Trace Fossils And Sedimentary Environments Of The Cretaceous Basin In Western Henan Province

This research focuses on the trace fossils and sedimentary environments of the Cretaceous basin in Western Henan Province, using an integrated approach of sedimentaology, ichnology, petrology and geochemistry, three aspects of results are chiefly obtained as follows:(1) Abundant of trace fossils are discovered in the Yuyang, Tantou and Xixia basins,including invertebrate trace fossils 13 ichnogenus and 27 ichnospecies, and other unnamed burrows, bird trackways and Rhizoliths. They can be classied into domichnia,repichnia, fodinichnia, pascichnia and fugichnia according to the principle of behavioral classifications, which domichnia and fodinichnia are priority to other types. Comparing to trace fossils among the three basins, the conclusions are: ① The biological individuals of Later Cretaceous are larger than the Early Cretaceous. ② Trace makers are more adapted to living and activity in relatively stable habitat of Later Cretaceous.(2) Based on the study of lithological structural features, grain size characteristics,geochemical characteristics, sedimentary sequences and ichnoassemblages, the sedimentary environments are recognized in the Cretaceous basin of Western Henan province. The Tantou Basin deposited in an arid setting typified by alluvial fan,lacustrine fan delta and lake systems. The Ruyang Basin was interpreted mainly as alluvial fan and pond deposits during the semi-arid setting. The Xixia Basin deposited in a semi-arid setting typified by alluvial fan, braided fluvial, meandering fluvial and fluvio-lacustrine systems.(3) According to the compositions, distributions, occurrences of trace fossils and sedimentary environments, 11 ichnoassemblages are established in alluvial fan, pond deposits at the fan edge, lacustrine fan-delta plain to fan-delta front, shore and shallow lacustrine, channel environment of bradied and meandering river, natural levee and crevasse splays, flood plain, and periodically exposed fluvio-lacustrine sedimentary environments.The ichnoassemblages occurred in the Yuyang, Tantou and Xixia basins, which can be classified into Scoyenia ichnofacies.The research results not only enrich the trace fossils database of terrestrial origin but also offer new data to complete furthercontinental ichnofacies mode, and also provide the evidences on palaeoenvironments of the Yuyang, Tantou and Xixia basins. The 11 types of ichnoassemblage models have the potential to study of trace fossils and improve palaeoenvironmental analysis of other terrestrial basins.