Scholarly record

GEOPHYSICS IN GOLD EXPLORATION: SOME APPLICATIONS TO NORTHERN PORTUGAL GOLD DEPOSITS

Sara Leal, Rui Moura, Alexandre Lima, Aleksandr Pivtorak, Diogo Rodrigues

Abstract

The geophysical surveys methods have not been extensively used in gold exploration in Northern Portugal. This is based on the fact that most mineralized zones contain low and erratic sulphide contents. In this work were tested three different types of geophysical surveys combined with geochemical surveys, in order to define anomalies that are closely correlated with the locations of known mineralized zones. The aim of the work is to study some gold deposits in Northern Portugal (Lagoa Negra and Castromil) with the purpose of obtaining valuable information of the mineralogical and petrogenetically features of these gold deposits, and how it would facilitate the understanding of the regional distribution and formation of gold deposits. Ground Penetrating Radar (GPR), Very Low frequency (VLF) electromagnetic methods combined with 2D Electrical Resistivity techniques can contribute towards defining structures, and are particularly important where extensive cover exists and may also play an important role in the mapping of lithology and the lithological contacts. The magnetic surveys revealed and confirmed two possible areas with sulphide mineralization, one with pyrrhotite and other with Fe-sulphide oxidation proven by during drilling campaign in this area. This work demonstrates how the combination of geophysics and geochemical methods, together with geological sampling, can be used to help delineate possible structures that host gold mineralization.

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