皖南竹溪岭与W-Mo成矿密切相关的弱分异Ⅰ型花岗闪长岩成岩条件及其地质意义  

2023.Diagenetic conditions and geological significance of weakly fractionation I-type granodiorite closely related to W-Mo mineralization in Zhuxiling,southern Anhui Province,China

作　　者：孔志岗[1] 毛景文[2] 梁婷[3] 徐生发[4] 李杨林 许红兵 金修勇 KONG ZhiGang;MAO JingWen;LIANG Ting;XU ShengFa;LI YangLin;XU HongBing;JIN XiuYong(Faculty of Land Resources Engineering,Kunming University of Science and Technology,Kunming 650093,China;MNR Key Laboratory of Metallogeny and Mineral Assesment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Earth Science and Resources,Chang an University,Xi'an 710064,China;No.332 Geological Team,Anhui Bureau of Geology and Mineral Exploration,Huangshan 242700,China)

机构地区：[1]昆明理工大学国土资源工程学院,昆明650093 [2]中国地质科学院矿产资源研究所,自然资源部成矿作用与资源评价重点实验室,北京100037 [3]长安大学地球科学与资源学院,西安710064 [4]安徽省地质矿产勘查局332地质队,黄山242700

出　　处：《岩石学报》2023年第6期1619-1648,共30页Acta Petrologica Sinica

基　　金：国家自然科学重点基金项目(41430314);云南省科技计划项目企业基础研究应用基础研究联合专项(202101BC070001-003);云南省重大科技项目(202202AG050006);昆明理工大学引进人才科研启动基金项目(KKZ3202221023);云南省地球系统科学重点实验室开放课题(ESS2021004)联合资助。

摘　　要：江南钨矿带是近年来中国新发现W矿床最多的成矿区带之一,是近年研究热点地区。该钨矿带的东部主要发育与弱分异Ⅰ型花岗质岩石密切相关的W-Mo矿床,其成岩成矿机制和条件还不清楚,成岩条件研究是该类型矿床成岩成矿模型研究的基础。因此本文以竹溪岭W-Mo多金属矿床为例,利用角闪石-斜长石温度计、角闪石全Al压力计,角闪石氧逸度计算和黑云母氧逸度投图结果,限定花岗闪长岩的成岩条件,在此基础上,探讨成岩模式。结果显示:早期结晶的角闪石结晶温度为849-881℃,压力为241-330MPa,对应结晶深度9.11-12.4km,logf_(02)=-12.8--12.2;角闪石主结晶阶段的温度为774-841℃,压力为123-209MPa,对应结晶深度为4.40-7.90km, logf_(02)=-13.9--12.7;黑云母结晶时的氧逸度logf_(02)≈-15.0--13.0;显示岩浆从早期到晚期,由深而浅,温度不断降低,氧逸度不断升高。角闪石、黑云母矿物化学特征显示,壳幔岩浆混合作用是竹溪岭花岗闪长岩的主要成岩机制,岩浆上侵过程中经历了两期角闪石结晶事件。江南钨矿带W-Mo多金属矿床的成岩成矿与晚侏罗世古太平洋板块(Izanagi板块)的俯冲作用密切相关。In recent years,many tunsten deposits were discovered in Jiangnan tungsten belt,which is one of the hot areas of geological research.Many W-Mo deposits,closely related to weakly fractionation I-type granitic rocks,are well developed in the eastern tungsten belt.The mechanism and conditions of petrogenesis and mineralization are still unclear.The study of diagenetic conditions is the basis of the study of the diagenetic and metallogenic model of this type of deposit.Here we present different mineral thermal-barometers,f O 2 calculation data of Zhuxiling W-Mo polymetallic deposit in order to place constraints on the diagenetic conditions and diagenetic models.Our results show that:the crystallization temperature of early crystallized amphibole is 849~881℃,the pressure is 241~330MPa,the emplaced depth is 9.11~12.4km,log f O 2=-12.8~-12.2;and the crystallization temperature of the main crystallization stage of amphibole is 774~841℃,the pressure is 123~209MPa,the emplacement depth is 4.40~7.90km,log f O 2=-13.9~-12.7;and the log f O 2 of biotite is-15.0~-13.0.The temperature of magma decreases and oxygen fugacity increases from early to late magma.The chemical characteristics of amphibole and biotite minerals show that crust-mantle magma mixing is the main diagenetic mechanism of Zhuxiling granodiorite.Two stages of amphibole crystallization events occurred during the magma upwelling process.The diagenesis and mineralization of the W-Mo polymetallic deposit in Jiangnan tungsten belt are closely related to the subduction of the Paleo-Pacific plate(Izanagi plate)during the Late Jurassic.

关 键 词：江南钨矿带 弱分异Ⅰ型花岗质岩石 竹溪岭花岗闪长岩 成岩条件 成岩模型 

分 类 号：P618.67[天文地球—矿床学]