西藏嘎拉勒铜金矿床的成岩成矿时代与岩石成因:锆石U-Pb年龄、Hf同位素组成及辉钼矿Re-Os定年

发布时间：2018-02-15 07:23

本文关键词： 岩浆活动成矿作用俯冲碰撞 V 拉勒岩石学　出处：《地球科学》2017年06期 　论文类型：期刊论文

【摘要】：西藏嘎拉勒铜金矿床作为构造背景反演指示针的成岩成矿年代学研究较为匮乏,使得该成矿带区域背景-构造-岩浆-成矿活动系列研究步履维艰,利用LA-ICP-MS(laser ablation inductively coupled plasma mass spectrometry)锆石U-Pb测年、辉钼矿Re-Os定年及Lu-Hf同位素技术,首次全面厘定了区内侵入岩侵位时序、探讨了岩石成因并确定了成矿时代.结果表明,成矿前闪长岩成岩年龄为155.8±2.3Ma,侵位于晚侏罗世初期,εHf(t)值分布于-14.68~-8.34,平均值-11.74,是班公湖-怒江特提斯洋南向俯冲的产物;花岗闪长岩为矿区成矿母岩,其成岩年龄为88±1Ma(MSWD=0.56,n=21),εHf(t)值分布于5.84~9.20,平均值7.72,成矿后花岗斑岩成岩年龄为84.67±0.80Ma(MSWD=1.9,n=18),εHf(t)值分布于6.32~9.78,平均值8.40,二者均为晚白垩世侵位,为拉萨地体与羌塘地体汇聚的产物;矿区辉钼矿Re-Os等时线年龄为88.55±0.60Ma(MSWD=0.60,n=8),与成矿母岩(花岗闪长岩)成岩年龄一致.研究表明,在班公湖-怒江特提斯洋南向俯冲至碰撞过程中在矿区内均有相应的岩浆活动响应,嘎拉勒铜金矿床则为典型的碰撞期成矿作用的产物.
[Abstract]:The diagenetic and metallogenic chronology of the Galal copper gold deposit as an indicator of tectonic background inversion in Tibet is relatively scarce, which makes it difficult to study the series of regional setting, tectonic-magmatic and metallogenic activities in this metallogenic belt. Using LA-ICP-MS(laser ablation inductively coupled plasma mass dating, Re-Os dating and Lu-Hf isotopic technique, the emplacement sequence of intrusive rocks in the area is determined for the first time, the genesis of the rocks is discussed and the metallogenic age is determined. The diagenetic age of metallogenic diorite is 155.8 卤2.3 Ma.The transgression is located in the early late Jurassic, the 蔚 Hfct) is distributed in the range of -14.68 ~ 8.34, the average value is -11.74, which is the product of southward subduction of Tethys in Bangong Lake and Nujiang River, and the granodiorite is the ore-forming mother rock of the ore area. Its diagenetic age is 88 卤1 卤1 Ma MSWD0. 56GW ~ (21), 蔚 Hft2) is distributed in 5.84 ~ 9.20 with an average value of 7.72. The diagenetic age of post-metallogenic granitic porphyry is 84.67 卤0.80 Ma MSWDN _ (1.9) ~ (18), 蔚 Hft) distributed in 6.32 ~ (9.78) with an average value of 8.40, both of which are the product of late Cretaceous emplacement and convergence of the Lhasa and Qiangtang terrane, and the diagenetic age of the granitic porphyry is 84.67 卤0.80 Ma, and the mean value of 蔚 Hftt is 8.40. The Re-Os isochron age of molybdenum deposit is 88.55 卤0.60 Ma, which is consistent with the diagenetic age of ore-forming parent rock (granodiorite). The Galal copper-gold deposit is the product of typical collisional mineralization.
【作者单位】：中国地质调查局成都地质调查中心;成都理工大学地球科学学院;中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室;中国地质调查局发展研究中心;
【基金】：中国地质调查局地质调查项目(No.DD20160015) 国家自然科学基金项目(No.41402178) 公益性行业科研专项(No.201511017) 成都地质调查中心所控基金项目(No.所控基[2015]-06)
【分类号】：P597.3;P618.41;P618.51

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