Short-wave infrared spectroscopy for vectoring mineralization in intermediate-sulfidation epithermal deposits: A case of study on La Primavera Au–Ag vein system, Neuquén basin, Argentina

IF 3.4 3区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Applied Geochemistry Pub Date : 2025-08-26 DOI:10.1016/j.apgeochem.2025.106537

María Celeste D'Annunzio , María Agustina Cócola , Nora Rubinstein , Leonardo Strazzere

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引用次数: 0

Abstract

The La Primavera vein system is an intermediate sulfidation deposit part of the Andacollo mining district (184,600 tn @ 47,100 oz AuEq). The mineralized structures are hosted in Upper Triassic to Lower Jurassic bimodal volcanic and epiclastic rocks. These rocks underwent very low-grade metamorphism due to crustal thinning and elevated thermal gradients associated with the evolution of the rift Neuquén Basin, and are overprinted by hydrothermal alteration related to the epithermal veins. Short-wavelength infrared (SWIR) spectroscopy has been used to identify specific spectral reflectance alteration minerals features. This study integrates spectral, petrographic, and geochemical analyses of alteration minerals and whole rock, associated with La Primavera epithermal vein system, to evaluate the controls on the hydrothermal alteration and the potential of spectral techniques in mineral exploration. The results demonstrate that host rock composition plays a primary role in the development of alteration assemblages. Variations in the spectral absorption features of phyllosilicates, particularly illite and chlorite, reflect compositional differences that can be linked to relative changes in temperature and fluid acidity. The W|2200| absorption feature of illite varies systematically along sampled transects, indicating both lithological control and proximity to mineralized structures. Also, the Illite Spectral Maturity (ISM) values are higher near the veins and decrease with distance, providing a reliable vector toward mineralization. Similarly, chlorite compositional variation serves as an effective indicator of proximity to mineralized structures. Intermediate Fe–Mg chlorites occur near the veins, while Mg-rich varieties dominate distal zones. In addition, this combination of techniques has been a useful tool for distinguishing mineral phases specific to regional metamorphism from those related to hydrothermalism. In this way, spectral analysis has been proven to be a powerful tool in the initial steps of low to intermediate epithermal deposits exploration.

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短波红外光谱在中硫化浅成低温热液矿床中的矢量成矿作用——以阿根廷neuquaciman盆地La Primavera金银脉系为例

La Primavera矿脉系统是Andacollo矿区（184,600吨/ 47100盎司当量）的中间硫化矿床的一部分。矿化构造赋存于上三叠统至下侏罗统双峰火山岩和碎屑岩中。这些岩石由于地壳变薄和与纽泉盆地裂谷演化相关的热梯度升高而经历了极低程度的变质作用，并被与浅成热液脉相关的热液蚀变覆盖。短波长红外光谱（SWIR）已被用于识别蚀变矿物的特定光谱反射率特征。通过对La Primavera浅成热液脉系蚀变矿物和全岩的光谱、岩石学和地球化学分析，评价了热液蚀变的控制因素和光谱技术在矿产勘查中的潜力。结果表明，寄主岩石组成对蚀变组合的发育起主要作用。层状硅酸盐，特别是伊利石和绿泥石的光谱吸收特征的变化反映了成分的差异，这种差异可能与温度和流体酸度的相对变化有关。伊利石的W| ~ 2200|吸收特征沿采样样条有系统变化，表明其受岩性控制，且与矿化构造接近。此外，伊利石光谱成熟度（ISM）值在靠近矿脉的地方较高，随距离的增加而降低，为成矿提供了可靠的矢量。同样，绿泥石成分的变化可以作为矿化构造接近程度的有效指标。中间铁镁绿泥石分布在脉体附近，而富镁品种则在远端区域占主导地位。此外，这种技术组合已成为区分区域变质作用矿物相与热液作用矿物相的有用工具。通过这种方式，谱分析已被证明是低至中浅成热液矿床勘探初期阶段的有力工具。

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来源期刊

Applied Geochemistry 地学-地球化学与地球物理

CiteScore

6.10

自引率

8.80%

发文量

272

审稿时长

65 days

期刊介绍： Applied Geochemistry is an international journal devoted to publication of original research papers, rapid research communications and selected review papers in geochemistry and urban geochemistry which have some practical application to an aspect of human endeavour, such as the preservation of the environment, health, waste disposal and the search for resources. Papers on applications of inorganic, organic and isotope geochemistry and geochemical processes are therefore welcome provided they meet the main criterion. Spatial and temporal monitoring case studies are only of interest to our international readership if they present new ideas of broad application. Topics covered include: (1) Environmental geochemistry (including natural and anthropogenic aspects, and protection and remediation strategies); (2) Hydrogeochemistry (surface and groundwater); (3) Medical (urban) geochemistry; (4) The search for energy resources (in particular unconventional oil and gas or emerging metal resources); (5) Energy exploitation (in particular geothermal energy and CCS); (6) Upgrading of energy and mineral resources where there is a direct geochemical application; and (7) Waste disposal, including nuclear waste disposal.