太平洋板块俯冲与中国东部中生代地质事件_孙卫东

矿物岩石地球化学通报·专题研究·Bu lletin of Mineralogy,Petrology and Geochemistry

Vol.27No.3,July2008太平洋板块俯冲与中国东部中生代地质事件

孙卫东1,2,凌明星1,3,汪方跃1,3,丁　兴1,3,

胡艳华1,3,周继彬1,杨晓勇2

1.中国科学院广州地球化学研究所,广州510640;

2.中国科学技术大学地球和空间科学学院,合肥230026;

3.中国科学院研究生院,北京100049

摘　要:中国东部至少自侏罗纪开始就一直处于俯冲大洋板块之上,但是有关俯冲板块对其影响程度一直有不同的认识。最近的研究表明,太平洋海山岛链的时空分布显示太平洋板块的漂移方向曾发生多次转折,这些转折与白垩纪中国东部的构造演化和岩浆事件有着密切的时空耦合关系。从时代和力学性质上看,太平洋板块俯冲方向的改变在很大程度上控制着中国东部中生代的盆地演化和郯庐断裂活动等重要地质事件。这些认识为理解中国东部构造演化提供了新的视角,包括岩石圈减薄的机制、郯庐断裂的演化,以及燕山期大规模岩浆活动等。本文重点分析了太平洋板块俯冲与中国东部中生代岩浆活动的对应关系。在125～140M a太平洋板块向南西方向俯冲,造成中国东部岩石圈减薄,软流圈卸载上涌,发生减压部分熔融;约125M a,太平洋板块漂移方向发生了大幅度转折,形成安第斯式的俯冲挤压,岩石圈停止减薄和减压部分熔融,出现岩浆宁静期。随着俯冲的深入,到110M a前后俯冲板块后撤,形成弧后拉张,岩浆活动又重新开始。

关　键　词:太平洋;板块俯冲;中生代;成矿作用;岩浆活动

中图分类号:P541 文献标识码:A 文章编号:1007-2802(2008)03-0218-08

Pacific Plate Subduction and Mesozoic Geological Event in Eastern China

SUN Wei-do ng1,2,LING M ing-x ing1,3,WANG Fang-yue1,3,DING Xing1,3,

H U Yan-hua1,3,ZH OU Ji-bin1,YANG Xiao-y ong2

1.Guangzhou I nstitute of Geochemistry,T he Chinese Academy of S ciences,Guangz hou510640,China;

2.S chool of Earth and S pace Sciences,University of Science and Technology of China,He f ei230026,China;

3.Graduate University o f the Chinese Academy o f Sciences,Beij ing100049,China

Abstract:Eastern China became an active continent al margin since Jurassic or even earlier.The ef fects of plate sub-duction on eastern China geological evolution,in particular,whether the great igneous event and associated miner-alization were controlled by plate subduction.Recent study show s t hat the drifting direction of the Pac ific plate changed several times as indicated by island chains.T hese changes in drifting direction coordinate well with tectonic and magmatic event s in eastern China,including the development of M esozoic basins and the evolution of Tan-Lu faults,etc.All these provide us new perspective on eastern China tectonic histo ry,e.g.,lithosphere dest ruction, Yanshanian great igneous event.This contribution focuses on the assoc iation between Pacific plate subduction and eastern China magmatism.The Pac ific plate drift ed sout hwest w ards betw een125-140M a,resulting in roughly north-south ward extension,and consequently upwelling of the ast henosphere,and decompressional partial melt-ing.A bout125M a,the drifting direction of the Pacific plate changed dramatically,leading to A ndes type compres-sion in eastern China.Cor respondingly,lithosphere thinning as well as decompressional partial melting stopped. As subduction continued,slab-roll back and backarc ex tension st arted at about110M a,following magmatism reac-tivation.

Key words:east ern China;Pacific;plate subduction;M esozoic;mineralization;magmatism

收稿日期:2008-06-12收到

基金项目:国家重点基础研究发展规划项目(2006C B403505);国家自然科学基金资助项目(40525010);中国科学院百人计划项目

第一作者简介:孙卫东(1966—),男,博士,研究员,主要从事地球化学和矿床学研究.E-mail:w eidongsu n@.