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现代地质 ›› 2023, Vol. 37 ›› Issue (03): 801-812.DOI: 10.19657/j.geoscience.1000-8527.2022.087

• 实验、应用与环境地球化学 • 上一篇    下一篇

云南潞西上芒岗金矿区白云岩风化的地球化学基因

张改侠1(), 孙金佳杰2, 龚庆杰2(), 江彪3, 严桃桃4   

  1. 1.中国地质科学院,北京 100037
    2.中国地质大学(北京)地球科学与资源学院,北京 100083
    3.中国地质科学院矿产资源研究所,北京 100037
    4.中国地质科学院地球物理地球化学勘查研究所,河北 廊坊 065000
  • 收稿日期:2022-05-05 修回日期:2022-10-08 出版日期:2023-06-10 发布日期:2023-07-20
  • 通讯作者: 龚庆杰,男,博士,教授,博士生导师,1972年出生,地球化学专业,主要从事元素地球化学和勘查地球化学的教学与科研工作。Email: qjiegong@cugb.edu.cn
  • 作者简介:张改侠, 女,硕士,高级工程师,1985年出生,地球探测与信息技术专业,主要从事元素地球化学研究工作。Email: gaixia85@qq.com
  • 基金资助:
    自然资源部地球化学探测重点实验室开放基金课题(IGGEW2021030)

Geochemical Genes for the Weathering of Dolomite at the Shangmanggang Gold Deposit Area in Luxi, Yunnan, SW China

ZHANG Gaixia1(), SUN Jinjiajie2, GONG Qingjie2(), JIANG Biao3, YAN Taotao4   

  1. 1. Chinese Academy of Geological Sciences, Beijing 100037, China
    2. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
    3. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
    4. Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang, Hebei 065000, China
  • Received:2022-05-05 Revised:2022-10-08 Online:2023-06-10 Published:2023-07-20

摘要:

地球化学基因是近年来提出的地球化学成分分类与物质来源示踪的新技术。目前研究主要集中在基因稳定性检验和地质样品溯源等方面,大多涉及岩浆岩的风化过程,尚未运用到碳酸盐岩的风化过程。本文选取云南潞西上芒岗金矿区白云岩风化剖面为研究对象,调查白云岩在风化过程中地球化学基因的变化特征。结果发现,白云岩风化在成土阶段主要表现为白云石的淋失,在土壤演化阶段CaO、Na2O含量已淋失殆尽,其他元素因性质不同而呈现出不同的风化行为。化学风化指标CIA和WIG均可定量表征剖面中样品的风化程度,但CIA有可能反映的是白云岩源沉积物的风化程度,WIG则可以较好地表征白云岩的风化程度。基于稀土元素基因、岩性基因和矿化基因分析认为上芒岗金矿区风化剖面的母岩白云岩成分是相对均匀的,属于类中性成分且具金矿化异常特征,其稀土元素基因与上陆壳类似。依据矿化基因划分的矿化异常样品本身并不一定含矿,但具有成矿潜力。金矿化基因的矿化相似度R可以作为母岩是否可形成风化壳型金矿床的判据,这为成矿物质来源研究提供了新的思路和手段。

关键词: 白云岩, 风化, 地球化学基因, 上芒岗金矿, 矿化相似度

Abstract:

Geochemical gene is a new technique to classify and trace geological materials. The current research focuses on testing the gene steady properties and traceability of soils from the weathering of magmatic and (minor) carbonate rocks. Two weathering profiles developed on dolomite in the Shangmanggang gold deposit at Luxi (Yunnan Province, SW China) were investigated for the steady properties of geochemical genes, including lithogenes (LG01 and LG03), metallogene (MGAu and MGW), and REE (rare earth element) genes (REEG01 and REEG02). The geochemical results indicate that the dolomite was totally leached during the pedogenetic stage, followed by the soil evolution stage. Chemical weathering indices of CIA (chemical index of alteration) and WIG (weathering index of granite) were used to quantify the degrees of weathering, however the CIA may indicate the weathering degrees of the provenance sediments of dolomite. Therefore, WIG is better than CIA to determine the weathering degrees of carbonate rocks. Based on the results of heredities and inheritances of geochemical genes on weathering products, the parent rocks may have been geochemically homogeneous. The dolomite and its weathering products are classified as the intermediate-like compositions on felsic similarities of lithogenes, as anomalous gold-mineralized samples on mineralization similarities of gold metallogene, similar to the upper continental crust on REE genes. Although the anomaly materials classified on mineralization similarities of gold metallogene are not necessarily gold ores, they have likely the potential to offer ore-forming materials. The mineralization similarity of gold metallogene can be used to determine whether a weathering-type deposit was formed on the parent rock, which offers new insight or technique on tracing the provenance of ore-forming materials.

Key words: dolomite, weathering, geochemical gene, Shangmanggang gold deposit, mineralization similarity of metallogene

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