Comparison of groundwater composition from the Monturaqui and Punta Negra Basins, northern Chile: implications for porphyry copper exploration

IF 1 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Geochemistry-Exploration Environment Analysis Pub Date : 2022-02-14 DOI:10.1144/geochem2021-056

C. Rissmann, M. Leybourne, C. Benn, J. Kidder, L. Pearson

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Abstract

Groundwaters recovered from the Salar de Punta Negra and Monturaqui basins in the Atacama Desert of northern Chile exhibit distinctly different isotopic, major, trace, and porphyry copper elemental compositions related to contrasting morphostructural, geochemical, and hydrodynamic settings. Comparison of these distinct groundwater signatures with groundwaters from known porphyry copper deposits (Salar de Hamburgo and Spence Deposit), can be used to determine if either basin might be prospective for porphyry copper mineralization. Groundwaters within the Punta Negra Basin exhibit geochemical characteristics consistent with other closed basin settings throughout the arid Andes. Elemental and isotopic compositions within the Punta Negra Basin reflect closed basin evaporitic processes consistent with the hyperarid, volcanic setting of the central Andes. Pathfinder metals and isotopic compositions are not consistent with porphyry copper type mineralization as described for groundwaters within the Salar de Hamburgo Basin, and the Spence Deposit. Within the Monturaqui Basin the geochemical composition of groundwaters are characteristic of diffuse hydrothermal activity. Sulfur isotopic composition within the waters of the northern Monturaqui Basin exhibit δ34SCDT isotopic signatures that fall within the range for sulfide mineralization as reported for groundwaters in and around the Spence Deposit and the Salar de Hamburgo. However, porphyry copper related elements within the Monturaqui Basin are impoverished relative to groundwaters of the Spence and Escondida Deposit. Such impoverishment in porphyry related elements, taken in conjunction with enriched δ13CPDB compositions, elevated groundwater temperatures, groundwater compositions dominated by HCO3, SO4, and Si, and the proximity of the Monturaqui Basin to the current magmatic arc are consistent with a volcanic hydrothermal origin. In summary, the groundwater geochemistry of the Monturaqui and Punta Negra Basins are not indicative of porphyry copper-type mineralization. Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues

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智利北部Monturaqui和Punta Negra盆地地下水成分的比较：对斑岩铜矿勘探的启示

从智利北部阿塔卡马沙漠的Salar de Punta Negra和Monturaqui盆地开采的地下水显示出明显不同的同位素、主铜、微量铜和斑岩铜元素组成，这与对比鲜明的形态结构、地球化学和流体动力学环境有关。将这些不同的地下水特征与已知斑岩铜矿床（Salar de Hamburgo和Spence矿床）的地下水进行比较，可以用来确定任何一个盆地是否具有斑岩铜矿化的前景。Punta Negra盆地内的地下水表现出与整个干旱安第斯山脉其他封闭盆地环境一致的地球化学特征。Punta Negra盆地内的元素和同位素组成反映了封闭盆地蒸发过程，与安第斯山脉中部的超干旱火山环境一致。探路者金属和同位素组成与Salar de Hamburgo盆地和Spence矿床地下水中描述的斑岩铜型矿化不一致。在Monturaqui盆地内，地下水的地球化学成分具有扩散热液活动的特征。Monturaqui盆地北部水域的硫同位素组成显示出δ34SCDT同位素特征，该特征属于Spence矿床和Salar de Hamburgo及其周围地下水的硫化物矿化范围。然而，相对于Spence和Escondida矿床的地下水，Monturaqui盆地内的斑岩铜相关元素贫乏。斑岩相关元素的这种贫化，再加上富集的δ13CPDB成分、升高的地下水温度、以HCO3、SO4和Si为主的地下水成分，以及Monturaqui盆地靠近当前岩浆弧，都与火山热液成因一致。总之，Monturaqui和Punta Negra盆地的地下水地球化学并不表明斑岩铜型矿化。主题集：本文是与勘探和环境问题相关的水化学集的一部分，可在以下网站获取：https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues

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来源期刊

Geochemistry-Exploration Environment Analysis 地学-地球化学与地球物理

CiteScore

3.60

自引率

16.70%

发文量

审稿时长

1 months

期刊介绍： Geochemistry: Exploration, Environment, Analysis (GEEA) is a co-owned journal of the Geological Society of London and the Association of Applied Geochemists (AAG). GEEA focuses on mineral exploration using geochemistry; related fields also covered include geoanalysis, the development of methods and techniques used to analyse geochemical materials such as rocks, soils, sediments, waters and vegetation, and environmental issues associated with mining and source apportionment. GEEA is well-known for its thematic sets on hot topics and regularly publishes papers from the biennial International Applied Geochemistry Symposium (IAGS). Papers that seek to integrate geological, geochemical and geophysical methods of exploration are particularly welcome, as are those that concern geochemical mapping and those that comprise case histories. Given the many links between exploration and environmental geochemistry, the journal encourages the exchange of concepts and data; in particular, to differentiate various sources of elements. GEEA publishes research articles; discussion papers; book reviews; editorial content and thematic sets.