First evidence of Late Carnian radiolarians from the Izmir-Ankara suture complex, central Sakarya, Turkey: implications for the opening age of the Izmir-Ankara branch of Neo-Tethys

Within the Late Cretaceous mélange complex of the Izmir-Ankara suture zone in central Sakarya area, north-western Turkey, a megablock with radiolarian cherts associated with basaltic pillow lavas has been dated by radiolarians. The studied radiolarian assemblage and conodonts yielded an early Late Carnian age. This age is the oldest obtained from the chert blocks all along the suture belt and has important implications for the rifting/opening age of the Izmir-Ankara branch of the Tethys ocean in north-western Turkey. Based on this new data, it is concluded that during the Late Triassic the Izmir-Ankara seaway was connected to the other Tethyan oceanic branches and deep enough to provide chert sedimentation and exchange radiolarians with the main open oceans. It is further suggested that the long-lasting misinterpretation of a Liassic rifting/opening of the Izmir-Ankara ocean should be revised.     

西藏普兰县姜叶玛地区中二叠统西兰塔组中的有孔虫及其地质意义

西藏雅鲁藏布江缝合带蛇绿混杂岩中混杂着大小不一的二叠纪灰岩块体,它的来源一直颇有争议,这些灰岩块体中动物群的古生物地理面貌是判断其来源的重要手段。姜叶玛灰岩体是位于西藏普兰县境内混杂在中生代蛇绿混杂岩中的一个大型二叠纪灰岩块体。其中,中二叠世西兰塔组中含有丰富的非?有孔虫化石,它们主要由Neodiscus,Climacammina,Pachyphloia和Lysites组成,伴生有Dagmarita,Deckerella,Globivalvulina,Neoendothyra,Lasiodiscus,Lasiotrochus,Tetrataxis,Geinitzina,Ichthyofrondina,Nodosaria,Nodosinelloides,Agathammina,Septoagathammina和Shanita,时代相当于中二叠世Capitanian期。古生物地理上,Lysites和Shanita的出现表明这个动物群属于基墨里生物区,它们从古生物地理上以及生物多样性上和印度板块北缘的巴基斯坦盐岭地区以及藏南喜马拉雅区的同时代动物群有显著差别。结合前期?类动物群古生物地理的研究,姜叶玛灰岩块体很可能位于拉萨地块与喜马拉雅之间的新特提斯洋海山上,与两个地块之间都有一定的隔离。这也说明新特提斯打开的时间早于中二叠世。     

Late Carnian (Tuvalian,Tropites dilleri zone) ostracods (Crustacea) from the Mufara Formation (Monte Scalpello,Central-Eastern Sicily,Italy)

Ostracod association from the Upper Triassic (Tropites dilleri zone of the Carnian stage) of the sedimentary succession (Mufara Formation) exposed along the east side of Monte Scalpello (Catenanuova, central eastern Sicily) has been studied for the first time. The specimens, silicified, are rare but well preserved and often consist of complete carapaces. They belong to eight families: Healdiidae, Cavellinidae, Bairdiidae, Acratiidae, Bythocyprididae, Pontocyprididae, Judahellidae, Glorianellidae. Twenty-three taxa have been listed; the family Bairdiidae is the most represented among all the others with fifteen species. Four species are new: Bairdia scaliae n. sp., Acratia maugerii n. sp., “Anchistrocheles” gemmellaroi n. sp. and Judahella? montanarii n. sp. Other species are left in open nomenclature because of the lack of specimens.