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冀东地区太阳沟钼矿床成因探讨:来自年代学、地球化学及S、Pb同位素的证据
投稿时间:2020-04-13  修订日期:2020-06-17  点此下载全文
引用本文:
DOI:10.19762/j.cnki.dizhixuebao.2020240
摘要点击次数: 16
全文下载次数: 23
作者单位E-mail
徐国新 河北省地矿局第八地质大队 xuguoxin-069888@163.com 
李玉静 河北省地质矿产研究中心  
孙金龙 河北省地矿局第八地质大队 84086313@126.com 
和越 河北省地矿局第八地质大队  
赵迪 河北省地矿局第八地质大队  
刘晓波 河北省地质矿产研究中心  
王丹 河北省地质矿产研究中心  
基金项目:本文为河北省地矿局科研基金项目“河北省兴隆太平村矿集区钼金稀有多金属矿成矿规律与区域找矿方向研究”(项目编号:454-0601-YBN-G9A6)资助的成果。
中文摘要:太阳沟钼矿床位于冀东地区,矿区内出露的岩性主要为花岗斑岩和黑云母二长花岗岩,矿体主要赋存于花岗斑岩及其围岩接触带内,多呈透镜状、脉状产出。本文通过锆石U-Pb定年、全岩地球化学分析、辉钼矿Re-Os同位素测年及金属矿物S、Pb同位素分析,对太阳沟钼矿床的成岩、成矿时代准确厘定,并对矿床成因及成矿过程进行探讨。锆石U-Pb定年结果显示,花岗斑岩与黑云母二长花岗岩样品的206Pb/238U加权平均年龄分别为154.8±1.5Ma、156.5±1.2Ma。辉钼矿的Re-Os同位素测年获得155.79±0.93Ma的模式年龄加权平均值,与锆石U-Pb年龄在误差范围内一致,表明其为晚侏罗世构造-岩浆活动产物。全岩地球化学特征表现为高硅、富碱,属准铝质、高钾钙碱性系列;相对富集轻稀土元素和Rb、Sr等大离子亲石元素,亏损重稀土元素和Nb、Ta等高场强元素,属高分异I型花岗岩。黄铁矿S、Pb同位素分析结果表明,S同位素组成分布比较集中,δ34S黄铁矿值均为正值(介于1.3‰~1.8‰之间,平均值为1.53‰);Pb同位素组成较为均一(206Pb/204Pb值范围为16.76~17.44,207Pb/204Pb值范围为15.28~15.43,208Pb/204Pb值范围为36.64~37.46),均显示成矿物质主要来自受地幔混染的下地壳物质熔融。综合岩石学、年代学、地球化学及S、Pb同位素特征,本文认为:太阳沟钼矿床属于斑岩型钼矿床,是晚侏罗世古太平洋板块俯冲产生的壳幔相互作用引发下地壳物质部分重熔,富集大量的金属元素(Mo),最终上升侵位、沉淀成矿。
中文关键词:锆石U-Pb定年  辉钼矿Re-Os年龄  地球化学  S、Pb同位素  太阳沟钼矿床
 
Genesis of the Taiyanggou molybdenum deposit in eastern Hebei Province: evidence from chronology, geochemistry and S、Pb isotopic compositions
Author NameAffiliationE-mail
xu guoxin Eighth Geological Bridage of Hebei Geology and Mineral Resources Exploration Bureau xuguoxin-069888@163.com 
li yujing Hebei geological and Mineral Research Center  
sun jinlong Eighth Geological Bridage of Hebei Geology and Mineral Resources Exploration Bureau 84086313@126.com 
he yue Eighth Geological Bridage of Hebei Geology and Mineral Resources Exploration Bureau  
zhao di Eighth Geological Bridage of Hebei Geology and Mineral Resources Exploration Bureau  
liu xiaobo Hebei geological and Mineral Research Center  
Wang Dan Hebei geological and Mineral Research Center  
Abstract:The Taiyanggou molybdenum deposit is located in eastern Hebei Province. Intrusions exposed in this deposit are granite porphyry and biotite monzogranite. The ore bodies mainly occur as lenticles and veins in granite porphyry and at the contact zone between granite and wall rocks..This study reports zircon U-Pb dating, whole rock geochemistry, the molybdenite Re-Os isotopic age and S, Pb isotopic analyses, which is hepful to determine the diagenetic and metallogenic epoch, and to discuss the genesis and metallogenic process of the Taiyanggou molybdenum deposit. The weighted mean 206Pb/208U ages of the granite porphyry and biotite monzogranite are 154.8±1.5Ma and 156.5±1.2Ma, respectively. Re-Os model age weighted average of molybdenite is 155.79±0.93Ma that obtained by Re-Os isotope dating, which is within the margin of error of zircon U-Pb ages, indicated they are the product of the late Jurassic tectonic-magmatic activity. Geochemical characteristics show that the granites have high silicon, high alkali, and belong to high-K calc-alkaline series and highly differentiated type I granite, with enrichment of large ion lithophile elements (LREE, Rb, Sr, Ba) and depletion of high field strength elements (HREE, Nb, Ta, Ti). According to the analysis of S and Pb isotopes, the composition distribution of S isotope is relatively concentrated, the δ34Spyrite values are all positive (1.3‰~1.8‰, average of 1.53‰). The composition of Pb isotope is uniform (206Pb/204Pb values of 16.76~17.44, 207Pb/204Pb values of 15.28~15.43, 208Pb/204Pb values of 36.64~37.46), indicating that the metallogenic materials mainly derived from the melting of the lower crust materials mixed with the mantle. Combined with the characteristics of petrology, chronology, geochemistry and S, Pb isotopes, it is suggested that the Taiyanggou molybdenum deposit belongs to porphyry molybdenum deposit. The crust-mantle interaction caused by the subduction of the late Jurassic Pacific plate induce partial remelting of the lower crust, so as to enrich large numbers of Mo elements, and finally emplacement and sediment formed ore deposit.
keywords:Zircon U-Pb dating  Molybdenite Re-Os age  Geochemistry  S,Pb isotopes  Taiyanggou molybdenum deposit
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