塔里木周边前陆褶皱带构造几何学和运动学定量化研究

The project is a pioneering attempt to rigorously integrate in geological and geophysical data to describe and ananlyse the geometry and kinematics of Kuche fold-and thrust belt, the southern front of the Chinese TianShan and Kashi-Yecheng fold-and thrust belt, the northern front of the Pamir-Western Kunlun. On the basis of our interpretation 20000 Km seismic reflection profiles in Kuche and Kashi-Yecheng regions by integrating surface geology investigation, structural measurement, well data, the Kuche fold-and thrust belt may be divided into four structural domains and the Kashi-Yecheng fold-and thrust belt divided into three structural domains based on their style of deformation. In the Kuche area, the 60 km wide fold-and thrust belt is characterized by a number north dipping thrusts and east-west trending blind folds. Near the TianShan front, southward-directed contractional deformation has folded and faulted Mesozoic and Paleogene. Toward the Tarim basin, the Miocene to Holocene sediments steeply folded along the Quilitake and Yaken anticlines. In the Kashi-Yecheng area, the structures include basement-involved compressive folds, duplexes, and triangle zones along the Pamir-Western Kunlun front, and low-angle blind thrusts with hanging walls over them in deeper ramps that propagate northward toward the foreland. The timing of deformation is best constrained by growth strata and unconformities correlated to the available magnetostratigraphy in Kuche and Kashi-Yecheng regions. The widespread Miocene to Pliocene unconformities are found in the north part of the Kuche belt, and the growth strata on both sides of the Quilitake and Yaken anticlines were deposited at late Pleistocene in the south part of the Kuche belt. These imply as development of thrusts in the southern Chinese TianShan may have propagated southward toward the foreland, the initial thrusting occurred at Miocene. The time of initiation of deformation on the Kashi-Yecheng fold-and thrust belt is poorly known. The thrust faults along the Pusha and Sugete anticlines may have occurred at late Pliocene and along the Guman and Yijisha anticlines, toward the foreland, at Pleistocene to Holocene as the northward displacement of the Pamir-Western Kunlun. We found the Aksu active fault in Kuche belt and the Wupor active fault in the Kashi-Yecheng belt. Our 10Be-26Al cosmogenic dating of cumulative vertically offset surfaces along an active fault suggests that a maximum shortening rate of about 5.7±2 mm/yr is inferred at Aksu area since Holocene (12000 year). The balanced cross-sections have been constructed from depth-converted interpretations of seismic lines and detail surface structural data in Kuche and Kashi-Yecheng regions. The 3D structural models were developed from the balanced cross sections in order to constrain the coplex structural regions. The models suggest that at least 40-60 km of crustal shortening with the range of shortening rates of 2-2.5 mm/yr in the Kuche fold-and thrust belt and 23-70 km of crustal shortenin in the Kashi-Yecheng fold-and thrust belt have occurred during the late Cenozoic. This project has wider implications for a better understanding of the dynamics of the intracontinental convergence in the central Asia and its relations to the India-Eurasian collision and supports the petroleum exploration and earthquake geology in the piedmonts of the Tianshan and the Pamir-Western Kunlun.

通过详细研究塔里木盆地周边前陆褶皱带的构造变形, 建立二维、三维的构造模型、模饣指垂乖毂湫喂? 定量化研究构造变形的几何特征和运动过程, 预测深部构造和地下疃喜? 确定前陆褶皱带构造变形历史和机理, 探讨塔里木地区地壳变形机制, 对塔里木地区地壳动力学、油气资源的勘探开发和地震预测都具有重要意义.