小秦岭镰子沟金矿床成矿物质来源与成矿过程
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中国地质大学(北京),中国地质大学(北京),中国地质大学(北京)地球科学与资源学院,中国地质大学(北京),中国地质大学(北京)

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Material Sources and Ore-Forming Process of the Lianzigou Gold Deposit in Xiaoqinling
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China University of Geosciences, Beijing,School of the Earth Sciences and Resources, China University of Geosciences (Beijing),China University of Geosciences, Beijing,China University of Geosciences, Beijing

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    摘要:

    镰子沟金矿是小秦岭驾鹿金矿田内的一个十分重要的金矿床,主要赋存于太古宇太华群秦仓沟组深变质片麻岩系中。金矿体受构造破碎蚀变带控制,主要呈脉状产出,走向与矿区主要断裂方向(北东向)基本一致。在金矿体两侧由内向外可见以钾长石化+硅化、绢云母化+硅化+黄铁矿化、绿泥石化+绿帘石化为特征的蚀变分带现象。氢氧同位素组成显示成矿流体具有岩浆水和大气降水混合的特征。氦氩同位素结果说明成矿流体具有壳幔混合来源的特点。硫同位素组成表明,矿石硫明显富集轻硫的特征,可能和成矿过程中硫同位素分馏作用有关。矿石铅同位素组成较为稳定,可能来源于太华群围岩。氢、氧、硫、铅同位素均指示了成矿过程中的水-岩反应:成矿流体在早期为富含K+的碱性热液,在上涌过程中与浅部流体逐渐混合,同时与围岩发生充分接触,通过水-岩反应进行物质和能量的交换,在矿体和围岩接触带形成了以钾长石化为特征的蚀变分带。随着成矿作用的进行,含矿热液的物理化学条件不断发生变化,同时金可能以Au(HS)2-和Au(HTe)2-形式在流体中迁移,最终在适宜的条件下沉淀、富集成矿。

    Abstract:

    The Lianzigou gold deposit is an integral part of the Jialu gold orefield in the Xiaoqinling region, with orebodies occurring mainly within highly metamorphic gneiss of the Qincanggou Formation of the Archaeozoic Taihua Group. The orebodies occur as veins and are controlled by the NEtrending structural fracture altered zone, with the trending direction parallel to NEtrending major faulting. On both sides of orebodies are the alteration zonation characterized by potassicsilicification, sericitizationsilicificationpyritization, chloritizationepidotization from core to the rim of the orebodies. The H and O isotopic compositions show that oreforming fluids comprised mainly mixture of magmatic water and meteoric water. HeAr isotope results demonstrate mixing feature of crustal and mantlederived components. The sulfur isotopic compositions in sulfides indicate that ores are characteristic of enrichment of light sulfur, which maybe result from sulfur isotope fractionation during the process of mineralization. The ore lead isotopic compositions are relatively homogeneous, suggesting a possible source of the Taihua Group (wallrock) for lead in ores. The H, O, S and Pb isotope compositions indicate the waterrock interaction during mineralization. The early K+rich alkaline oreforming fluid mixed with the shallow fluid and then fully reacted with the wall rock to exchange materials and energy through waterrock reaction, generating potassic alteration zone in the wall rock. With mineralization continuing, the oreforming hydrothermal fluids changed physicchemical conditions and carried Au to migrate in the forms of Au(HS)2- and Au(HTe)2-, finally resulting in precipitation and enrichment of gold in a more favorable environment.

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王雷,刘家军,翟德高,朱文兵,孟旭阳.2018.小秦岭镰子沟金矿床成矿物质来源与成矿过程[J].地质学报,92(2):341-358.
WANG Lei, LIU Jiajun, ZHAI Degao, ZHU Wenbing, MENG Xuyang.2018. Material Sources and Ore-Forming Process of the Lianzigou Gold Deposit in Xiaoqinling[J]. Acta Geologica Sinica,92(2):341-358.

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  • 收稿日期:2016-06-25
  • 最后修改日期:2017-02-28
  • 录用日期:2018-01-12
  • 在线发布日期: 2018-02-02
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