| 胡应友,程宇康,张刚阳,易继尧,秦志鹏.西藏南部扎西康双峰式岩浆岩的地球化学特征及成因成矿意义[J].矿产勘查,2026,17(1):41-57 |
| 西藏南部扎西康双峰式岩浆岩的地球化学特征及成因成矿意义 |
| Geochemical characteristics and genesis metallogenic significance of bimodal magmatic rocks in Zhaxikang, southern Xizang |
| 投稿时间：2025-01-14 |
| DOI：10.20008/j.kckc.202601004 |
| 中文关键词: 双峰式岩浆岩 岩石成因 扎西康 西藏南部 |
| 英文关键词: bimodal magmatic rocks petrogenesis Zhaxikang southern Xizang |
| 基金项目:本文受国家自然科学基金项目(41302066)、四川省自然科学基金项目(2023NSFSC0796)和西藏华钰矿业股份有限公司博士后基金(80303-SHX070)联合资助。 |
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| 中文摘要: |
| 西藏南部特提斯喜马拉雅的扎西康矿区出露一套以辉绿岩和流纹岩为主的双峰式岩浆岩组合,该套岩浆岩组合的岩石成因和成矿意义仍然存在争议。本文在前人工作的基础上，对两类岩浆岩开展了年代学、地球化学和 Sr-Nd同位素分析。结果显示扎西康辉绿岩和流纹岩均形成于早白垩世(135~133 Ma)。辉绿岩 TiO2含量为 3.49%~4.38%，富集 LREE、HFSE，亏损 LILE， Sr/86Sr初始值为 0.707357~0.707929，87143Nd/144Nd初始值为 0.512550~0.512598，εNd(t)值为 1.60~2.53，具有高钛 OIB型玄武岩的地球化学特征，由 Ⅱ型富集地幔的石榴石二辉橄榄岩经历 5%～15%的熔融形成。流纹岩具有较高的 REE和 HFSE含量(Zr+Nb+Y+Ce＞350×10-6)10000*Ga/Al为 2.33~3.32，TZr为 955~999 ℃，具有高温 A型花岗岩的地球化学特征，主要由地壳物质的部分，熔融形成。扎西康双峰式岩浆岩是 Kerguelen地幔柱与岩石圈地幔作用的产物，形成于 Kerguelen地幔柱活动导致的东冈瓦纳大陆裂解的构造背景，代表了东冈瓦纳大陆裂解的初始阶段。双峰式岩浆岩在早白垩世的侵位过程中产生的热动力促使了围岩地层中成矿物质的活化迁移和初始富集。扎西康铅锌多金属矿床成矿作用过程中，岩浆岩作为成矿前的围岩与成矿期含矿热液流体之间具有丰富的物质交换。 |
| 英文摘要: |
| In the Tethyan Himalaya of southern Xizang, the Zhaxikang mining district exposes a bimodal mag-matic rock assemblage dominated by diabase and rhyolite. However, the petrogenesis and metallogenic significanceof this set of magmatic rock assemblages remain controversial. Based on previous work, this study conducted geo-chronological, geochemical, and Sr-Nd isotopic analyses on the two types of magmatic rocks. The results indicatethat both the Zhaxikang diabase and rhyolite formed during the Early Cretaceous (135-133 Ma). The diabase exhib-its TiO2 contents of 3.49%-4.38%, enrichment in LREE and HFSE, depletion in LILE, initial 87Sr/86Sr ratios of 0.707357-0.707929, initial 143Nd/144Nd ratios of 0.512550-0.512598, and εNd(t) values of 1.60-2.53, displaying geo-chemical characteristics of high-Ti OIB-type basalt. It was formed by 5%-15% partial melting of garnet lherzolitemantle from a Type II enriched mantle source. The rhyolite exhibits high concentrations of rare earth elements(REE) and high field strength elements (HFSE) (Zr+Nb+Y+Ce> 350×10-6), with 10000*Ga/Al ratios ranging from 2.33 to 3.32 and zircon saturation temperatures (TZr) between 955 and 999 ℃. These geochemical characteristics areindicative of high-temperature A-type granite, which is formed through the partial melting of crustal materials. TheZhaxikang bimodal magmatic rocks are products of the interaction between the Kerguelen mantle plume and thelithospheric mantle, formed in a tectonic setting of East Gondwana breakup induced by the Kerguelen mantle plumeactivity, representing the initial stage of East Gondwana continental rifting. The thermal dynamics generated duringthe emplacement of bimodal magmatic rocks in the Early Cretaceous facilitated the activation, migration, and initialenrichment of ore-forming materials in the surrounding rock strata. During the mineralization process of the Zhaxi-kang lead-zinc polymetallic deposit, the magmatic rocks, as pre-ore surrounding rocks, experienced extensive mate-rial exchange with the ore-bearing hydrothermal fluids. |
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