王钊飞,隋清霖,贺永康.西昆仑沙子沟铜矿区花岗闪长岩年代学、地球化学及Hf同位素特征[J].西北地质,2019,52(3):90-110
西昆仑沙子沟铜矿区花岗闪长岩年代学、地球化学及Hf同位素特征
Geochronology, Geochemistry and Hf Isotopic Compositions of the Granodiorite in the Shazigou Copper Deposit, West Kunlun
投稿时间:2018-12-11  修订日期:2019-04-11
DOI:10.19751/j.cnki.61-1149/p.2019.03.009
中文关键词:  锆石U-Pb年代学;Hf同位素;地球化学;花岗闪长岩;沙子沟铜矿床;西昆仑
英文关键词:zircon U-Pb dating;Hf isotopes;geochemistry;granodiorite;Shazigou copper deposit;West Kunlun
基金项目:自然资源部中国地质调查局地质调查项目“西昆仑大红柳滩-甜水海地区大型矿产资源基地综合调查”(DD20190143),国家自然科学基金项目“西昆仑塔什库尔干地区赞坎铁矿床流体包裹体研究及对膏盐层参与铁矿成矿的启示(41503046)
作者单位E-mail
王钊飞 中国地质调查局西安地质调查中心/西北地质科技创新中心, 自然资源部岩浆作用成矿与找矿重点实验室, 陕西 西安 710054
汉中西北有色七一一总队有限公司, 陕西 汉中 723000 
 
隋清霖 中国地质调查局西安地质调查中心/西北地质科技创新中心, 自然资源部岩浆作用成矿与找矿重点实验室, 陕西 西安 710054 qlinsui163.com 
贺永康 中国地质调查局西安地质调查中心/西北地质科技创新中心, 自然资源部岩浆作用成矿与找矿重点实验室, 陕西 西安 710054  
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中文摘要:
      沙子沟铜矿床位于西昆仑造山带西段,矿区内发育与成矿关系密切的花岗闪长岩体。笔者针对该岩体开展了岩石地球化学、锆石U-Pb年代学及Lu-Hf同位素组成的研究。LA-ICP-MS锆石U-Pb测年结果为(213.7±2.6)Ma,为锆石结晶年龄,属于晚三叠世;锆石Hf同位素组成表明εHf(t)值为-2.72~1.21,显示成岩过程中有少量幔源岩浆的参与;岩石地球化学结果表明花岗闪长岩具有富钙、富钾、富镁、富铁的特征,铝饱和指数A/CNK为0.99~1.04(<1.1),具有中等强度的负Eu异常(δEu为0.54~0.94,平均为0.79),富集Rb、Th、K、Nd、Sm和LREE等大离子亲石元素,亏损Ba、Nb、Ta、Sr、P、Ti和HREE等高场强元素,显示了I型花岗岩的特征。沙子沟铜矿床成因为岩浆热液型,其早期成矿时代与沙子沟花岗闪长岩形成时代吻合,成矿物质主要来自造山带下地壳,矿区弱过铝质I型花岗岩为成矿提供物源和热源。笔者认为沙子沟花岗闪长岩构造背景属古特提斯洋俯冲碰撞造山作用之后的后碰撞伸展构造,源岩可能由地幔底侵古老陆壳,是壳源花岗质岩浆与幔源基性岩浆发生强烈混合作用的产物,正是这种壳幔物质交换为区内铜多金属矿化提供大量成矿物质来源。
英文摘要:
      The Shazigou Copper deposit is located in the western part of West Kunlun Orogenic Belt, and the granodiorite in this deposit is closely related to copper mineralization. In this paper, the major and trace elements, zircon U-Pb dating and in-situ zircon Hf isotopic compositionof the granodiorite have been reported and studied. The LA-ICP-MS zircon U-Pb dating yields an age of late Triassic (213.7±2.6)Ma, which has been interpreted as the crystallization age of zircons extracted from the granodiorite. The zircon Hf isotope data shows that εHf(t) values vary from-2.72 to 1.21, indicating the involvement of a small portion of mantle-derived magma during the granodiorite diagenesis. Geochemical data indicates that these granodiorite belongs to I-type granite based on the following characteristics, such as enrichment in Ca, K, Mg and Fe, A/CNK values from 0.99 to 1.04 (<1.1), medium to strong negative Eu anomalies (δEu=0.54~0.94, average is 0.79), enrichment in large ion lithophile element (Rb,Th,K,Nd,Sm) and LREE, depletion in high field strength element (Ba,Nb,Ta,Sr,P,Ti) and HREE. The Shazigou copper deposit is ascribed to magmatic hydrothermal type. Its early metallogenic age coincides with the intrusion of the Shazigou granodiorite. The ore-forming materials are mainly from the lower crust of the orogenic belt. In this mining area, the weakly aluminous I-type granite provides material and heat sources for mineralization. Therefore, it's considered that the Shazigou granodiorite was formed in a post-collisional extension regime, following the Paleo-Tethyan orogeny. The source rocks might be the product of the strong mixing of crust-derived granitic magma and mantle-derived basic magma, which was caused by the mantle intruded into the ancient continental crust. The exchange interaction of crust-mantle materials provides a large amount of ore-forming materials for the copper polymetallic mineralization in the Shazigou area.
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