Thesis/Dissertation Guide For Postgraduates Of Northwest University

The Xinjiang Jimsar sag of Permian Lucaogou Formation(P21)is a very important tight reservoir.Previous studies believe that this set of strata in Lucaogou Formation is normal lake facies,lacustrine facies clastic sedimentary rocks and carbonate sedimentary transitional.According to a study in the Junggar basin research team for many years,found from Late Carboniferous to Permian in Jimsar sag located in the eastern area of the basin is an intracontinental rift,and influenced by the magmatic hydrothermal fluid in the sedimentary period,the formation of hydrothermal exhalative sedimentary environment of Jimsar sag characteristic.In addition to the normal sedimentary terrigenous clastic rocks,it is also the first time to find the hydrothermal exhalative sedimentary rocks related to volcanic activities and magmatic activities.Hydrothermal exhalative sedimentary rocks is related to magmatic rock assemblages,and deep source hydrothermal activity:lamellar alkaline peralkaline tuffs(neutral andesite)and ultramafic tuffs(carbonate),also found signs in the study area is rich in algae and biological activities.The Jimsar sag in Permian Lucaogou Formation of rock types,mineral characteristics,sedimentary characteristics and formation environment of the following understanding:(1)Hydrothermal exhalative sedimentary rocks can be divided into five categories,mainly dolomite and tuff.There are various types of sedimentary rocks in the area,which mainly include horizontal bedding and cross bedding,and also found that the bedding and drainage structures are equivalent to the deformed structures,and the special biogenic structures in this area.Lucaogou group develops a set of related activities of the volcano tuff(volcano clastic rocks)and tuffaceous dolomite,micritic dolomite and other microorganisms.The petrological and mineralogical identification and comprehensive geochemical analysis,that the mineral assemblage in this area is formed in the special environment,the hydrothermal exhalative sedimentary magmatic hydrothermal and mantle composition,volcano activity.(2)According to the geochemical experiment and analysis of Lucaogou Formation of rocks,the conclusions are as follows:? carbon and oxygen isotope analysis results shows that the study area in the high salinity in the deposition period of poor water circulation,the lake environment evaporation faster,and by the mixing of hydrothermal fluid and lake water.?According to the experimental analysis of major and trace elements,through the sample of vanadium(V),nickel(Ni)and strontium(Sr)and barium(Ba)and the ratio of redox sensitive elements,indicating the continental sedimentary environment in high salinity,hypoxia.? On the rare earth elements,samples show LREE are enriched in the distribution pattern of LREE,and appeared weak positive Ce anomalies and negative Eu anomalies,reflected in a weak alkaline oxidation,reduction and the formation of sedimentary environment in the low temperature.(3)There are some special biological form is different from the normal mineral Lucaogou Formation of hydrothermal exhalative sedimentary rocks,some are well preserved in the biological and biological structure,after the death of the other minerals account.Common to the mineralization of iron mineralization,mineralization,silicification,as well as some biological cavity and bone fragments.The structure and type of metasomatic minerals presumably Ostracoda,trilobites and other creatures.This kind of organism mainly occurs in the crystal-grade dolomite layer,which is closely related to the magma genesis calcite.