Paper No. 134-9
Presentation Time: 11:00 AM
INTEGRATED SEDIMENTOLOGICAL AND PALAEONTOLOGICAL ANALYSIS OF THE LATE CHATTIAN PLATFORM CARBONATES WITH LARGER FORAMINIFERA AND CORALLINE ALGAE FROM THE SE IBERIAN PENINSULA
Sedimentological and palaeontological analyses were performed on a kilometre-scale continuous carbonate rock exposure with larger foraminifera and coralline algae from the Benitatxell Range in the Prebetic Domain (SE Iberian Peninsula). Similar and coeval bio- and lithofacies found worldwide constitute important hydrocarbon systems such as the Asmari Formation in southwest Iran. The strata studied crop out approximately in a depositional-strike direction. The carbonates contain abundant rotaliids such as lepidocyclinids, which exhibit up to decimetric sizes, Amphistegina, Operculina and Neorotalia. Few specimens of Miogypsinoides formosensis were identified. On this latter account, the limestone unit was dated as latest Chattian (foraminiferal Shallow Benthic Zone 23). Coralline algae recognized mainly belong to the genera Mesophyllum, Lithothamnion, Sporolithon and Lithoporella. The occurrence of Ditrupa calcitic hollow tubes is also characteristic. Tests of Amphistegina and lepidocyclinids show a great range of size and shape variations indicating important transport of sediment. Skeletal components exhibit high degrees of abrasion, fragmentation, encrustation and bioerosion. These taphonomic signatures are indicative of slow sedimentation rates and reworking. Rudstone textures with micrite filling the intergranular pore space dominate. Hydrodynamic structures were not observed. The platform carbonates studied were deposited during a long-term normal regressive stage of relative sea level. This regression was preceded and followed by transgressions of Early Chattian and Early Miocene age, respectively. During this time interval, available accommodation in the Prebetic Zone was mainly controlled by regional tectonics linked to the Alpine contraction. The limestones examined were formed under warm, tropical to subtropical regimes during the latest Chattian interglacial period. This interpretation is supported by the dominance of larger foraminifera, which nowadays occur in warm low latitudes.