青海境内三叠系上巴颜喀拉山亚群中部遗迹化石的发现及几点思考

青海境内三叠系上巴颜喀拉山亚群中部发现大量不同类型的遗迹化石,对造山带成层有序地层划分与对比尤为重要。根据遗迹化石的组合及其与地层的关系,可划分5个组合带(自上而下):5)Bergaueria-Helminthoidichnites;4)Helminthoidichnites-Circulichnis;3)Monocraterion-Helminthoida;2)Palaeophycus-Paleodic-tyon;1)Helminthoi-dichnites-Phycosiphon。这些不同类型遗迹化石可能与具体环境的关系并不紧密,而与岩性、水流活动密切相关。

DISCOVERY OF THE TRIASSIC ICHNOFOSSILS IN MIDDLE PART OF THE UPPER BAYANHARASHAN SUBGROUP IN QINGHAI AND ITS IMPLICATIONS

In the Bayanharashan area of eastern Kunlun Mountains, the Bayanharashan Subgroup consists of a series of stratified rocks with evidence for low-grade metamorphism and recognizable sedimentary structures. Ichnofossils, only briefly mentioned in previous studies of the Bayanharashan Subgroup, have been found from the middle part of the Upper Bayanharashan Subgroup in this study. Five trace fossil assemblages have been recognized. These are, in ascending order, 1) the Helminthoidichnite-Phycosiphon Zone, 2) the Palaeophycus-Paleodictyon Zone, 3) the Monocraterion-Helminthoida Zone, 4) the Helminthoidichnite-Circulichnis Zone, and 5) the Bergaueria-Helminthoidichnites Zone. These ichnofossil assemblages are not closely related to paleoenvironments; instead, they appear to be associated with lithologies and hydrodynamic conditions.