投稿时间：2011-06-10
修订日期：2012-04-10
中文摘要:东秦岭钼矿带内的金堆城、南泥湖、上房沟、石家湾、雷门沟、东沟、夜长坪等钼矿床均产于燕山期小规模的花岗斑岩体中。近些年来,在大面积出露的老君山花岗岩基内及其与围岩的接触带中亦发现了斑岩型钼矿床和矿点,是一个找矿潜力较大的远景区。为了总结该区钼矿的成矿规律和建立成矿模式,以便更有效地指导找矿勘查,笔者在矿床地质特征和成因研究的基础上,对钼矿的成矿作用时限进行了约束。硫同位素研究显示,老君山地区钼矿床(点)的δ34S值为2.4‰~6.3‰,表明其硫很可能来自岩浆流体。氢、氧同位素研究表明,其成矿流体的δDV-SMOW为-108‰~-82‰,δ18OV-SMOW为6.3‰~10.4‰,反映出成矿流体来自混合的岩浆水与大气降水。文章对该区3个钼矿床(点)的6件不同矿化类型的辉钼矿样品进行了Re-Os同位素测年,获得了辉钼矿的Re-Os模式年龄为(109.8±1.6)~(114.5±1.7) Ma,等时线年龄为(114.3±3.4) Ma,表明其成矿作用发生于早白垩世,与赋矿的老君山花岗岩体的侵位年龄相一致,应为同一岩浆-构造-流体活动的产物。老君山地区钼矿床(点)与东沟、鱼池岭、汤家坪和沙坪沟等斑岩钼矿床,均形成于早白垩世中国东部区域岩石圈大规模伸展的构造环境。
Abstract:Jinduicheng, Nannihu, Shangfanggou, Shijiawan, Leimengou, Donggou and Yechangping molybdenum deposits occur in Yanshanian small-size porphyry granite of eastern Qinling molybdenum belt. In recent years, molybdenum deposits (ore spots) have also been found in large-size Laojunshan granitic batholith and surrounding rocks in contact with host rocks,and the Mo deposits of Laojunshan area belong to the porphyry-contact zone type and have considerable prospecting potential. In order to summarize metallogenic regularity and establish mineralization model so as to guide exploration and prospecting effectively,the authors made a constraint on the age of molybdenum mineralization on the basis of the geological characteristics and the genesis. δ34S values of the sulfur isotopic range from 2.4‰ to 6.3‰, suggesting that sulfur probably came from magmatic fluid. Hydrogen and oxygen isotopic components of typical ores indicate that δDV-SMOW values of ore-forming fluids are from -82‰ to -108‰, while δ18OV-SMOW vary from 6.3‰ to 10.4‰, suggesting that the-ore-forming fluids might have been produced by mixed magmatic and meteoric water. Six molybdenite-bearing samples of different mineralizing types were selected for precise Re-Os dating by using such ionic mass spectrographs as inductance coupling, which yielded model ages ranging from (109.8±1.6) Ma to (114.5±1.7) Ma and an isochron age of (114.3±3.4) Ma. The deposit was formed in Early Cretaceous, which is consistent with the emplacing age of the host rock Laojunshan granitic pluton. The authors thus believe that they are products of the same magma-structure-fluid activity. The Mo deposits of Laojunshan area were formed at the same time as Donggou, Yuchiling, Tangjiaping and Jinzhai Mo deposits, and hence should be the response to Late Mesozoic large-scale regional lithospheric extension.
keywords:geology geochemistry deposit characteristics Re-Os isotopic age molybdenite extensional environment Laojunshan area western Henan
文章编号：
中图分类号：P618.65
文献标志码：
基金项目:本文得到全国危机矿山接替资源找矿项目(编号:20089949)资助
引用文本：
孟芳,叶会寿,周珂,高亚龙.2012.豫西老君山地区钼矿地质特征及辉钼矿 Re-Os同位素年龄[J].矿床地质,31(3):480~492MENG Fang,YE HuiShou,ZHOU Ke,GAO YaLong.2012.Geological characteristics and molybdenite Re-Os isotopic dating of Mo deposits in Laojunshan area, western Henan[J].Mineral Deposits31(3):480~492
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