三江特提斯复合造山与成矿作用

Superimposed orogenesis and metallogenesis in Sanjiang Tethys

三江特提斯构造带作为全球特提斯构造在中国大陆最典型的发育地区,经历了复杂而完整的演化历史:从晚前寒武纪—早古生代泛大陆解体与原特提斯洋形成,经古特提斯多岛弧盆系发育与古生代—中生代增生造山/盆山转换,到新生代印度-亚洲大陆碰撞与叠加改造,完好地记录了超级大陆裂解→增生→碰撞的完整演化历史和大陆动力学过程,可谓是中国大陆构造演化的典型缩影。复合造山和叠加转换导致了三江特提斯域复杂的成矿演化,主要表现为:①在构造转换阶段,于元古代刚性基底基础上发育大量叠加改造型矿床,具有独特的金属组合(Sn-Cu,Sn-Pb-Zn,Fe-Cu等);②火山成因块状硫化物(VMS)矿床伴随特提斯岩石圈演化,连续发育于陆缘裂谷(Cu)→初始洋盆(Cu-Zn)→大洋岛弧(Cu-Zn-Pb)→弧间裂谷或弧后盆地(Pb-Zn-Ag)→弧-陆碰撞裂陷盆地(Cu-Pb-Zn)等阶段及诸环境;③特提斯阶段的岛弧型斑岩Cu矿被碰撞造山阶段的大陆型斑岩Cu矿所取代;④世界级规模的金属成矿带和巨型矿床,在新生代碰撞造山期"爆发式"产生。尽管已有的研究从整体上勾画出了三江特提斯域的基本构造特征和成矿面貌,但仍有许多重要问题尚未解决:①三江复合造山带构造叠加、增生汇聚、碰撞转换等重大地质事件的精准时限及内在关联;②地质环境对成矿的控制作用;③壳幔相互作用过程对矿集区形成和成矿元素超常富集的制约作用;④典型成矿系统的时空结构、物质结构与矿床成因类型;⑤成矿系统发育机制和大型矿床的形成机理。显然,这些问题的解决必将导致三江复合造山带形成、演化和成矿作用研究的重大突破。

The Sanjiang Tethyan area experienced the superpoimsed transition from Tethyan tectonic evolution in Late Paleozoic to continental collision orogeny in Cenozoic,resulting in the accumulation of massive multi-stage mineralizations and large amounts of metallic industrial ore deposits. The complex metallogenic evolution of this area finds expression in the following aspects：① Large amounts of complex superimposed and reworked ore deposits were developed on the Proterozoic substrate of rigid continental segment,with special metallic associations of Sn-Cu,Sn-Pb-Zn and Fe-Cu. ② Volcanics-hosted massive sulfide deposits were developed throughout the evolution of Tethyan lithosphere,from continental margin rift （Cu）,through initial ocean basin （Cu-Zn）,ocean arc （Cu-Zn-Pb） and interarcual rift valley or back-arc basin （Pb-Zn-Ag）,to rift basin caused by arc-continental collision （Cu-Pb-Zn）. ③ Island-type porphyry copper deposits at the Tethyan stage were replaced by continental-type porphyry copper deposits at the collision orogeny stage. ④ Metallic ore-forming belt and gigantic ore deposits of world class,such as the Yulong porphyry Cu-Mo metallogenic belt,the Lanping Zn-Pb-Cu-Ag metallogenic belt,the Ailaoshan Au metallogenic belt,the Chuanxi REE metallogenic belt,the Tengchong-Lianghe Sn metallogenic belt,were generated ＂explosively＂ during the collision orogeny in Cenozoic. Although successful researches on tectonic and metallogenic cheracteristics have been conducted for the Sanjiang Tethyan Metallogenic Domain,many important scientific problems remain unsolved,such as：① Precise time limits and internal connections between tectonic superposition,continental accretion and convergence,and collision and transformation. ② The control of geological setting over mineralization. ③ The constraint of the crust-mantle interaction on the formation of ore deposit clusters and the anomalous concentration of large amounts of ore materials. ④ Space-time structure,material structure and genetic type of ore deposits of the typical metallogenic system. ⑤ The development mechanism of metallogenic systems and the formation mechanism of large-sized ore deposits. It is obvious that the solution of these problems will be a great breakthrough in the study of the tectonic evolution and metallogenesis of the Sanjiang Tethyan Metallogenic Domain.