德兴斑岩铜矿床研究新进展  

New Research Progress of the Dexing Porphyry Copper Deposit

作　　者：周清[1,2] 姜耀辉[2] 廖世勇[1] 靳国栋[3] 赵鹏[2] 刘铮[2] 贾儒雅[2] 

机构地区：[1]中国地质调查局成都地质矿产研究所,成都610081 [2]南京大学地球科学与工程学院,南京210093 [3]中国地质调查局南京地质矿产研究所,南京210016

出　　处：《地质论评》2013年第5期933-940,共8页Geological Review

基　　金：国家自然科学基金青年基金资助项目(编号41202067;41202048);重点项目(编号40730313);国家"973"计划(编号2012CB416706;2011CB403105);中国地质调查局项目(编号12120113036000)的成果

摘　　要：江西德兴铜矿是中国东部最大的斑岩型铜矿床,前人对该矿床的成矿流体来源及演化方面的研究取得了较为一致的认识,但在含矿斑岩成因、成矿物质来源、成矿环境等其它方面还存在有较大的争论.最新研究成果表明,德兴铜矿的含矿斑岩形成于中侏罗世早期（170.2～ 171.0 Ma）古太平洋板块向欧亚大陆俯冲形成的大陆边缘环境,由俯冲大洋板片（主要为上覆沉积物）部分熔融形成的具高Sr、Sr/Y和La/Yb比值特征的高钾钙—碱性熔体,在其上升过程中与岩石圈地幔相互作用所形成.超大型的Cu-Au多金属成矿作用与岩浆侵入作用几乎同时发生,成矿物质主要由洋片（P-MORB）中富含Fe3＋的岩浆释放出的流体或熔体在上升途中与上覆岩石圈地幔相互作用后从岩石圈地幔中萃取出来.而在晚侏罗世中期（约153.5Ma）,区内转换为由俯冲大洋板片rollback形成的弧后伸展环境,形成了壳—幔混源成因的闪长质侵入岩脉群,但没有显示出良好的矿化作用；到了早白垩世晚期（100.9～106.5 Ma）,德兴斑岩铜矿区内发生一次热液成因的Cu（-Au？）成矿作用事件,叠加于原先大规模的主成矿事件之上.The Dexing porphyry copper deposit, Jiangxi Province, is the largest porphyry copper deposit in eastern China. Previous studies indicated that the ore-forming fluids were dominantly derived from the magmatic system, plus additional meteoric water, but there have been some controversies on the petrogenesis of the ore- bearing porphyries and the tectonic setting and ore-forming source of this deposit. Our new studies have suggested that the Dexing porphyries were emplaced in a continental arc setting coupled with the westward subduction of the Palaeo-Pacifie plate in the early Middle Jurassic （170.2 -171.0 Ma）. Partial melting of the subducted slab （mainly overlying sediments）, with subsequent melts interacting with the lithospheric mantle wedge, formed the high-K calc-alkaline porphyry magmas with high St, Sr/Y and La/Yb affinities. The large scale Cu--Mo--Au mineralization was nearly contemporaneous with the magmatism, and the ore-forming source were extracted from the Fe3＋ -rich fluids/magmas released by the P-MORB interacting with the lithospheric mantle wedge. However, during the middle Late Jurassic（ - 153.5 Ma）, Dexing area had been converted to a back-arc or an intra-arc extension environment triggered by the rollback of the palaeo-Pacifie plate, and there formed the ore-barren dioritic intrusions with a crust--mantle mixing source. Moreover, there had formed a hydrothermal Cu （Au？） metallogenie event superimposed on the porphyry Cu--Mo--Au mineralization during the late Early Cretaceous.

关 键 词：德兴斑岩铜矿 岩石学成因 成矿物源 板块俯冲 热液锆石 

分 类 号：P618.41[天文地球—矿床学]