走滑断裂、“挤压性盆-山构造”与油气资源关系的探讨

Role of Large-Scale Strike-Slip Faults in the Formation of Petroleum-Bearing Compressional Basin-Mountain Range Systems

了解含油气盆地的形成及其演化的影响因素对于含油气盆地的勘探和开发是至关重要的 .以美国西部的圣安德烈斯断裂带及伴生的南加州油气盆地作为参考 ,对中国青藏高原北部与阿尔金走滑断裂系相关的盆 -山构造进行了剖析 .探讨阿尔金走滑断裂系在其演化过程中 ,怎样控制区域应力场、变形构造及盆地的形成 ,进而制约油气的迁移和圈闭 .分析结果表明与圣安德烈斯断裂带在美国南加州的盆 -山构造体系所起的作用相比较 ,阿尔金走滑断裂系在青藏高原北部的盆-山构造体系的形成和演化中起相似的作用 .青藏高原相对于塔里木盆地的斜向运动导致在阿尔金走滑断裂的东南形成走滑 -挤压构造域 .形成一系列的走滑和推覆构造 ,在地形上表现为包括柴达木盆地在内的有序的盆 -山相间的构造体系 .与南加州富含油气的盆地相似 ,阿尔金走滑断裂及相配套的走滑

Understanding the factors that affect the formation and evolution of petroleum-hearing sedimentary basins plays a critical role in the prospecting and exploitation of oil fields. The formation and evolution of the highly-order coastal and on-land petroleum-bearing Cenozoic basins and their bounding mountain ranges in southern California, USA were initiated and controlled by the San Andreas fault system, a large-scale plate boundary transform fault that separates the Pacific plate from the North American plate. The northeast oblique movement of the Pacific plate relative to the North American plate in conjunction with the big bend of the San Andreas fault in southern California produces intense contractional strain across the Transverse Ranges and leads to the formation of a series of fault and fold structures that shape the salient landscape of southern California. For comparison, we have conducted detailed structural analyses on the basin-mountain range systems in the northern Qinghai-Tibet plateau to discuss the role of the Altyn Tagh fault in (1) development of regional contractional stress field; (2) formation of structures and sedimentary basins; (3) generation of structures that facilitate the migration and capture of oil and gas. Results show that the Altyn Tagh fault has played a similar role in the formation of the spectacular basin-mountain systems to that of the San Andreas fault. The oblique convergence of the Qinghai-Tibet terrane relative to the Tarim basin resulted in the formation of transpressional tectonic regime to the southeastern of the Altyn Tagh fault. Such oblique convergence resulted in a series of strike-slip and thrust faults. As a consequence, the areas from the Kunlun Mountains to the Qilian Mountains form spectacular landforms characterized by alternations of basins and mountain ranges. For both cases of the southern California and the northern Qinghai-Tibet plateau, thrust faulting not only provides a viable mechanism for the migration of oil or gas, but also resulted in fault-propagation folds which serve as the favorable capture structure for oil and gas. One of the key factors that generate such a highly organized petroleum-bearing basin-mountain system is oblique convergence induced slip partitioning which results in the dextral horizontal slip along a major strike slip fault and vertical slip along numerous blind or exposed thrust faults.