机构地区:[1]中国地质大学(北京)地质过程与矿产资源国家重点实验室,北京100083 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]中国地质大学(北京)海洋学院,北京100083
出 处:《地学前缘》2020年第2期106-136,共31页Earth Science Frontiers
基 金:国家自然科学基金委特提斯地球动力系统重大研究计划项目(91855217);国家重点基础研究发展计划“973”项目(2015CB452606,2009CB421008);高等学校学科创新引智计划“111”项目(BP0719021);国家自然科学基金面上项目(41772069,41872246)。
摘 要:复合造山与复合成矿是中国区域构造演化与成矿的典型特色,其复杂的成矿物质来源、多变的构造驱动机制、丰富的成矿作用类型以及多期的活化改造过程一直是区域成矿理论研究的热点。西南三江特提斯造山带是中国复合造山的典型缩影,其经历了古生代与中生代原-古-中-新特提斯增生造山和新生代印度-欧亚大陆碰撞造山演化过程,具有复杂的复合造山演化时空格架。为系统阐释复合造山背景下的复合成矿作用,更科学地指导区域找矿勘查工作,本文在详细解析三江特提斯复合造山的基础上,依据成矿系统理论划分出与增生造山相关的原特提斯、古特提斯、中特提斯、新特提斯和与碰撞造山作用相关的挤压褶皱、拆沉伸展、挤压走滑、伸展旋扭等成矿系统;发现复合成矿作用显著,并识别出四类5个主要复合成矿系统,包括昌宁-孟连带增生-碰撞造山海底喷流(VMS)型Pb-Zn-Cu+岩浆热液型Mo-Cu、义敦岛弧和腾冲-保山地块增生+碰撞造山岩浆热液型Cu-Mo-Sn-W、兰坪盆地碰撞造山盆地卤水(MVT)型Pb-Zn+岩浆热液型Cu-Pb-ZnAg和扬子西缘碰撞造山富碱斑岩Au-Cu-Mo+造山型Au;详细解剖各复合成矿系统组成要素和形成机理,据此凝练出复合成矿系统理论,即指复合造山构造转换时空域中不同时期多种成矿作用或者同一时期不同成矿作用复合形成的地质系统;提出构造转换复合于早期岛弧带或者裂谷带是形成复合成矿系统的主要机制。Composite orogeny and composite metallogenesis are salient features of the regional tectonic evolution and metallogeny in China,respectively.The complex sources of ore-forming materials,variable mechanisms of tectonic driving,divers genetic types of mineralization and the multi-stage of remobilization and overprint,have been the research interest in the scope of regional metallogenic theory.The Sanjiang Tethyan orogenic belt in Southwest China is a typical miniature of composite orogeny in China.It has a complex spatial-temporal composite orogenic framework,undergoing the evolution of the Proto-,Paleo-,Meso-and Neo-Tethyan accretionary orogeny in Paleozoic and Mesozoic and the collisional orogeny between Indian and Eurasian plates in Cenozoic.In order to systematically explain the composite metallogenesis under the background of composite orogeny and guide the regional exploration scientifically,in this paper,based on the theory of metallogenic system,we divide Proto-,Paleo-,Meso-and Neo-Tethyan metallogenic system related to accretionary orogeny,and squeezing folds,removal extension,squeezing slip,stretching rotation metallogenic system related to collisional orogeny,recognize that composite metallogeny is significant,and identify four types of typical composite metallogenic systems in five metallogenic belts,including accretionary-collisional orogenic VMS Pb-Zn-Cu+ magmatic-hydrothermal Mo-Cu along the Changning-Menglian suture zone,accretionary+collisional magmatic-hydrothermal Cu-Mo-Sn-W in the Yidun arc and Tengchong-Baoshan block,collisional orogenic MVT Pb-Zn+magmatic-hydrothermal Cu-PbZn-Ag in the Lanping basin and collisional orogenic alkali-rich-porphyry(Au-Cu-Mo)+orogenic Au type along the western margin of the Yangtze block. We also analyze the components each composite metallogenic system in detail,and propose the theory of composite metallogenic system,which means that geological systems formed by superimposition or interaction of multiple metallogenic events with different times or genetic types dr
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