伊犁盆地阿吾拉勒山西缘二叠系沉积特征研究

Permian sedimentary environment of the west margin of Awulale mountains,Yili basin

二叠系是伊犁盆地目前主要的勘探目标之一,伊犁盆地二叠系铁木里克组是主要的烃源岩层位,深入研究伊犁盆地二叠纪沉积特征对指导油气勘探具有重要意义.以阿吾拉勒山西缘野外实测剖面为基础,结合前人成果,通过岩性和岩石组合分析、沉积相分析,研究了该地区二叠纪沉积环境演化过程,明确了该地区铁木里克组暗色泥岩的形成环境.结果表明:阿吾拉勒山西缘二叠纪发育滨浅湖、辫状河三角洲平原、辫状河、冲积扇、火山喷发5种沉积相,整体属于陆相湖盆边缘环境;受控于区域大地构造演化,研究区在二叠纪发生过2次湖侵—湖退,沉积环境经历了冲积扇—辫状河—滨浅湖—辫状河三角洲平原—滨浅湖—辫状河—辫状河三角洲平原—辫状河—冲积扇的演化过程,于三叠纪初演变为物源区;研究区铁木里克组暗色泥岩形成于沼泽环境.

The Permian system of Yili basin is one of the main exploration target at present and the Permian Tiemulike formation is the main source rock.The study of the Permian sedimentary characteristics has important guiding significance for the oil and gas exploration in Yili basin.Based on the field measurement of outcrop profile in the west margin of Awulale mountains and previous research results,by analyzing lithology and rock-association as well as the sedimentary facies,the sedimentary environment evolution of the research area was studied,and the depositional environment of the Tiemulike dark mudstone in this area was clearly identified.The results showing 5types of sedimentary facies（shore-shallow lake facies,braided fluvial delta plain facies,braided fluvial facies,alluvial fan facies and volcanic eruption facies）indicate that the study area was mainly in the continental lacustrine margin environment during Permian.Controlled by the regional tectonic evolution,lake transgression and lake re-gression took place in the area in Permian for twice.Owing to that,the sedimentary environment experiences a successive evolution process in the order of ＂alluvial fan,braided river,shore-shallow lake,braided fluvial delta plain,shore-shallow lake,braided river,braided fluvial delta plain,braided river and alluvial fan＂.In Triassic,the research area turned into one of the provenances of Yining depression.The Tiemulike dark mudstone in the study area is formed in swamp environment.