| 赵元鑫,王佳彬,韩晓涛,陈军典,任毅,常影,徐云霞.云南九顶山和宝丰寺富碱斑岩地球化学特征及岩石成因[J].矿产勘查,2025,16(4):683-694 |
| 云南九顶山和宝丰寺富碱斑岩地球化学特征及岩石成因 |
| Geochemical characteristics and petrogenesis of Jiudingshan and Baofengsi alkali rich porphyry in Yunnan |
| 投稿时间：2024-07-23 |
| DOI：10.20008/j.kckc.202504001 |
| 中文关键词: 富碱斑岩 地球化学特征 C型埃达克岩 物质来源 |
| 英文关键词: Alkali rich porphyry geochemical characteristics C-type adakite material source |
| 基金项目:本文受国家重点基础研究发展规划项目(973项目)(2015CB452600)资助。 |
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| 中文摘要: |
| 沿金沙江—哀牢山断裂带，分布一条 NW向的富碱斑岩带。近年来在该带中段发现大量与富碱斑岩具有密切成因联系的金铜钼矿床，因此，富碱斑岩的成因机制是研究带内矿床的关键钥匙。本文以富碱斑岩带中段的九顶山、宝丰寺岩体为研究对象，运用全岩主、微量及 Sr-Nd同位素方法，探讨该区内富碱斑岩的地球化学特征、岩石成因及源区性质。主量元素结果显示高 K2O、Na2O，强烈富碱，属高钾钙碱性—钾玄岩系列，过铝质(A/CNK=0.79～1.28)；微量元素结果显示强烈富集轻稀土元素,轻重稀土明显分馏((La/Yb)N=8.38～55.50)，轻微 Eu负异常(δEu=0.61～0.82)Ce异常不明显，富集 Rb、Th、U、K和 La等大离子亲石元素，亏损高场强元素，显示“TNT”异常。Sr-Nd同位素，的研究分析暗示岩浆发生过混合作用。区内岩石主、微量元素地球化学特征相似，为同源岩浆产物；具有埃达克质岩石的岩石类型和矿物组合特征，为 C型埃达克岩，岩浆起源于加厚下地壳的熔融作用，并伴有地幔物质的加入，经历了较为显著的壳幔混合作用。 |
| 英文摘要: |
| In recent years, a large number of gold-copper-molybdenum deposits closely related to the forma-tion of alkali-rich porphyry have been discovered in the central section of thenorthwest-trending alkali-rich por-phyry belt along the Jinshajiang-Ailaoshan Suture Zone in Southwest China. Thus, the genetic mechanism of alkali-rich porphyry is gradually being recognized as the key to studying the deposits within the belt. Using major andtrace element whole-rock analyses, along with Sr-Nd isotope methods, we investigated the geochemical characteris-tics, petrogenesis, and source region properties of the alkali-rich porphyry from Jiudingshan and Baofengsi in thecentral section of the alkali-rich porphyry belt. The major element results indicated high K.O and Na.O contentswhich showed strong alkali enrichment and would classify the rocks as high-potassium calc-alkaline to potassic ba-salt series with a peraluminous nature (A/CNK = 0.79-1.28). The trace element results showed strong enrichmentof light rare earth elements with a notable fractionation between light and heavy rare earth elements (La/Yb) . = 8.38-55.50). There are slight negative Eu anomalies (δEu = 0.61-0.82) and no significant Ce anomalies. Thesamples were also enriched in large-ion lithophile elements such as Rb, Th, U, K, and La, but show a depletion ofhigh-field strength elements, indicating a "TNT" anomaly. The Sr-Nd isotope analysis suggests that the magma un-derwent mixing. The major and trace element geochemical characteristics of the rocks in the area are similar, indi-cating they were products of the same magma. They exhibit the rock types and mineral assemblages characteristic ofadakite, classified as C-type adakitic rocks. The magma originated from the melting of a thickened lower crust, withthe addition of mantle material, and underwent significant crust-mantle mixing. |
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