جستجوی مقالات مرتبط با کلیدواژه « early cenomanian » در نشریات گروه « زمین شناسی »

In order to study of the systematic and paleoecology of Cretaceous (Aptian-Early cenomanian) Brachiopods, the Estakhrooyeh section in NW Baghin, west of Kerman City with 190 m in thickness was studied and sampled. The Middle part of this section contains diverse assemblages of macrofossils such as Brachiopods, Echinoderms, Gastropods, Bivalves and Corals. This biostratigraphic research resulted in to examine 5 genera and 10 species of brachiopoda of Sellithyrididae family for the first time from this section. The Brachiopods indicate Aptian-Early Cenomanian ages for these sediments. The Faunal assemblages suggest a shallow and suitable environment prevailed during the deposition of the strata.

The thick layers of late Aptian- early Cenomanian deposits in the northwest of Kerman, which consist of mainly marl and limestone has been sampled and studied. The thickness of the succession in the Basab area is 380 meters and is subdivided into 4 distinct and informal units that named Lower Basab Marl, Lower Basab Limestone, Upper Basab Marl and Upper Basab Limestone. The base of this section overlies paraconformably the Jurassic (Liassic) sandstones, while the upper boundary is an erosional surface and covered by the Neogene deposits. Among the macrofossil assemblages that found in this section, the Oysters that belong to three families of Gryphaeidae, Palaeolophidae and Ostreidae are more abundant. The Gryphaeidae family with 80% is more abundant than other families and discussed in this paper. Seven genera and species of this family are reported. Palaeoecological studies and taphonomy effects on the surface of specimens show a warm, shallow environment (intertidal and sublittoral) with a high energy during the deposition of the strata. The Oysters in studied area is very similar to those specimens reported from Egypt in the Wadi Qena Basin.

For study of systematic and palaeoecology of Mid-Cretaceous Oysters, the Basab section, with 380 m thickness, west of Kuhbanan, northwest of Kerman, was measured and sampled. The section comprises a high diverse fauna (macro and microfossils), such as Echinoids, Bivalves, Oysters, Brachiopods, Gastropods, Corals, Ammonites, Foraminifers and Ostracods. The fossils indicate Late Aptian- Early Cenomanian age for the studied section. Eleven genera and species of Mid-Cretaceous Oysters are reported for the first time from the region. The fossils assemblages show a shallow and favorable condition during the deposition of the strata. The study of the Oysters indicates that the peak of abundance of the fossils correlates with high values of δ13C curve. This implies deposition of high amount of organic carbon, low oxygen condition, elimination of other taxa and opportunistic character of the Oysters.