Mapping Potential Targets for Gold Mineralization: a Methodological Approach Based on Score Balances of Soil geochemical Data in the Amapari area, Amapá State, Brazil

Authors

DOI:

https://doi.org/10.11137/1982-3908_2025_48_63376

Keywords:

Compositional data, Potential gold targets

Abstract

Geochemical exploration in deeply weathered tropical terrains is often hampered by a strong modification of the primary geochemical signals on the surface, making it difficult to locate potential targets for gold mineralization relying on geochemical assays for Au in soil samples. This problem is particularly relevant in rain forest equatorial regions such as the Amapari area, Amapá state, Brazil, where the gold ore is hosted in a hydrothermally altered banded iron formation and where the prevailing humid tropical conditions contributed to developing regolith profiles that may be several tens of meters thick, topped by lateritic crusts or highly leached colluvial soils. In this study, we apply an innovative methodology based on score balances and data mining. The data set is composed of a vast soil geochemical survey conducted in the region. A training step based on mineralized and non-mineralized samples is essential to select the best variables to be adopted in a balanced formula whose score will be calculated over a validation area. The proposed method was successfully applied to highlight a mineralized trend in the Amapari region, which was not previously detected considering only Au grade or any other potential pathfinder metal alone. The method may be used in other regions and even for other valuable metals.

Author Biographies

Luis Paulo Braga, Universidade Federal do Rio de Janeiro

Luis P V Braga holds a degree in Mathematics from the Pontifical Catholic University of Rio de Janeiro (1973), a Master's degree in Mathematics from the Pontifical Catholic University of Rio de Janeiro (1977) and a PhD in Systems and Computer Engineering from the Coordination of Postgraduate Programs. Degree in Engineering (1984) and Specialization in Electronic Commerce from Fundação Getúlio Vargas (2001). He was a professor at Colégio Santo Inácio, at the Pontifical Catholic University of Rio de Janeiro, at the Coordination of Postgraduate Programs in Engineering at UFRJ, at the Military Institute of Engineering, at the Mathematics Institute at UFRJ and at CECIERJ. He was Coordinator of the Systems and Computer Engineering Program at COPPE, Head of the Statistical Methods Department and Director of the Mathematics Institute. He was Coordinator of Extension Courses at UFRJ and representative of Associate Professors at CPPD. He received awards from the Rio de Janeiro City Council, the Military Institute of Engineering and SEBRAE. He is currently a collaborating professor in the Department of Geology at UFRJ, working mainly on the following topics: geostatistics, data mining and distance learning. He is also an evaluator of the SINAES System, a member of the Lions Club Academy of Sciences and Letters (ALAC) and the director of the University Observatory Project.

Claudio Porto, Universidade Federal do Rio de Janeiro

Geólogo pela UFRJ em 1979; MSc em “Mineral Exploration” em 1986 e Doutorado em 1991, ambos pela Royal School of Mines do Imperial College of Science and Technology, Londres, Inglaterra. No período de 1997 a 1999 foi “Senior Research Fellow” junto à “Exploration and Mining Division” da “Commonwealth Scientific and industrial Research Organization” (CSIRO), em Perth, Austrália, onde trabalhou em projetos de pesquisa em exploração mineral para Au e metais base em co-operação com empresas de mineração Australianas, coordenadas pela AMIRA. Atualmente é Prof. de Geologia Econômica no Departamento de Geologia da UFRJ, onde leciona e conduz pesquisas aplicadas à exploração mineral, tendo desenvolvido vários projetos em parceria com empresas do setor mineral no Brasil e no exterior.

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Published

2025-05-08

How to Cite

Vieira Braga, L. P., Gerheim Porto, C. and Casado, J. (2025) “Mapping Potential Targets for Gold Mineralization: a Methodological Approach Based on Score Balances of Soil geochemical Data in the Amapari area, Amapá State, Brazil”, Anuário do Instituto de Geociências. Rio de Janeiro, BR, 48. doi: 10.11137/1982-3908_2025_48_63376.

Issue

Vol. 48 (2025): Anuário do Instituto de Geociências

Section

Geology

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