古太平洋板块中生代在欧亚大陆下的俯冲历史：东北亚陆缘火山岩与增生杂岩证据

The subduction history of the Paleo-Pacific plate beneath the Eurasian continent has been a controversial issue during Mesozoic. When did the subduction of the Paleo-Pacific plate beneath the Eurasian continent begin? How many times did the subduction of the Paleo-Pacific plate happen during Mesozoic? What’s the extent influenced by each subduction? These problems have not been solved. This program studies the geochronology, rock association, and their spatial variation of Mesozoic volcanic rocks and accretionary complexes in the northeastern Eurasian continent, combined with the palaeomagnetic and geophysical data in the region, with the aim of constraining the beginning time of the subduction and subduction history of the Palaeo-pacific plate beneath the Eurasian continent during Mesozoic. This program is of not only important theoretical significance for revealing the nature and history of the interaction between the oceanic and continental plates, but also significant real implications for revealing regional ore-forming background in NE Asia during Mesozoic.

中生代期间，古太平洋板块在欧亚大陆下的俯冲历史一直是地学领域研究的热点与争论的焦点问题之一。古太平洋板块在欧亚大陆下的俯冲起始于何时？中生代期间有几次俯冲作用？每次俯冲作用影响的空间范围如何？这些问题至今仍没有得到回答。本项目拟通过对欧亚大陆东北缘（中国的东北和俄罗斯的远东）中生代火山岩和陆缘增生杂岩的年代学、岩石组合及其空间变异的研究，结合古地磁和地球物理测深资料，来查明中生代古太平洋板块在欧亚大陆下俯冲开始的时间；揭示中生代期间古太平洋板块在欧亚大陆下的俯冲历史及影响的空间范围。该项研究不仅对揭示东北亚大陆中生代洋-陆相互作用的性质与历史具有重要理论意义，而且对查明东北亚中生代区域成矿背景具有重要的现实意义。

中生代期间，古太平洋板块在欧亚大陆下的俯冲历史一直是地学领域研究的热点与争论的焦点问题之一。本项目对欧亚大陆东北缘（中国的东北和俄罗斯的远东）中生代火成岩和陆缘增生杂岩的年代学、岩石组合及其空间变异进行了研究。结果表明：1）古亚洲洋在中亚造山带东段的最终闭合时间为中三叠世，且为自西向东的剪刀式闭合；2）中生代古太平洋板块在欧亚大陆下俯冲的起始时间为早侏罗世；3）晚侏罗世-早白垩世早期欧亚大陆东缘处于走滑的构造属性,从而导致了陆缘增生杂岩从低纬度到高纬度的构造就位；4）早白垩世晚期-古近纪东北亚陆缘岩浆作用的向东收缩，揭示了古太平洋板块俯冲和后撤的构造过程；5）古太平洋板块俯冲影响的空间范围可达大兴安岭的东缘，而蒙古-鄂霍次克构造体制影响的空间范围主要在松辽盆地以西和冀北-辽西地区。上述研究成果不仅对揭示东北亚大陆中生代洋-陆相互作用的性质与历史具有重要理论意义，而且对查明东北亚中生代区域成矿背景具有重要的现实意义。