大陆碰撞与特提斯洋消亡的沉积响应

Continental collision is one of the most fascinating consequences of continental dynamics and plate tectonics. The Tethyan paleogeographic domain, stretching from the European Alps to the Zagros, the Himalaya and the Tibetan Plateau, is a classic area for continental-collision studies. The stratigraphic and provenance investigations carried out in recent years have allowed a careful reconstruction of sedimentary processes associated with continental collision between India and Asia, leading us to propose a methodological approach considered to be an effective rationale apt to constrain the timing and modality of the continental collision process. Its application to other mountain ranges worldwide, however, remains to be tested. The present new project will focus on strata deposited before and after continental collision in selected areas of various mountain belts, including the Alpine foreland basin of southern France, southeastern Turkey and northern Pakistan. We will investigate facies and provenance changes and reconstruct the geometry of basin fills to test the sedimentary response of continental collision and improve on current depositional models of continental collision. Furthermore, based on the established depositional response of the continental collision process, this project will focus on the Jurassic to Cretaceous strata in the Bangong-Nujiang domain to constrain the timing and process of the Lhasa-Qiangtang continental collision, and the demise of the Bangong-Nujiang Ocean, which lay to the north and closed earlier than the Neo-Tethys Ocean.

大陆碰撞研究是大陆动力学研究的核心组成，是对板块构造理论的重要补充。特提斯构造域是大陆碰撞研究的经典地区。基于印度-亚洲大陆碰撞带提出的沉积学方法和地质模型，其普适性和规律性还有待于进一步检验和完善。为此，本项目拟重点以大陆碰撞相关的沉积物源区改变和盆地性质转变两种沉积学方法为手段，以法国东南部、土耳其东南部、巴基斯坦北部等地区大陆碰撞带的关键地层为研究对象，对其进行详细的沉积学、地层学、物源分析、沉积盆地研究，验证大陆碰撞过程的沉积学方法，完善大陆碰撞演化的理论体系。在此基础上，精细解剖班怒带区域侏罗-白垩系地层，从沉积学角度重建拉萨-羌塘大陆碰撞与班公-怒江洋的消亡过程。

以青藏高原中南部、伊朗西部、土耳其东南部、法国东南部等特提斯典型的大陆碰撞带为研究对象，以验证大陆碰撞过程的沉积学方法和完善大陆碰撞演化的理论体系为科学目标，开展了详细的沉积学、地层学、物源分析、地质年代学、古地理重建等研究。本项目取得的主要认识包括：（1）进一步将印度-亚洲初始碰撞时间约束为61-59 Ma，提出“同碰撞海沟盆地”的概念，总结了造山带海沟盆地的识别方法，提出了造山带原型盆地恢复的新思路和要素；（2）将拉萨-羌塘碰撞时间约束为166 Ma，将班怒带剥露时间限定在122 Ma之前，重建了班怒洋从打开至关闭的地质过程；（3）重建了土耳其-伊朗新特提斯缝合带蛇绿岩仰冲至阿拉伯-欧亚板块陆陆碰撞的过程；（4）重新评估了阿尔卑斯“欠充填周缘前陆盆地”建立的地质证据，提出更符合地质事实的裂谷盆地的替代性模型。项目研究成果对于理解特提斯演化、大陆碰撞、沉积盆地动力学、青藏高原初始生长等具有重要的科学意义。项目执行期间共发表学术论文23篇，其中第一作者和通讯作者国际SCI论文18篇，培养博士和硕士研究生9人。