塔里木盆地库车坳陷中生界构造古地理分析

运用区域地面地质、地震、钻测井等资料的综合分析,对库车坳陷中生界的盆地结构、构造样式、中生界各层序原始地层厚度和沉积相分布、古隆起形态、区域构造演化等方面进行研究,重建了库车坳陷中生代盆地构造古地理,并对盆地原型成因进行分析。库车坳陷残留中生界总体上为北厚南薄、北剥南超的地质结构,北部强烈角度不整合在南天山海西期褶皱带,南部微角度不整合面在寒武-奥陶系之上,南部边缘沿着温宿-西秋-牙哈古隆起有基底断裂活动。北部单斜带为冲积扇和辫状河三角洲,克拉苏构造带为深湖,南部沿着古隆起带为缓坡三角洲、浅湖。库车坳陷中生代原型盆地位于南天山海西期造山带和塔里木克拉通边缘过渡带之上,地壳均衡可能是盆地沉降的主要动力。南缘古隆起带在南天山洋扩张期为塔里木克拉通台地与被动大陆边缘的台地边缘,南天山洋闭合期为前陆隆起带,发育基底断裂和断块差异活动,在中生代有继承性活动,晚新生代新天山挤压隆升使古隆起带发生挤压变形,成为新天山逆冲变形造山楔的前锋。

The Mesozoic Tectonic Palaeogeographic Analysis in Kuqa Depression of Tarim Basin

Using the regional geological, seismic, and well data, this paper investigates the Mesozoic basin structure and tectonic style, Mesozoic original thickness of strata and depositional system, paleo-uplift topography, and regional tectonic evolution in Kuqa depression. Subsequently the paleogeography of the Mesozoic basin is reconstructed and factors of basin prototypes in Kuqa depression are analyzed. The residual Mesozoic strata in Kuqa depression show that the geological structure becomes thinner from the north to the south, and is stripped in the north and overlapped in the south. The northern part is marked by a large angular unconformity on Hercynian fold belt of south Tianshan, and the southern part shows a gentle angular unconformity on Cambrian or Ordovician. The basement faults have movements along with the WenSu-XiQiu-YaHa palaeohighs in the southern edge. The alluvial fan and braided river delta were developed in the northern monoclinal belt, and the deep-lake facies was developed in Crassus structural belt. Along with the southern palaeohighs were the gentle slope delta and a shallow lake. The Mesozoic prototype basin of Kuqa depression belongs to the transitional zone of Hercynian orogenic belt in southern Tianshan and the Tarim craton. The isostasy may be the main factor on the passive margin of the subsidence of Mesozoic basin. During the expansion of the Southern Tianshan Ocean, the southern palaeohighs were on the passive margin of Tarim cratonic platform. When the southern Tianshan ocean closed, the southern palaeohighswerelocatedonaupliftedbeltoftheforeland.Basementfaultsweredevelopedwithfaultblockshavingdifferentmovementsand the southern palaeohighs were inherited in the Mesozoic. In the late Cenozoic, the southern palaeohighs experienced compressional deformationassociated with the up lift of new Tianshan,and then became the frontal thrust deformation of orogenicwedge in the new Tianshan.