黑龙江东部鸡西盆地构造反转和剥露过程对东亚陆缘晚白垩世重大构造事件的响应

A wealth of evidence suggest that a major tectonic event occurred in the East Asian margin during Late Cretaceous, leading to the large-scale shortening and tectonic uplift across the continental interiors. However, the response to the major tectonic event in NE China remains not well understood. This project, focusing on the Jixi basin in NE China which is characterized by typical shortening deformation and tectonic uplift, is designed to reveal the cooling and exhumation history of the Chengzihe-Muling Formation sandstone and the basement granite in the basin based on apatite fission track and U-Th-He analyses; to constrain the timing of the regional unconformity underlying the Houshigou Formation by dating the volcanic rocks of the Dongshan and Houshigou Formation using zircon U-Pb analyses; to clarify the spatio-temporal changing patterns of the structural deformation of the basin based on the seismic profile interpretation and balanced section restoration. And on this basis, this study will discuss the tectonic inversion and exhumation of the Jixi Basin during Late Cretaceous. The research results are expected to provide key quantitative constraints on the timing, altitude and history of the intracontinental response to Late Cretaceous tectonic event in the East Asian margin, and to offer supports for discussing the Late Cretaceous geodynamics of the continental margin.

大量证据表明晚白垩世时期东亚陆缘经历了重要的构造事件，导致了大陆内部的大规模挤压和构造隆升，但对于这一陆缘重大构造事件在中国东北地区的响应情况仍然不够明晰。本申请拟选择东北地区挤压变形和构造隆升较为典型的鸡西盆地为研究对象，利用磷灰石裂变径迹和U-Th-He方法，定量分析城子河-穆棱组砂岩和基底花岗岩的冷却剥露历史；利用锆石U-Pb年代学方法分析东山组和猴石沟组火山岩年龄，精确限定猴石沟组底部区域不整合面时代；基于地震剖面精细解释和平衡剖面恢复，详细分析盆地构造变形的时间-空间变化规律；在此基础上探讨鸡西盆地晚白垩世构造反转和剥露过程。研究成果为认识东亚陆缘晚白垩世重大构造事件陆内响应的时间、幅度和过程提供关键性定量约束，也为探讨东亚陆缘晚白垩世的地球动力学提供支撑。

项目的背景：大量证据表明晚白垩世时期东亚陆缘经历了重要的构造事件，导致了大陆内部的大规模挤压和构造隆升，但对于这一陆缘重大构造事件在中国东北地区的响应情况仍然不够明晰。.主要研究内容：本申请选择东北地区挤压变形和构造隆升较为典型的鸡西盆地为研究对象，利用利用磷灰石裂变径迹(AFT)和镜质体反射率(Ro)方法，定量分析城子河-穆棱组砂岩和基底花岗岩的冷却剥露历史；利用锆石U-Pb年代学方法分析猴石沟组火山岩年龄，精确限定猴石沟组底部区域不整合面时代；基于地震剖面精细解释和平衡剖面恢复，详细分析盆地构造变形的时间-空间变化规律；在此基础上探讨鸡西盆地晚白垩世构造反转和剥露过程。.重要结果、关键数据：热年代学研究结果表明盆地在晚白垩世期间(~100-65Ma)发生了快速冷却，平均冷却速率为1.2-2°C/Ma，在中晚始新世(~45-35Ma)和早中新世(~20-10Ma)也出现了显著的快速冷却，平均冷却速率分别约为8-12°C/Ma和 2.3-4°C/Ma；猴石沟组凝灰岩高精度年代学分析表明，猴石沟组底部年龄为~103Ma (Albian末期)，这一结果与前人基于古生物化石推测猴石沟组时代为Albian末期- Cenomanian期的认识是一致的，表明猴石沟组底部区域不整合面时代为Albian末期；构造变形分析表明鸡西盆地在晚白垩世初期和晚白垩世中晚期遭受了两期挤压变形，晚白垩世挤压变形和海侵终止开始于Albian末期- Cenomanian期，早于松辽盆地的晚白垩世挤压变形的启动。.科学意义：研究成果为认识东亚陆缘晚白垩世重大构造事件陆内响应的时间、幅度和过程提供关键性定量约束，有效合理地解释了东北亚陆缘海侵事件的机制，对认识区域海侵事件与全球海平面升降不一致的问题带来了重要的启示，也为探讨东亚陆缘晚白垩世的地球动力学提供支撑。