Zircon U–Pb geochronology and Hf isotopic constraints on the petrogenesis of the Late Silurian Shidonggou granite from the Wulonggou area in the Eastern Kunlun Orogen,Northwest China

ABSTRACT

The Wulonggou area in the Eastern Kunlun Orogen (EKO) in Northwest China is characterized by extensive granitic magmatism, ductile faulting, and orogenic gold mineralizations. The Shidonggou granite is located in the central part of the Wulonggou area. This study investigated the major as well as trace-element compositions, zircon U–Pb dates, and zircon Hf isotopic compositions of the Shidonggou granite. Three Shidonggou granite samples yielded an average U–Pb zircon age of 416 Ma (Late Silurian). The Late Silurian Shidonggou granite is peraluminous, with high alkali contents, high Ga/Al ratios, high (K₂O + Na₂O)/CaO ratios, and high Fe₂O₃^T/MgO ratios, suggesting an A-type granite. The Shidonggou granite samples have zircon ε_Hf(t) values ranging from ?7.1 to +4.4. The Hf isotopic data suggest that the Late Silurian granite was derived from the partial melting of Palaeo- to Mesoproterozoic juvenile mantle-derived mafic lower crust. Detailed geochronological and geochemical data suggest that the Late Silurian granite was emplaced in a post-collisional environment following the closure of the Proto-Tethys Ocean. Combining data of other A-type granitic rocks with ages of Late Early Silurian to Middle Devonian, such post-collisional setting related to the Proto-Tethys Ocean commenced at least as early as ~430 Ma (Late Early Silurian), and sustained up to ~389 Ma (Middle Devonian) in the EKO.     

甘肃省肃北县石硐沟银多金属矿床地质特征及矿床成因

石硐沟银多金属矿床位于野牛滩岩体的外接触带,与塔儿沟钨矿毗邻,矿体NW-SE向石硐沟断裂破碎带的严格控制,矿体赋存于破碎带中,呈似层状,含矿岩石为角砾状硅化灰岩及含炭千枚岩。前长城系北大河群为成矿提供物质来源。矿带（体）严格受石硐沟断裂（F1）控制,同时受岩性界面的控制,矿体无一例外均产出于F1断裂带中。野牛滩花岗闪长岩体为矿液的运移、循环,成矿物质的萃取、富集提供热动力条件。矿床剥蚀程度较浅,深部找矿潜力较大。     

Micromine软件在石硐沟银多金属矿区中的应用

基于Micromine软件平台,结合石硐沟银多金属矿相关地质资料,建立三维地表模型并叠加地质数据,能真实有效地揭示与矿床有成因联系的各种因素的相互关系。在此基础上,运用距离反比法对矿体进行空间品位赋值,快速估算矿产资源储量,并构建探采工程系统模型,为矿床的勘探、开采设计和施工管理提供科学依据。     

甘肃肃北石硐沟银多金属矿床地质特征及找矿前景

石硐沟矿区位于祁连造山带西段,中祁连北缘的深大断裂是区内的重要导矿、导热构造,为成矿物质的迁移富集提供了重要的条件。该矿床属中低温热液交代矿床,热液来源与野牛滩花岗闪长岩的侵入作用有关。沿断裂破碎带找矿前景广阔,有发展成大型银多金属矿床的前景。     

甘肃省石硐沟银多金属矿床富集规律及找矿前景

石硐沟银多金属矿床位于北祁连加里东造山带西段,与塔尔沟大型钨矿床为同一成矿系列。矿区出露地层主要为前长城系北大河群,为一套中一深变质岩系;石硐沟断裂（F1）为区内主要控矿断裂。矿带（体）严格受其控制;矿体呈似层状,含矿岩石为角砾状硅化灰岩;银矿化与铅矿化呈正相关,与锌矿化呈一定负相关。矿体品位及厚度均具膨大缩小,分段富集特点,矿体总体向东倾伏。矿带向东西均有延伸,沿断裂破碎带找矿前景广阔。矿体深部及东西延伸方向尚未控制到矿体边界,向东矿体延伸空间较大。沟系土壤异常指示效果明显,异常向西未封闭,西部具有较大的找矿前景。