The Comparative Study Of Standard Stratotype-section In Middle Devonian At East And West Of Junggar,Xinjiang

Using the field,indoor,test,and comprehensive research methods,according to the requirements of the strata guide to reclean and revise the typical stratigraphical(stratotype)sections of the Middle Devonian strata;Focus on the comparison of rock combinations,biological combinations,top(bottom)contact relationships,and sedimentary environments in each typical stratigraphical(stratotype)sections and gain the following understanding:1.It was confirmed that the Kurumudi group and the underlying formation are regionally angular unconformity contact: the basal conglomerate developed at the bottom,the characteristics are clear,and the angles between the underlying Mayler range are unconformity.The two sides of the strata are extremely clear on the remote sensing image,with good distinguishability and an ideal layer profile.2.It is re-determined that the siliceous rock as the bottom mark layer of the Barluk and interface with the Kurumudi group.There is no feasible regional mark layer for the division and comparison of the Barluk and the Kurumudi group,and because the rock groups of the two groups are very similar,therefore,the interface of the two groups and the artificiality of the regional geological mapping inevitablly.The survey found that the Barluk group exposed a layer of light-colored siliceous rock layers that are easily identified and easily distinguishable from the upper and lower layers,and the output and the area extensions are extremely stable,and are found throughout the entire Maierle formation.This is the mark layer,which is an excellent division of the two sets of interfaces;3.The zircon U-Pb age of 391.5 Ma was obtained in the basalt of the Beitashan Formation in the East Junggar,and confirming that the age is Middle Devonian(roughly equivalent to the Eifelian).The zircon U-Pb age of the basalt in the YunduKala Formation was385.2±4 Ma,confirming that it was in the Middle Devonian(approximately equivalent to the Givert period).The peak age of detrital zircon was 412 Ma in Devonian Kurumudi Formation of Tiechanggou Hatu Fault Northern,west Junggar,the zircon age are concentrated in 390 ~425 Ma,and combined with the data of fossils in this group.The Kurumudi Formation was Middle Devonian,which provided important new evidence for the geological age of this group.4.According to the comparison of the Middle Devonian strata between the Ertai stratigraphic communities in East Junggar and the Beitashan stratigraphic area,it is found that the two stratigraphic communities are not comparable from the rock characteristics,biological assemblages and sedimentary environments.The Sharburti mountain stratigraphiccommunities and the Middle Devonian strata in the Mayle mountainous area are compared,It is found that two stratigraphic communities are also not comparable in biological assemblages,rock characteristics and sedimentary environments.5.According to the Ertai stratigraphic communities in East Junggar,the Beita mountain stratigraphic plot,the Middle Devonian strata in West Junggar Sharburti mountain and Mayle mountainou stratigraphic communities are compared,and it is found that the eastern and Western Junggar strata can be compared in the bio-assemblage,the rock assemblage and the sedimentary environment,but the whole can not be compared.