桐柏山老湾金矿带与燕山期岩浆作用有关的岩浆热液金多金属矿床成矿作用——来自地球化学、年代学证据及控矿构造地质约束  

Magmatic hydrothermal gold and polymetallic metallogenesis related to Yanshanian magmatism of Laowan gold belt,Tongbai Mountain:Evidence from geochemistry,geochronology and ore-controlling structural geological constraints

作　　者：杨梅珍[1,2] 陆建培[2] 付静静[2] 任爱琴[3] 王世峰 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,湖北武汉430074 [2]中国地质大学资源学院,湖北武汉430074 [3]河南省地质矿产勘查开发局第三地质调查队,河南信阳464000 [4]河南鑫源黄金公司,河南桐柏474750

出　　处：《矿床地质》2014年第3期651-666,共16页Mineral Deposits

基　　金：地质过程与矿产资源国家重点实验室开放课题(编号:GPMR201014);河南省国土资源厅2010年度省两权价款地质矿产科技攻关资助项目(编号:2010-61-1)的资助

摘　　要：老湾金矿带为桐柏山北麓一条重要的金多金属成矿带,其内的老湾和上上河金矿床的控矿构造,分属脆性右行走滑断裂体系中压扭性P型和张扭性R型断裂。老湾金矿床的矿脉呈右形侧列、向南相对缓倾,以浸染状、条带状、网脉状的蚀变岩型矿化为特征。上上河金矿床的矿脉平行展布,向北陡倾,除浸染状蚀变岩型矿化外,石英脉型矿化较发育。该矿带的金矿化类型与断裂构造性质具有明显的耦合关系。右行断裂控矿体系晚于韧性剪切带形成,更晚于区域峰期变质作用,这排除了热液成矿作用与早期区域变质和韧性剪切变形之间的成因联系。矿带矿化元素显示,以松扒花岗斑岩脉带为中心的Mo→Cu-Pb-Zn-Ag→Au空间分带特征。矿石硫同位素较窄的变化范围和较均一的组成(δ34S值多变化在1.69‰～5.99‰),显示单一深源岩浆硫特征。矿石与燕山期花岗岩的铅同位素的相似性,表明它们可能源自相同的源区。含金石英脉石英流体的氢、氧同位素(δ18O流体值为3.2‰～5.4‰,δD值为-86.3‰～-53.5‰)显示了成矿流体的岩浆来源。花岗斑岩锆石U-Pb同位素年龄为(138.9±3.3)Ma,与前人测得的矿脉中热液云母(39Ar/40Ar法)的成矿年龄基本一致。综合分析认为,老湾金矿带金多金属成矿作用与燕山期浅成岩浆作用具有密切的时空关系和成因联系。The Laowan gold belt is an important gold polymetallic metallogenic belt on the northern side of the Tongbai Mountain. Ore-controlling structures of Laowan and Shang Shanghe gold deposits within the metallogenic belt belong to compression-shear P type and tension-shear R type of brittle dextral strike-slip fault system respectively. The gold lodes of the Laowan gold deposit are characterized by the right echelon of three larger ore vein belts, relatively gently southward dip, and disseminated, stripped and veinlet altered rock-type mineralization. The gold lodes of the Shangshanghe gold deposit are characterized by the paralleled ore veins, steep northward dip,and well-developed quartz vein-type mineralization besides altered rock-type mineralization. These phenomena reveal the coupling relationship between mineralization and ore-controlling fault properties. The ore-controlling dextral strike-slip fault was formed later than the ductile shear zone and much later than peak regional metamorphism, and it precludes the genetic relationship between the hydrothermal mineralization and the regional metamorphism and ductile shear deformation. The ore-forming elements within the ore belt display Mo→Cu-Pb-Zn-Ag→Au zoning centered on Songpa granite porphyry dyke zone. The narrow range and homogeneous composition（δ^34S is mostly in the range of 1.69‰-5.99‰）of δ34S values of ores reveal the deep seated magmatic sources of sulfur. The similarity of Pb isotopes of ores to those of Yanshanian granite implies that they were probably derived from the same source. The ore-forming fluid in quartz of Au-bearing quartz vein has the composition of 3.2‰-5.4‰ for δ^18Ofluid and -86.3‰--53.3‰ for δ18D, suggesting the magmatic origin of the ore-forming fluid. The ^39Ar/^40Ar age 〔（138.9±3.3） Ma〕 of granite porphyry obtained by zircon U-Pb isotope is largely coeval with the ore-forming age obtained from hydrothermal mica contained in the ore vein. It can be concluded that the gold and polymetallic metalloge

关 键 词：地球化学 右行走滑断裂体系 地质年代学 岩浆热液成矿作用 老湾成矿带 桐柏山 

分 类 号：P618.51[天文地球—矿床学]