关于印度与欧亚大陆初始碰撞时间的讨论

发布时间：2018-02-27 09:40

本文关键词： 印度与欧亚大陆初始碰撞时间判别标志转换断层板块俯冲带岩浆作用构造变形　出处：《中国科学:地球科学》2017年03期 　论文类型：期刊论文

【摘要】：关于印度与亚洲大陆初始碰撞时间,目前存在3种主流认识,即(65±5)、(45±5)和(30±5)Ma.文中厘定了5种碰撞判别标志,包括板块运动速率的突然衰减、俯冲型岩浆作用的停止、大陆之间的物质交换、海洋的消亡和构造变形.通过综合分析认为,在上述3种认识中,(65±5)Ma构造事件符合一个判别标志,即物质交换——冈底斯碎屑物质在此时出现在印度板块北缘,不过,在此时冈底斯再次发生大规模的岩浆活动,反映出俯冲作用发生活化,意味着两大陆仍未碰撞.俯冲成因的冈底斯岩浆作用在白垩纪末-第三纪初(72~65Ma)间断了约7Myr,文中提出这可能与构造转换有关,即特提斯俯冲消减带被转换断层置换,亚洲与印度大陆由此呈水平走滑汇聚,到了约65Ma,随着新俯冲带的形成,岩浆作用重新开始,直到约45Ma结束.(45±5)Ma的构造事件导致海相沉积和俯冲型岩浆作用的停止,符合大部分大陆碰撞判别标志,文中定义为初始碰撞时间.(30±5)Ma的构造事件与上述判别标准多不符合,反映的是印度和亚洲大陆大规模陆内汇聚作用,即硬碰撞,由此形成青藏高原现今的地质、地貌格局.文中得出的结论是:印度与欧亚大陆的汇聚并非仅仅是受新特提斯海的俯冲消减协调,两者在足够接近时经历了3个阶段,即早期的水平走滑汇聚(72~65Ma)、初始碰撞((45±5)Ma)和晚期的陆内汇聚((30±5)Ma).
[Abstract]:As to the initial collision time between India and the Asian continent, there are three kinds of mainstream cognition, namely, 65 卤5 + 45 卤5) and 30 卤5 Ma. Five kinds of discriminant markers of collision are determined in this paper, including the sudden attenuation of the velocity of plate movement and the cessation of subduction magmatism. The material exchange between continents, the extinction of the ocean and the tectonic deformation. Through the comprehensive analysis, it is concluded that the tectonic event of 65 卤5 Ma accords with a discriminant marker in the above three kinds of cognition. That is, mass exchange-Gangdis clastic material appeared in the northern margin of the Indian plate at this time, but at this time Gangdis again occurred large-scale magmatism, reflecting the activation of subduction, This means that the two continents have not collided. The Gangdis magmatism of subduction origin interrupted about 7Myr during the late Cretaceous to the early Tertiary. It is suggested in this paper that this may be related to tectonic transformation, that is, the replacement of converted faults in the Tethys subduction zone. This resulted in horizontal strike-slip convergence between Asia and the Indian continent, and at about 65 Ma, magmatism resumed with the formation of the new subduction zone until the end of about 45 Ma and the tectonic event of 45 卤5 Ma resulted in the cessation of marine sedimentary and subductive magmatism. The tectonic events defined in this paper as the initial collision time of 30 卤5 Ma do not accord with the above criteria, reflecting the large-scale continental convergence between India and Asia, that is, the hard collision. It is concluded that the convergence of India and Eurasia is not only coordinated by the subduction of the New Tethys Sea, but also goes through three stages when they are close enough. That is, the early horizontal strike-slip convergence is 72n 65 Ma, the initial collision is 45 卤5 Ma) and the late continental convergence is 30 卤5 Ma.
【作者单位】：岩石圈演化国家重点实验室中国科学院地质与地球物理研究所;中国科学院青藏高原地球科学卓越创新中心;
【基金】：中国科学院战略性先导科技专项(B类)项目(编号:XDB03010500) 国家自然科学基金项目(批准号:41672220,41130312)资助
【分类号】：P542

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