【作者】 张力；

【导师】 朱光；

【作者基本信息】 合肥工业大学 ， 构造地质学， 2010， 硕士

【摘要】 华北克拉通东部在白垩纪至古近纪发生克拉通破坏和岩石圈减薄期间,沿郯庐断裂带中段周边发育了一系列伸展盆地。这给我们提供了一个很好的机会去了解克拉通坏期间伸展应力场的演变规律,进而可以分析克拉通破坏的动力学背景。本论文工作选择华北克拉通东部的郯庐断裂带中段周边白垩-古近纪伸展盆地为研究对象,通过它们沉积中心与格局的变化规律及各期正断层擦痕应力场分析,发现区内早白垩世早-中期为NWW-SEE拉伸,早白垩世晚期为NW-SE拉伸,晚白垩世-古近纪为近N-S拉伸。通过将华北克拉通伸展方向的演变与太平洋区大洋板块运动方向进行对比分析,发现它们之间是相吻合的,即各阶段伸展方向与同时期的大洋板块运动方向是一致的。这反映华北克拉通东部区域拉伸方向的演变受控于太平洋区大洋板块运动,克拉通破坏的动力学背景应为弧后伸展。本次工作所发现的弧后大陆边缘伸展方向和大洋板块运动方向相吻合,支持弧后拉张机制应为板片后退模式。本次工作认为,弧后伸展期间,大洋板块运动方向应平行于海沟后退方向,而后者具体控制了弧后大陆边缘的伸展方向。更多还原

【Abstract】 The long-term rifting of Cretaceous to Paleogene during craton destruction and lithospheric thinning of the eastern North China Craton (NCC) provides a good opportunity to understand evolution of extensional direction and geodynamic setting of the destruction. Cretaceous-Paleogene rift basins around the middle segment of the Tan-Lu fault zone in the eastern NCC were chosen for studies in this work. On the basis of basin depocenter patterns and normal fault slip data, it is shown that the extension experienced an evolution from WNW-ESE extension of the earliest-middle Early Cretaceous, NW-SE extension of the latest Early Cretaceous to nearly N-S extension of the Late Cretaceous-Paleogene. Correlation of the extensional directions in the eastern NCC and oceanic plate motions show that they were parallel to each other. It is suggested therefore that the extensional direction evolution was controlled by the oceanic motion and the craton destruction took place under a back-arc spreading setting. The coupling relation between the directions of the overriding plate extension and oceanic plate motion supports the slab rollback model for the back-arc extension. It is proposed that the trench retreat direction generally parallel to the oceanic plate motion directly controls the extension direction in the overriding plate.更多还原