摘要
甘肃北山南带是我国西北地区重要的金属矿床富集区,前红泉金矿床是该区新发现的一处大型矿床。该矿床位于塔里木陆块区的敦煌陆块基底杂岩隆起带,其形成与韧性剪切带及其演化过程中产生的韧-脆性变形带密切相关。根据脉体穿切关系和矿物共生组合特征,成矿过程可划分为石英-黄铁矿阶段、石英-多金属硫化物阶段和碳酸盐-石英阶段。为深入探讨前红泉金矿床的成矿流体、成矿物质来源及矿床成因等关键问题,本研究开展了详细的岩相学和矿相学观察、流体包裹体及H-O-S同位素等分析。结果表明,成矿流体以富液气液两相包裹体为主,同时存在少量富气气液两相包裹体、CO_(2)-H_(2)O包裹体、纯液相包裹体及纯气相包裹体。成矿流体的完全均一温度集中在197~302℃之间,盐度为1.2%~6.7%NaCleqv,密度为0.60~0.92 g/cm^(3),属于中低温、低盐度、低密度的CO_(2)-H_(2)O-NaCl体系,并含有少量CH4和N2。主成矿阶段的成矿压力为11.69~38.27 MPa,成矿深度为1.17~3.83 km。石英的δDV-SMOW值为-101.5‰~-81.1‰, δ^(18)O_(V-SMOW)值为14.08‰~18.35‰,计算获得的δ^(18)_(H_(2)O)值为6.30‰~10.57‰,表明成矿流体以变质流体为主,并混入少量岩浆流体。黄铁矿的34SV-CTD值为9.75‰~10.77‰,指示成矿物质中的硫主要来源于变质地层。综合研究表明,前红泉金矿的形成经历了流体混合作用,其成矿过程与二叠纪–三叠纪柳园裂谷闭合及板块碰撞造山引发的韧性剪切作用密切相关,矿床成因类型属于造山型金矿。
The southern Beishan orogenic belt in Gansu Province is a significant enrichment zone for metal deposits in northwest China,and the Qianhongquan gold deposit,a newly discovered large-scale deposit,is located in this region.The Qianhongquan gold deposit occurs in the Dunhuang basement complex uplift of the Tarim Block and is structurally controlled by a ductile shear zone and associated ductile-brittle deformation zones.By analyzing vein cross-cutting relationships and mineral paragenetic assemblages,the ore-forming process can be divided into three distinct stages:the quartz-pyrite stage,the quartz-polymetallic sulfide stage,and the carbonate-quartz stage,sequentially from early to late.Comprehensive petrographic observations,coupled with fluid inclusion studies and H-O-S isotope analyses,were conducted to investigate the characteristics of ore-forming fluids,material sources,and genetic model of the Qianhongquan gold deposit.Analytical results reveal that the fluid inclusions are predominantly gas-liquid two-phase inclusions,with minor CO_(2)-H_(2)O inclusions,pure liquid phase inclusions,and pure gas phase inclusions.The homogenization temperatures of fluid inclusions range from 197–302,with corresponding℃salinities of 1.2%–6.7%NaCleqv and densities of 0.60–0.92 g/cm3,characterizing the ore-forming fluid as a medium-low temperature,low salinity,and low density CO_(2)-H_(2)O-NaCl(±CH4-N2)system.The ore-forming pressure during the main mineralization stage is estimated at 11.69–38.27 MPa,corresponding to an ore-forming depth of 1.17–3.83 km.Stable isotope analyses yieldδDV-SMOW values of quartz ranging from−101.5‰to−81.1‰andδ^(18)O_(V-SMOW) values between 14.08‰and 18.35‰.The calculatedδ^(18)_(H_(2)O) values of 6.30‰–10.57‰demonstrate that the ore-forming fluids were predominantly metamorphic in origin,with minor contribution from magmatic fluids.Sulfur isotope compositions of pyrite(34SV-CDT=9.75‰–10.77‰)indicate that the sulfur was derived from metamorphic rocks.Integrated analysis demonstrates that fluid mixing played an important role in the mineralization of the Qianhongquan gold deposit,and mineralization was closely associated with ductile shearing triggered by the closure of the Permian-Triassic Liuyuan rift and subsequent plate collision orogeny.Therefore,the Qianhongquan deposit is interpreted to be an orogenic-type gold deposit based on its genetic characteristics.
作者
李省晔
杨镇熙
张晶
赵吉昌
陈世明
胡小春
刘钊
张立涛
王振
LI Shengye;YANG Zhenxi;ZHANG Jing;ZHAO Jichang;CHEN Shiming;HU Xiaochun;LIU Zhao;ZHANG Litao;WANG Zhen(Hebei GEO University,Shijiazhuang 050031,Hebei,China;Fourth Institute of Geological and Mineral Exploration of Gansu Bureau of Geology and Mineral Resources,Jiuquan 735000,Gansu,China;Key Laboratory of Mineral Resources Exploration,Gansu Province,Jiuquan 735000,Gansu,China;College of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu 610059,Sichuan,China;Engineering Research Center for Silicate Solid Waste Resource Utilization of Hebei Province,Shijiazhuang 050031,Hebei,China)
出处
《大地构造与成矿学》
北大核心
2025年第6期1410-1427,共18页
Geotectonica et Metallogenia
基金
甘肃省重点人才项目(2023RCXM04)
甘肃省科技计划项目(24JRRF004、22JR5RA819)
甘肃省省级基础地质调查项目(甘资财环[2020]28号)
甘肃省地质勘查基金项目(202301-D01)
甘肃省自然资源厅科技创新项目(202423、 202424)
河北省自然科学基金项目(D2021403056)
甘肃省基础地质调查项目(甘资勘函[2022]63号)联合资助。
关键词
矿床成因
稳定同位素
流体包裹体
前红泉金矿床
北山地区
ore deposit genesis
stable isotopes
fluid inclusions
Qianhongquan gold deposit
Beishan region
