东秦岭钼矿Re-Os同位素年龄及其成矿动力学背景  

RE-OS ISOTOPIC AGES OF MO DEPOSITS IN EAST QINLING AND THEIR GEODYNAMIC SETTINGS

作　　者：李永峰[1] 王春秋[1] 白凤军[1] 宋艳玲 

机构地区：[1]中国地质大学地球科学与资源学院 [2]河南省地质勘查局第十一地质队,河南商丘476000

出　　处：《矿产与地质》2004年第6期571-578,共8页Mineral Resources and Geology

基　　金：国家重点基础研究发展规划项目 ( G19990 43 2 11)的部分研究成果

摘　　要：东秦岭钼矿带位于华北克拉通南缘 ,集中分布于陕西省的金堆城地区、河南省栾川县南泥湖 -三道庄 -上房沟、嵩县雷门沟地区。钼矿床类型主要为斑岩型、斑岩 -矽卡岩型 ,少量热液碳酸盐岩脉型。采用电感耦合等离子体质谱仪法对南泥湖钼矿田、雷门沟钼矿床等 4个矿床 8件辉钼矿进行了 Re-Os同位素年龄测定 ,获得南泥湖矿床的辉钼矿 Re- Os模式年龄为 14 1.8± 2 .1Ma;三道庄矿床的辉钼矿 Re- Os模式年龄为 14 4 .5± 2 .2～ 14 5 .0± 2 .2 Ma,平均为 14 5 .0± 2 .2 Ma;上房沟矿床的辉钼矿 Re- Os模式年龄为 14 3.8± 2 .1～ 14 5 .8± 2 .1Ma,平均为 14 4 .8± 2 .1Ma;6件样品的等时线年龄为 14 1.5±7.8Ma(2σ) ;雷门沟钼矿床的 2件辉钼矿样品的 Re- Os模式年龄为 131.6± 2 .0～ 133.1± 1.9Ma,平均为 132 .4± 2 .0 Ma。结合前人资料 ,认为东秦岭钼矿的形成时代局限于 2 2 1.5± 0 .3～ 132 .4± 2 .0 Ma之间 ,主要出现在 2 2 1.5± 0 .3Ma左右和 14 4 .8± 2 .1～ 132 .4± 2 .0 Ma时限之间 ,其对应的地球动力学背景分别为华北克拉通与扬子克拉通的碰撞造山后陆内造山和伸展过程。The East Qinling molybdenum metallogenic belt is Located on the southern margin of the North China craton. Molybdenum deposits are mostly concentrated in a zone stretching from the Jinduicheng area of Shaanxi Province in the west to the Nannihu-Sandaozhuang-Shangganggou area of Luanchuanxian and the Leimenggou of Songxian in western Henan province. The major types of molybdenum deposits are porphyry and porphyry skarn, less are types of hydrothermal carbonatite vein. The contents of 187Re and 187Os of molybdenite of the molybdenum deposits are determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) , with analytical errors of Re and Os between 0.11-0.4% (2σ) . The obtained results show that the Re-Os model ages are between 145.8 ±2.1～141.8 ±2.1Ma ; 141.8±2.1Ma for the Nannihu deposit, 145.4 ±2.0～144.5 ±2.2Ma (average: 145.0 ±2.2Ma ) for the Shandaozhuang deposit and 145.8±2.1～143.8±2.1Ma (average: 144.8 ±2.1Ma ) for the Shangfanggou deposit and 131.6±2.0～133.1±1.9Ma (average: 132.4±2.0Ma) for the Leimengou deposit. Re-Os isotopic dating for the molybdenite in the deposits shows an isochron age of 141.5±7.8Ma(2σ), with errors of Re/Os ages between 2.0-2.2% . The minerlization ages of the molybdenum deposits in East Qinling are within 221.5±0.3～132.4±2.0Ma , and mainly cluster two pulses of 221.5±0.3Ma and 144.8±2.1～132.4±2.0Ma in combination of former research. The former pulse geodynamically correspond to the extensional periods of postcollision orogenic process between North China and Yangtze cratons. The latter pulse correspond to the transformation period of the tectonic system from NS to nearly EW directions in East China.

关 键 词：钼矿床 成矿年龄 RE-OS同位素 地球动力学背景 东秦岭 

分 类 号：P618.65[天文地球—矿床学] P597[天文地球—地质学]