Study On The Contradistinction Between Qijiaojing Formation And Liushugou Formation Of The Upper Carboniferous In The Barkol Area Of Xinjiang

Basing on the regional geological surveying project(scale at1:250000),the authorstudies the Qijiaojing Formation and Liushugou Formation of upper carboniferous in Barkolarea of Xinjiang by field geology survey. The division and contradistinction is moresystemic researched by studying its space spreading feature,contact relationship,stratigraphicsequence,rock association, the characteristics of fossil,age and sedimentary environment.Innear three years of field survey and general research, the author acquires some viewpoints, asfollows:1.The Qijiaojing Formation focused on the Qijiaojing syncline of the west study area, but theLiushugou Formation is distributed in the peripheral area of Qijiaojing Formation,they arenot contacting directly.The Qijiaojing Formation is distributed inside of hinge zone ofsyncline,and the Liushugou Formation is outside.The Qijiaojing Formation and LliushugouFormation are separated to angular unconformities on the Jiangbasitao Formation of theupper carboniferous.The top of Qjiaojing Formation and Liushugou Formation is parallelunconformities by Qijiagou Formation and Ashikara Formation whose age is middle latecarboniferous.Both are the same space spreading feature.2.The Qijiaojing Formation and Liushugou Formation can be compared and also divided intothree members.The lower member of Qijiaojing Formation is the rhythm which is made up ofmafic rock to intermediate-mafic volcanic rock, volcaniclastic rock and sedimentary rock.Themiddle member of Qijiaojing Formation is made up of clasolite with less extrusive rockintermediate layers.The rock association of the upper member of Qijiaojing Formation issimilar with the lower member,but it has more intermediate rock.The lower member ofLiushugou Formation is made up of basic volcanic rock and basic volcaniclastic rock withless intermediate volcanic rock in some area.The middle member of Liushugou Formation ismade up of intermediate-mafic volcano effusive facies rock with less mafic extrusive rockand normal sedimentary rock.The upper member of Liushugou Formation is made up ofnormal sedimentary clasolite and volcaniclastic rock with less intermediate-acidic extrusiverock. 3.The fossil assemblages of Qijiaojing Formation and Liushugou Formation are quitesimilar,both have much in common with the zoolite and phytolite,for example: Calamites andNoeggerathiopsis,Linoproductus and Dictyoclostus.According to the Zircon U-Pb age of301Ma±10Ma obtained from the basalt in Qijiaojing Formation, and the Zircon U-Pb age of314.0Ma±1.1Ma obtained from the rhyolite in Liushugou Formation,the two evidences canbe ascertained the age of the Qijiaojing Formation and Liushugou Formation is latecarboniferous.They are the same era.4.The consist of Qijiaojing Formation is intermediate-mafic volcanic rock with sedimentaryrock intermediate layers, and the sedimentary environment is considered as the center ofrift basin deposition in upper carboniferous.The consist of Liushugou Formation isintermediate-mafic rock to acidic rock with sedimentary rock intermediate layers, and thesedimentary environment was considered as the edge of rift basin deposition in uppercarboniferous.Their circumstance are different.