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西昆仑阿克萨依铁矿二长花岗岩岩石成因及动力学背景:年代学、地球化学及Sr-Nd-Pb-Hf同位素约束
引用本文:董瑞,王核,闫庆贺. 西昆仑阿克萨依铁矿二长花岗岩岩石成因及动力学背景:年代学、地球化学及Sr-Nd-Pb-Hf同位素约束[J]. 大地构造与成矿学, 2021, 45(2): 370-388. DOI: 10.16539/j.ddgzyckx.2021.02.008
作者姓名:董瑞  王核  闫庆贺
作者单位:中国科学院 广州地球化学研究所 矿物学与成矿学重点实验室, 广东 广州 510640;中国科学院大学, 北京 100049;中国科学院 广州地球化学研究所 矿物学与成矿学重点实验室, 广东 广州 510640
基金项目:新疆维吾尔自治区重点研发专项"新疆和田县超大型锂铍铷矿床成因及资源综合利用研究";国家自然科学基金项目;中国科学院广州地球化学研究所135项目;国家重点研发计划;新疆维吾尔自治区重大科技专项"和田南部喀喇昆仑稀有金属成矿带成矿规律研究";国家十二五科技支撑计划项目;第二次青藏科考项目
摘    要:
对甜水海地块东北部阿克萨依矽卡岩型铁矿区内与矿化有关的二长花岗岩开展LA-ICP-MS锆石U-Pb年代学、全岩主微量元素、Sr-Nd-Pb同位素及锆石Lu-Hf同位素研究,旨在厘定花岗岩的形成时代、岩石成因及成矿动力学背景.LA-ICP-MS锆石U-Pb定年结果表明,二长花岗岩侵位年龄为12.37±0.18 Ma(中新...

关 键 词:阿克萨依  矽卡岩铁矿  二长花岗岩  中新世  伸展背景

Petrogenesis and Geodynamic Setting of Akesayi Cenozoic Monzo-granite in West Kunlun: Constraints from Geochronology,Geochemistry and Sr-Nd-Pb-Hf Isotopes
DONG Rui,WANG He,YAN Qinghe. Petrogenesis and Geodynamic Setting of Akesayi Cenozoic Monzo-granite in West Kunlun: Constraints from Geochronology,Geochemistry and Sr-Nd-Pb-Hf Isotopes[J]. Geotectonica et Metallogenia, 2021, 45(2): 370-388. DOI: 10.16539/j.ddgzyckx.2021.02.008
Authors:DONG Rui  WANG He  YAN Qinghe
Affiliation:(Key Laboratory of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China)
Abstract:
This study focus on the monzogranite intrusion related to the Akesayi skarn Fe deposit which is located in the eastern part of the Tianshuihai terrane,West Kunlun.In this paper,we report new results of laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)U-Pb zircon dating,chemical and Sr-Nd-Pb isotopic compositions of the whole-rock samples,and zircon Lu-Hf isotopic compositions,and discuss the petrogenesis and geodynamic settings of the intrusions in Akesayi.LA-ICP-MS zircon U-Pb dating of the monzogranite yields a concordant age of 12.37±0.18 Ma,which means that the intrusion was formed in the Miocene.The monzogranite belongs to high-K calc-alkaline and shoshonite series,and is characterized by moderate fractionated REE patterns with weak negative Eu anomalies.The monzogranite has geochemical signatures resembling that of the adakites,such as high Sr(432–1174μg/g)and Sr/Y ratio(64.8–203),with low Y(3.08–18.11μg/g)and Yb(0.35–1.39μg/g)contents.The Harker,La/Sm-La and La/Yb-La diagrams show that the magmatic evolution is dominated by fractional crystallization.Combined with the negative correlation between SiO2 and Y,Yb,positive correlation between SiO2 and Sr/Y,it can be inferred that the adakitic monzogranite may be derived from fractional crystallization of mantle-derived basaltic magmas.The Sr-Nd-Pb isotopic compositions of the rocks show affinity of the Northern Tibetan Plateau Geochemical Province(NTPGP),which indicate that the magma may be originated from the enriched mantle source that had been metasomatismed by the subduction fluid.Contamination of the continental crust may account for the highly variedεHf(t)values and relatively low Mg#of the monzogranite.Integrating with previous geochronological and geological results,we propose that the monzogranite and related Fe mineralization in the Akesayi deposit were likely formed at a regional extension background induced by the huge mantle upwelling.
Keywords:Akesayi  skarn Fe deposit  monzogranite  Miocene  regional extension
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