江西阳储岭两期岩浆活动与钨成矿作用的关系:来自黑云母地球化学的证据  

Genetic relationship between the two-period magmatism and tungsten mineralization in the Yangchuling deposit,Jiangxi Province:Evidence from biotite geochemistry

作　　者：郑瑜林 赵正[1] 张长青[1] 李宏伟 李彪 ZHENG YuLin;ZHAO Zheng;ZHANG ChangQing;LI HongWei;LI Biao(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,China;School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;The Fifth Geological Brigade of Hebei Bureau of Geology and Mineral Resources,Tangshan 063000,China)

机构地区：[1]自然资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,北京100037 [2]合肥工业大学资源与环境工程学院,合肥230009 [3]中国地质大学(北京)地球科学与资源学院,北京100083 [4]河北省地矿局第五地质大队,唐山063000

出　　处：《岩石学报》2022年第2期495-512,共18页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41973046);国家社会科学基金重大项目(19ZDA111);国家重点研发计划项目(2016YFC0600208);中国地质调查局项目(JYYWF20180502)联合资助.

摘　　要：阳储岭斑岩型W-Mo矿床位于江南造山带中部,是华南地区最早发现的斑岩型钨钼矿床。已探明WO_(3)资源储量6.13万吨(平均品位0.2%),Mo资源储量1.69万吨(平均品位0.03%~0.06%),其成矿作用与中生代花岗质岩浆活动密切相关。区内发育早期花岗闪长岩和晚期二长花岗斑岩,钨矿体以细脉状和浸染状产于二长花岗斑岩体内,而花岗闪长岩内未见矿化。两期岩浆活动与钨成矿的关系尚不明确,制约其含矿差异性的因素尚不清楚。本文以花岗闪长岩和二长花岗斑岩中的黑云母为研究对象,对比研究两类岩浆结晶分异程度、氧逸度、岩浆流体卤素浓度,探讨其对钨成矿的制约。黑云母主量元素分析结果显示,阳储岭两类岩浆岩均为壳源,但显著不同于S型花岗岩的Mg/(Fe+Mg)和Al^(VI)值,指示其具有I型花岗岩的特征。黑云母的微量元素信息显示,相对于花岗闪长岩中的黑云母(类型一),二长花岗斑岩中的黑云母(类型二)显示低的K/Rb、Nb/Ta比值,高的Rb、Cs、Nb和Ta含量,表明其分异程度较花岗闪长岩更高,更有利于钨的富集。两类黑云母所指示的岩浆氧逸度均在NNO缓冲线附近,表明其母岩浆均为还原性岩浆,但二长花岗斑岩显示出更为还原的特征,还原环境有利于钨矿的形成。类型二黑云母比类型一黑云母具有低的IV(F)但高的IV(F/Cl)值,表明其F富集程度更高。通过黑云母计算出对应岩浆流体的log(f H_(2)O/f HF)^(fluid)、log(f H_(2)O/f HCl)^(fluid)、log(f HF/f HCl)^(fluid)值。结果表明类型二具有比类型一更低的log(f H_(2)O/f HF)^(fluid)、log(f H_(2)O/f HCl)^(fluid)值,显示二长花岗斑岩流体中更加富含HF和HCl。而类型二高的log(f HF/f HCl)^(fluid)值,显示出其更高的HF/HCl比值,对应了更高的结晶分异程度。阳储岭晚期二长花岗斑岩与早期花岗闪长岩为同一岩浆房分离结晶作用的产物,矿化存在于二长花岗斑岩顶部,岩浆结晶The Yangchuling porphyry W-Mo deposit is located in the middle part of the Jiangnan orogenic belt,which is recognized as the first typical porphyry type W-Mo deposit in South china.Reporting 63100t of WO 3 with an average grade of 0.2%and 16900t of Mo metal with a grade range of 0.03%~0.06%.The W-Mo mineralization is closely related to the Mesozoic granitic magmatism.Disseminated W mineralization is intimately associated with the late-stage monzogranite porphyry whereas the early-stage granodiorite is barren,it remains obscure as to the relationship between two types of magmatic rocks and what control their contrasting ore-forming potential.In this study,we compared the major and trace elements of biotites from the monzogranite porphyry and granodiorite,respectively,to explore their geochemical differences in magma differentiation,oxygen fugacity and halegon fugacity that may affect their mineralization potential.Major elements compositions of biotites in Yangchuling show that both granodiorite and monzogranite porphyry are derived from crust material,significant different Mg/(Fe+Mg)ratio and Al^(VI) values from the biotite in S-type granite worldwide indicating they are I-type granite.Trace elements of biotite can used to evaluate the differentiation degree of magma.The lower K/Rb,Nb/Ta ratios and higher Rb,Cs,Nb and Ta contents in biotite from monzogranite porphyry relative to biotite in granodiorite indicate higher differentiation degree of monzogranite porphyry,which is conducive to the enrichment of W.Both of magma lies near the NNO buffer line,but monzogranite porphyry shows more reducing characteristics,and the reducing conditions are conducive to mineralization.The biotite(type 2)in the monzongranite porphyry has a lower IV(F)and a higher IV(F/Cl)value indicating higher F enrichment relative to biotite(type 1)in the granodiorite,The halogen fugacity log(f H_(2)O/f HF)^(fluid),log(f H_(2)O/f HCl)^(fluid),log(f HF/f HCl)^(fluid)of associated magmatic fluid calculated by biotite show type 2 has a lower log(f

关 键 词：阳储岭W-Mo矿 黑云母 氧逸度 卤素逸度 岩浆分异 

分 类 号：P578.959[天文地球—矿物学] P618.67[天文地球—地质学]