青海曲麻莱-治多地区巴颜喀拉山群(上三叠统)遗迹化石

首次对青海南部曲麻莱-治多地区巴颜喀拉山群上部(上三叠统)遗迹化石进行了系统采集,共采获遗迹化石33属54种。据遗迹化石的形态、习性、水深等环境成因特征,可划分为两类组合:一类以Cosmorhaphe,Helminthopsis,Helminthoida,Megagrapton,Paleodictyon等为主,产生于浊流事件前;另一类以Chondrites,Neo-nereites,Palaeophycus,Phycosiphon,Planolites,Zoophycos等为主,产生于浊流事件后,两者均为半深海-深海Nereites遗迹相的典型代表,反映晚三叠世研究区应为浊流沉积发育的复理石相沉积。

TRACE FOSSILS OF THE UPPER TRIASSIC BAYANHARSHAN GROUP IN THE QUMARLEB-ZHIDOI AREA, SOUTHERN QINGHAI

Trace fossils from the upper pant of the Bayanharshan Group (Upper Triassic) in Qumarleb-Zhidoi area, Southern Qinghai Province, have been systematically gathered for the first time, they comprise 54 ichnospecies in 33 ichnogenera. The main ichnogenera include Arthrophycus,Asterichnus,Chondrites,Circulichnis,Cosmorhaphe, Didymaulichnus, Helminthoida,Helminthopsis,Megagrapton,Neonereites,Nereites,Palaeophycus,Palaeodictyon,Pelecypodichnus,Phycodes,Phycosiphon,Planolites,Xiangquanheichnus,Zoophycos and so on. According to the morphology, ethnology and water depth, the studied trace fossils include two ichno-assemblages: one formed before turbidity flows, such as Cosmorhaphe,Helminthopsis,Helminthoida,Megagrapton,Palaeodictyon etc., and the other emplaced after the turbidity event, such as Chondrites,Neonereites,Palaeophycus,Phycosiphon,Planolites,Zoophycos, etc. Both of these assemblages are typical representatives of the bathyal-abyssal Nereites ichnofacies, which therefore would indicate that the Late Triassic pant of the Bayanharshan Group of the studied area was formed in a flysch facies with abundant turbidity currents.