摘要
多才玛铅锌矿床位于青海省东羌塘地块,是近年来发现的超大型铅锌矿床。为加强该矿床成矿地质背景研究,对花岗斑岩进行了锆石U-Pb年代学和岩石地球化学特征研究,讨论岩石成因、岩浆源区和构造背景。花岗斑岩锆石U-Pb年龄为257.1 Ma±7.0 Ma,为二叠世末期。花岗斑岩SiO_(2)、Na_(2)O、K_(2)O质量分数较高,且相对富钾,贫Al_(2)O_(3)、CaO、MgO;富集轻稀土元素和Rb、Th、U等大离子亲石元素,相对亏损重稀土元素和Nb、Ta、P、Ti等高场强元素;稀土元素球粒陨石标准化配分曲线显示右倾型,具有中等Eu负异常,表明该岩体经历了斜长石的分离结晶过程,或者在源区存留部分斜长石。花岗斑岩属于准铝质—略过铝质高钾钙碱性系列岩石,具有A2型花岗岩的特点,源区主要由中上地壳变质沉积岩组成,形成于洋壳俯冲过程中与板块后撤作用有关的伸展环境,与古特提斯洋俯冲作用有关。
The Duocaima Pb-Zn deposit,located on East Qiangtang Block in Qinghai Province,is a super-large Pb-Zn deposit discovered in recent years.To strengthen the study of the metallogenic geological setting of the ore deposit,zircon U-Pb geochronology and petrogeochemical characteristics of granite porphyry were studied,and the petrogenesis,magma source area,and tectonic setting were discussed.The zircon U-Pb age of granite porphyry was determined to be 257.1 Ma±7.0 Ma,indicating its formation in the late Permian period.The granite porphyry exhibits high mass fractions of SiO_(2),Na_(2)O,and K_(2)O,with relative potassium enrichment,but depletion in Al_(2)O_(3),Ca O,and MgO;it is enriched in light rare earth elements(LREEs)and large-ion lithophile elements(LILEs)such as Rb,Th and U,while relative depleted in heavy rare earth elements(HREEs)and high-field-strength elements(HFSEs)such as Nb,Ta,P and Ti.The chondrite-hormalized rare earth element(REE)diagram shows a right-leaning trend with moderate Eu negative anomalies,indicating that the rock mass has undergone the fractional crystallization process of plagioclase,or some plagioclase remains in the source region.The granite porphyry falls within the metaluminous to weakly peralu-minous high-potassium calcium alkaline series,and exhibits characteristics of A2-type granite.The source region is mainly composed of metamorphic sedimentary rocks in the mid-upper crust,formed in an extensional setting related to slab retreat during oceanic crust subduction,and associated with the subduction of the Paleo-Tethys Ocean.
作者
于明辉
曹守林
韦顺
Yu Minghui;Cao Shoulin;Wei Shun(Institute of Scientific Research,Jilin University;Qinghai Provincial Key Laboratory of Concealed Mineral Exploration;College of Earth Sciences,Jilin University)
出处
《黄金》
2025年第11期86-94,共9页
Gold
基金
青海省地质勘查专项基金项目(2023085029ky004)
青海省隐伏矿勘查重点实验室开放性研究课题资助项目(2025qhyfkf01)。
