论岩浆热液矿床的成矿期——以南岭地区燕山期钨矿为例  

On the ore-forming period of magmatic—hydrothermal deposits——A case study of the Yanshanian tungsten deposits in the Nanling Range

作　　者：汪相[1] 楼法生[2] WANG Xiang;LOU Fasheng(School of Earth Sciences and Engineering,Nanjing University,Nanjing,210023;Institute of Geological Survey and Research of Jiangxi Province,Nanchang,330030)

机构地区：[1]南京大学地球科学与工程学院,南京210023 [2]江西省地质调查研究院,南昌330030

出　　处：《地质论评》2022年第2期507-530,共24页Geological Review

基　　金：国家自然科学基金资助项目(编号:41872047)的成果。

摘　　要：中国岩浆热液型钨矿主要赋存在南岭地区的燕山期花岗岩体内部或周围。目前,尚无法精准地测定此类钨矿的成矿年龄,统计上,得出了两期钨成矿作用:150~160 Ma(主成矿期)和130~140 Ma(次成矿期),然而,这困扰了对南岭钨矿成矿作用及其与花岗岩关系的理解。笔者等将综合分析各种最新资料,对成矿母岩、深部岩浆房和成矿机制开展系统的讨论,从而针对南岭钨矿的成矿模式给出明确的判断:①燕山早期呈岩基、岩株状的黑云母二长花岗岩不是南岭钨矿的成矿母岩,150~160 Ma的年龄值不是钨成矿作用的年龄值;②燕山晚期呈岩株、岩瘤、岩脉状的二云母/白云母碱长花岗岩是潜在的钨源载体,但其体积太小,也无法满足成矿母岩要求;③当组合燕山早期主体花岗岩(黑云母二长花岗岩)、燕山晚期补体花岗岩(二云母/白云母碱长花岗岩)和燕山晚期钨矿三者为一体时,一种新颖的成矿模式被构建起来:一个长期存活的深部岩浆房可以分异出富含成矿物质的残余岩浆;当这种岩浆沿着张性断裂快速侵位时,将发生流体—熔体之间的溶离作用,碱性硅质流体形成含黑钨矿的石英脉,而强硅铝质熔体固结为二云母/白云母碱长花岗岩;④130~140 Ma的二云母/白云母碱长花岗岩与黑钨矿石英脉是一对同源分体,两者的同步出现充分展示了成矿物质“源—运—储”的完整过程。该认识不仅可以合理地解释与岩浆热液矿床有关的多种地质现象(如“小岩体成大矿”),而且更新了岩浆热液成矿作用理论,更加重要的是为找矿勘探提供了确切的指导方向。Magmatic—hydrothermal tungsten deposits in China are mainly hosted within or around the Yanshanian granitic plutons in the Nanling Range.Actually the ore-forming ages of these tungsten deposits are very difficult to be precisely determined,resulting in two periods of tungsten mineralization in statistics:150~160 Ma(primary ore-forming period)and 130~140 Ma(second ore-forming period),this puzzles understanding of tungsten mineralization and its relationship with granite in the Nanling Range.This paper will analyze the recent documents in tectonic,petrolographic,geochemical and geochronological domains,and discuss on parental rocks,deep-seated magma chamber and ore-forming mechanism to provide some positive estimations relative to metallogenic model of the tungsten mineralization in the Nanling Range:①The early Yanshanian biotite monzogranites occurred as batholith or stock could not be parental rocks to tungsten deposits in the Nanling Range,thus the ore-forming ages of 150~160 Ma are open to doubt.②The late Yanshanian two-mica/muscovite alkalifeldspar granites occurred as stock,boss and vein are potential providers of tungsten source,but not parental rocks to tungsten deposits in the Nanling Range due to their too small volume.③When combining main intrusion(biotite monzogranite),subsequent intrusion(two-mica/muscovite alkali-feldspar granites)and tungsten deposit as a whole,a new metallogenic model could be established:the residual magma enriched in ore-forming materials(tungsten,fluxing components,and aqueous fluid)could occur in a long-lived magma chamber,which intruded rapidly in the extensional system and splitted into two portions(i.e.fluid—melt immiscibility):an alkaline and silicious fluid and a strongly felsic melt.The fluid portion ascended quicker in the top of extensional system and formed as the wolframite-bearing quartz vein,whereas the melt portion arrived later and filled the bottom of extensional system and solidified as the two-mica/muscovite alkali-feldspar granites.④Therefore,the tw

关 键 词：南岭 钨矿 成矿期 成矿母岩 岩浆房 

分 类 号：P618.67[天文地球—矿床学]