Clay Minerals (2001) 36, 615–620
Clay mineralogy of the Tertiary sediments in the Internal Subbetic of Ma´ laga Province, S Spain: implications for geodynamic evolution ´ - G A R C I´ A 1 , M . M A R T I´ N - M A R T I´ N 2 F. J. ALCALA ´ PEZ-GALINDO1,* A. LO
AND
1 Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Facultad de Ciencias, Fuentenueva s/n, 18002 Granada, and 2 Departamento de Medio Ambiente y Ciencias de la Tierra, Universidad de Alicante, Facultad de Ciencias, AP 99, 03080 Alicante, Spain
(Received 8 February 2000; revised 23 March 2001)
Several mineralogical and geochemical studies have been undertaken with the aim of determining the sedimentary and palaeogeographic characteristics of the Betic (Subbetic) mesozoic marine series (e.g. Puy, 1979, for the Triassic; Palomo, 1987; Rodrı´guez-Tovar, 1993, for the Jurassic; Lo´pezGalindo, 1986 and Martı´nez-Ruiz, 1994, for the Cretaceous). However, little is known of the mineralogical, sedimentary and palaeogeographic characteristics of the Tertiary in this domain (cf. Martı´n-Martı´n et al., 1994; Alcala´-Garcı´a et al., 1997, 1998a,b). This paper describes the mineralogy of the Tertiary sediments from the High Chain (Internal Subbetic, Aze`ma et al., 1979), the Tajo Almarado ´ guila Complex (Campo de (Penibetic) and the A Gibraltar Complex, Peyre, 1974), located in southern Spain (Fig. 1). During the Tertiary this area was the most remote part of the south Iberian palaeomargin, close to the Betic Flysch domain (Martı´n-Algarra, 1987) which separated the Betic Internal and External Zones. The sediments range in age from Palaeocene to early Burdigalian. In the High Chain, the sediments consist of microcodites (Palaeocene), marls, calcarenites and calcareous conglomerates (Eocene–early Aquitanian) and silexites (early Burdigalian); they occur in a series of discontinuous outcrops. The
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sediments of the Tajo Almarado are marls and marly limestones (Palaeocene–early Burdigalian). ´ guila Complex are The Tertiary sediments of the A of similar age and general facies to those from the High Chain. The Tertiary, in these three domains, is arranged in four depositional sequences, bound by unconformities (Palaeocene, Eocene, late Oligocene–Aquitanian and early Burdigalian). According to the palaeogeographic reconstructions, the Penibetic must have constituted the most inland part of the Subbetic which extended towards the Betic Flysch domain and laterally towards the proximal platforms of the High Chain (also in a internal position), whereas the materials of the ´ guila Complex have been linked with the A transition between the Betic–Riffian Internal Zone and the Flysch Domain (Predorsalian in Olivier, 1984).
METHODS One hundred and twenty samples (63 from the High Chain, 22 from the Tajo Almarado and 35 from the ´ guila Complex) of the most clay-rich levels were A examined by X-ray diffraction (XRD) using a Phillips PW 1710 diffractometer with automatic slit and Cu-Ka radiation. Analysis was performed on both the whole sample and on the clay fraction (
