| 亚贵拉-沙让-洞中拉矿集区中新生代岩浆岩Hf同位素特征与岩浆源区示踪 |
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| 引用本文：高一鸣,陈毓川,王成辉,侯可军.2011.Zircon Hf isotopic characteristics and constraints on petrogenesis of Mesozoic-Cenozoic magmatic rocks in Nyainqentanglha region, Tibet[J].Mineral Deposits,30(2):279~291 |
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| 基金项目:本文为国家973项目(编号：2011CB403103)、青藏专项项目（编号：1212010012005）资助的成果 |
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| 中文摘要:选择西藏念青唐古拉地区的工布江达—墨竹工卡县亚贵拉-沙让-洞中拉铅锌钼铜银矿集区典型的中新生代岩浆岩作为研究对象，详细研究了岩体中锆石的Hf同位素组成。亚贵拉燕山期石英斑岩（λπ35）锆石的176Hf/177Hf比值为0.282 090～0.282 480，εHf(t)为 -7.750～-21.449，TDM2为1 679～2 543 Ma；亚贵拉喜马拉雅期石英斑岩（λπ16）锆石的176Hf/177Hf为0.282 413～0.282 805，εHf(t)为-11.463～2.460，TDM2为980～1 864 Ma；亚贵拉喜马拉雅期花岗岩（γ35）锆石的176Hf/177Hf比值为0.282 601～0.282 800，εHf(t)值在-2.279～2.182之间，TDM2为996～1 279 Ma；亚贵拉喜马拉雅晚期花岗斑岩（γπ36）锆石的176Hf/177Hf比值为0.282 600～0.282 830之间，εHf(t)为-5.676～3.128之间，TDM2为900～1 461 Ma；沙让喜马拉雅期角闪闪长岩（δψk）锆石的176Hf/177Hf比值为0.282 700～0.282 790，εHf(t)值为-1.536～1.618，TDM2为1 019～1 219 Ma；洞中拉燕山期花岗斑岩锆石的176Hf/177Hf比值为0.282 142～0.282 396，εHf(t)为-19.744～-10.620，TDM2为1 857～2 430 Ma。通过与驱龙铜矿含矿斑岩、林子宗火山岩Hf同位素特征对比研究，认为：① 亚贵拉两期次侵入的石英斑岩体（λπ35、λπ16）具有不同的Hf同位素地球化学特征。② 亚贵拉燕马拉雅期石英斑岩（λπ35）与洞中拉燕山期石英斑岩的锆石Hf同位素特征相似，176Hf/177Hf比值、εHf(t)值、两阶段Hf模式年龄（TDM2）暗示其源区为古老地壳物质；亚贵拉喜山期石英斑岩（λπ16）（66 Ma）、亚贵拉花岗岩（γ16）（62 Ma）、亚贵拉花岗斑岩（γπ36）（17 Ma）、沙让角闪闪长岩（δψk）（53 Ma）、林子宗火山岩和驱龙含矿岩体的Hf同位素组成暗示其形成于古老地壳与亏损地幔的混染，不同地质体锆石Hf同位素组成的差异可能与幔源岩浆中混入古老地壳物质的不同比例有关。 |
| 中文关键词:地球化学 锆石Hf同位素 亏损地幔 古老地壳 洞中拉-亚贵拉-沙让 冈底斯-念青唐古拉 西藏 |
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| Zircon Hf isotopic characteristics and constraints on petrogenesis of Mesozoic-Cenozoic magmatic rocks in Nyainqentanglha region, Tibet |
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| Abstract:In this paper, the Mesozoic-Cenozoic magmatic rocks in Yaguila-Sharang-Dongzhongla ore-forming area serve as the object for zircon Hf isotope study by means of LA-MC-ICP-MS. Hf isotopic compositions of the zircons from Yanshanian Yaguila quartz porphyry (λπ35) show that the ratio of 176Hf/177Hf is 0.282 090～0.282 480, the εHf (t) value is -7.750～-21.449，and the TDM2 value is 1 679～2 543 Ma; Hf isotopic compositions of the zircons from Himalayan Yaguila quartz porphyry (λπ16) show that the ratio of 176Hf/177Hf is 0.282 413～0.282 805, the εHf (t) value is -11.463～2.46，and the TDM2 value is 980～1 864 Ma; Hf isotopic compositions of the zircons from Himalayan Yaguila granite (γ35) show that the ratio of 176Hf/177Hf is 0.282 601～0.282 800, the εHf (t) value is -2.279～2.182，and the TDM2 value is 996～1 279 Ma; Hf isotopic compositions of the zircons from late Himalayan Yaguila granite-porphyry show that the ratio of 176Hf/177Hf is 0.282 600～0.282 830, the εHf (t) value is -5.676～3.128，and the TDM2 value is 900～1 461 Ma; Hf isotopic compositions of the zircons from Himalayan Sharang hornblende diorite show that the ratio of 176Hf/177Hf is 0.282 700～0.282 790, the εHf (t) value is -1.536～1.618，and the TDM2 value is 1 019～1 219 Ma; Hf isotopic compositions of the zircons from Yanshanian Dongzhongla quartz porphyry show that the ratio of 176Hf/177Hf is 0.282 142～0.282 396, the εHf (t) value is -19.744～-10.620，and the TDM2 value is 1 857～2 430 Ma. Based on a comparison with the Hf isotopic compositions of the zircons from porphyry of the Qulong ore deposit and Linzizong volcanic rock, the authors have reached some conclusions: ① The characteristics of Hf isotope of two intrusion stages of Yaguila quartz porphyry (λπ35)(λπ16) are different from each other. The characteristics of Hf isotope of Yanshanian Yaguila（λπ35）and Dongzhongla quartz porphyries are similar to each other, suggesting that the rocks were formed by the crust base materials. ② The Hf isotope of Yaguila and Sharang Himalayan igneous rocks (λπ16，γ16，γπ36,δψk) ，Linzizong volcanic rock and Qulong quartz porphyry shows the rock is the combination of the crust base materials and the depleted mantle, The different εHf (t) value of these igneous rocks may because of the different proportion of the crust base materials or the depleted mantle during the hybridization of them. |
| keywords:geochemistry, zircon Hf isotope, depleted mantle, ancient crust,Dongzhongla-Yaguila-Sharang, Nyainqentanglha, Gangdese, Tibet |
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