多造山带控制下的四川复合前陆盆地初析

深入研究四川盆地的起源及其演化过程，对该区进一步的油气勘探开发具有重大的现实意义。为此，根据2008-2010年度国家科技重大专项攻关研究的成果，将川西前陆盆地和大巴山前陆盆地合二为一，通称为四川前陆盆地，并给出了支持这一观点的4点主要证据，即：相同的大地构造背景、形成机制对前陆盆地的影响、“形”与“质”两方面的统一性、共同拥有同一个前陆隆起带。重点分析了盆地区域构造背景及演化过程、原型盆地与主控造山带的关系，结果表明，四川前陆盆地经历了不同时期由不同造山带控制、沉积范围变化大、沉积中心频繁迁移的复杂演化过程，不同类型盆地的垂向叠置，不同时期原型盆地的横向叠加，构成了多造山带控制下的复合型前陆盆地。最后，对盆地构造区带进行了划分，共划分出：造山带后缘推覆构造带、造山带前缘出露前锋逆掩推覆构造带、造山带山前隐伏前锋构造带、前陆盆地中央坳陷带、前陆盆地前缘斜坡带、前陆盆地前缘隆起区等6个一级构造带以及15个次级构造带。

Preliminary analysis of the Sichuan Foreland Basin under control of multiple orogenic belts

A detailed study of the origin and evolution of the Sichuan Basin is of great significance to further exploration and development in this basin.Based on previous study results,it is proposed that the western Sichuan and Dabashan foreland basins are combined into one basin generally named the Sichuan Foreland Basin.Four major evidences are presented to support this viewpoint : the same tectonic settings,the same impact of forming mechanism on the foreland basin,the unity of " appearance " and " nature ",and the same foreland bulge.Particularly,we focused on the analysis of the regional tectonic settings and evolution process of this basin as well as the relationship between the prototype basin and major structural zones.The results show that the Sichuan Foreland Basin has experienced a complex evolution process controlled by different orogenic belts in different geologic periods,during which the extent of sedimentation changed greatly and the depocenter migrated frequently.The vertical overlapping of different types of basins and lateral superimposition of prototype basins of different ages resulted in the Sichuan Foreland Basin under the control of multiple orogenic belts.As a result,6first-order and 15second-order structural zones are identified.The 6first-order structural zones include nappe structural zone at the trailing edge of orogenic belt,exposed front overthrust structural zone at the front edge of orogenic belt,piedmont blind front structural zone,central depressed zone of foreland basin,front slope zone of foreland basin,and front uplifted zone of foreland basin.