投稿时间：2021-09-09
修订日期：2021-10-25
网络发布日期：2022-01-11
中文摘要:朱溪W-Cu矿床是近年来在江南斑岩-矽卡岩W矿带发现的一个超大型矿床,其成矿作用特点在国内外众多研究者的关注下逐渐明朗,但构造对成矿作用的控制机制尚未明确。文章基于矿床地质特征的观察,对与蚀变和矿化有关的构造进行解析,依据矿脉(体)的穿切关系,主要厘定出5种具先后次序的控矿构造类型:早期挤压背景下形成的近水平贫矿热液脉(H脉),挤压向伸展转换背景下形成的陡倾波状张剪性含矿脉(R脉),水压致裂主导的流体逃逸构造和近直立平直白钨矿-石英-白云母脉(F脉),以及晚期伸展拆离背景下形成的角砾构造。其中,R脉为矽卡岩型W-Cu矿体的主要赋存形式,F脉为白钨矿-石英-白云母脉型矿体的主要赋存形式。结合前人同位素年代学资料,提出研究区经历了161 Ma以前的挤压,153~145 Ma期间挤压向伸展转换,145 Ma以后的伸展构造背景。其中,挤压向伸展转换时期的断层阀行为控制了朱溪W-Cu成矿作用。据此,文章将朱溪W-Cu矿床的断层阀模型划分为破裂前、断层阀(地震破裂)、流体充填(地震泵吸)、自愈合和再循环等5个阶段。矿化主要发生在断层阀模型的流体充填阶段,表现为压力骤降和流体沸腾,对应矽卡岩成矿期的退蚀变作用和浸染状W-Cu矿化,白钨矿-石英-白云母脉成矿期与白云母密切共生的细脉浸染状W-Cu矿化。朱溪W-Cu矿床的形成与燕山中晚期古太平洋俯冲板片沿扬子和华夏板块间的结合部位撕裂(156~135 Ma)导致岩石圈挤压向伸展转换并形成壳源过铝质-偏铝质花岗岩浆作用相关。
Abstract:The Zhuxi W-Cu deposit located in the Jiangnan porphyry-skarn W belt in South China, is a recently discovered giant deposit. The characteristics of mineralization have become clear with the attention of many researchers worldwide, but the controlling mechanism of structure on mineralization is not clear yet. Based on the structural analysis of alteration zone and orebodies, this paper classifies five main ore-controlling structural types according to the relationship of ore-veins(orebodies): the early sub-horizontal barren hydrothermal veins(H veins) under the compression setting, the steep-dipping undulating tension-shear ore veins(R veins) under the compressionextension transition setting, the fluid-escape structure and sub-vertical straight scheelite-quartz-muscovite veins(F veins) mainly as the results of fluid fracturing, and the breccia structure formed in a late extensional detachment setting. Among them, the R and F veins are the dominant occurrences of skarn-type and scheelite-quartzmuscovite vein-type W-Cu orebodies, respectively. On the basis of a large number of previous isotope chronology studies, we propose that the study area had experienced the compression setting before 161 Ma, the compressionextension transition during 153~145 Ma, and the extensional setting after 145 Ma. The giant W-Cu mineralization is controlled by the fault-valve behavior during transition. The fault-valve behavior applied in the Zhuxi W-Cu deposit can be divided into five stages: prefailure, fault-valve(seismogenic fault failure), fluid-filling(postfailure discharge), self-filling, and repetition of cycle. The mineralization occurs at the fluid-filling stage and presents pressure sharply-decrease and fluid boiling, corresponding to the retrograde alteration and disseminated W-Cu mineralization in skarn, and the vein-disseminated W-Cu mineralization closely intergrown with muscovite in the scheelite-quartz-muscovite veins. Genesis of the Zhuxi W-Cu deposit is related to the Paleo-Pacific plate tearing along the junction between the Yangtze and Cathaysia plates at Middle-Late Yanshanian(at 156~135 Ma), and resultant crust-derived peraluminous-metaluminous granitic magmatism during the dynamic transition of lithosphere from compression to extension.
keywords:geology W-Cu mineralization tectonic transition from compression to extension stress interaction between the fault-valve behavior and fluid Zhuxi
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基金项目:国家自然科学基金项目(编号:41772069)、国家重点研发计划项目(编号:2016YFC0600509)、中国地质调查局地质调查项目(编号:12120113089600、12120114028701、1212011085472)联合资助
引用文本：
贺晓龙,张达,吴淦国,狄永军,张志辉,李芳,胡擘捷,霍海龙,李宁,张鑫明,蔡梦颖,欧阳永棚,魏锦.2021.构造转换背景下应力与流体相互作用控制华南朱溪超大型W-Cu矿床成矿作用[J].矿床地质,40(6):1135~1159HE Xiao-long,ZHANG Da,WU Gan-guo,DI Yong-jun,ZHANG Zhi-hui,LI Fang,HU Bo-jie,HUO Hai-long,LI Ning,ZHANG Xin-ming,CAI Meng-ying,OUYANG Yong-peng,WEI Jin.2021.Control of interaction between stress and fluid in tectonic transition background on metallogenesis of giant Zhuxi W-Cu deposit, South China[J].Mineral Deposits40(6):1135~1159
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