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李楠,张志超,刘兴武,刘基. 2018. 微细浸染状金矿化与脉状金-锑矿化关系:西秦岭阳山金矿带例析. 岩石学报, 34(5): 1312-1326
微细浸染状金矿化与脉状金-锑矿化关系:西秦岭阳山金矿带例析
作者单位
李楠 中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083 
张志超 中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083 
刘兴武 中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083 
刘基 中国地质大学地质过程与矿产资源国家重点实验室, 北京 100083 
基金项目:本文受国家重点基础研究发展规划项目(2015CB452606)、国家自然科学基金项目(41702072)、国家公益性行业科研专项经费项目(201411048)、中国地质调查局地质调查项目(12120114038301)、高等学校学科创新引智计划(B07011)和中国地质大学(北京)基本科研业务费专项资金资助项目(2-9-2014-055、2-9-2017-269)联合资助.
摘要:
      阳山是西秦岭金矿带已探明金储量最大的独立金矿,金矿化主要呈微细浸染状分布于千枚岩和花岗质岩脉中,锑矿化主要分布于花岗质岩脉与千枚岩接触带的石英±方解石脉中,是研究微细浸染状金矿化与脉状金-锑矿化的时间、空间和成因关系的理想选区。成矿主阶段微细浸染状黄铁矿-毒砂矿化已有大量研究,而晚阶段脉状金-锑矿化特征及其与主阶段微细浸染状金矿化关系尚待查明。论文系统研究了成矿晚阶段流体包裹体组合特征、辉锑矿及石英的矿物学、稀土和微量元素特征,并与成矿主阶段进行对比,以期理清阳山金矿带金矿化与锑矿化的关系。流体包裹体组合显微测温结果显示,成矿晚阶段流体均一温度为271.3~288.3℃,具有中低温、低盐度、富Cl和CO2、还原性的变质流体来源的特征,与成矿主阶段一致。辉锑矿呈轻稀土富集、重稀土亏损的"右倾式"稀土配分模式,并可见中-弱的Eu负异常和强的Ce负异常,与千枚岩和花岗质岩脉的稀土元素配分模式相似。辉锑矿富含Ag、Au、As等微量元素,与赋矿围岩中这些元素的高背景值有关。结合硫化物硫同位素数据,指示阳山金矿带成矿物质来源可能为赋矿的千枚岩和花岗质岩脉:在区域构造抬升引发的退变质过程中,千枚岩和花岗质岩脉发生变质脱挥发分作用,释放出金等成矿物质。金矿化与锑矿化贯穿整个成矿作用,随着成矿温度、压力的变化,以及成矿流体成分的演化,成矿早、主阶段以微细浸染状含金硫化物为主,发育位置较深,成矿晚阶段以自然金-辉锑矿脉为主,发育位置较浅,在矿带尺度上符合造山型金矿地壳连续成矿模式的垂向分布规律。本文查明了阳山金矿带微细浸染状金矿化与脉状金-锑矿化的关系,明确其为造山型金矿浅成金-锑矿化,并在此基础上提出了找矿方向,为西秦岭及其他地区类似金矿床的理论研究与找矿勘探提供了有益参考。
英文摘要:
      Yangshan is the largest independent gold deposit in the West Qinling gold belt. Gold mineralization is mainly disseminated in phyllite and granitic dikes, while antimony mineralization is mainly hosted in quartz ±calcite veins which are located in the contact zone between granitic dikes and phyllite. Therefore, the Yangshan gold belt is an ideal object to study the temporal-spatial-genetic relationship between disseminated gold mineralization and vein-type gold-antimony mineralization. Previous studies mainly focused on the main ore stage pyrite-arsenopyrite mineralization, but the characteristics of late ore stage vein-type gold-antimony mineralization and the relationship with the main ore stage disseminated gold mineralization has rarely been reported. The late-ore stage fluid inclusion assemblage, the mineralogy, REE and trace elements of stibnite and quartz are studied in this paper. Comparison between late ore stage and main ore stage mineralization is done to clarify the relationship between gold and antimony mineralization in the Yangshan gold belt. Based on the microthermometry of fluid inclusion assemblage, the Th of the late ore stage fluid is 271.3~288.3℃, with low salinity and enrichment in Cl and CO2. The reduced late ore stage fluid is sourced from metamorphic fluid, which is consistent with the main ore stage fluid. The REE of stibnite shows a light REE enrichment pattern with negative Eu anomalies and strong negative Ce anomalies, which is similar to the REE features of phyllite and granitic dikes. Stibnite is enriched in Ag, Au, As, which is due to the high background values of these elements in the host rocks. Integrated with sulfur isotope data from gold-bearing sulfides, it can be indicated that the ore-hosting phyllite and granitic dikes may be the metal source for the gold mineralization in the Yangshan gold belt. Gold and other ore materials were released from the devolatilization of the phyllite and granitic dikes during the retrograde metamorphism induced by the regional tectonic uplift. Gold and antimony mineralization develop through the whole mineralization. The deep disseminated gold-bearing sulfides are dominated in the early and main ore stages, and the shallow vein-type native gold-stibnite is the major mineralization style in the late ore stage, which are controlled by the changing of temperature, pressure and components evolution of ore fluids and are in accordance with the vertical distributing regularities of crustal continuum model for the orogenic gold deposits. The relationship between disseminated gold mineralization and vein-type gold-antimony mineralization is clarified and the Yangshan gold belt is defined to be an epizonal orogenic gold-antimony belt. Finally, the prospecting direction is indicated based on the above studies. This research will provide beneficial reference for the theoretical study and prospecting of similar gold deposits in West Qinling or other area worldwide.
关键词:辉锑矿  流体包裹体组合  稀土元素  微量元素  阳山金矿带  造山型金矿
投稿时间:2017-12-01  修订日期:2018-03-23
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主办单位:中国矿物岩石地球化学学会
印刷版(Print): ISSN 1000-0569 网络版(Online): ISSN 2095-8927
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