Permian-Triassic Trace Fosslls in the Eastern Kunlun Orogenic Belt

Key words: 
• Eastern Kunlun /
• orogenic belt /
• trace fossils /
• non-smithian stratigraphy /
• tectonic slices

Abstract: Both the Skolithos ichnofacies and the Nereites ichnofacies have been recognized in the Permian-Triassic of the eastern Kunlun orogenic belt.In the case of the strong deformation,metamorphism and position variation in an orogenic belt,it is difficult to find the body fossils and the physical depositional structures .But the identification of the environment is very important to the study of the structures and the evolution of the orogenic belt, so we must find another efficient way .Through two years of hard works on the trace fossils in eastern Kunlun orogenic belt,we identified Skolithos,Palaeophycos, Gordia,Baugouria, Thalassinoides,Rhizocorallium and so on in the lower part of Hongshuichuan Formation and merged these trace fossils into Skolithos ichnofacies.In many flgsch slices and limestones slices, we found many deep-sea trace fossils,such as Palaeodictyon,Protopalaeodictyon,Helminthoida and Chondrites, which belongs to Nereites ichnofacies . Since professor Kenneth J.Hsii made inaugyrated work in San Franciscomelange,many geologists have tried to recover the original tempoal sequences,position sequences and lithofacies sequences of the orogenic stratigraphy,But body fossils are rare in the orogenic stratigraphy,tgpical epositional structares wrer rebuilt by tectonic and metamorphosed actirities,losing their initial faces.Though two-years field work in eastern orogenic belt,we found that trace fossils can determine the sedimentary environmedt of some orogenic slices-the melange,bing significant to the recovering of lithofaties sequences of ovogenic stratigraphy. Furthermore,using trace fossils,we also can contrast stratigraphy in orogenic belt.We fourd an important feature in the lower part of Hong shuichuar Formation that the “skolithos” is very abundant.On the base of field investigation,we ascribe the stratum uhich have abundant “skolithos” and familiar lithology to the lower part of Hong shuichuar Formation. Studies of trace fossils can play a significant role in a sedimentary environmental analysis,stratigraphical correlation and identification of tectonic slices in an orogenic belt.