This paper describes Mesozoic trace fossils collected by the Hebei Geological Survey during mapping of the Sage region in 2001 and by China University of Geosciences during mapping of Jiangzi and Yadong regions in 2002.These trace fossils occurred in the following locations and geological ages:Fossil site 1:Late Cretaceous rocks in Sage and Jilong,fore-arc basins in Gangdisi and flyschdepositsintheAngrenFormationShigatseGroup.Fossilsite2:LateTriassicNiejeiFormationinLaguigangri,Kangmaregion,northernHimalayas;EarlyMiddleJurassicTianbaGroup,Early Cretaceous Jiabula Formation, and Late Cretaceous Zongzhue Formation flysch deposits.Fossil site 3: (small amount) Late Cretaceous Gangbacunkou Formation in the southern part of northern Himalayas.12 ichnogenera and 14 inchnospecies are described.Mostofthesetracefossils5inchnogeneraand7inchnospecieshaveneverbeenreportedinChinapreviously includingtwonewinchnospeciesEthologicalcharacteristicsofthesetracefossils,including9commonMesozoicandCenozoicichnogenera,thatoccurredinflyschdeposits around the world, were analyzed. According to their taphonomic environment andpreservationalstyle,thesetracefossilscan be divided into two categories:thefirsttypeisknownaspost-turbiditetraceswhicharepredominatedbyfeedingandgrazingtrails in the deep sea,forexample,Gyrophyllites,Phymatoderma,HelminthoidaandPhycosiphon.Thesetracesarecharacterizedbyactivebackfills.Thisgroupalsoincludesanimalswithchemosymbiosisthathasadoptedlowsoxygenconditions,suchaschondritesandcladichnus.Thesecondtypeispre-turbiditegraphoglyptidawhicharecharacterizedbycomplextunnelingsystemthatwasfilmedbybacteriaandgardening(Agrichnia).RepresentativesofthistypeareMegagrapton,Rhabdoglyphus,andHelicorhaphe.ThesedescribedtracefossilsalsoincludedwellingandfeddingstructuressuchasSchaubcylindrichnus,Syringgomorpha, and Cubichnia that are aligned with water currents such as Sagittichnus.Except for Tibet,Mesozoicdeepseaflychstrata(especiallyLateTrassicandJurassicCretaceousrocksarerarelydevelopedinotherpartsofChina.Thus,thesetracefossilsprovideuniquevaluablematerialtowardbetterunderstandingofsedimentology,stratigraphy, and paleogeography in Tibet.
About author: Yang Shipu, born in 1925, graduated from the department of Geology of Tsinghua University in 1950, and received graduate training at the Moscow University of the former Soviet Union during 1955-1959.Currently, he is a professor of geology at the China University of Geosciences, conducting research and teaching on Carboniferous stratigraphy, brachiopods, paleoecology, and ichnology.
Cite this article:
. MESOZOIC TRACE FOSSILS FROM SAGE-JIANGZI REGION,SOUTHERN XIZANG(TIBET),AND THEIR ETHOLOGICAL ANALYSIS[J]. JOURNAL OF PALAEOGEOGRAPHY, 2003, 5(1): 44-62.
. MESOZOIC TRACE FOSSILS FROM SAGE-JIANGZI REGION,SOUTHERN XIZANG(TIBET),AND THEIR ETHOLOGICAL ANALYSIS[J]. JOPC, 2003, 5(1): 44-62.
