西藏山南努日超大型钨多金属矿床岩浆演化对区域成矿作用指示
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山西省地勘局217地质队,天津地质调查中心,成都地质调查中心,成都地质调查中心,成都地质调查中心,成都矿产综合利用研究所,成都矿产综合利用研究所,山西省地勘局217地质队

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国家自然科学基金项目(面上项目,重点项目,重大项目),国家重点基础研究发展计划(973计划)


Evolution Characteristics of Magma in the Nuri Superlarge Polymetallic Deposit, Tibet: Implications for Regional Mineralization in the Shannan Ore Cluster Area
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No.217 Geological Party ,Datong, Shanxi,037008, China,Tianjin Center, China Geological Survey,Chengdu Center, China Geological Survey,Chengdu Center, China Geological Survey,Chengdu Center, China Geological Survey,Institute of Multipurpose Utilization of Mineral Resources,Institute of Multipurpose Utilization of Mineral Resources,No.217 Geological Party ,Datong, Shanxi

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    摘要:

    努日超大型多金属矿床是近年来冈底斯成矿带发现的首例白钨矿矿床,通过对矿区不同产状、岩性的岩浆岩开展主量元素、微量元素、稀土元素、锆石U- Pb年代学、Re- Os同位素、Sr- Nd- Pb- Hf同位素等综合研究,研究结果表明:努日矿区岩浆岩演化序列为石英闪长玢岩(93.42±0.76 Ma)→安山岩(92.04±0.71 Ma)→黑云母花岗岩(50.46±0.56 Ma)→花岗闪长斑岩(24.83±0.21 Ma),从高钾钙碱性到钙碱性系列均有分布,其中石英闪长玢岩含SiO2 57.19%~58.23 %, K2O 1.71%~2.2%, 总碱含量高(5.28%~5.77%), 含A12O3 14.14%~16.45%,CaO含量中等(2.33%~4.11%),里特曼指数(σ)为1.79~2.07,铝指数(A/CNK)为0.77~0.82,Mg#指数47.19~49.51, 岩石富集大离子亲石元素Rb、U、Pb、Ba、Th,轻重稀土分异明显,LREE/HREE为10.25~11.07,具有弱的Ce异常,相对较低的87Sr/86Sr初始比值(0.7039~0.706),具有埃达克岩特征;安山岩含SiO2 54.17%~60.27%, K2O 1.78%~2.25%, A12O3 17.89%~22.65%。里特曼指数σ为1.32~2.34,铝指数(A/CNK)为0.91~1.54、Mg#指数48.14~52.04, 岩石富集大离子亲石元素Rb、U、Ba、Th,轻重稀土分异明显,LREE/HREE为986~1694,具有明显的的Eu负异常,为正常岛弧岩浆岩特征;黑云母花岗岩含SiO2 64.90%~66.12 %, K2O 2.31%~23.86%, 总碱含量高(6.47%~7.01%), 含A12O3 15.52%~16.15%、CaO含量中等(2.33%~4.11%),里特曼指数σ为1.45~2.17,铝指数(A/CNK)为0.93~1.02,Mg#指数28.49~36.55, 岩石富集大离子亲石元素Rb、U、Pb、Ba、Th,轻重稀土分异明显,LREE/HREE为6.26~7.29,具有强的Eu负异常,小于大陆地壳值的87Sr/86Sr初始比值(0.704488~0.704584),具有岛弧岩浆岩特点;花岗闪长斑岩含SiO2 59.12%~74.97%, K2O 0.83%~3.67%, 总碱含量高(2.77%~6.89%),含A12O3 11.31%~17.06%、CaO含量中等(5.32%~6.22%),里特曼指数σ为0.24~2.64,铝指数(A/CNK)为0.75~0.93,Mg#指数35.11~51.57, 岩石富集大离子亲石元素Rb、U、Ba、Th,轻重稀土分异明显,LREE/HREE为9.866~16.93,具有弱的Eu负异常,其87Sr/86Sr初始比值(0.705745~0.706073),稍小于大陆地壳,其εHf(t)为2.76716~8.66174,暗示来源于新生的大陆地壳,具有埃达克质岩特点。黄铜矿Re- Os同位素特征显示矿区存在三期矿化事件,与矿集区内成矿事件吻合较好,对于指导下一步矿集区寻找不同时代成矿事件具有重要意义。

    Abstract:

    The Nuri superlarge polymetallic deposit is the first scheelite deposit recently found in the Gangdese metalloginic belt. Based on the geological suvery, this study carried out geochemical analysis, zircon UPb chronolgy, Re- Os isotope and Sr- Nd- Pb- Hf isotope for the magmatic rocks in the mining area. The results show that the magma sequence evolved from quartz diorite porphyrite (93.42+0.76 Ma), to andesite (92.04+0.71 Ma), biotite granite (50.46+0.56 Ma), granodioriteporphyry (24.83+0.21 Ma), suggesting an evolution from the high potassium calcalkaline to calcalkaline series. Quartz diorite porphyrite has SiO2of (57.19%~58.23 %) and K2O of (1.71%~2.2%), high total alkalinity of (5.28%~5.77%), A12O3 of (14.14%~16.45%) and medium CaO of (2.33%~4.11%). It is also characterzied by Rittmann index of (1.79~2.07) and A/CNK of (0.77~0.82), Mg# values of 7.19~49.51, enrichment in Rb, U, Pb, Ba and Ths; LREE/HREE of (10.25~11.07), enrichment in LREE relative to HREE, and weak Ce anomaly, lower (87Sr/86Sr)t of (0.7039~0.706), suggesting that quartz diorite porphyrite is characterisitc of adakite. Andesite contain SiO2(54.17%~60.27%), K2O (1.78%~225%), A12O3 (17.89%~22.65%), and Rittman value σ(1.32~2.34), A/CNK (0.91~1.54), Mg# (48.14~52.04). It also enriches in Rb, U, Ba and Th, and distinct differentiation of LREE and HREE with LREE/HREE (9.86~16.94) and obvious Ce anomaly, suggesting the feature of normal island- arc magmatic rocks. Biotite granite contains the SiO2 (64.90%~66.12 %), K2O (2.31%~23.86%), total alkalinity (6.47%~7.01%) and A12O3 (15.52%~16.15%) and CaO (2.33%~4.11%), the σ (1.45~2.17), A/CNK (0.93~1.02), Mg#(28.49~36.55), enrichment of Rb, U, Pb, Ba and Th, and the LREE/HREE (6.26~7.29) and obvious Eu anomaly, and (87Sr/86Sr)t (0.704488~0.704584), suggusting the feature of islandarc magmatic rocks. Granodioriteporphyry contains SiO2 (59.12%~7497%) and K2O (0.83%~3.67%),high total alkalinity (2.77%~6.89%) and A12O3 (11.31%~17.06%),CaO (5.32%~6.22%), the σ(0.24~2.64) and A/CNK(0.75~0.93), Mg#(35.11~51.57), enrichment of Rb, U, Ba and Th and the LREE/HREE(9.866~16.93), Eu anomaly and the (87Sr/86Sr)t (0.705745~0.706073) whcih εHf(t)(2.76716~8.66174), implying that it originated from new- born continental crust and is characteristic of adakite. Re- Os isotope of pyrite shows three phases of mineralization events in the Nuri mining area, suggesting that the magmatic evolution coincides well with the mineralization events in the ore cluster area. This study is of great significance for prospecting in the ore cluster area with different metallogenic time and events.

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闫国强,王欣欣,黄勇,刘洪,黄瀚霄,田恩源,赖杨,赵晋.2018.西藏山南努日超大型钨多金属矿床岩浆演化对区域成矿作用指示[J].地质学报,92(10):2138-2154.
YAN Guoqiang, WANG Xinxin, HUANG Yong, LIU Hong, HUANG Hanxiao, TIAN Enyuan, LAI Yang, ZHAO Jin.2018. Evolution Characteristics of Magma in the Nuri Superlarge Polymetallic Deposit, Tibet: Implications for Regional Mineralization in the Shannan Ore Cluster Area[J]. Acta Geologica Sinica,92(10):2138-2154.

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  • 收稿日期:2017-10-22
  • 最后修改日期:2018-03-20
  • 录用日期:2018-10-29
  • 在线发布日期: 2018-10-29
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