岩石圈中热压系数的计算

中国中西部地区发育众多前陆冲断带,它们具有构造变形复杂、油气潜力大和有别于经典前陆盆地的沉积和油气地质特征,但其成因过程和动力学并不清楚。文中利用中西部盆地区的地温、岩石热物性参数和地热学模拟技术,分析该区岩石圈热状态和流变学特征,进一步结合其他地质、地球物理资料,揭示盆地区的深部构造特征和岩石圈性质。研究表明,中西部各主要盆地的岩石圈具有厚度大、强度高、地温低等热-流变学特征,表现为刚硬块体;而其周缘和造山带区却表现为温度高、强度低和厚度小等特征,是构造变形的易发区。在此基础上讨论了岩石圈性质和变形过程等深部构造对前陆盆地成因演化的控制作用,进而初步归纳这类陆内再生前陆盆地的成因演化机制:发育于小型克拉通块体的边缘,其就位受控于岩石圈热-流变学非均质性和构造继承性,其动力来源是新生代印度-欧亚大陆碰撞及其持续的挤压作用。上述研究为探讨中国中西部地区的前陆盆地成因机制提供了深部资料和岩石圈热-流变学约束。

Thermo-rheological structure of continental lithosphere beneath major basins in central-western China: implications for foreland basin formation.

The pervasively existing foreland fold and thrust belts in the central-western China are characterized by complex deformation style, considerable oil and gas potential and unique sedimentary and petroleum geology that is different from the classical foreland basins, but the formation process and geodynamics of basin of this type are still open and controversial.Integrating geo-temperature data derived from oil and gas exploration, thermophysical parameters available and geothermal modeling, here we present the thermal state, rheology of the continental lithosphere of the basins in central-western China, and further reveal the deep structure and lithospheric properties of this area, combined with other geological and geophysical observations available there.Our result shows that the lithosphere of those basins is of relative strong rigidity with little deformation interior, as featured by large thickness and strength, low temperature, and is contrary to that of the orogenic belts around the place where the lithosphere shows high temperature, relatively small strength and thickness, and is apt to deform.The control of deep structure, for instance, the lithospheric properties and deformation style, on the formation of foreland basin in the central-western China is also discussed, and preliminary mechanism of this intracontinental reworking foreland basin is summarized as follows: the foreland basin of this type is located usually in the rim of the rigid craton block, and this emplacement is governed by the thermo-rheological heterogeneities of lithosphere and tectonic inheritance, under the driving forces from the Cenozoic India-Asia collision.This study of deep structure will provide some thermo-mechanical constraints on the understanding of foreland basin formation.