Permian Tectono-Stratigraphic Sequence And Basin Evolution In Junggar Basin

Permian was the key tectonic change time during the formation and evolution of Junggar Basin,which is the natural lab in developing basin analysis theory.Permian has the largest petroleum resources quantity of all horizon and broad prospects.So,studying Permian Tectonostratigraphic sequences,discussing basin evolution history,have momentous significance in deeply understanding Junggar Basin petroleum geological conditions and developing oil and gas resources forcast.Based on sequence stratigraphy and structural geology and the latest drilling,logging,and seismic data,Permian stratigraphic system was rebuilt.Based on regional unconformities,we finished the sequence stratigraphic division,and analyzed the evolution stages of the basin.Based on the research above,in accordance with the point-line-face,the sedimentary filling process of the Junggar Basin in Permian periods was rebuilt.This thesis mainly made the following results and understanding:(1)Two first-grade(C/P,P/T),one secondary(P1 / P2)and three third-grade(P2w / P3 w,P2x / P2 w,P1j / P1f)unconformities can be found in Permian of the Junggar Basin.They are all controlled by tectonic movements.Unconformities types mainly include truncations and onlaps.Mahu Sag,Shawan Sag and Zhongguai High are the typical unites developing unconformities,so are the sags in the East Uplift,Mosuowan High,Dongdaohaizi Sag,Fukang Sag in the Central Depression.(2)According to the grade of unconformities,the Junggar basin can be divided into Middle-Upper Permian and Lower Permian two secondary tectonic layers,Jiamuhe group,Fengcheng group,Xiazijie group,Lower-Wuerhe group and Upper-Wuerhe group five third-grade tectonic layers.(3)The charecteristics of the sedimentary filling process of the Junggar Basin in Permian are as follows: The northwest margin experienced vocanic facies of Jiamuhe group to fan delta plain subfacies of Fengcheng group to alluvial fan facies of Xiazijie group to fan delta facies of Lower-Wuerhe group;The Mahu-Shawan Sag of the Central Depression experienced fan delta facies of Jiamuhe group to coastal shallow-lake facies from Fengcheng group to Middle-Upper Permian;The Dongdaohaizi-Fukang Sag part experienced shallow-lake facies of Jiamuhe group to fan delta and coastal shallow-lake facies of Fengcheng group to coastal shallow-lake facies of Middle-Upper Permian;Eastern Uplift experienced fan delta and alluvial fan facies of Lower Permian to coastal shallow-lake and fan delta facies of Middle-Upper Permian.Junggar basin evolved into continental faces and marine-continental transitional faces from Permian,which is an important marine-continental conversion turing point.Depocenter located at Karamay-Xiazijie step-fault zone in northwest margin of Junggar basin in Early Permian,Mahu Sag in Middle Permian,Penyijingxi Sag in Late Permian.Depocenter migration southwards during Permian.(4)The evolution of Junggar Basin experienced the peripheral foreland basin stage during Jiamuhe formation,combined foreland basin stage during Fengcheng formation,foreland basin is sustainably developing during Middle Permian,during Upper-Wuerhe group,foreland basin transformed into depression basin.