Highly fractionated Jurassic I-type granites and related tungsten mineralization in the Shirenzhang deposit, northern Guangdong, South China: Evidence from cassiterite and zircon U-Pb ages, geochemistry and Sr-Nd-Pb-Hf isotopes
Highly fractionated Jurassic I-type granites and related tungsten mineralization in the Shirenzhang deposit, northern Guangdong, South China: Evidence from cassiterite and zircon U-Pb ages, geochemistry and Sr-Nd-Pb-Hf isotopes
复制标题
华南粤北石人掌矿床高度分异侏罗纪I型花岗岩及相关钨矿化：来自锡石和锆石U-Pb年龄、地球化学和Sr-Nd-Pb-Hf同位素的证据
DOI：
10.1016/j.lithos.2018.04.030
复制
发表时间：
2018-07-01
期刊：
影响因子：
3.5
通讯作者：
Peng, Ning-Jun
中科院分区：
文献类型：
--
作者：
Jiang, Hai;Jiang, Shao-Yong;Peng, Ning-Jun
石人掌钨存款矿床位于南岭钨锡多金属带东段的北方，是典型的黑钨矿-石英脉型存款矿床。矿脉受北西向断裂控制，主要赋存于奥陶系变质沉积岩中，在隐伏花岗岩体的穹窿中也有少量发现，呈典型的五层垂直分带。隐伏花岗岩体主要由两个侵入相组成，即外带的斑状黑云母花岗岩（G1）和内带的中细粒二长花岗岩（G2）。本文报道了石人掌钨存款矿床新的辉长岩U-Pb年龄和硫化物Pb同位素，结合隐伏花岗质岩石新的锆石U-Pb年龄和Hf同位素、元素地球化学和Sr-Nd-Pb同位素，旨在阐明与矿有关的花岗岩的成因以及钨矿化与花岗质岩浆作用的联系。LA-ICP-MS锆石U-Pb定年得到G1和G2的加权平均年龄分别为164 +/- 2 Ma和162 +/- 4 Ma。含黑钨矿石英脉和晶簇状石英脉中锡石的加权平均年龄分别为164 ± 2 Ma和160 ± 2 Ma。这些年龄表明，石人掌存款中的花岗岩侵入体和相关的W-（Sn）成矿作用均起源于晚侏罗世（约100万年）。160 Ma）。石人掌花岗质岩石为弱过铝质、高度分馏的I型花岗岩。详细的元素和同位素数据表明，花岗岩类岩石来自部分熔融的古元古代基底岩石在一个相对较浅的深度类似于30公里的玄武岩浆底侵触发，并经历了广泛的分离结晶角闪石，黑云母，长石，独居石和/或褐帘石。石人掌1型花岗岩的形成背景为古太平洋板块向北西俯冲的陆弧环境。长石和硫化物的铅同位素组成具有可比性，表明矿脉中的铅为岩浆成因。综合矿脉与隐伏花岗质岩石的时空关系及硫化物和花岗岩的铅同位素特征，认为石人掌存款矿床的钨矿化与隐伏花岗质岩石有成因联系。结晶分异作用和熔体-流体相互作用可能对花岗岩型钨矿化的形成起重要作用。(C)2018爱思唯尔B. V.保留所有权利。
The Shirenzhang tungsten deposit is a classic wolframite-quartz vein-type deposit located in northern Guang-dong Province, eastern segment of the Nanling W-Sn polymetallic belt. The ore veins, controlled by the NW striking fault system, are mainly hosted in the Ordovician metasedimentary rocks and can also be found with less amount in the cupola of the concealed granitic stock, displaying a typical five-floor vertical zonation proposed by the Chinese geologists. The concealed granitic stock mainly comprises two intrusive facies, the porphyritic biotite granite (G1) in the outer zone and the medium- to fine-grained monzogranite (G2) in the inner zone. In this paper, we report new cassiterite U-Pb ages and Pb isotopes of sulfides for the Shirenzhang tungsten deposit, combined with new zircon U-Pb ages and Hf isotopes, elemental geochemistry and Sr-Nd-Pb isotopes of the concealed granitic rocks, with aims to elucidate the origin of the ore-related granites and the link between the tungsten mineralization and granitic magmatism. LA-ICP-MS zircon U-Pb dating gives the weighted mean ages of 164 +/- 2 Ma for G1 and 162 +/- 4 Ma for G2, respectively. Cassiterite from the wolframite-bearing quartz vein and the drusy quartz vein yield the weighted mean ages of 164 +/- 2 Ma and 160 +/- 2 Ma, respectively. These ages suggest that both the granitic intrusion and related W-(Sn) mineralization in the Shirenzhang deposit were initiated during the late Jurassic (ca. 160 Ma). The Shirenzhang granitic rocks are weakly peraluminous highly fractionated I-type granites. Detailed elemental and isotopic data demonstrate that the granitic rocks were derived from partial melting of the Paleoproterozoic basement rocks at a relatively shallow depth of similar to 30 km triggered by underplating of basaltic magma, and underwent extensive fractional crystallization of hornblende, biotite, feldspar, and monazite and/or allanite. A continental arc setting induced by northwesterly subduction of the paleo-Pacific plate is suggested for the genesis of the Shirenzhang 1-type granites. The comparable Pb isotopic compositions of feldspar and sulfides imply that the lead in the ore veins was of magmatic origin. Integrating the spatial-temporal relationship between the ore veins and the concealed granitic rocks with the Pb isotopes from the sulfides and granites, we suggest that the tungsten mineralization is genetically linked with the concealed granitic rocks in the Shirenzhang deposit. Fractional crystallization and melt-fluid interaction may play an important role on the formation of the granite-related tungsten mineralization. (C) 2018 Elsevier B.V. All rights reserved.