滇东地区裂谷盆地内火山—侵入岩序列与金属成矿
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有色金属矿产地质调查中心 矿山生态环境资源创新实验室

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P542

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云南省企业基础研究应用基础研究联合专项-重大项目“锡铜层间矿赋矿层位研究”、国家科技支撑项目《东川-易门铜矿山深部及外围勘查技术及示范研究》(2006BAB01B09);科技部转制科研院所专项资金项目 (2011EG115022)和(2006BAB01B09);国土资源部公益性行业科研专项项目(201511016-1)。第一


The volcanic-intrusive rock sequences and metal mineralizations in rifted basin in the eastern Yunnan Province, China
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China Non-ferrous Metals Resource Geological Survey

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    摘要:

    碱性岩浆对金属成矿和金属矿集区有独特控制作用,因火山—侵入岩序列与金属成矿和岩浆叠加侵入构造系统识别难度大,长期制约了深部勘探和找矿预测。本文以云南东川铁铜金矿集区(元古宙陆缘裂谷盆地)和个旧锡铜钨铯铷多金属矿集区(三叠纪弧后裂谷盆地)为主,采用大比例尺构造岩相学填图新方法,解析研究了碱性岩浆活动有关的火山-侵入岩侵入序列与岩石组合、裂谷盆地演化和岩浆叠加侵入构造系统,揭示了它们对滇东地区IOCG型、铜钴?金红石?稀土和锡铜钨铯铷多金属矿叠加成矿内在关系。研究认为:(1)云南东川铁铜金矿集区内,新太古代末碱性岩类以方解石钠长岩(2520±14 Ma)和碱性铁质苦橄岩(2529±77Ma)为主。新太古代?古元古代小溜口岩组(>2.50Ga)顶部古岩溶风化壳,受中元古代火山喷发-岩浆侵入构造叠加再造形成了特殊单元(独立填图单元, 2.5~1.8 Ga),它们是铜钴?金红石?稀土矿床的新找矿层位。(2)在中元古界因民组一段内,铁钠质碱性基性岩、铁钾质粗面岩和铁质碱性辉绿辉长岩等岩石组合形成于因民期火山断陷成盆期。因民组二段和三段是稀矿山式铁铜矿床储矿层位,铁铜矿层下盘铁钾质粗面岩为独居石型稀土成矿层位。在格林威尔造山期碱性钛铁质辉长岩(1097~1047Ma)-碱性钛铁质闪长岩-碱性二长斑岩等碱性钛铁质侵入岩体,形成了白锡腊深部IOCG矿床和金红石富集成矿。(3)在个旧三叠纪弧后裂谷盆地内,在三叠纪碱性苦橄岩和碱玄岩中形成了Sn-Cu-Zn-Li-Rb-Cs初始富集;在晚白垩世浅色花岗岩叠加成矿作用下,形成了金云母夕卡岩型锡铜钨铯铷矿床。(4)裂谷盆地内早期碱性岩中初始富集金属与后期富含成矿金属的碱性侵入岩叠加成矿可能是金属常超富集机理。在东川地区岩浆叠加侵入构造内,岩浆热液角砾岩筒对铜钴?金红石?稀土元素叠加富集成矿控制显著;在个旧地区浅色花岗岩侵入于碱性苦橄岩-碱玄岩中,对金云母夕卡岩型锡铜钨钴铯铷矿床的叠加富集成矿控制显著。

    Abstract:

    Alkali magmatism have special controlling on mineralizations in the metal ore-concentrated areas. However, obstacles have all the time placed on the deep exploration and mineral predication in the study area, for cognitive difficults exist on the volcanic-intrusive rock sequsences, metal mineralizations, and the magmatic superimposing intrusive tectonic system. Focused on the Dongchuan Fe-Cu-Au ore concentrated area (the Proterozoic marginal rifted basin) and the Gejiu Sn-Cu-W-Cs-Rb- polymetal ore-concentrated area (the Triassic arc-back rifted basin), the innovated mapping techniques of the tectonic lithofacies had been applied to dissect study on the volcanic-intrusive rock sequences related to the alkali magmatic activity, rifted basin evolution, rock associations, and magmatic superimposing intrusive system, in order to disclose the superimposing mineralizations of IOCG, Cu-Co-rutile deposits and Sn-Cu-W-Cs-Rb polymetallic deposits in the eastern Yunnan Province in China. This study suggests as the followings. First, the Neoarchean alkali rocks are composed of calcite albitite(2520±14 Ma)and Fe-rich alkalipicrite(2529±77Ma)in the Dongchuan Fe-Cu-Au ore-concentrated area. The Neoarchean-Paleoproterozoic Xiaoliukou Formation Complex(>2.50Ga)and its top part, a special mapping unit with homotopy in different lithofacies(2.5 to 1.80 Ga), are the new hosting strata of Cu-Co-rutile-REE mineralizations and had been reworked by the superimposed by the Mesoproterozoic volcanic-intrsuive rocks in the Dongchuan Fe-Cu-Au ore-concentrated area. Second, in the Mesoproterozoic the first member of the Yinmin Group, alkaline rocks, including rock assications of Fe-Na-rich alkali basic rocks, Fe-K-rich trachyte, and Fe-rich alkali diabase-gabbros, were formed at the Mesoproterozoic stage of volcanic rifting basin. Xikuangshan-type Fe-Cu deposits or IOCG deposits were hosted at the second to three members of the Mesoproterozoic Yinmin Group, Moreover, Fe-K-rich trachyte at the footwall of the Fe-Cu orebody hosted the monazite-type REE mineralization layer. IOCG system and rutile superimposing mineralization were formed in alkaline Ti-Fe-rich gabbros (1097 to1047Ma), alkaline Ti-Fe-rich diorites, and alkaline monzoporphyry, all of these rock associations were formed during the Greenville Orogeny in eastern Yunnan. Third, the Triassic alkalipicrite and tephrite with primary enrichment of Sn-Cu-Zn-Li-Rb-Cs were produced at the of the Triassic arc-back rifted basin in the Gejiu area at the Eastern Yunnan Province in China. While they were superimposed by leucogranite, and they were responsibly for Sn-Cu-W-Cs-Rb-bearing phlogopite-type skarn. Final, alkali rocks with initial enrichment of metals or mineralization in the early stage of the rifted basin, were superimposed by alkaline intrusive rocks with metal mineralizations at the late stage, which may be main hypernormal mechanism for metal mineralizations the rifted basin at the Eastern Yunnan Province in China. Breccia-pipe of magmatic hydrothermal fluids in the alkaline magmatic superimposing intrusive tectonic system has evident controls on hypernormal enrichment of Cu-Co-rutile-REE superimposing mineralization, whereas leucogranite intruded the alkalipicrite and tephrite with Sn-Cu-W-Cs-Rb primary enrichment are responsibly for hypernormal enrichment of Sn-Cu-W-Cs-Rb-bearing phlogopite-type skarn.

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  • 收稿日期:2023-08-12
  • 最后修改日期:2023-10-24
  • 录用日期:2023-11-06
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