库车前陆盆地的二维重力模拟与综合解释  

2-D Gravity Modeling and Integrated Interpretation of the Kuqa Foreland Basin,Northwest China

作　　者：王勤[1] 卢华复[1] 王良书[1] 徐鸣洁[1] 胡德昭[1] 嵇少丞 

机构地区：[1]南京大学地球科学系,南京210093 [2]Dpartement des Gnies Civil,Gologique et des Mines,cole Polytechnique de Montral

出　　处：《高校地质学报》2004年第2期227-238,共12页Geological Journal of China Universities

基　　金：国家自然科学重点基金项目G4 9832 4 0 ;"九五"攻关项目子专题 96 111 0 1 0 1 0 1资助

摘　　要：通过对库车前陆盆地的 2条MT测线和 3条地震剖面的重力二维模拟与综合解释 ,提高了在复杂变形带进行的构造建模的可靠性。模拟结果表明 ,库车前陆盆地是以断层相关褶皱作为滑动机制的前陆冲断带。沿下第三系膏盐岩和膏泥岩、侏罗系—三叠系煤系地层发育的滑脱层控制了断层相关褶皱的变形模式 ,并导致浅层背斜与深部圈闭的位置不一致。在盆地北面 ,南天山古生界入了北部单斜带的中生代地层 ,导致剩余重力异常值升高 ;盆地南面 ,新生界沉积厚度的增加使剩余重力值逐渐降低 ,局部盐体的堆积可形成重力异常低谷。此外 ,拜城凹陷基底的密度较高 ,可能是凹陷形成初期岩浆底侵的结果。推覆变形自天山向塔里木盆地推移 ,反映了中新世以来逐渐增强的南北向挤压应力和地壳缩短 ,是印度板块与欧亚板块碰撞的远距离效应。The intense deformation in the Kuqa foreland basin,northwest China,limited the seismic exploration and interpretation in this important gas field of China. This study is devoted to improving the reliability of predicting complex structures by 2-D gravity modeling and joint interpretation along 2 MT profiles and 3 seismic profiles across the Kuqa fold-and-thrust belt. The results indicate that fault-related folding is the basic deformation style in this foreland basin. The development of detachment along the Eocene gypsum rocks and gypseous mudstones,and along the Jurassic and Triassic coal-bearing formation stratigraphically controlled the deformation patterns of fault-related folds,and resulted in change of relative positions of gas traps at depth with anticline crests on the surface. Overall,in the north,a Paleozoic wedge of Tianshan has embedded into the Mesozoic strata of northern tilted zone and caused increased gravity anomalies;in the south,the increased sedimentation depth of the Cenozoic rocks decreased the gravity anomalies,and the accumulation of the Eocene salt body should be accounted for the low gravity value. The relatively higher density of basement in the Baicheng depression probably reveals an early regional uplift associated with intrusive igneous activity and continued extension. The thrust propagated progressively from Tianshan to the Tarim basin,which implies enhanced N-S compression and crustal shortening since the Miocene as a remote structural response to the India-Eurasia collision.

关 键 词：库车前陆盆地 二维重力模拟 地震剖面 大地电磁测深剖面 断层相关褶皱 

分 类 号：P631[天文地球—地质矿产勘探]