吉林大学学报(地球科学版) ›› 2022, Vol. 52 ›› Issue (5): 1610-1625.doi: 10.13278/j.cnki.jjuese.20220034

• 地质与资源 • 上一篇    下一篇

哀牢山成矿带长安金矿床成因:地质特征、流体包裹体测温和H-O-S-Pb同位素制约

辛 未1,孟元库1,许志河2,孙丰月3,钱 烨3   

  1. 1.山东科技大学地球科学与工程学院,山东 青岛 266590 

    2.防灾科技学院地球科学学院,河北 三河 065201 

    3.吉林大学地球科学学院,长春 130061

  • 收稿日期:2022-02-20 出版日期:2022-09-15 发布日期:2022-10-10

Genesis of Chang’an Gold Deposit in Ailaoshan Metallogenic Belt: Constraints from Geological Characteristic, Fluid Inclusion Thermometer and H-O-S-Pb Isotope

Xin Wei1,Meng Yuanku1, Xu Zhihe2, Sun Fengyue3, Qian Ye3   

  1. Technology, Qingdao 266590, Shandong,China 

    2. College of Earth Sciences, Institute of Disaster Prevention, Sanhe 065201,HebeiChina 

    3. College of Earth Sciences, Jilin University, Changchun 130061, China

  • Received:2022-02-20 Online:2022-09-15 Published:2022-10-10

摘要: 中国西南部哀牢山成矿带南段长安金矿床成因机制仍然有待研究,为了解其成矿物质与流体来源,掌握其矿床成因类型,给矿山找矿增储工作提供依据,本文以长安金矿床作为研究对象,通过详细的地质特征描述、流体包裹体测温学和矿石H-O-S-Pb同位素测试来研究成矿物质和流体来源、演化,进而制约矿床成因,建立成矿模式。研究结果表明:前人认为的近南北向构造F6并非断裂构造,而是隐爆角砾岩筒,其为长安金矿床的主容矿构造;主成矿阶段包裹体冰点温度绝大部分为-2.9~-0.7 ℃ ,对应盐度(w(NaCl))为1.22%~4.79%,均一温度为162~226 ℃,属于低温低盐度流体体系。长安金矿床成矿主阶段石英的δ18OH2O介于4.4‰~5.2‰之间,δD为-93.9‰~-85.9‰,落入岩浆水与大气水演化线之间,说明成矿流体为岩浆流体与大气水的混合物。长安金矿床黄铁矿的δ34S平均值为2.1‰(n=32),绝大多数介于0.0~3.6‰之间,具有明显的岩浆硫的特点,认为硫来源于岩浆岩;黄铁矿的铅同位素组成特点明显具有二元性,反映了岩浆铅和上地壳围岩铅的双重贡献。综上,认为成矿物质和流体主要来源于岩浆,后期大气水和围岩也对成矿流体物质有一定贡献;长安金矿床受隐爆角砾岩控制,与低硫化型浅成低温热液型金矿的特征相似,尽管其围岩并非传统的火山岩。

关键词: 哀牢山成矿带;长安金矿床;流体包裹体;H-O-S-Pb同位素, 成矿模式

Abstract:  The genetic mechanism of Chang’an gold deposit in the southern section of  Ailaoshan metallogenic belt in Southwest China remains to be restricted. To understand the source of ore-forming materials and fluids, and to illustrate its genetic type of deposit could provide a basis for the mine prospecting and reserve increasing. In this paper, the source and evolution of metallogenic materials and fluids in Chang’an gold deposit are studied based on detailed geological features, ore H-O-S-Pb isotope analysis and temperature measurement of fluid inclusions, and then the genesis of the deposit is restricted and the metallogenic model is established. The results show that the near-SN-trending F6 considered by predecessors is not a fault, but a cryptoexplosive breccia tube, which is the main ore hosting structure of Chang’an gold deposit. In the main metallogenic stage, the freezing point temperature of the inclusions is mostly -2.9--0.7 ℃, the corresponding salinity (w (NaCl)) is 1.22%-4.79%, and the homogenization temperature is 162-226 ℃, which belongs to the low temperature and low salinity fluid system. The δ18OH2O of quartz in the main metallogenic stage is between 4.4‰ and 5.2‰, and the δD is -93.9‰--85.9‰, which falls between the evolution line of magmatic water and atmospheric water, indicating that the ore-forming fluid is a mixture of magmatic fluid and atmospheric water. The averageδ34S of pyrite in Chang’an gold deposit is 2.1‰ (n = 32), most of which are between 0.0 and 3.6‰, with obvious characteristics of magmatic sulfur suggesting that S comes from magmatic rocks. The lead isotopic composition of pyrite has obvious duality, reflecting the dual contribution of magmatic and upper crustal surrounding rocks. Therefore, it is considered that the ore-forming materials and fluids are mainly derived from magma, and the later atmospheric water and surrounding rocks also contribute to the metallogenic fluids. Chang’an gold deposit, which has similar characteristics to low-sulfidation epithermal gold deposits, is dominated by cryptoexplosive breccias, although its surrounding rocks are not traditional volcanic rocks.

Key words: Ailaoshan metallogenic belt, Chang’an gold deposit, fluid inclusion, H-O-S-Pb isotope, metallogenic model

中图分类号: 

  • P59
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