Ichnology and Sedimentology of Fluvial Deposits in the Middle Triassic Youfangzhuang Formation,Henan Province, North China

摘要

INTRODUCTION Ichnofossils are the records of ancient animals' activities in/on the substrate, and are the indirect evidence of life in the earth's history. In comparison with their marine and lacustrine counterparts, fluvial ichnofaunas have not been extensively investigated to explore the sedimentary environmental conditions and the filling history (Buatois and Mangano, 2009). Due to fluidity, fluctuation and short duration of the sedimentary settings, application of ichnofossils in fluvial sediments cannot be simply extrapolated from marine and lacustrine settings. Recently, a number of ichnologic concepts (e.g., ichnofacies, ichnofabrics) were used to address ichnofossil distributions in the fluvial subfacies. We favor a combination of ichnology with sedimentology to study the fluvial filling history because ichnofacies or ichnofabrics and sedimentary structures will vary with the development of the fluvial sediments.