Lithogeochemistry in exploration for intrusion-hosted magmatic Ni-Cu-Co deposits

IF 1 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Geochemistry-Exploration Environment Analysis Pub Date : 2022-11-30 DOI:10.1144/geochem2022-025

S. Barnes

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引用次数: 1

Abstract

Magmatic Ni-Cu-Co-PGE deposits are notoriously difficult exploration targets owing to a lack of alteration haloes or other extended distal footprints. Success requires prediction of prospective terranes, followed by identification of suitable host intrusions and deposition sites within those intrusions. At the regional scale, potential ore-hosting magmas tend to have lithophile trace element trends falling on mixing lines between primitive or slightly depleted source mantle and typical upper continental crust, with several significant exceptions. Most known deposits have parent magmas that are in the upper range of FeO content for given MgO compared with baseline data sets for continental LIP magmas. At the scale of individual intrusions, the presence of cumulate rocks, both mafic and ultramafic, is key. These can be recognised in regional datasets using combinations of magnesium number (molar MgO/(MgO+FeO), Al 2 O 3 , TiO 2 and Zr contents. Combinations of alteration-resistant element ratios between Ni, Cr and Ti are also useful and can also be applied to moderately weathered samples. Concentrations and ratios of Cu and Zr are useful in discriminating chalcophile-enriched and depleted magmas suites. In combination, these approaches can be combined to discriminate highly prospective cumulate-dominated magmatic suites and individual intrusions from non-cumulate suites with limited potential. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6267664

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侵入型岩浆型镍铜钴矿床勘探中的岩石地球化学

岩浆Ni-Cu-Co-PGE矿床由于缺乏蚀变晕或其他延伸的远端足迹，是出了名的难以勘探的目标。成功需要预测未来的地层，然后确定合适的宿主侵入体和这些侵入体中的沉积地点。在区域尺度上，潜在的含矿岩浆倾向于亲石微量元素倾向，落在原始或轻度衰竭源地幔与典型上大陆地壳的混合线上，但有几个明显的例外。与大陆LIP岩浆的基线数据集相比，大多数已知矿床的母岩浆的FeO含量在给定MgO的上限范围内。在单个侵入的尺度上，基性和超基性的堆积岩的存在是关键。这些可以在区域数据集中通过镁含量(摩尔MgO/(MgO+FeO))、al2o3、tio2和Zr含量的组合来识别。Ni, Cr和Ti之间抗蚀变元素比率的组合也很有用，也可以应用于中等风化的样品。Cu和Zr的浓度和比值对判别富铜矿和贫铜矿岩浆组有重要意义。将这些方法结合起来，可以将具有高度远景的以累积层为主的岩浆层和单个侵入层与潜力有限的非累积层区分开来。补充资料:https://doi.org/10.6084/m9.figshare.c.6267664

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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.