The Division And Comparison Of The Carboniferous System In The Qianjin Ranch Area,E-Min,Western Junggar

This dissertation is object on the sedimentary stratum of Carboniferous System，whichis situated on the northern and southern of Xiemisitai fault zone, the Qianjin-Ranch area ofWestern Junggar, Xinjiang. Based on the study of rock association, organic fossil analysis,sedimentary environment, petrogeochemistry and contact relationship between the stratum,gained the achievement as follows:1. The Carboniferous Jiangzierkuduke Formation on the northern of Xiemisitai faultzone and the Carboniferous Jiangbasitao Formation and Heishantou Formation on thesouthern of Xiemisitai fault zone, has some difference on rock association.2. A lot of fossils were discovered from the calcareous siltstone and limestone gravel inthe Jiangzierkuduke Formation, which is consisted of brachiopoda, plants, corals,atactotoechus and sporopollen, the geologic period of this fossils all belong to the earlycarboniferous. Besides this, the zircon U-Pb age of pyroxene andesite at top ofJiangzierkuduke Formation is334.5±7.6Ma, and the zircon U-Pb age of dacite in HeishantouFormation is331±2.4Ma, this illustrate that the formation age of the carboniferous systemon the northern and southern of Xiemisitai fault zone is similar, both of them are the earlycarboniferous, which belong to the same age.3. The sedimentary environment of the Carboniferous System on the northern ofXiemisitai fault zone is located at the edge of the ocean basin and begin to transition frommarine to continent gradually, which is the marine-terrigenous facies, while the seawatersedimentation of the Carboniferous System on the southern of Xiemisitai fault zone is deeperthan the northern, and still keeps the littoral-neritic facies.4. The geochemical features of the Carboniferous volcanic rocks is the same inessentials while differing in minor points. On the major elements, both of them are similar inSiO2content, rich in Na and lack in K, belong to calc-alkaline series, both of them with thehigh of Al2O3, and the low of TiO2and P2O5, during the magmatic evolution, the changes ofthe corresponding oxides are similar, while the Carboniferous volcanic rocks of the southernare higer than the northern in Na2O+K2O and TiO2content. On the rare earth microelement,both of them are rich in LREE, and the differentiation of LREE and HREE is obvious,enriched in LILE and depleted in HFSE, which are similar to those of the island-arc volcanorocks. On the tectonic setting, both of them are produced by the the subduction of island-arc,and mixed with the subduction component.Besides this, the feldspars in the volcanic rocks all belong to alkali-feldspar, but most of them in the northern are albite, while most of themin the southern are orthoclase, and both of them have the alteration of albitization.Comparing with the Carboniferous System on the northern and southern of Xiemisitaifault zone, the Qianjin-Ranch area of Western Junggar, it is discovered that they are the samein essentials while differing in minor points, this illustrate that they are produced in a sameocean basin presumably. But it could form the different Carboniferous structures between thenorthern and southern of Xiemisitai fault zone, by the special sedimentary environment and aseries of multi-stage combined effect of the Xiemisitai fault.