Construe On Sedimentary Facies And Sedimentary Environment Of Lower Carboniferous Licorice Lake Group In The East Segment Of South Tianshan

Located in the northern margin of Tarim plate,South Tianshan is bounded by thesouthern margin fault of middle Tianshan in the north and close to middle Tianshan land,which save Paleozoic ocean basin remnant on the north side. Northern margin of Tarim plateexperience evolutionary processes of Passive continent margin and foreland basin duringPaleozoic,which is also the main area of ancient plate convergence andintracontinental superposition orogenic.The formation and evolution of basin reflect platetectonic and the control of lithosphere dynamics process,basin and orogen belt constitute thebasic field of continental dynamics and lithosphere study.So to study the evolution history ofthe south tianshan basin have profound significance on the study of the forming process ofSouth Tianshan orogen belt.While to sdudy the evolution history of the south tianshan basin,we need concrete research on its sedimentary strata、sedimentary facies、sedimentaryenvironment evolution and so on.The paper is on the basis of four images(malan、xinjingzi、baitutan、baitutang)1:50000regional geological survy project in Xinjiang,by means ofcollecting predecessor’s a lot of work in the area and neighbor area,analysising and dealingwith Lower Carboniferous Series Licorice Lake Group’s work data in this study area.Due tothe less work predecessors have done,this paper collect all aspects of data in detail,researchcompletely and systematically,get some understanding as follows:1、Lower carboniferous Licorice lake group deposit a series of neritic facies terrigenousclastic rocks and carbonate rocks,which devided into three lithologic members,The firstlithologic member：Gray to dark gray calcarenitic terrestrial bioclastic limestone,flint stripedevelop in limestone,local clip khaki calcareous shale、calcareous siltstone、lithic sandstone,horizontal bedding developed； The second member： calcarenitic calcirudyte clipcalcareous shale、 fine sandstone, local clip pebbly coarse sandstone, developparallel bedding、 inclined beddings、cross-beddings；The third member：gray thin-beddedfine sandstone,black siliceous rocks and siltstone interbed,local clip calclithite、grey-greyishgreen siltstone、 yellow thick pebbly coarse sandstone、 thick glutenite, developparallel bedding and inclined beddings.We collect Conodonts fossils in the fourth layer of thefirst lithologic member, they are Neopolygnathus sp., Neopolygnathus communis cf.dentatus(Druce,1969),Polygnathus nodosaries Ji, Xiong and Wu,1985,Pseudopolygnathus trigonicus pinnatus Voges.1959,Pseudopolygnathus sp.,the era belongs to Tournaisian inearly carboniferous.2、Licorice lake group of lower carboniferous has no overlying strata in this study area,while it is with Arpishmebulaq Formation of lower Devonian for fault contact.3、Licorice lake group of lower carboniferous profile in this study area can compare withregional Licorice lake group profile completely,such as rock association、biological aspect、stratigraphic contact and sedimentary facies.4、 According to the analysis of rock association characteristics、 paleontologycharacteristics、 the rock and minerals characteristics、 sedimentary structure mark、sedimentary sequence mark、grain size characteristics、silicalite characteristics of LicoriceLake Group,we come to a conclusion that main sedimentary environment is neritic-bathyaldeposit,which reflects the overall change from shallow to deep sea sedimentary process and itis devided into three subfacies: neritic transitional zone subfacies、tempestite subfacies、turbidite subfacies. The neritic transitional zone subfacies develop in the first and secondlithologic member, the basic sequence are limestone-argillaceous limestone,calclithite-calcar-eous shale,fine sandstone-calcarenite,which all constitute a cycle deposition；The tempestitesubfacies develop in the second and third lithologic member, the basic sequence iscalcarenite-conglomeratic limestone-conglomeratic sandstones-fine sandstone-siltstone clipblack silicalite,which consititute a small and medium-sized sedimentary sequence；Theturbidite subfacies develop in the third lithologic member, the basic sequence arefine-siltstone-black silicalite-calclithite and dark grey siltstone、pelitic siltstone-dark greybioclastic calcarenite,which constitute a cycle deposition..5、 According to the analysis of silicalite,Aierbin Paleozoie Basin belongs tocontinental margin deposits,which exist between Silurian and early early Carboniferous.In theearly early Carboniferous this research area developed neritic transitional zone subfacies、tempestite subfacies、turbidite subfacies sedimentary rock of neritic-bathyal environment.