Study Of Sedimentary-tectonic Evolution Since Late Paleozoic And Its Impacts On Oil And Gas Geological Conditions Of Yin-E Basin

Based on the study of regional geological tectonics and detailed field geological survey in Yin-E Basin of Western Inner Mongolia,this dissertation made a study on the evolution of sedimentary-tectonic and thermal history since Late Paleozoic by using vitrinite reflectance(Ro),apatite fission track(AFT),fluid inclusions and so on.5 innovative recognitions can be concluded.1.Formation age and type of Yin-E Basin can be redefined.During Late Silurian-Early Middle Devonian,Paleo-Asian Ocean was closed under the actions of the southward subduction of Mongolia oceanic plate and collision of Siberian Plate and Sino-Korean Plate.During Carboniferous-Permian,thick rock combination consists of volcanics,clasolite,carbonatite were deposited in Yin-E Basin,i.e.continental rift basin formed in Ejina Banner and its adjacent area,including Yingen-Ejin Banner basin,Beishan Basins group,etc.2.Distribution characteristics of tectonic-lithofacies paleogeography in Carboniferous-Permian can be researched systematically.During this period,the overall environment was active littoral and shallow sea type,sediments were mainly shallow marine volcanic-sedimentary formation,and lack of semi-deep and deep water sedimentary formation in slope facies.In conclusion,the sedimentary features were controlled by structural property of basin.3.Tectonic evolution since Hercynian can be researched.In Yin'E Basin,Tectonic evolution since Hercunian was divided into two stages,i.e.intracontinental rift valley and depression evolution in Late Hercynian,intracontinental basin-mountain tectonic evolution in Mesozoic-Cenozoic Era.There are four tectonic movements in basin,including:?Late Hercynian(P3-T1),?Early-middle Yanshan(J2-J3),?Late Yanshan(K2),?Himalayan(E-Q).Besides,the apatite fission track analysis was applied in different tectonic positions of basin;the ages were mainly 90±6?1599±11Ma,in which ages of Yagan area,located in central-northern basin,were mainly 90-113Ma,and ages of Shangdan area,located in eastern margin of basin,were mainly 129-159Ma,which reflected that tectonic uplifting in eastern basin was earlier than in central-northern basin.Therefore,it can be inferred that the research area was mainly dominated by tectonic movement in Mesozoic,and developed differential uplifting.4.Subsidence history since Carboniferous-Permian of research area was studied.During Carboniferous-Permian period,the erosion thickness varied from block to block in basin,in which the maximum value occurred in Lujing Depression,about 3205.59m.During Jurassic-Cretaceous period,controlled by different unlifting,the erosion thickness was still varied.The erosion thickness in Chagan depression was greater than in several depressions close to central basin.Based on the research of tectonic and sedimentary characteristics,distribution of Carboniferous-Permian source rock can be studied and found that thickness of source rock was turned to be thinner in the south and thicker in the north,besides,area became smaller gradually.Furthermore,according to degree of tectonic deformation and erosion,source rock in study area can be divided into four types.5.Buried history of Carboniferous-permian source rock in study area can be researched.During the Late Devonian-Permian,subsidence of Yin,e basin was relatively stable.In Late Permian,stratum of Carboniferous was buried deepest episodically,and source rock was transformed into low maturity-maturity stage.From late Permian to Triassic period,study area was always controlled by tectonic uplifting,and Triassic stratum was seldom developed.In Jurassic,the Yin'e Basin began to extend and deposit,but developed a few thickness,which had limited impact on the Carboniferous-Permian source rock evolution.From Late Jurassic to Late Cretaceous,the Yin'e basin experienced subsidence and uplift conversion.From Early Cretaceous to Late Cretaceous,the eastern margin and interior of basin got the maximum deposit thickness in different degrees and periods respectively.Thermal evolution of multiple sets of Permian hydrocarbon source rocks reached the highest degree and entered into main generation period.Besides,based on the analysis of organic components ratio determination of flue inclusion,relation between homogenization temperature and salinity analysis of flue inclusion,burial history and tectonic thermal evolution history,it can be inferred that there were two oil and gas migration processes,which developed in Middle-End of Permian and Early-Middle and-Late Cretaceous respectively.