Sedimentary Evolution Of Permian South Qilian Basin

The research main part is the south Qilian basin.The basin is located in the northeastern margin of qinghai-tibet plateau.The north is adjacent with mid of Qilian mountain,The south is near with ZongWuLong-qinghai nanshan,The northwest was cuted off by Altyn Tagh fault,and end up around Qinhai lake at the east,and the strike towards south from northwest.the area is up to about 6.3*10⁴ square kilometers in total.South qilian area is an important part of the southern orogenic bel of north China plate,because of its abundant geological phenomenon and the good expose conditions,the area has became a classy research area of our country’s orogenic bel.the study has important theoretical significance for the south qilian area of its prototype and evolution in different period and helpful to find the location of oil and gas,coal and other mineral resources there.Based on the former research achievements,through the field investigation and indoor research on Shule river area,Tianjun country,Qinghai province,and compare with other’s stratigraphic section of south Qilian basin of Permian,restore the south Qilian basin in different periods of the Permian basin prototype,all-round,multi-angle study of the south Qilian basin of Permian climate environment evolution process.The strata of the Permian of the south Qilian basin consisted by lemengou sedimentary,caodigousedimentary,hajiersedimentaryandzhongshigong sedimentary（from bottom to top strata）.the sedimentary of Permian lack of the deposit of early-stage.Most of deposit is come from middle and addvanced stage.The Permian south Qilian basin experienced a complete process of a transgression from Lemengou sedimentary period to Caodigou sedimentary period,and the regression from Caodigou sedimentary period to end of the Permian.From the perspective of sedimentary facies,in the Lemengou sedimentary period,the south qilian area widely developed shore land deposition.In the Caodigou sedimentary period,the sea level relatively rose,so that the bottom of this deposition in this period is mostly of carbonate deposition,and the shore clastic sedimentary facies in the upper deposition shows that the sea level begins to regression.In the Hajier phase,the sea level relative changed frequently,developed shoreland sedimentary facies well.Then in the Zhongshigong sedimentary period,the south Qilian basin became a restricted epicontinental sea develops delta deposition because of which was sealed by uplifted strata around the south Qiliang basin.Throughout the whole progresses,the south Qilian basin in Permian went through the warm and humid weather before mid of Caodigou sedimentary period,then comes to the Hajier sedimentary period,it was high temperature and drought in the early,then it changed back to warm and humid again but not last too long this time,during the period of Zhongshigong sedimentary period,it was return to the high temperature and drought climate again for a fairly long time.Overall,the climate of the south Qilian Permian is went through"warm and wet-temperary hot drought-warm and humid-fairly long time hot and drought"circles.