东天山岩浆铜镍硫化物矿床的多期次岩浆侵位与成矿作用--以黄山铜镍矿床为例  

Multiple stages of magma emplacement and mineralization of eastern Tianshan,Xinjiang: Examplified by the Huangshan Ni-Cu deposit

作　　者：毛亚晶[1,2,3] 秦克章[1,3] 唐冬梅[3] 薛胜超[2,3] 冯宏业[4] 田野[3] 

机构地区：[1]中国科学院新疆生态与地理研究所新疆矿产资源研究中心,乌鲁木齐830011 [2]中国科学院大学,北京100049 [3]中国科学院矿产资源研究重点实验室、中国科学院地质与地球物理研究所,北京100029 [4]河北联合大学矿业工程学院地质系,唐山063009

出　　处：《岩石学报》2014年第6期1575-1594,共20页Acta Petrologica Sinica

基　　金：国家自然科学基金重点项目(41030424);新疆有色集团东天山岩浆铜镍硫化物矿床预测评价研究项目联合资助

摘　　要：位于黄山-镜儿泉镁铁-超镁铁岩带西段的黄山铜镍矿田（包括黄山、黄山东、香山、黄山南矿床），是北疆最重毒镍矿产地。矿田内各岩体都是多期岩浆侵位形成的杂岩体，且黄山东和香山铜镍矿床存在多期成矿作用。本文选取黄。型隐伏铜镍矿床进行详细解剖，在此基础上探讨东天山地区多期成岩成矿作用及其勘查意义。黄山矿山开采揭露最新女现象系统观察，不同岩相中橄榄石、辉石（粒径、成分）的垂向和平面剖面变化表明黄山铜镍矿床由多期岩浆侵位形成，且；期次为主要成矿期。第三期次岩相主要由角闪二辉橄辉岩、角闪方辉橄辉岩和角闪橄榄岩组成。角闪二辉橄辉岩底部自榄石核部和边部具有明显的成分差异，其橄榄石的边部相对于核部F0值和Ni含量升高，由于橄榄石结晶过程中与晶间{物发生Fe-Ni的交换反应所致。第三期次的角闪方辉橄辉岩和角闪橄榄岩岩相中橄榄石的Fo值与角闪二辉橄辉岩中橄{Fo值相近，但Ni含量（500×10-6～2050×10-6）高于第二侵入期次角闪二辉橄辉岩中的Ni含量（160×10-6～1000×10-6）橄榄石和硫化物熔体的Fe—Ni交换反应或者不同的母岩浆性质是橄榄石Ni含量不同的主要原因。黄山岩体的斜方辉石古铜辉石，第三期次岩体角闪方辉橄辉岩和角闪橄榄岩中含有粗粒的古铜辉石，其最大粒径（4～8mm）大于角闪二辉橄岩中古铜辉石（2—4mm）。单颗粒古铜辉石的Mr值、CaO及Cr2O3含量从核部到边部有多次重复变化，反映岩浆成分存在多次变化。第三期次单斜辉石包裹的橄榄石的边部比核部具有更高的Ni含量（Fo值相似），结合Cu、Ni、Co等元素的垂直剖口化，本文提出新鲜岩浆补给是黄山主矿体（30号矿体）硫化物富集的重要控制因素。多次岩浆的补给暗示黄山为岩浆通道成矿系统。岩体变宽、局部膨大及岩体产Huangshan orefield, consisting of Huangshan, Huangshandong, Xiangshan and Huangshannan four Ni-Cu deposits in the west part of Huangshan-Jinerquan Permian mafic-ultramafic belt, is the most important nickel mineralization area in northern Xinjiang. This study choose the Huangshan （Huangshanxi in international literature） large Ni-Cu deposit as an example to discuss the multiple stages magma emplacement and the associated mineralization, because all of the deposits in the Huangshan camp have formed by more than two magma stages. Huangshan Ni-Cu deposit is a concealed Ni-Cu deposit. Grain size and major oxides of olivine and orthopyroxene of the Huangshan Ni-Cu deposit varies from different lithofacies, vertically and horizontally. Based on these variations, this paper suggests that the Huangshan Ni-Cu deposit formed by three separated magmas. The compositional discrepancy of Fo value and Ni content in olivine from the bottom of olivine websterite （phase III） may caused by Fe-Ni exchange between sulfide melt and olivine. Olivine orthopyroxenite and hornblende lherzolite of phase III are the major ore-bearing lithofacies of the Huangshan deposit. The Fo value in olivine crystals in phase III are similar in different rock types, while olivine in olivine orthopyroxenite and lherzolite have higher Ni content （500 × 10 -6 ~ 2050 × 10 -6 ） than olivine in olivine websterite （ 160 × 10 -6 ~ 1000 × 10-6 ）. Maximum grain size of bronzite in olivine orthopyroxenite and lherzolite （4 -8ram） is much larger than these in olivine websterite （2 -4 mm）. Mg# value, CaO and Cr2 03 contents of bronzite show repeated changes from the core to the rim, implying the magma composition have been interrupted during bronzite crystallization. The rim of olivine wrapped in clinopyroxene in phase III has higher Ni content than the core of the olivine （with similar Fo value） suggests magma replenishment during olivine crystallization. This, together with the vertical cross-section variation of Cu, Ni, Co in drill

关 键 词：橄榄石 斜方辉石 多期次岩浆作用 多期成矿作用 黄山铜镍矿床 东天山 

分 类 号：P618.41[天文地球—矿床学] P618.63[天文地球—地质学]