摘要
Over the last 30 years,terrestrial ichnofossil research was mostly focused on three ichnofacies:the Scoyenia ichnofacies,characterizing transitional fluvio-lacustrine environments,the Mermia ichnofacies,characterizing fully lacustrine settings,and the Termitichnus ichnofacies,characterizing terrestrial environments,especially,paleosol deposits.Specially in China,many terrestrial ichnofossils,including at least 24 ichnogenera from fluvial deposits and 59 ichnogenera from lacustrine deposits,have been found in Mesozoic and Cenozoic basins.Most of them belong to the common elements of the three ichnofacies and consist of feeding,grazing,crawling,dwelling,and resting traces and rhizoliths.Based on the composition,occurrence and distribution characteristics of trace fossils from terrestrial sedimentary basins of China,36 ichnoassemblages have been proposed.However,the most common 12 ichnoassemblages,in which six are found in fluvial sedimentary environments from the Upper Cretaceous of the Sichuan Basin in western China and Xixia Basin in western Henan Province,include:(1)Scoyenia-Rusophycus ichnoassemblage generated in the floodplain along channels and the shallow water swales or lakes(such as oxbow lakes);(2)Skolithos-Arenicolites ichnoassemblage produced in the high energy sandy bar(heart bar or point bar)of the channel environment;(3)Gastruichnus-Palaeophycus ichnoassemblage developed in the channel-levee environment;(4)Beaconites-Taenidium ichnoassemblage occurring in the embankment(crevasse splay)sedimentary environment;(5)Beaconites-Rhizolithos ichnoassemblage appearing in the floodplain sedimentary environment,and(6)Beaconites-Scoyenia ichnoassemblage distributed in the periodically exposed overbank lake(extremely shallow lacustrine)sedimentary environments.The other six ichnoassemblages are found in lacustrine sedimentary environments:(1)Scoyenia-Skolithos ichnoassemblage always developed in periodically exposed,extremely shallow lakeshore and interdistributary bay of the lake delta plain under drought or semiarid climate conditions;(2)Palaeophycus-Arenicolites ichnoassemblage formed in the lakeshore to the upper part of the shallow lake,corresponding to the lake delta plain to delta front;(3)Planolites-Teichichnus ichnoassemblage generated in the lower part of the shallow lake,restricted lake bay or distal front delta;(4)Vagorichnus-Helminthopsis ichnoassemblage developed in the deeper lacustrine(profundal)turbidite sedimentary environment;(5)Mermoides-Neonereites ichnoassemblage occurring in the quiet deep or deeper lacustrine sedimentary environment;and(6)Semirotundichnus-Chondrites ichnoassemblage formed in even deeper lacustrine sedimentary environments with lower oxygen content.
Over the last 30 years,terrestrial ichnofossil research was mostly focused on three ichnofacies:the Scoyenia ichnofacies,characterizing transitional fluvio-lacustrine environments,the Mermia ichnofacies,characterizing fully lacustrine settings,and the Termitichnus ichnofacies,characterizing terrestrial environments,especially,paleosol deposits.Specially in China,many terrestrial ichnofossils,including at least 24 ichnogenera from fluvial deposits and 59 ichnogenera from lacustrine deposits,have been found in Mesozoic and Cenozoic basins.Most of them belong to the common elements of the three ichnofacies and consist of feeding,grazing,crawling,dwelling,and resting traces and rhizoliths.Based on the composition,occurrence and distribution characteristics of trace fossils from terrestrial sedimentary basins of China,36 ichnoassemblages have been proposed.However,the most common 12 ichnoassemblages,in which six are found in fluvial sedimentary environments from the Upper Cretaceous of the Sichuan Basin in western China and Xixia Basin in western Henan Province,include:(1)Scoyenia-Rusophycus ichnoassemblage generated in the floodplain along channels and the shallow water swales or lakes(such as oxbow lakes);(2)Skolithos-Arenicolites ichnoassemblage produced in the high energy sandy bar(heart bar or point bar)of the channel environment;(3)Gastruichnus-Palaeophycus ichnoassemblage developed in the channel-levee environment;(4)Beaconites-Taenidium ichnoassemblage occurring in the embankment(crevasse splay)sedimentary environment;(5)Beaconites-Rhizolithos ichnoassemblage appearing in the floodplain sedimentary environment,and(6)Beaconites-Scoyenia ichnoassemblage distributed in the periodically exposed overbank lake(extremely shallow lacustrine)sedimentary environments.The other six ichnoassemblages are found in lacustrine sedimentary environments:(1)Scoyenia-Skolithos ichnoassemblage always developed in periodically exposed,extremely shallow lakeshore and interdistributary bay of the lake delta plain under drought or semiarid climate conditions;(2)Palaeophycus-Arenicolites ichnoassemblage formed in the lakeshore to the upper part of the shallow lake,corresponding to the lake delta plain to delta front;(3)Planolites-Teichichnus ichnoassemblage generated in the lower part of the shallow lake,restricted lake bay or distal front delta;(4)Vagorichnus-Helminthopsis ichnoassemblage developed in the deeper lacustrine(profundal)turbidite sedimentary environment;(5)Mermoides-Neonereites ichnoassemblage occurring in the quiet deep or deeper lacustrine sedimentary environment;and(6)Semirotundichnus-Chondrites ichnoassemblage formed in even deeper lacustrine sedimentary environments with lower oxygen content.
基金
supported by the National Natural Science Foundation of China(No.41272117 and No.41102002)
the International Cooperation Program of Henan Province(No.124300510039)
