water Gastropods and more seldom 22
Cardiidae. There is fully identity between mollusk assemblages of Flexuosian and Subrhomboidal layers (with Congeria subrhomboidea Andrus.). The difference between them is only in absence of Congeria subrhomboidea in Flexuosian layers and in different quantitative correlation of one and the same species of Cardiidae and Dreissena. In Subrhomboidal layers the main fossils are Cardiidae, but in Flexuosian layers - the Dreissena. So, the difference between Flexuosian and Subrhomboidal layers is mainly in character of facies. The existence of these different facies (Rhomboidal and Flexousian), unusual for Pontian of Euxinic basin, caused the existence of three types of succession of Pontian layers in Western Georgia. 1. The type classic for Black Sea: Upper Pontian Subrhomboidal layers Lower Pontian Meotian 2. Bia type, distributed in Megrelia (outcrop Bia): Upper Pontian Rhomboidal layers Subrhomboidal layers Lower Pontian Meotian 3. Jumi type, distributed in Samegrelo (Jumi outcrop) and in Abkhazia (outcrop Pokveshi): Upper Pontian Flexuosian layers Subrhomboidal layers Flexuosian layers Meotian There is some regularity in distribution of Flexuosian and Rhomboidal layers. They are presented only in central part of Rioni 23
bay (Khobi and Zugdidi regions in Samegrelo and Ochamchiri region in Ablkhazia) and are fully absent in peripheral parts (southern Guria and northern Abkhazia). In central part of Rioni Bay is absent the classic type of succession of Pontian deposits, such as Lower Pontian-Subrhomboidal horizon-Upper Pontian, being complicated by Rhomboidal or by Flexuosian facies. But the Subrhomboidal facies is always presented. Such distribution of Pontian facies indicates that the conditions of accumulation in central and peripheral parts of Rioni Bay were not similar. The accumulation of Rhomboidal layers was going in unquiet zone of shallow water, and the accumulation of Flexuosian layers - in deeper part of bay, possible, in more quite water. Such big variety of facies in Rioni bay complicated the building of stratigraphical scheme for Pontian stage even for such comparably not big territory as is Western Georgia. The Kimmerian stage The Kimmerian deposits are distributed in same region as Pontian, but they occupied smaller territory and are not penetrated so far inside country. The Kimmerian deposits are represented only by shallow water facies. This allows concluding that the Kimmerian Sea retreated and the territory of dry land increased. The most western outcrop of Kimmerian is situated on the left bank of Bzibi river, where it is represented by Azovian substage. The upper part of conglomerates (thickness about 2000 m) contains the interbeds with Paradacna deformis Ebersin (Ebersin 1947). The outcrop of whole Kimmerian is situated near the v. Mukhujirkhva, which contains the fauna of mollusks and Ostracoda similar to those of Duabian in upper part. The mollusks are represented by the following taxa: Congeria turgidopsis Andrus., Dreissena iniquivalvis (Desh.), Dr. theodori Andrus., Dr. cyclorampha Dav. et 24
Krest., Phyllocardium planum (Desh.), Oraphocardium alatoplanum (Andrus.), Or. oraphense (Dav.), Limnocardium (Tauricardium) squamulosum (Desh.), L. (Euxinicardium) subsyrmiensis Andrus., Pomtalmyra crassatellata (Desh.), Pseudocatilus donacoides (Andrus.), Macrodacna maciae (Tschel.), Prosodacna leptopsamatha Dav., Paradacna abchasica N. Djan., Stenodacna angusticostata (Rouss.), Euxinimargaria mandarinica (Sen.), Melanopsis acuminata Sen., M. spinigera Sen., Suchumica sp. Among Ostracoda were determined: Caspiocypris labiata (Zal.), C. candida (Livent.), C. rectoides (Krst.), C. merculensis Vek., Caspiolla acronasuta (Livent.), C. balcanica (Zal.), C. lobata (Zal.), C. prochazkai (Pok.), C. elegans (Mehes.), C. pseudoacronasuta Vek., Bakunella dorsoarcuata (Zal.), B. abchasica Vek., Pontoniella acuminate (Zal.), P. acuminata pontica Agal., P. acuminata striata Mandelt., P. angusta Vek., P. naninae Vek., Ampocypris lunatus Krst., Cypria tocorjescui Hang., Cypria arma Schneid., Cypria phaseolina Vek., Candona combiba Livent., C. pultipora Pok., Candoniella suzini Schneid., Eucypris subovata Vek., Advenocypris schneiderae Vek., Cyterisa bogatschovi Livent., C. bogatschovi quadrituberculata Vek., C. bogatschovi plana (Klein)., C. duabica Vek., Leptocythere andrussovi (Livent.), L. bosqueti (Livent.), L. praebosqueti Suz., Cyprideis littoralis (Brady), Tyrrhenecythere acuminata (Scheid.), T. cf. pseudoconvexa (Livent.), Loxoconcha eichwaldi Livent., L. petasa Livent., L. mandelstami Vek., L. tuberculata Vek. Among all Upper Neogene deposits the Kimmerian layers on Duabi river are the most studied, which are very rich in fossils. The description of Duabi outcrop is given below. Kmr2 1. Cobble roundstone conglomerates ................................. 5 m 2. Yellow sands, with mollusks in lower layers: Congeria turgidopsis Andrus., Dreissena theodori Andrus., Dr. polymorpha weberi Sen., Dr. cf. dilitata Andrus., Dr. cf. 25
cyclorampha Dav. et Krest., Oraphocardium oraphense (Dav.), Limnocardium (Euxinicardium) fervidum Ebers., L.(Moquicardium) praemoquicum Dav., Pontalmyra suboxypleura (Gab.), Pseudocatillus donacoides (Andrus.), Macrodacna maxima (Andrus.), Prosodacna longiuscula Sen., Pr. leptopsamatha Dav., Pr. aff. callopistes Dav., Pachydacna duabica (Dav.), Prionopleura prionopleura aeetae (Dav.), Chartoconcha cf. bayerni (R. Hoern.), Plagiodacna carinata (Desh.), Unio sp., Viviparus abchasicus Tab., Bithynia sp., Micromelania sp., M. cf. nobilis Sen., Neritina sp., Pyrgula sp., Planorbis sp. ............................… 10 m 3. Ferruginous sandstone with Congeria turgidopsis Andrus., Limnocadium (Euxinocardium) Takt., L. (E.) fervidum Ebers., Pontalmyra suboxypleura (Gab.), Pseudocatillus donacoides (Andrus.), Macrodacna maxima (Andrus.), Prosodacna longiuscula Sen., Pr. leptopsamatha Dav., Pr. aff. callopistes Dav., Pachydacna duabica (Dav.), Prionopleura prionopleura aeetae (Dav.), Chartoconcha cf. bayerni (R. Hoern.), Unio sp., Viviparus abchascus Tab., Bithynia sp., Micromelania sp., M. cf. nobilis Sen., Neritina sp., Pyrgula sp., Planorbis sp. ……………………..….... 0.5 m 4. Yellow-gray clays, with numerous Viviparus and following mollusks: Dreissena iniquivalvis (Desh.), Dr. rostriformis (Desh.), Dr. polymorpha weberi Sen., Phyllocardium planum (Desh.), Oraphocardium alatoplanum (Andrus.), Limnocardium (Tauricardium) squamulosum (Desh.), L. (Euxinicardium) fervidum Ebers., L. (Moquicardium) praemoquicum Dav., Pontalmyra crassatellata (Desh.), Pseudocatillus donacoides (Andrus.), Ps. pleonexia (Dav.), Macradacna maxima Andrus., Prosodacna leptopsamatha Dav., Pachydacna duabica (Dav.), Prionopleura prionopleura aeetae (Dav.), Chartoconcha cf. bayerni (R. Hoern.), Pla26
giodacna modiolaris epidemia Dav., Viviparus abchasicus Tab., Bithynia sp., Pyrgula sp. ………………….….. 1.5 m 5. Bluish-gray clays with Dreissena polymorpha weberi Sen., Limnocardium (Euxinicardium) fervidium Ebers., Pseudocatillus pleonexia (Dav.), Prosodacna leptopsamatha Dav., Pr. callopistes Dav., Pachydacna duabica (Dav.), Arcicardium planacardo Andrus., Plagiodacna carinata (Desh.), Unio sp. …………………………………………....... 1.5 m 6. Yellow-gray clays with numerous Viviparus and following mollusks: Congeria caucasica Sen., C.mirabilis Sen., C. turgidopsis Andrus., Dreissena angusta (Rouss.), Dr. iniquivalvis (Desh.), Dr. abchasica Sen., Dr. polymorpha weberi Sen., Dr. cf. pseudomirabilis Tschel., Phyllocardium planum (Desh.), Limnocardium (Euxinicardium) aff. subsyrmiense Andrus., L. (E.) fervidum Ebers., Pontalmyra crassatellata (Desh.), Pseudocatillus donacoides (Andrus.), ps. pleonexia (Dav.), Ps. cf. praecolorata Eber., Macradacna maciae (Tschel.), M. maxima (Andrus.), M. commilitans (Dav.), Prosodacna callopistes Dav., Pr. leptopsamatha Dav., Pachydacna duabica (Dav.), P. transilis Eber., Caladacna escheri (C. May), Chartoconcha bayerni (R. Hoern.), Plagiodacna carinata (Desh.), Arcicardium planacardo Andrus., Viviparus nataliae Mikh., V. abchasicus Tab., Suchumica (?) cf. gracilis Sen., Bithynia sp., Micromelania sp. M. acuminata Sen., M. cf. nobilis Sen., M. iulonii Gab., Neritina sp., Pyrgula sp., Planorbis sp.… 1 m 7. Blue-gray clays with Dreissena theodori Andrus., Limnocardium (Euxinicardium) aff. subsyrmiense Andrus., L. (Eux.) fervidum Ebers., Pseudocatillus pleonexia (Dav.), Macradacna maxima (Andrus.), Prosodacna longiuscula Sen., Pr. callopistes Dav., Pachydacna transilis Eber., P. cf. helenae Gab., Cartoconcha cf. bayerni (R. Hoern.), 27
Unio sp., Viviparus nataliae Mikh., Melanopsis sp., Pyrgula sp. ………………………………………………... 2 m 8. Yellowish-gray clays with numerous Viviparus and following mollusks: Dressing iniquivalvis (Desh.), Dr. theodori Andrus., Dr. cf. dilitata Andrus., Dr. polymorpha weberi Sen., Dreissenomya aperta (Desh.), Phyllocardium planum (Desh.), Oraphocardium alatoplanum (Andrus.), Limnocardium (Tauricardium) squamulosum (Desh.), L. (Euxinicardium) fervidum Ebers., Pontalmyra crassatellata (Desh.), P. multistriata (Rouss.), Pseudocatillus pleonexia (Dav.), Macradacna maxima (Andrus.), Prosodacna leptopsamatha Dav., Pr. callopistes Dav., Pachydacna transilis Eber., Chartoconcha bayerni (R. Hoern.), Plagiodacna carinata (Desh.), Viviparus nataliae Mikh., V. abchasicus Tab., Bithynia sp., Melanopsis sp., M. cf. nobilis Sen., Neri tina sp., Pyrgula sp., Planorbis sp. ………………….... 1 m 9. Yellowish-gray clays ………………...…..…………. 0.5 m 10. Yellowish-gray sandstones with Congeria turgidopsis Andrus., Dreissena polymorpha weberi Sen., Limnocardium (Euxinicardium) fervidum Ebers., L. (Moquicardium) moquicum Sen., Pontalmyra crassatellata (Desh.), Pseudocatillus pleonexia (Dav.), Macradacna maxima (Andrus.), Prosodacna leptopsamatha Dav., Pachydacna transilis Eber., Chartoconcha cf. bayerni (R. Hoern.), Viviparus nataliae Mikh., V. abchascus Tab., Melanopsis sp., M. cf. nobilis Sen. ……………………………………….… 0.3 m 11. Pink clays …………..………………………….……... 1 m 12. Yellowish sandstones with Congeria caucasica Sen., Dreissena angusta (Rouss.), Dr.theodori Andrus., Oraphocardium alatoplanum (Andrus.), Limnocardium (Euxinicardium) fervidum Ebers., Pseudocatillus pleonexia (Dav.), Prosodacna leptopsamatha Dav., Pr. callopistes Dav., Pachy28
dacna transilis Eber., Prionopleura colchica Dav.,Unio sp., Chartoconcha cf. bayerni (R. Hoern.), Unio sp., Viviparus abchasicus Tab., Melanopsis sp., M. cf. nobilis Sen .. 0.4 m 13. Yellowish-gray sandy-argillaceous deposits with Congeria caucasica Sen., C. submirabilis (Tschel.), Dreissena rostriformis (Desh.), Dr. theodori Andrus., Dr. cyclorampha Dav. et Krest., Oraphocardium alatoplanum (Andrus.), Limnocardium (Euxinicardium) fervidum Ebers., L. (Moquicardium) moquicum Sen., Pontalmyra crassatellata (Desh.), P. multistriata (Rouss.), Pseudocatillus sp., P. pleonexia (Dav.), Macradacna maxima (Andrus.), Prosodacna leptopsamatha Dav., Pachydacna transilis Eber., Prionopleura colchica Dav., Caladacna escheri (C. May), Chartoconcha cf. bayerni (R. Hoern.), Plagiodacna modiolaris epidemia Dav., Oxydacna tertiana Ebers., Unio sp., Viviparus abchasicus Tab., Melanopsis sp., M. cf. nobilis Sen. ..….. 2-3 m 14. Conglomerates with Congeria caucasica Sen., Prosodacna leptopsamatha Dav., Plagiodacna modiolaris epidemia Dav., Viviparus abchasica Tab. ………….…….. 0.3-0.5 m 15. Yellowish-gray sandy-argillaceous deposits with Dreissena rostriformis (Desh.), Dr.theodori Andrus., Dr. cf. dilitata Andrus., Dr. acuminta Sen., Limnocardium (Euxinicardium) fervidum Ebers., L. (Moquicardium) moquicum Sen., Pseudocatillus donacoides (Andrus.), Macradacna maxima (Andrus.), Prosodacna longiuscula Sen., Pr. callopistis Dav., Pachydacna duabica (Dav.), Prionopleura colchica Dav., Viviparus abchasicusTab., Melanopsis sp., M. cf. nobilis Sen. ……………………..…….……….. 4 m 16. Conglomerates with Congeria caucasica Sen., C. mirabilis Sen., C. turgidopsis Andrus., C. submirabilis (Tschel.), Dreissena rostriformis (Desh.), Dr. angusta (Rouss.), Dr. obliqua Sen., Dr. theodori Andrus., Dr. cf. dilitata And29
rus., Dr. cyclorampha Dav. et Krest., Dr. pseudomirabilis Tschel., Limnocardium (Euxinicardium) fervidum Ebers., L. (Moquicardium) moquicum Sen., Pseudocatillus donacoides (Andrus.), Prosodacna longiuscula Sen., Pr. callopistis Dav., Pachydacna duabica (Dav.), Prionopleura colchica Dav., Chartoconcha aff. bayerni (R. Hoern.), Viviparus abchasicus Tab., Melanopsis sp. ……………….. 0.5 m 17. Yellowish-gray sandstones …………...………...….. 1.2 m 18. Conglomerates with Congeria caucasica Sen., C. submirabilis Tschel., Dreissena obliqua Sen., Dr. theodori Andrus., Dr. dilitata Andrus., Dr. ex gr. rostriformis (Desh.), Limnocardium (Euxinicardium) fervidum Ebers., Pseudocatillus donacoides (Andrus.), Ps. monachorum Ebers., Macradacna maxima (Andrus.), Prosodacna longiuscula Sen., Pr. leptopsamatha Dav., Pachydacna duabica (Dav.), Prionopleura colchica Dav., Chartoconcha (?) sp., Horiodacna (?) rumana Sabba, Unio sp., Melanopsis sp., M. spinigera Sen., M. nobilis Sen. Neritina sp., N. unguiculata Sen., Hydrobia sp., Pyrgula sp. Lythogliphus sp. .… 0. 2 m Judging from the lists of fauna, there is not essential difference in composition of mollusks between separate layers of section. During the whole time of accumulation of Duabian deposits this part of Rioni Bay was shallow basin with low salinity and with mobile water. So, it is impossible to speak about different stretches of Kimmerian. Whole Duabian section must be dated as Upper Kimmrian or Kamishburunian horizon. The same conclusion was done on the basis of Ostracoda (Vekua, 1975). In all layers of section the following taxa were determined: Caspiocypris labiata (Zal.), C. candida (Livent.), C. rectoides (Krst.), C. filona (Livent.), C. aff. orientalis (Krst.), Caspiolla acronasuta (Livent.), C. balcanica (Zal.), C. lobata (Zal.), C. prochazkai (Pok.), C. elegans (Mehes.), C. pseudoacronasuta Vek., C. 30
rostriformis Vek., C.filona (Livent.), C. abchasica Imn., Bakunella dorsoarcuata (Zal.), B. abchazica Vek., Pontoniella acuminata (Zal.), P. loczy (Zal.), P. naniae Vek., Amplocypris lunatus Krst., Cypria tocorjescui Hang., C. arma Schneid., C. phaseolina Vek., Candona combiba Livent., C. praecandida Vek., Candonella suzini Schneid., C. aff. albicans Brady, Advenocypris schneiderae Vek., A. duabiensis Vek., Cyterisa bogatschovi Livent., C. bogatschovi quadrituberculata Vek., C. bogatschovi plana (Klein) Vek., C. duabica Vek., Leptocythere andrussovi (Livent.), Cypridides littoralis (Brady), Loxoconcha eichwaldi Livent., L. petasa Livent., L. mandelstami Vek., L. aliena Vek., Cytherura leilae kujalnicensis Vek. As it can be seen, the predominate position in composition of assemblage is occupied by representatives of family Cyprididae and fresh water genera Candona, Candonella and Cypria. The brackish genera of family Cytheridae are nearly fully absent. Quite different are Kimmerian deposits on left bank of river Galizga, where they are overlap by Egrissian (Kujalnician) deposits. In literature it is known as Pokveshi outcrop. The fauna from this outcrop was studied by many geologists. Such great interest toward this section can be explained by the fact that the exact stratigraphical level of Kujalnician deposits near Odessa at first was determined just here (Mikhailovskiy, 1905). The description of section Galizga is given below. Kmr 2 1. Blue-gray clays without mollusks, but with rich assemblage of Ostracoda: Caspiocypris labiata (Zal.), C. candida (Livent.), Caspiolla acronasuta (Livent.), C. prochazkai (Pok.), Bakunella dorsoarcuata (Zal.), Pontoniella acuminata (Zal.), P. schemachensis Mandelst., P. angusta Vek., Cyterisa bogatschovi (Livent.), Leptocythere circumsulcata Suz., L. multituberculata Livent., Loxoconcha eichwaldi Livent., L. petasa Livent., L. mandelstami Vek. .……. 5 m
31
2. Conglomerates with: Congeria aff. submirabilis Tschel., Dreissena angusta (Rouss.), Dr. iniquivalvis (Desh.), Dr. rostriformis distinct (C. May.), Dr. obliqua Sen., Dreissenomya sp., Phyllocardium planum (Desh.), Oraphocardium alatoplanum (Andrus.), Limnocardium (Euxinicardium) misargyridae Dav., L. (Moquicardium) moquicum Sen., Limnodacna cf. cristulata Ebers., Pontalmyra cassatellata (Desh.), P. multistriata Rouss., Pseudocatillus cf. zlatarskii Andrus., Prosodacna semisulcata (Rouss.), Pr. leptopsamatha Dav., Pachydacna cf. duabica (Dav.), Caladacna escheri (C. May), Chartoconcha cf. bayerni (R. Hoern.), Plagiodacna carinata (Desh.), Plagiodacna modiolaris epidemia Dav., Stenodacna angusticostata (Rouss.), Oxydacna sp., Arcicardium planacardo Andrus., Viviparus cassaretto Rouss., Suchumica multicostata Sen., S. incipiens (Akchv.), Micromelania sp., Neritina sp. ..….. 0,2 m 3. Ferruginous sandstone with Congeria submirabilis Tschel., Dreissena. angusta (Rouss.), Dr. iniquivalvis (Desh.), Dr. rostriformis distincata (C. May)., Dr. obliqua Sen., Dr. abchasica Sen., Dr. polymorpha weberi Sen., Phyllocardium planum (Desh.), Pontalmyra crassatellata (Desh.), P. multistriata (Rouss.), Pseudocatillus cf. zlatarskii Andrus., Ps. pleonexia Dav., Macridacna maciae Tschel., Prosodacna semisulcata (Rouss.), Pr. leptopsamatha Dav., Plagiodacna modiolaris epidemia Dav., Stenodacna angusticostata (Rouss.), Oxydacna sp., Arcicardium planacardo Andrus., Viviparus cassaretto Rouss., V. aff. nataliae Mikh., Planorbis sp. ……………………………………...…. 30 m 4. Blue-gray clays with mollusks as in layer 3……..…… 30 m 5. Ferruginous sandstone with mollusks: Congeria submitrabilis Tschel., Dreissena angusta (Rouss.), Dr. iniquivalvis (Desh.), Dr. rostriformis distincta (C. May.), Dr. abchas32
ica Sen., Dr. polymorpha weberi Sen., Dreissenomya aperta crassa Bolg., Phyllocardium planum (Desh.), Oraphocardium alatoplanum (Andrus.), O. oraphense (Dav.), Limnocardium (Taur.) squamulosum (Desh.), L. (Euxinicardium) misargyridae Dav., Pontalmyra crassatellata (Desh.), P. multistriata (Rouss.), P. panticapaea (R. Hoern.), P. aff. medeae Dav., Pseudocatillus donacoides Andrus., Ps. cf. zlatarskii Andrus., Pseudocatillus pleonexia Dav., Macridacna maxima (Andrus), Macridacna maciae Tschel., M. cf. sokolovi (Andrus.), Prosodacna macrodon major Andrus., Prosodacna semisulcata (Rouss.), Pr. leptopsamatha Dav., Pachydacna suchumica (Andrus.), P. cf. duabica (Dav.), Caladacna escheri (C. May), Chartoconcha cf. bayerni (R. Hoern.), Plagiodacna modiolaris (Rouss.), Pl. modiolaris epidemia Dav., Stenodacna angusticostata (Rouss.), Oxydacna tenericardo (Andrus.), O. aff. tertiana Ebers., Arcicardium planacardo Andrus., Viviparus cassaretto Rouss., V. aff. nataliae Mikh., Euxinomargaria mandarinica (Sen.), E. margarita carinata (Sen.), Suchumica multicostata Sen., S. insipiens (Akchk.), Bithynia sp., Planorbis sp., Zagrabica sp., Hydrobia sp., Planorbis sp. The composition of Ostracoda is also very rich: Caspiocypris labiata (Zal.), C. candida (Livent.), C. rectoides (Krst.), C. aff. orientalis (Krst.), Caspiolla lobata (Zal.), C. prochazkai (Pok.), C. elegans (Mehes.), C. pseudoacronasuta Vek., Bakunella dorsoarcuata (Zal.), B. abchasica Vek., B. djanelidzeae Vek., Pontoniella acuminata (Zal.), P. acuminata pontica Zal., P. acuminata striata Mandelst., P. schemachensis Mandelst., P. angusta Vek., P. naniae Vek., P. schemachensis Mandelst., P. angusta Vek., Cypria tocoriescui Hang., C. phaseolina Vek., Advenocypris schneiderae Vek., A. duabiensis Vek., Cyterissa bogatschovi Liv33
Egr
2
ent., C. bogatschovi quadrituberculata Vek., C. bogatschovi plana (Klein), C. duabica Vek., Leptocythere andrussovi (Livent.), L. bosqueti (Livent.), L. praebosqueti (Livent.), Tyrrhenocythere pontica (Livent.), T. truncata (Schneid.), Loxoconcha eichwaldi Livent., L. tuberculata Vek., L. mandelstami Vek., L. bicostata Vek., Cytherura leilae kujalnicensis Vek. In upper part of layer were seen: Leptocythere pokveschica Vek., Tyrrhenocythere imnadzeae Vek., T. pontica arevadzeae Vek. ……………….... 1 m 6. Blue-gray clays with mollusks: Deissena polymorpha weberi Sen., Dr. choriensis Tschel., Limnocardium (Euxinicardium) misargyridae Dav., Pontalmyra medeae (Dav.), P. medeae celaeno (Dav.), Pseudocatillus pleonexia (Dav.), Ps. donacoides postdonacoides (Dav.), Macridacna maciae Tschel., Didacnomya vulgaris (Sinz.), Prosodacna macrodon (Desh.), Pachydacna suchumica (Andrus.), Chartoconcha postcimmeria Dav., Viviparus sp., Suchumica gracilis Sen., Euxinomargaria mandarinica (Sen.), Neritina sp., Zagrabica sp., Micromelania sp., Melanopsis sp. Ostracoda: Caspiocypris labiata (Zal.), C. candida (Livent.), C. rectoides (Krst.), C. filona (Livent.), Caspiolla prochazkai (Pok.), C. acronasuta (Livent.), C. pseudoacronasuta Vek., C. balcanica Zal., Bakunella dorsoarcuata (Zal.), B. abchazica Vek., B. djanelidzeae Vek., Pontoniella acuminata (Zal.), P. acuminata pontica (Agal.), P. schemachensis Mandelst., P. angusta Vek., P. naniae Vek., P. varia Vek., Amplocypris lunatus Krst., Cypria tocoriescui Hang., C. arma Schneid., C. phaseolina Vek., Candona combiba Livent., Candonella suzini Schneid., Stenocypia neomeniata Vek., Advenocypris schneiderae Vek., A. duabensis Vek., Cyterissa bogatschovi Livent., C. bogatschovi quadrituberculata Vek., C. bogatschovi plana (Klein.), C. du34
abica Vek., C. galeata Vek., Mediocytherideis apatoica (Schneid.), Leptocythere andrussovi (Livent.), L. cf. gubkini (Livent.), L.circumsulcata Suz., L. cf. notras (Livent.), L. subcaspia Livent., L. kazakhaschvilii Vek., L. nodigera Pok., L. taktakishvilii Vek., L. bosqueti (Livent.), L. praebosqueti (Livent.), L. pokveschica Vek., Cypridides littoralis (Brady), Tyrrhenocythere pontica (Livent.), T. pontica arevadzeae Vek., T. imnadzeae Vek., T. kujalnicensis Imn., T. truncata (Schneid), T. originalis Imn., T. quadrata Imn., T. cf. pseudoconvexa (Livent.), T. notabilis Imn., T. cf. azerbaidjanica (Livent.), Loxoconcha eichwaldi Livent., L. petasa Livent., L. mandelstami Vek., L. tuberculata Vek., L. bituberculata Vek., L. abchazica Vek., L. aliena Vek., L. bicostata Vek., Cytherula limata medeae Vek., C. leilae kujalnicensis Vek., Xestoleberis celulosus Vek., Kovalevskiella turrianensis praeturrianensis Vek. (Vekua, 1975). …………………………………………..…………... 0.4 m Egr3? 7. Blue-gray clays with same fauna as in layer 6, but more seldom. Ostracoda: Caspiolla acronasuta (Livent.), C. pseudoacronasuta Vek., C. balcanica Vek., Bakunella dorsoarcuata (Zal.), B. abchazica Vek., B. djanelidzeae Vek., Pontoniella acuminata (Zal.), P. acuminate pontica (Agal.), P. schemachensis Mandelst., P. angusta Vek., P. naniae Vek., P. varia Vek., Cypria arma Schneid., Candonella suzini Schneid., C. aff. albicans Bradly, Stenocypria neomeniata Vek., Cyterissa bogatschovi Livent., C. duabica Vek., Mediocytherideis apatoica Schneid., Leptocythere cf. nostras (Livent.), Loxaconcha djaffarovi Schneid., L.petasa Livent., L. bicostata Vek., Tyrrhenocythere imnadzeae Vek., T. originalis Imn. ………………… 12 m By data of Ostacoda the layer 1 belongs to Lower Kimmerian (Vekua, 1975). The layers 2, 3 and 5 contian the similar assemblages 35
of fauna typical for second part of Kimmerian. By composition of mollusks the age of layer 6 can be determined as Middle Egrissian (Kujalnician). The distribution of Egrissian fauna is limited mainly by this level, although some Cardiidae and Dreissena can be seen rarely in lower part of layer 7, which possibly belongs to lower part of Upper Egrissian (Vekua, 1970). So, it is possible to conclude that in outcrop Galisga the Kimmerian is represented by upper part. The Lower Kimmerian is determined only by the data of Ostracoda. Judging by macrofauna the Egrissian is represented by Etserian horizon (Middle Egrissian). Hiatus is between Kimmerian and Egrissian, which embraced whole Lower Egrissian. In Samegrelo the outcrops of Kimmerian deposits are known near v. Khobi and Nodjikhevi, where are represented the different parts of stage. In outcrop Nodjikhevi the following mollusks of Lower Kimmerian are determined: Dreissena iniquivalvis (Desh.), Dr. rostriformis (Desh.), Dr. cf.dilitata Andrus., Dr. polymorpha weberi Sen., Phyllocardium planum (Desh.), Oraphocardium alatoplanum (Andrus.), Limnocardium (Moquicardium) praemoquicum Dav., Pontalmyra multistriata (Rouss.), P. crassatellata (Desh.), Macradacna maxima (Andrus.), Prosodacna leptopsamatha Dav., Pachydacna duabica (Dav.), Paradacna deformis Ebers., Plagiodacna carinata (Desh.), Stenodacna praeangusticostata Ebes., Suchumica sp. In outcrop Khobi the Upper Kimmerian is represented with the following mollusks: Dreissena angusta (Rouss.), Oraphocardium alatoplanum (Andrus.), Pontalmyra crassatelata (Desh.), Caladacna escheri (C. May.), Valenciennius sp. The Kimmerian deposits are widely distributed on the territory of Guria. Here the rich assemblages of mollusks and Ostracoda were described from deposits distributed on r. Orapho (Djashi, Taktakishvili, 1977). The mollusks are represented by the following species: 36
Congeria turgidopsis Andrus., C. caucasica Sen., Dreissena abchasica Sen., Dr. dilitata Andus. Dr. cyclorampha Dav. et Krest., Oraphocardium oraphense (Dav.), Limnocardium (Euxinicardium) subsyrmiense Andus., Limnocardium (Moq.) moquicum (Sen.), Lim. (Moq.) guriense (Dav.), Pontalmyra multistriata (Rouss.), P. panticapaea (R. Hoem.), Didacnomya vulgaris (Sinz.), Pseudocatillus zlatarskii Andrus., Prosodacna semisulcata (Rouss.), Pros. macrodon (Desh.), Paradacna stratonis Andrus., Caladacana escheri (C. May.), Chartoconcha bayerni (R. Hoem.), Arcicardium oraphense Andrus., Euxinomargaria mandarinica (Sen.), Suchumica gracilis Sen., Melanopsis spinigera Sen., Mel. nobilis Sen., Mel. acuminata Sen. Among Ostracoda were determined: Caspiocypris labiata (Zal.), C. candida (Livent.), C. kimmerica Vek., C. filona (Livent.), C. ex. gr. ornatus Hanganu, Caspoilla acronasuta (Livent.), C. pseudoacronasuta Vek., C. lobata (Zal.), C. balcanica (Zal.), C. rostriformis Vek., C. mislojini Krst., C. flutimarginata Sokač, Lineocypris ex. gr. nonreticulata Sokač, L. reticulata (Mehes), L. ex. gr. granulose Zal., Bakunella dorsoarcuata (Zal.),B. abchasica Vek., B. aff. djanelidzeae Vek., B.djanelidzeae Vek., Pontoniella acuminata striata Mandelst., Candonopsis arcana Krst., Amplocypris acuta Krst., Advenocypris duabiensis Vek., Cytherisa bogatschovi (Livent.), C. bogatschovi plana (Klein), C. bogatschovi triformis Mandelst., C. duabica Vek., Tyrrhenocythere notabilis Imn., Pontoleberis pontica Stanceva. As it was mentioned above, on the territory of Guria the Kimmerian deposits are known near t. Ozurgeti. Here along r. Bjuja and Achistskali the Upper Pontian is overlapped by Lower Kimmerian. This section was described by many geologists (Gabunia, 1948; Djanelidze, 1957; Chelidze, 1974). By the data of Ebersin and Dsvelaya (1962), the layers of this outcrop are the analogues of Bosforian horizon, distributed on Kerch peninsula. 37
So, on the basis of macrofaina the Kimmerian stage is divided into two parts: Lower - Azovian and Upper - Kamishburunian, in which composition two stages are united: the former Middle (Kamishburunian) and Upper Kimmerian (Panticapeian). The Kimmerian deposits of Western Georgia are distinguished by existence of some types of facies unknown in other regions. There are three types: Duabian, Pokveshian and mixed type. All they are connected to Upper Kimmerian. The Duabian type is distributed on left bank of r. Duabi. Here the Kimmerian deposits are represented by sandstones, conglomerates, clays with numerous shells of mollusks. The deposits of this type were accumulated in troubled, desalting water with good aeration, probably in conditions of delta. The Pokveshian type is distributed only on r. Galizga, near v. Pokveshi. It is represented by ferruginous sandstone, clays and conglomerates. The deposits of this type were accumulated in quite water, which desalting was not strong. The third mixed type is transitional between the first and second ones. It is developed on whole territory of Georgia. At whole, the Kimmerian layers of Rioni bay differed from the simultaneous deposits of Kerch peninsula, the classic region of their development, by more brackish assemblages of mollusks, by existence of trouble places of shallow sea, surrounded by the mountainous dry land with numerous rivers transporting the big terrigenous materials. At the same time the wide and open marine basin with flat bottom and not desalting water existed on the Kerch peninsula. Probably, here the pressure of dry land on a character of basin was not so strong, as it had place in the Caucasus.
38
The Kujalnician (Egrissian) stage Kujalnician deposits at first were discovered on Northern part of the Black Sea, near t. Odessa, on western coast of Kujalnician lagoon (Sintsov, 1875). Till 1978 this outcrop was considered as the stratotypical section of whole Black Sea province. On the territory of Western Transcaucasus the Kujalnician deposits at first were revealed in Abkhazia on left coast of r. Galidzga, near v. Pokveshi (Mikhailovskiy, 1905). Later the Kujalnician deposits were found in Guria. In the region of village Khvarbeti the layers conformably bedded on the Kimmerian were described. The upper part of this new suite is represented by deposits with tests of Dreissena, overlapped by deposits with Micromelania and Pyrgula (Il’in 1929). The peculiar character of fauna didn’t allow determining the age of new suite. It was made later after the comparison of faunas from Guria and Kujalnician deposits of Abkhazia, where together with taxa typical for Western Transcaucasus the elements common with Kujalnician of Odessa occurred (Il’in, 1930). Firstly the Kujalnician deposits were divided into two parts: lower, with rich and various fauna of Didacna and upper part with Dreissena (Il’in, 1931). The same idea was expressed by Davitashvili (1932), who considered the layers with Dreissena as the upper part of Kujalnician deposits, distributed in region of r. Natanebi basin. Then the Kujalnician deposits of Abchazia were divided on three horizons: lower - with mixed Kimmerian-Kujalnician fauna, middle - with typical Kujalnician fauna and upper - with tests of Dreissena (Chelidze, 1959). By opinion of author such division was not final, because it was made on the basis of outcrop from Abkhazia. The decision of this problem he connected with further study of the deposits on the territory of Guria, where the Kimmerian, Kujalnician and Gurian are represented by full sections. 39
On the territory of Western Transcaucasus the area of Kujalnician deposits is much narrow than of Kimmerian and Pontian. They are known mainly in Guria and on the territory of Abkhazia, where are represented by middle part in sections Merkula and Galidzga-Pokveshi. Ebersin (1940) from section Merkula described the following mollusks: Dreissena cf. weberi Sen., Limnocardium sp., Monodacna (Pseudocattillus) cf. postdonacoides Dav., Mon. (Pseud.) cf. pleonexia Dav., Macrodacna cf. subriegeli (Sinz.), Macr. aff. maxima Andrus., Prosodacna cf. semisulcata (Rouss.), Pachydacna kujalnicensis (Andrus.), C. prochaskai (Pok.)., Later this outcrop was studied by Kitovani and the following species of mollusks were determined: Dreisesna polymorpha pokweschica Sen., Dr. weberi Sen., Pontalmyra medeae (Dav.), Didacnomya ex. gr. vulgaris (Sinz.). By opinion of Kitovani (Kitovani, Imna dze, 1974; Kitovani, 1976) the upper layers of section belong to Gurian stage. The outcrop Merkula was studied by Vekua. (1970, 1975). On basis of rich assemblage of Ostracoda the deposits of this section were dated as transitional between Kimmerian and Kujalnician: Caspiocypris labiata (Zal.), C. candida (Livent.), C. filona (Livent.), C. rectoides (Krst.), C. aff. orientalis, C. merculensis Vek., Caspiolla rostriformis Vek., C. elegans Mehes., C. merculica Vek., C. pseudoacronasuta Vek., C. acronasuta (Livent.), C. balcanica (Zal.), C. lobata (Zal.), Bakunella dorsoarcuata (Zal.), B. abchazica Vek., Pontaniella acuminate (Zal.), P. acuminata striata Mandelst., P. schemachensis Mandelst., P. naniae Vek., P. acuminate pontica (Agal.), Amplocypris lunatus Krst., Cypria paseolina Vek., Candona praecandida Vek., C. combiba Livent., Stenocypria neomeniata Vek., Advenocypis schneiderae Vek., A. duabiensis Vek., Cyterissa bogatschovi (Livent.), C. bogatschovi plana (Klein), C. duabica Vek., Mediocytherideis apatica (Schw.), Cyprideis littoralis (Brady), Trachileberis cf. frigusa Klein., Tr. pontica (Livent.), Tr. cf. azerba40
idjanica (Livent.), Tr. kujalnicensis Imn., Tr. pontica (Livent.), Loxoconcha aliena Vek., L. mandelstami Vek., L. petasa Livent., L. eichwaldi Livent., L. abchzica Vek. The mixed character of assemblage and presence of Trachileberis cf. azerbaidjanica (Livent.), Tr. kujalnicensis Imn. in its composition, allows to date the deposits of Merkula as Lower Kujalnician (Vekua, 1975). According to Taktakishvili (1984) the layers of section Mercula are transitional between Middle and Upper Kujalnicain. So, only the Middle Kujalnician is presented in Abkhazia. After Kimmerian there is the hiatus, which embraced the whole lower part of this stage. The Guria is the territory of the best development of Kujalnician in whole Black Sea region. The full outcrops are distributed around the village Khvarbeti, along the left bank of r. Natanebi, beginning from v. Natanebi till t. Ozurgeti (Southern Guria). The comparative study of Kujalnicain deposits of Guria and Odessa revealed the definite differences between them both in thickness and in the composition of fauna. The deposits of Odessa region is the small part of Kujalnician distributed on the territory of Guria. Here this stage occupies the definite stratigraphical position between Kimmerian and Gurian what is impossible to say about the Northern part of Black Sea. In Guria the dominant components of fauna are the brackish mollusks, as in Odessian layers the main role have the freshwater gastropods. On the basis of this the Kujalnician of Guria was distinguished as the separate stratigraphical unit under the name Egrissian stage and divided into three horizons: Skurdumian, Etserian and Tsikhisperdian or Dreissenian. The outcrop Tsikhisperdi was chosen as the stratotypical section (Taktakishvili, 1978 a,b,c; 1984). Below is given the description of this outcrop: Egr 1 1. Blue-gray clays with following mollusks: Dreissena decipiens (C. May), Phyllocardium planum (Desh.), Limnocar41
dium (Tauricocardium) squamulosum (Desh.), L. (Ecericardium.) ecericum Ebers., Preudocatillus donacoides postdonacoides (Dav.), Prosodacna (?) sp., Caladacna (?) sp., Valenciennius sp., Zagrabica sp., …...…….....…. 40 m 2. Dreissena decipiens (C. May), Dr. iniquivalvis (Desh.), Dr. choriensis (Tschel.), Phyllocardium planum (Desh.), Limnocardium (Taurcardium) squamulosum (Desh.), L. (Ecericardium) ecericum Ebers., Pontalmyra panticapaea gurianthica (Tschel.) Caladacna aff. escheri (C. May), Arcicardium aff. oraphense Takt., Zagrabica sp. ………..... 0.5 m In layers 1,2 were seen the following Ostracoda: Caspiocypris labiata (Zal.), C. candida (Livent.), C. filona (Livent.), C. kimmeriensis Vek., C. ornatus Hanganu, Lineocypris ex. gr. nonreticulata Sokač, L. ex gr. granulosa (Zal.), Caspiolla mislodjini Krstič, C. abchazica Imn., C. venusta Zal., C. balcanica (Zal.), C. lobata (Zal.), C. pseudoacronasuta Vek., Bakunella dorsoarcuata (Zal.), B. abchazica Vek., B. djanelidzeae Vek., Pontoniela acuminata Zal., P. hastata Krstič, P. acuminata striata Mandelst., Candonopsis aff. arcana (Krstič), Hungarocypris ex. gr. auriculata (Reuss.), Advenocypris sp., A. duabiensis Vek., Cytherissa bogatschovi (Livent.), C. bogatschovi plana (Klein) C. bogatschovi triformis Livent., C. juschatirensis Karm. 3. Ferruginous sandstone with Dreissena choriensis (Tschel.), Dr. rostriformis colchica Tschel., Limnocardium (Taur.) sp., Limnocardium (Euxinicardium) misargyridae Dav., L. (Eceric.) ecericum Ebers., Pontalmyra medeae (Dav.), P. medeae celaeno (Dav.), P. panticapaea gurianthica (Tschel.), Didacnomya phasiaca Dav., D. daliae (Tschel.), Pseudocatillus pleonexa (Dav.), Arcicardium aff. oraphense Takt., Viviparus sp., Euxinomargaria mandarinica (Sen.), Valenciennius kujalnicus Takt., Zagrabica sp. ...1 m
42
4. Ferruginous gray sandstone with following mollusks: Dreissena choriensis (Tschel.), Dr. rostriformis colchica Tschel., Limnocardium (Euxinicardium) misargyridae Dav., L. (Eceicardium) ecericum Ebers., Pontalmyra medeae (Dav.), Didacnomya phasiaca Dav., D. daliae (Tschel.), Pseudocatillus donacoides postdonacoides (Dav.), Ps. pleonexia (Dav.), Chartoconcha postcimmeria Dav., Euxinomargaria mandarinica (Sen.), Micromelania sp., Zagrabica sp., Planorbis sp. Ostracoda: Caspiocypris candida (Livent.), C. labiata (Zal.), C. ornatus Hanganu, C. kimmeriensis Vek., Lineocypris ex. gr. nonreticulata Sokač, Caspiolla rostriformis Vek., C. gracilis (Livent.), C. liventabina (Evlachova), C. ex. gr. flectimarginata Sokač, C. balcanica (Zal.), C. pseudoacronasuta Vek., C. karatengisa Mandelst., C. mislodjini Krst., Pontoniella schemachensis Mandelst., P. glabra Krst., P. accuminata (Zal.), P. loczyi (Zal.), Bakunella abchazica Vek., B. abchazica kujalicensis Vek., B. hanganui Vek., Amplocypris dorsobrevis Sokač, Cypria tocoriescui Hanganu, C. kerchensis Karm., Advenocypris schneiderae Vek., A. duabiensis Vek., Typllocyprella aff. elongata Sokač, Cyterissa bogatschovi (Livent.), C. bogatschovi plana (Klein), Leptocythere andrussovi (Livent.), L. bosqueti (Livent.), L. olteanui Vek., L. papaianopoli Vek., Tyrrhenocythere pontica (Livent.), Loxoconcha petasa Livent., Pontoleberis pontica Stancӗva, Xestoleberis lutrae Schnei., X. chanakoi Livent. ………………………..…………………………….…. 3 m Egr3 5. Coquina formed by Dreissena rostriformis colchica Tschel. Besides, in lower part of layer are presented: Limnocardium (Euxin.) Dav., Pontalmyra medeae (Dav.), Chartoconcha postcimmeria (Dav.), Euxinomargaria mandarinica (Sen.), Limnocardium (Euxinicardium) misargyridae Dav., 43
Micromelania sp. Among Ostracoda are: Caspiocypris filona (Livent.), Lineocypris ex. gr. nonreticulata Sokač, Caspiolla balcanica (Zal.), C. acronasuta (Livent.), C. pseudoacronasuta Vek., C. gracilis (Livent.), Pontaniella acuminata (Zal.), P. schemachensis Mandelst., Cypria kerchensis Karm., Bakunella dorsoarcuata (Zal.), B. hanganui Vek., Advenocypris schneiderae Vek., Cyterissa bogatschovi (Livent.), Leptocytere olteanui Vek., L. papainopoli Vek., Loxiconcha petasa Livent., Pontoleberis pontica Stanc., Tyrrhenocythere pontica (Livent.), Xestoleberis lutrae Schn. .…………………………………………..…. 6 m Gur1 6. Yellow-gray sandstones with Pyrgula sp. and Micromelania sp. ……………………………………………………... 2 m The layers 1, 2 belong to the lower part of Egrissian, poor in fauna. The layers 3, 4 are the middle part of stage with rich fauna. The upper part of Egrissian is the layer 5, represented by coquina, formed by shells of Dreissena. The layer 5 belongs to Lower Gurian. As in this section the contact between Kimmerian and Kujalnicain is not clear, the section Tsinagele was described as a stratotype of stratigraphical borders, where the Kimmerian is conformably overlapped by Egrissian (Taktakishvili, 1978, 1978a). The description of this outcrop is given below: Kmr2 1. Yellow-gray sandstones with Kimmerian fauna: Dreissena sp., Dr. iniquivalvis (Desh.), Dr. abchasica Sen., Dr. theodori Andrus., Dr. polymorpha weberi Sen., Phyllocardium planum (Desh.), Oraphocardium alatoplanum (Andrus.), O. oraphense (Dav.), Pontalmyra crassatellata (Desh.), P. panticapaea gurianthica (Tschel.), Prosodacna macrodon (Desh.), Pr. calopistes Dav., Chartoconcha bayerni (R. Hoem.), Arcicardium cf. oraphense Andrus. …...… 2-3 m Egr1 2. Yellow-gray clays with Dreissena decipiens (C. May), Dr. iniquivalvis (Desh.), Limnocardium (Ecericardium) eceric44
um Ebers.), P. panticapaea gurianthica (Tschel.), Pseudocatillus pleonexia (Dav.) .……...……………… 2 m Interruption in deposition …...……………………… 20 m Egr2 3. Yellow-gray clays with Dreissena sp., Limnocardium (Euxinicardium) misargyridae Dav., Pontalmyra medeae (Dav.), P. panticapaea gurianthica (Tschel.), P. daliae (Tschel.), Chartoconcha postcimmeria Dav., Oraphocardium oraphense (Dav.). ………………………………………...…... 3 m 4. Yellow-gray sandstones with Deissena polymorpha weberi Sen., Dr. choriensis Tschel., Dr. rostriformis colchica Tschel., Dr. choriensis Tschel., Limnocardium (Taurcardium) sp., L. (Euxinicardium) misargyridae Dav., L. (Ecericardium) ecericum Ebers., Pontalmyra medeae (Dav.), P. medeae celaeno (Dav.), Didacnomya phasiaca Dav., Pseudocatillus donacoides posdonacoides (Dav.), Ps. pleonexia postcimmeria Dav., Macrodacna maxima (Andrus.), Prosodacna calopistes Dav., Chartoconcha postcimmeria Dav., Valenciennius kujalnician Takt., Euxinomargaria mandarinica (Sen.), Micromelania sp., Zagrabica sp., Planorbis sp. ……………………...………………... 0.5 m 5. Yellow-gray clays with the same assemblage of mollusks …………………………………………..…………… 10 m Egr3 6. Yellow-gray clays full of shells of Driessena. In some parts of this layer Pseudocatillus sp., Micromelania sp., Pyrgula sp. were seen. ……………………..……….……... 10 m Gur1 7. Yellow-gray clays with Micromelania sp. and Pyrgula sp. The age of layer 1 is Upper Kimmerian. The layer 2 is transitional between Kimmerian and Egrissian and can be considered as its lower part. The layers 3-5 belong to Middle Egerissian and the layer 6 - to Upper Egrissian. It is the coquina, formed by shells of Dreissena. The layer 7 belongs to Lower Gurian.
45
So, by composition of mollusks the Egrissian is divided on three horizon: the lower - Skurdumian, Middle - Etserian and Upper Tsickisperdian. The Skurdumian (thickness about 50 m) has the narrow distribution, restricted by basin of r. Skurdumi (Guria) and contains poor assemblage of mixed Kimmerian-Kujalnician mollusks. The Etserian horizon (thickness about 5 - 20 m) is distributed on the territory of Guria and Abkhazia and is characterized by rich composition of fauna. The Tsikhisperdian horizon is represented by coquina, which is formed by some species of Dreissena. There is an opinion that it belongs to Gurian stage (Kitovani, Imndaze, 1991; Kitovani, Imnadaze, Torosov 1991). By the data of Ostracoda the Skurdumian horizon contains the upper Kimmerian assemblage. The new taxa typical for Kujalnician, appeared only in Etserian, when the dominate position was occupied by family Cytheridae (the genera Tyrrhenocythere, Leptocythere, Loxoconcha, Xestileberis, Pontoleberis) and the family Cyprididae became the secondary taxa (the genera Bakunella, Pontoniella, Candonella, Cypria, Stenocypris). As about the Tsikhisperdian horizon (layer with Dreissena) it really corresponds to the final stage of development of Kujalnician Ostracoda. The full outcrops of Egrissian are known also near v. Gogoreti and Khvarbeti. On r. Orapho it is represented by middle and upper parts of this stage.
46
The pollen assemblages of the Upper Neogene Deposits of Western Georgia The most of outcrops described in previous parts of the work were studied by pollen analysis (Ramishvili, 1969; Shatilova et al., 1998, 2000, 2001, 2002, 2005, 2007, 2007a, 2011; Maissuradze et al., 2013). Pollen and spores are presented nearly in all layers of Pontian, Kimmerian and Kujalnikian allowing reconstructing the development of vegetation during the whole period of accumulation of Later Neogene deposits.
The Pontian stage Pontian outcrops are known from Abkhazia, Megrelia and Guria, but only in three localities (Otapi, Urta-Zana and Bia) the Novorossian substage is represented by full series of deposits. In all other sections the Eupatorian is absent and the Lower Pontian begins by the Odessian horizion. The analysis of samples from the Otaphi and Urta-Zana sections (Maissuradze et al. 2013) shows a transition from the rich and diverse pollen flora of Meotian to poor assemblages with a predominance of pine in Eupatorian (fig. 3). The changes in composition of vegetation, probably, were connected with decrease of humidity, phenomenon, which at the end of the Miocene embraced whole Southern part of Russian Plain (Shchekina, 1979). In Odessian the number of pollen grains of genera Podocarpus, Abies, Cedrus, Tsuga, representatives of family Taxodiaceae and especially of genus Carya increased (fig. 4).
47
48
Fig. 3. The pollen diagram of Upper Meotian and Lower Pontian deposits from outcrop Otaphi
49
Fig. 4. The pollen diagram of Pontian deposits from Gogoreti outcrop
50
Fig. 5. The pollen diagram of Pontian deposits from outcrop Kulitskhali
After the Odessian the climate became more stable, warm and humid. During the Portaferian the polydominant deciduous forest with subtropical plants in lower mountain belt stabilized (fig.5).It was probably during this climatic optimum that the Kodorian macroflora accumulated (Kolakovsky 1964). According to Kolakovsky the Kodorian flora is unique and one of the richest in Eurasia. The subtropical character of the vegetation confirms the existence in Kolkhida of a major refuge for Tertiary species that gradually died out. The Kodorian flora was mainly composed of subtropical plants especially in riparian forest and lower mountain belt communities. Herewith we want to discuss briefly the question about boundary between Odessian horizon and Lower Flexuosian layers. The pollen assemblages of both stratigraphical units reveal the similar picture of vegetation and climate development. So, we propose to move the boundary between Lower and Middle Pontian up to the upper boundary of Lower Flexuosian layers (Shatilova et al., 2007), what was accepted also by Taktakishvili (1984). The later stretches of the Middle Pontian and the beginning of the Late Pontian were characterized by repeated shifts of forest boundaries. Polydominant forest became predominant communities at the end of Late Pontian (fig. 6). Probably it was a second climatic optimum corresponding to the accumulation of the Bichvinta (Pitsunda) flora (Kolakovsky 1962). The Pontian pollen assemblages we compared with those from synchronous deposits of Northern part of Black Sea coast. In both regions the rhythmic changes of epochs with different climate can be traced. However in the Western Georgia the frequency and amplitudes of these changes were weaker. The main difference between the Northern Black Sea coast and Western Georgia was in terms of humidity. In the north, the Pontian was a time of declining temperatures and xerophytisation (Ananova, 1974), while in Kolkhida after 51
Lower Pontian during the whole Upper Cenozoic the precipitation increased side by side with gradually lowering of temperatures.
Fig. 6. The pollen diagram reflecting the changes in the distribution of the major forest communities during the Pontian (prepared by landscape-phytocenological method)
52
The Kimmerian stage The pollen analysis of deposits from Abkhazia, Guria and Megrelia allows tracing the dynamics of climate and vegetation during the Kimmerian (Shatilova et al., 2002, 2007a, 2011). The warmest climate, close to the subtropical, occurred at the end of the Azovian and first half of Kamishburunian (Fig. 7, 8). Data from this period reflect a decrease of the role of conifer forests. This indicates a temperature rise during these stretches of the Kimmerian, agreeing with the proposition of a global Pliocene optimum in the Azovian-Kamishburunian interval (Zubakov, 1990; Borsenkova, 1992). This period reflects the accumulation of the Duabian flora, the assemblage with poorer taxonomic diversity compared to the Kodorian flora. Cooling climates during the upper part of Portaferian and the beginning of Bosforian, which led to the extinction of a large number of angiosperms from the plain and lower belt, may explain the poorer composition of the Duabian flora. The number of ferns and angiosperm plants of families Fagaceae, Lauraceae, Berberidaceae, Hamamelidaceae, Araliaceae and Arecaceae became exitnct on the territory of Western Georgia. In spite of this Kolakovsky (Kolakovsky, Shakryl 1978) claims that the evergreen plants still occupied first place in Kimmerian landscapes. This conclusion was made on the basis of macrofossils and interpreted as a result of climatic optimum. On the whole it is possible to suppose that polydominant deciduous forest existed on the plains and in the lower mountain belt with relict subtropical communitues in refugia, the area of which changed depending on the climatic conditions. According to Kolakovsky (1956) the composition of these forests was very variable. He distinguished three groups of plants: 1. Plants of a humid monsoonal climate; 2. Hygrophilous plants with ecological similarities to the species of Atlantic North American lowland and ripar-
53
Fig. 7. The pollen diagram of Upper Pontian and Kimmerian deposits from outcrop BjujaAchistskali
ian forests; 3. Sclerophyllius, cold-hardy species tolerant to high summer temperatures and with ecological similarities components of
54
55
Fig. 8. The pollen diagram of Kimmerian deposits from Du outcrop Duabi
subxerophilous Mediterranean forests. At high elevations the warmtemperate forest was replaced by broadleaf and coniferous formations. After the Duabian optimum the climate was changed and the pine became the dominant of the vegetation cover. The end of Kimmerian was warm but the flora was nearly devoid of the subtropical element. During this time had place also the periodic shifts in darkconifers and pine forests areas (Fig.9).
Fig. 9. The pollen diagram reflecting the changes in the distribution of the major forest communities during the Kimmerian
56
The Kujalnician (Egrissian) stage The full sections of Kujalnician occured only in Guria, where it is distinguished as the separate unit under the name Egrissian stage and divided on three horizons: Skurdumian, Etserian and Tsikhisperdian. The outcrop Tsikhisperdi (fig.10) was chosen as the stratotypical section (Taktakishvili, 1978 a,b,c; 1984). The deposits of Skurdumian horizon are known mainly in Southern Guria in sections Tsikhisperdi, Tsinagele, Gogoreti, Kurchkha, Nakhobilevi, Gogoreti, Khvarbeti and Orapho. As it was noted above, pine pollen was dominant in Kamishburunian (after the Duabian optimum), when the bulk of subtropical elements died out. The next dry period had place in the upper part of the Skurdumian, leading to the disappearance of evergreen forest communities altogether. The most widely distributed part of Kujalnician is the Etserian horizon. It is known nearly in all sections of Guria and in Abkhazia, where is represented in two sections: Galidzga-Pokveshi and Merkula. The Middle Kujalnician is characterized by rich but changeable pollen assemblages that is the main sign of Kuyalnician at whole, which differ it from Kimmerian. The outcrops of Upper Kujalnician are known only in Southern Guria. The Tsikhisperdian horizon is characterized by poor assemblages of fauna and flora. The mollusks are represented by some species of Dreissena, which in some outcrops formed the coquina. The main characteristic sign of pollen flora is the predominance of dark-conifers. By the data of mollusks the outcrop Galidzga-Pokveshi is divided on two parts. The lower part is dated as Middle-Upper Kimmerian. The following layers belong to Middle Kujalnician (Djashi, Taktakishvili, 1978; Taktakishvili, 1984).
57
58
Fig. 10. The pollen diagram of Egrissian deposits from outcrop Tsikhisperdi
The pollen assemblages from Kimmerian layers of Galidzga section at first were studied by Mtchedlishvili (1963) and pollen data of upper layers of Kimmerian and Kujalnician deposits were published by Shatilova (1966; 1974). Later the samples from whole section of Kimmerian and Kujalnician deposits distributed on the r. Galidzga and near v. Pokveshi were again studied by us. According to the pollen data there is quite big differences between assemblages of Kimmerian and Middle Kujalnikian (fig.11). The fauna from section Merkula was studied by Kitovani (Kitovani, Imnadze, 1974; Kitovani, 1976), who supposed that the upper layers of section belong to Gurian stage. By the data of Ostracoda the deposits of Merkula are Lower Kujalnikian (Vekua, 1975). According to Taktakishvili (1984) it is the upper part of Middle Kujalnician. The same conclusion can be done on the basis of pollen assemblages (fig.12). Probably they reflect the vegetation of climatic optimum, which had place at the end of the Etserian time (Shatilova et al., 2011). On the basis of given above data the history of vegetation and climate of Western Transcaucasia during the Upper Neogene was reconstructed. The warm and humid climate dominated here during the Pontian and the first half of Kimmerian favored the development of rich vegetation.The lower mountain belt was occupied by subtropical forest as indicated by Kodorian and Duabian macrofloras, fossilized in Pontian and Kimmerian deposits of Abkhazia. The first sharp fluctuation of climate was in Upper part of the Late Kimmerian, after Duabian optimum, when pine became the main component of forests. The same event had place in Early Kujalnician, after which on the territory of Abkhazia and Guria the phenomenon of mass extinction of thermophilic elements had place and the subtropical community as a separate unite disappeared on the territory of Western Transcaucasus. During the Kujalnician two main formations existed: the dark-conifer forest and polydominant forest, 59
60
Fig. 11. Pollen diagram of Kimmerian and Middle Kujanician deposits from outcrop Galidzga-Pokveshi
61
Fig. 12. Pollen diagram of Middle Kujanician deposits from outcrop Merkula
which occupied the middle and lower mountain zones. Here warmtemperate deciduous trees were the main components. The subtropical relicts of the ancient floras continued to preserve in the composition of this formation. In the Middle Kujalnician the humidity increased, but the temperature became unstable. It was the reason of successive changes of dark-conifer forests by deciduous warm-temperate communities. At the end of the Middle Kujalnician the climatic optimum had place, when the area of polydominant forest reached its maximum. The optimum was followed by the period of cold humid climate, which embraced the whole Upper Kujalnician. The area of polydominant communities shrank and dark-conifer forest rose to prominence (Fig. 13). At whole the Kujalnician significantly distinguished from preceding epochs of Pliocene both by the absence of evergreen communities and by the frequency of periods with low temperatures, which amplitude of drop increased in the Tsikhisperdian. After Kujalnician the development of Kolkhida climate was mainly connected with the changes of temperatures under the influence of glacial and interglacial epochs, whereas the humidity remained high and nearly stable during the whole following time. So, during the Late Neogene in development of flora and climate of Western Georgia two main turning-points can be distinguished. One had place on the boundary between the Meotian and Pontian, when the flora was impoverished and the climate became not so stable than in previous epochs of Miocene. The second turning-point is connected with the upper part of Kimmerian. Under the influence of the first sharp climatic fluctuation the mass extinction of thermopiles elements had place and the subtropical communities, as the separate unit, disappeared on the territory of Western Georgia.
62
Fig. 13. The pollen diagram reflecting the changes in the distribution of the major forest communities during the Kujalnician
63
1
2
Bryopsida
Anthoceropsida
Lycopsida
Selaginellopsida
Selaginellopsida
Sphagnaceae
Anthocerotaceae
Lycopodiaceae
Selaginellaceae
Selaginellaceae
Kujalnician
Family
Kimmerian
Classis
Pontian
The list of plants determined by pollen data from Upper Neogen deposits of Western Georgia is given below (Table)
4
5
6
Species
3 Distverrrusporis pliocenicus (Kr.) Grabowska Sphagnum cuspidatum Ehrh. &Hoffm.
x
x
x
Sphagnum sp. Rudolphisporis rudolphii (Kr.) Kr. et Paclt.
x
Anthoceras sp. Lycopodium alpinum L. L.annotinum L.
x x
x
x
x
L. clavatum L.
x
x
x
L. complanatum L.
x x
L. densum Sw.
x
x
L. inundatum L.
x
x
L. selago L.
x
x
x
L. serratum Thunb. Echinatisporis longechinus Kr. Lusatisporis punctatus Kr. Muerrigerisporis sp. Selaginella eggersii Sodiro S. fusca Mtch.
x
x
x
x
x
64
x x
x
x
x
x
x
x
1 Selaginellopsida
Ophioglossopsida
2 Selaginellaceae
Ophioglossaceae
Osmundaceae
3 S. sanguinolenta (L.) Spring. S. sibirica(Milde) Hieron. Bothrychium simplex Hitchc. Ophglossisporites sp. Ophioglossum lusitanucum L. O.vulgatum L. Baculatisporites irenae Kohlman-Adamska Osmunda cinnamomea L. O. claytoniana L. O. regalis L.
Schizaeaceae Polypodiopsida Lygodiaceae
Pteridaceae
Polypodiopsida
Pteridaceae
Todea sp. Reticulosporis polonicus Kr. Schizaea sp. Lygodium japonicum (Thbg.)Sw. L. reticulatum Sch. Cryptogramma acrostichoides R.Br. C. crispa (L.) R. Br. C.brunnoniana R. Br. Pteridacidites boerzsoenyensis Nagy (St. & Sh.) P.dentatiformis Sh.&St. P. grandifoliiformis St.&Sh. P. guriensis Sh. &St. P.kimmeriensisSh.&St
65
4
5
6 x x
x
x
x
x x
x
x
x
x
x
x
x
x
x
x
x
x
x x x x
x x
x
x
x
x
x
x
x
x
x
x
x
x
x
x x
x x
x
1
2
Pteridaceae
Polypodiopsida
Adiantaceae
3 P. longifoliiformis Sh. &St, P. pseudocreticus St. &Sh. P. rarotuberculatus Sh.& St. P.remotifolioidea Sh. & St. P. spiniverrucatus St.&Sh. P. variabilis St.& Sh. P. venustaeformis St. &Sh. P. verus (Mtch.)Sh.& St. P. vittatoides St.&Sh. Adiantum sp. Anogramma sp. Pityrogramma sp. Polypodium aureum L. P. serratum (Wild.) Futo P.tuberculatum Mtch.
Polypodiaceae
4 x
5 x
x x x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x x
x
x x
x
x
x
x
x
x
x
P. verrucatum Ram.
x
x
x
P. vulgare L. Verrucatosporites megafavus Kr. V. megabalticus (Kr.) Kr. V.poriacus Kr.
x
x
x
x
x
x
x
x
x
Microgramma sp. Hymenophyllaceae
6
Pyrrosia sp. Hymenophyllum rotundum Mtch.
66
x x
x
x
x
x
1
2 Thyrsopteridaceae
Dicksoniaceae
Cyatheaceae
Dennstaedtiaceae
Polypodiopsida
Aspleniaceae
Aspidiaceae
3 Cibotium glaucum (Sw.)Hr.& Arn. Dicksonia reticulata Purc D. unitotuberata Purc.
5
6
x
x
x
x
x
x
D. antarctica R. Br.
x
x
D. fibrosa Col.
x
D. luculenta Purc.
x
Alsophila sp.
x
Cyathea sp.1
x
Cyathea sp.2 Verrucatosporites histiopteroides W. Kr. V. favus (R.Pot.) Th.& Pf. Asplenium rutamuraria L. A.incisum Thumb. A. septentrionale (L.) Hoffm. Athyrium alpestre (Hoppe) Ryl. A. yokoscense (Fr. et Sav.) Christ Cyclosorus fragilis (L.) Bernh. Dryopteris filix mas (L.) Schott. D. oriades Fom. D. raddeana Fom. D. thelypteris (L.) A. Gray D. rigida (Hoffm.) Und. Polystichum lonchitis (L.)Roth P. aff. craspedosorum (Maxim.) Diels
67
4 x
x x
x
x
x
x
x
x
x
x x x x x x x x x x x x x x
1
2
Aspidiaceae Polypodiopsida
Davalliaceae Gikgoopsida
Ginkgoaceae Podocarpaceae
Phyllocladaceae Araucariaceae
Pinopsida
Pinaceae
3 Woodsia fragilis (Trev.) Moore W. polystichoides Eaton W. alpina (Bolton.) S.F. Gray Verrucatosporites alienus (Pot.)Th.& Pf. V.clatriformis Kr.
4
Gingko biloba L. Dacrydium aff. cupressinum Soland. Podocarpus aff. neriifolius D. Don Phyllocladus aff. trichomanoides D. Don Araucaria sp.
x
Abies alba Mill.
x
x
x
A. cephalonica Loud. A. cilicicaeformis N. Mtch. A. nordmanniana (Stev.) Spach Abiespollenites sivakii Nagy A. maximus Kr.ex Nagy Cathaya krutzschii (Sivak) Ziebinska-Tworzydlo Cedrus deodara Loud. C. atlantica Manetti
x
x
x
x
x
x
x
x
x
C. libani Laws.
x
C. sauerae N. Mtch. Cedripites parvisaccatus (Zauer) Kr. C. deodaraeformis Nagy
68
5
6 x x x x
x x
x x x
x
x x
x
x
x
x
x
x
x
x
x
x x
x
1
Pinopsida
2
Pinaceae
3 C.balansaeformis Nagy C. dacrydioides Kr. Keteleeria caucasica Ram. K. aff. fortunei (Murr.) Carr. Picea minor N. Mtched. P. complanataeformis N. Mtched. P. orientalis L. P. aff. schrenkiana Fish. et Mey Piceapollis praemarianus Krutzsch ex ThiellePfeiffer P. sacculiferoides Krutzsch ex Hochuli P.tobolicus (Panova) Krutzsch Pinus pithyusa Stev. Psudotsuga aff. glauca Mayr Tsuga aculeata Ananova T. canadensis (L.)Carr. T. diversifolia (Maxim. )Mast. T. inordinata Mched.
4
5 x
x
x
x
x
6 x
x x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
T. korenevae Mched.
x
x
x
T.meierii Mched.
x
x
x
T .patens Downie
x
x
x
T.pattoniana Engelm.
x
x
x
T.schatilovae Mched.
x
x
x
T. sivakii Mched.
x
x
x
69
x
x
1
2
Pinaceae
Sciadopityaceae
Pinopsida
Taxodiaceae
Cupressaceae
Gnetopsida
Ephedraceae
Dicotyledoneae
Myricaceae
3
4
T. tortuosa Mched. T. aff. blaringhemii Flous T. aff. yunannensis (Franch.) Mast. Tsuga typ piccolo Sciadopitys aff.verticillata Sieb.et Zucc. Cunninghamia aff. lanceolata (Lambert) Hooker Glyptostrobus aff. pensilis (Stauton) Koch Sequoia aff. sempervirens (Lamb.) Endel. Sequoidendron aff. giganteum (Lindl.)Buchh. Metasequoia aff.glyptostroboides Hu et Cheng Cryptomeria japonica D. Don Taxodium aff. distichum (L.) Rich. Libocedrus aff. deccurens Tor. Cupressus sp. Ephedra aff. distachya L. Distachyapites bernheidensis (Krutzsch) Grabowska &Wazynska Comptonia grandis Glad. C. imperfecta Glad.
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
70
5
6
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x x
x
x
x
x
x
x
x
x x
1
2
Myricaceae
Dicotyledoneae
Juglandaceae
3 Myricipites bituitus (Pot.) Nagy M.rubraeformis Grab.& Wazyn. M. pseudorurensis (Pflug) Grab.& Wazyn. Carya aquatica (Michx.) Nutt. C. aff. glabra (Mill.) Sweet C.cordiformis (Wangh.) C. Koch C. ovata (Mill.) C. Koch C. spakmania Trav.
4
x
x
x
x
x x
x x
x
x
x
x
x
x
x
x
x
x
x
x
x x x x
x
71
x x
x
x
x
x
x
J. insularis Grieseb. J.nigra L. J. aff. rupestris Egelm. J. aff. regia L.
6 x
C. aff. texana Buckley C. aff. tomentosa (Lam.) Nutt. Cyclocarya aff. paliurus (Batalin) Ilinsk. Engelhardtia aff. wallichiana Lindl. Momipites punctatus (Pot.) Nagy M. quietus (Pot.) Nichols Platycaryapollenites miocaenicus Nagy P. anticyclus (Krutzsch et Vanhoorne) Kedves Oreomunnea sp. Juglans cinerea L.
5
x x
x x
x
x
x
1
2 Juglandaceae Salicaceae
Betulaceae
3 J.sigillata Dode Salixipollenites capreaformis Pland. Alnus aff. incana (L.) Moench. Betulaepollenites costataeformis Grab. & Wazyn. Carpinus betulus L.
4
5
x x x x
x
x
x
C. caucasica Grossh.
x
x
x
C. orientais Mill.
x
x
x
Corylus avellana L.
C. aff. maxima Mill.
Fagaceae
Ulmaceae
Ostrya sp. C. aff. crenata Sieb. et Zucc. Castanea sativa Mill. Fagus orentalis Lipsky Quercus aff. castaneifolia C.A.M. Quercus aff. pontica C. Koch. Quercopollenites rubroides KohlmanAdamska & Ziembinska.Tworzydlo Q. granulatus Nagy Celtis sp. Celtispollenites komloensis Nagy Ulmipollenites maculosus Nagy U. undulosus Wolff.
72
x
x
C. ferox Wall
Dicotyledoneae
6
x
x
x
x
x
x x
x
x
x
x
x
x
x x x
x x x x
x x
1
2
Ulmaceae
Eucommoaceae
Magnoliaceae
Nymphaeaceae
Platanaceae Dicotyledoneae
Hamamelidaceae
Rosaceae Fabaceae Rutaceae Anacardiaceae
3 Zelkova carpinifolia (Pall.) Dipp. Z. serrata (Tumb.) Makino Zelkvaepollenites thiergardii Nagy Eucommia ulmoides Oliv. Liriodendron tulipifera L. Magnolia acuminata L. Magnolia grandiflora L. Nelumbo sp.
4 x
5 x
6 x x
x x x
x x
x
x
x
x
x
x
Nuphar sp.
x
x
Nympheae sp. Platanus aff. orientalis L Corylopsis aff. cordata Merll ex Li Altingia aff. excelsa Norr. Liquidambar formosana Hance L. aff. orientalis Mill.
x
x x
x
x
x
x x
x
x
x
x
L .styraciflua L.
x
x
x
L. aff. turgaica Kupr. Parrotia persica DC (C.A. Mayer) Sycopsis colchica Ram. Amygdalus sp.
x x
x
x x
Sanguisorba sp. Acacia sp. Phellodendron aff. amurense Rupr. Cotinus aff. coggygria Scop.
73
x
x x
x x x
1
2 Anacardiaceae Aceraceae
Aquifoliaceae
Celastraceae Staphyleaceae Vitaceae
Dicotyledoneae Tiliaceae
Sterculiaceae Trapaceae Myrtaceae
Onagraceae
3
4
5
6
Toxicodendron sp.
x
Acer aff. campestre L. Aceripollenites reticulatus Nagy Ilex aff. colchica Poiark. Ilexpollenites margaritatus (Pot.)Thiergart Euonymus aff. europea L. Staphylea colchica Stev. Parthenocissus quinquefolia (L.) Planch. Tilia caucasica Rupr.
x x x x
x
x
x
x
x
x
x
x
x
T.aff. dasystyla Stev.
x
T. cordata Mill.
x
T. platyphyllos Mill.
x
T. tomentosa Moench.
x
T. aff. ledebouri Borb. Intratriporopollenites instructus (Pot.)Th.et Pflug In. parainstructus Krutzsch In. insculptus Mai
x
Sterculia sp. Trapa aff. colchica Alb. Myrtaceidites myrtiformis Simoncsics Epilobium sp. Corsinipollenites parvus (DoktorowiczHrebnicka) Slodkowska
74
x x x x x x x
x
x
x
1
2 Alangiaceae
Nyssaceae
Araliaceae
Dicotyledoneae
Apiaceae Ericaceae
Symplocaceae
Convolvulaceae
Caprifoliaceae
Monocotyledoneae
Arecaceae
3 Alangium kurzii Craib. Nyssa aff. aquatica L. Nyssa aff. sylvatica L. Nyssapollenites pseudocruciatus (Pononie) Th. N. rodderensis Thiergart Aralia aff. hispida Michx. Brassaiopsis sp.
4
x
x
x
x
x
x
x
x
x
x x x
x
x x
x x x
x
x
x
x x x
x x
Lonicera sp. Lonicerapollis gallwitzii Krutzsch Viburnum sp.
x x x
Nipa sp.
x
Sabal sp.
x
75
6
x
Fatsia sp. Hedera colchica C.Koch Caucalis sp. Rhododendron sp. Ericipites callidus (Potonie)Krutzsch Symplocos paniculata Wall. Symplocoipollenites triangulus (Potonie)Potonie S.rarobaculatus (Thiele- Pfeiffer) Ashraf &Mosbrug. Convolvulus sp.
5
x
Conclusion The present work is the result of joint investigation of molluska, foraminifera, ostracoda, pollen and spores from the Upper Neogene deposits of Western Georgia the stratotypical region of Eastern Paratethys. On the territory of Western Georgia the Pontian, Kimmerian and Kujalnician deposits are represented by full series of deposits rich in fossil material, thus presenting the complete picture of the development of marine fauna and terrestrial flora. The Lower Pontian is represented by the Eupatorian and Odessian horizons. With the data of macrofauna the Eupatorian deposits are characterized by impoverished assemblages of brackish mollusks. In the Black Sea - Caspian region the representatives of the genera Eupatoria, Dreissena, Prosodacna, Monodacna first appeared in the Eupatorian. The composition of microfauna also underwent significant changes. In the Meotian deposits foraminifera are the predominant fossils while the Ostracoda are represented by single tests. In the Eupatorian assemblage though consists of the mixed Meotian – Pontian composition. In the Odessian time (Lower Pontian), besides the species of genera Pontoniella and Bakunella, the representatives of genera Caspiocypris, Lineocypris, Leptocythere and species Loxoconcha djaffarovi Schneid. and Cytherura perata Schneid. penetrated from several basins of the Paratethys in to the Rionian bay. The Meotian relicts fully disappeared, but generally the assemblage of Ostracoda became richer. For the foraminifera the ecological conditions of the desalted Odessian Sea proved fatal and so in the deposits of this basin they are represented only by single taxa. In Western Georgia some unusual for Euxinic basin facies of the Middle Pontian are represented: the Rhomboidal layers, with Congeria rhoboidea M. Hoern. and the lower and upper Flexuosian 76
layers with Congeria flexuosa Takt. These different facies (Rhomboidal and Flexuosian) triggered the emergence of three types of succession of the Middle Pontian deposits: the type classical for the Black Sea, the Bia type and the Jumi type. Such variety of facieses in the Rioni bay complicated drawing up stratigraphical scheme of the Pontian stage even for such comparably not big territory as Western Georgia. In the Middle Pontian deposits the assemblages of Ostracoda are rich and various. At this time began predominate the representatives of genera Caspiolla, Caspiocypris. The similar process continued in the Upper Pontian. On the whole the Pontian assemblages contain: the immigrants, penetrating from the Pannonian, Dacian and Eugenian basins; the taxa from freshwater basins; the Meotian relicts and the native taxa. The Kimmerian deposits can be found in the same regions as Pontian but they occupied smaller territory and are represented only by shallow water facies. On the basis of macrofauna the Kimmerian stage of Western Georgia is divided into two parts: the lower - Azovian and the upper – Kamishburunian, in which two substages are united: the Kamishburunian and the Panticapeian. The Kimmerian deposits of Western Georgia are characterised by existence of three types of facies, unknown in other regions: Duabian, Pokveshian and a mixed type. They are all connected to the Upper Kimmerian. The Kimmerian fauna of Ostracoda was formed from the Pontian taxa and the taxa originaned inside the Kimmerian basin. In the Lower Kimmerian gradual adaptation of the Pontian elements to new environment proceeded. In the Middle Kimmerian flourishing of some genera of the family Cyprididae could be observed. In the Upper Kimmerian alongside the rich typical Kimmerian asse77
mblage of Ostracoda, there appeared single representatives of species Leptocithere pokveshica Vek., Trachileberis pontica arevadzeae Vek., Tr. imnadzeae Vek., which began flourishing in the Kujalnician On the territory of Western Georgia the area of the Kujalnician deposits is much narrower than that of the Kimmerian and Pontian. They are known mainly in Guria and in Abkhazia, where they are represented by middle part. The comparative study of the Kujalnicain deposits of Guria and Odessa revealed definite differences between them both in thickness and in the composition of fauna. On the basis of this the Kujalnician of Guria was distinguished as a separate stratigraphical unit under the name of the Egrissian stage and divided into three horizons: Skurdumian, Etserian and Tsikhisperdian or Dreissenian. The Skurdumian horizon contains the upper Kimmerian assemblage of Ostracoda. A new taxa typical for Kujalnician appeared only in Etserian, when the family Cytheridae occupied a dominating position while the family Cyprididae became the secondary taxa. The Tsikhisperdian horizon corresponds to the final stage of the development of the Kujalnician taxa of Ostracoda. All outcrops of the Pontian, Kimmerian and Kujalnikian deposits described by the data of fauna were studied by pollen analysis. The samples from the Otapi and Zana deposits revealed sharp changes in pollen assemblages at the boundary of the Meotian and Pontian. They show a transition from the rich and diverse vegetation into poor communities with a predominance of pine occupying nearly all altitudes. So, in the eastern part of the Black Sea region the Eupatorian horizon can be considered as a level, after which the Miocene stage of development of marine and terrestrial biocenosis was replaced by the Pliocene one.
78
The differences between the vegetation of the Meotian and the following stages of the Neogene are in the quantity of subtropical plants in the composition of flora on the whole, as well as in the position, which they occupied in plant communities. After the Meotian their number kept deminishing. After the Pontian in the lower mountain belt continued to preserve the subtropical community, but its composition in the Kimmerian was much poorer. During the Kujalnician the lower and middle mountain belts were covered with rich polydominant forests of deciduous plants with great number of relicts of the past epochs. So, during the Late Neogene two main turning-points can be distinguished in the development of flora and climate of Western Georgia. One took place on the boundary between the Meotian and Pontian, when the flora was impoverished and the climate became less stable than in previous epochs of the Miocene. The second turning-point is connected with the upper part of Kimmerian. The mass exitnction of thermopiles elements occurred under the influence of the first sharp climatic fluctuation and the subtropical communities, as the separate unit, disappeared on the territory of Western Georgia.
79
დასავლეთ საქართველოს გვიანნეოგენურის პალეობიოლოგიური დახასიათება (მოლუსკები, ოსტრაკოდები, ფორამინიფერები, პალინომორფები)
რეზიუმე დასავლეთ საქართველო, რომლის ტერიტორიაზე პონტური, კიმერიული და კუიალნიკური სრული დანალექი სერიითაა წარმოდგენილი, აღმოსავლეთ პარატეთისის სტრატოტიპურ რეგიონს წარმოადგენს. აქ გავრცელებული ზედანეოგენური ნალექები შეიცავს მდიდარ ნამარხ მასალას (მოლუკები, ოსტრაკოდები, ფორამინიფერები, სპორები და მტვრის მარცვლები), რომლის შესწავლის შედეგად შესაძლებელი გახდა შესაბამისი ეპოქის ზღვიური ფაუნისა და ხმელეთის ფლორის განვითარების თითქმის უწყვეტი სურათის ასახვა. ქვედაპონტურის შემადგენლობაში ორი ჰორიზონტი გამოიყოფა - ევპატორიული და ოდესური. ევპატორიული ჰორიზონტი შეიცავს განმარილიანებული წყლის გაღარიბებულ მაკროფაუნას. შავი ზღვა-კასპიის რეგიონში გვარების Eupatoria, Dreissena, Prosodacna, Monodacna-ს წარმომადგენლები პირველად ამ დროს ჩნდებიან. მნიშვნელოვანი ცვლილებები მოხდა აგრეთვე მიკროფაუნის შემადგენლობაშიც. ასე მაგალითად, თუ მეოტურში გაბატონებულ ჯგუფს Foraminifera წარმოადგენს, ხოლო Ostracoda-ს ფორმები სპორადულად გვხვდება, ევპატორიულში მიკროფაუნის ასოციაციებს უკვე შერეული ხასიათი აქვს და არის წარმოდგენილი. 80
თანაბარი პროპორციით
ოდესურ დროში პარატეთისის სხვადასხვა აუზიდან რიონის უბეში გავრცელდა ოსტრაკოდების გვარების - Caspiocypris, Lineocypris, Leptocythere და Loxoconcha-ს მრავალი წარმომადგენელი და Cytherura-სა და Loxoconcha-ს მხოლოდ რამდენიმე სახეობა. მიუხედავად მეოტური რელიქტების გადაშენებისა, ოსტრაკოდების ასოციაცია გახდა უფრო მდიდარი. ამავე დროს განმარილიანებული ოდესური აუზის პირობები არახელსაყრელი იყო ფორამინიფერებისთვის და ამ ნელექებში ეს ჯგუფი მხოლოდ ერთეული ტაქსონითაა წარმოდგენილი. დასავლეთ საქართველოს შუაპონტურში გვხვდება ევქსინური აუზისთვის არატიპური ორი ფაციესი: Congeria rhoboidea-ს შემცველი (რომბოიდური) შრეები და Congeria flexuosa-ს შემცველი (ფლექსუოზური) შრეები. ამ გარემოებამ განაპირობა შუაპონტური ნალექების სამი თანმიმდევრული ტიპის არსებობა: კლასიკურის- ბიის და ჯუმის. შუაპონტურ ნალექებში მდიდარი და ნაირფეროვანია ოსტრაკოდების კომპლექსი. ამ დროს პირველად ჩნდება გვარი Tyrrhenocythere და იწყება გვარების Caspiolla-ს და Caspiocypris-ის წარმომადგენლების გაბატონება. მსგავსი სურათია გვიანპონტურშიც. ამავე დროს პონტური ოსტრაკოდების ასოციაციაში გვხვდებიან იმიგრანტებიც პანონური,
დაკიური და ევქსინური
აუზებიდან, მტკნარი წყლის აუზების ტაქსონები, მეოტური რელიქტები და ენდემური ფორმები. კიმერიულ ნალექებს, პონტურთან შედარებით, მცირე ტერიტორია უკავია და წარმოდგენილია მხოლოდ მარჩხი წყლის წარმონაქმნებით. გამოიყოფა: დუაბის, ფოქვეშის და შერეული ტიპის ფაციესები. მაკროფაუნის საფუძველძე კიმე81
რიული ნაწილდებოდა სამ ჰოროზონტად: აზოვური, კამიშბურუნული და პანტიკაპეური. ი. თაქთაქიშვილი (Тактакишвили, 1984) კიმერიულ სართულს, გეოლოგიური და პალეონტოლოგიური მოსაზრებების საფუძველზე, ყოფს ორ - აზოვურ და კამიშბურუნულ (კამიშბურუნული+პანტიკაპეური) ჰორიზონტებად. კიმერიული ასაკის ოსტრაკოდების კომპლექსები შედგება როგორც პონტურში, ასევე კიმერიულში წარმოშობილი ტაქსონებისგან. ადრეკიმერიულში პონტური ელემენტების ადაპტაცია ხდებოდა ახალ პირობებში. შუაკიმერიული Cyprididae-ს ოჯახის ზოგიერთი გვარის გაბატონების პერიოდია, ხოლო გვიანკიმერიულში მდიდარი ტიპური კიმერიული ოსტრაკოდების თანადროულად გაჩნდა Leptocithere pokveshica Vek., Trachileberis pontica arevadzeae Vek., Tr. imnadzeae Vek.-ს ერთეული წარმომადგენელი, რომელთა გაფურჩქვნა კუიალნიკურში მოხდა. დასავლეთ საქართველოში კუიალნიკური ნალექები სრულადაა წარმოდგენილი გურიაში, ხოლო აფხაზეთში კი გვხვდება მხოლოდ მისი შუა ნაწილი. გურიის და ოდესის კუიალნიკურის შესწავლამ აჩვენა, რომ მათ შორის არსებობს გარკვეული განსხვავება როგორც სიმძლავრეებში, ასევე ფაუნის შემადგენლობაში. სწორედ ამის საფუძველზე გურიის კუიალნიკური გამოყოფილ იქნა დამოუკიდებელ ბიოსტრატონად და ეწოდა ეგრისის სართული. აქ დადგენილია სამი ჰორიზონტი: სკურდუმული, ეწერული და ციხისფერდული (დრეისენიანი). სკურდუმული ჰორიზონტი შეიცავს გვიანკიმერიულ ოსტრაკოდებს. ახალი, 82
კუიალნიკურისთვის დამახასიათებელი ტიპური ტაქსონები ჩნდებიან მხოლოდ ეწერულ დროში, როცა იწყება Cytheridae-ს ოჯახის გაბატონება და Cyprididae-ს დაკნინება. ციხისფერდული (დრეისენიანი) დროის მონაკვეთს შეესაბამება კუიალნიკური ოსტრაკოდების განვითარების ბოლო სტადია. ფაუნით დათარიღებული პონტური, კიმერიული და კუიალნიკური ნალექების თითქმის ყველა ჭრილი შესწავლილია პალინოლოგიურადაც. ოტაფის და ზანის ჭრილების პალინოკომპლექსები ასახავენ მეოტურისა და პონტურის საზღვარზე მომხდარ მკვეთრ ცლილებებს, როცა მდიდარი და მრავალფეროვანი მცენარეული საფრის ნაცვლად მთის თითქმის ყველა სარტყელში განვითარდნენ ცენოზები, რომლებშიც ფიჭვია გაბატონებული. განსხვავება მეოტურ და გვიანნეოგენურ ფლორებს შორის ჩანს როგორც სუბტროპიკული მცენარეების რაოდენობაში, ისე პოზიციაში, რომელსაც შენარჩუნებული სუბტროპიკული ტაქსონები იკავებდნენ ცენოზებში. მოგვიანებით ამ ტაქსონების რიცხვი თანდათანობით მცირდებოდა. კიმერიულ დროს მთის ქვედა სარტყელში სუბტროპიკული ფორმაციის მცენარეულობა, პონტურთან შედარებით, ღარიბია. რაც შეეხება კუიალნიკურს, ამ დროს მთის ქვედადა შუა სარტყლებში გავრცელებული იყო ფოთოლმცვენი პოლიდომინანტური ტყე, რომლის შემადგენლობაში აგრძელებდნენ არსებობას წარსული ეპოქების მრავალრიცხოვანი რელიქტი.
83
ამრიგად, გვიანნეოგენური დროის განმავლობაში დასავლეთ საქართველოს ფლორისა და კლიმატის განვითარებაში გარდატეხის ორი ძირითადი მომენტი შეიძლება გამოიყოს: პირველი - მეოტურის და პონტურის საზღვარზე, როცა ფლორა გაღარიბდა და კლიმატი, მიოცენურის წინა ეპოქებთან შედარებით, გახდა ნაკლებად სტაბილური და მეორე - კიმერიულის დასასრულს, როდესაც მკვეთრმა ცვლილებებმა
გამოიწვია
თერმოფილური
ელემენტების
მასიური გადაშენება, რის შედეგად სუბტროპიკული ფორმაცია, როგორც დამოუკიდებული ერთეული, გაქრა დასავლეთ საქართველოს ტერიტორიიდან.
84
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Contents Introduction ………………………………………………………... 5 The faunistical assemblages of Upper Neogene deposits of Western Georgia …………………………………………………………... 7 The Pontian stage ……………………………………………… 7 The Kimmerian stage ………………………………………… 24 The Kujalnician (Egrissian) stage ……………………………. 39 The pollen assemblages of Upper Neogene deposits of Western Georgia …………………………………………………………. 47 The Pontian stage ……………………………………………... 47 The Kimmerian stage …………………………………………. 53 The Kujalnician (Egrissian) stage …………………………….. 57 Conclusion ……………………………………………………….. 76 რეზიუმე ……………………………………………………….... 80 References ………………………………………….…………….. 85
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