Physical properties of rocks, metasomatites, and ores at the Tunantza gold deposit, Ecuador

Background. The Cordillera del Condor in southeastern Ecuador hosts several gold deposits, including the Tunantza epithermal gold deposit and unexplored prospects. Furthermore, the relationship between physical properties and hydrothermal alteration assemblages as well as gold mineralization remains poorly studied, which can limit the interpretation of geophysical exploration data in this region. For the first time, this study presents the results of the analysis of selected physical properties of samples from the Tunantza deposit.

Aim. To evaluate the physical properties of rocks from the Tunantza gold deposit, establish their relationships with metasomatic facies, and identify mineralization zones.

Materials and methods. Geological materials and data obtained from the documentation of surface outcrops and underground workings were used. Petrographic analysis was carried out on 96 thin sections (86 standard and 10 polished sections). In total, 315 samples were analyzed to determine density, magnetic susceptibility, and specific electrical resistivity. Spatial interpolation was performed using the kriging method in QGIS.

Results. The influence of metasomatism and the presence of the ore body on physical properties is manifested by an increase in density and a marked decrease in magnetic susceptibility from the propylitic zone toward the ore body. Interpolation models indicate that the ore zone forms as a composite anomaly characterized by high density and low magnetic susceptibility, surrounded by a conductive halo and an external magnetic halo.

Conclusion. The results obtained demonstrate a relationship between breccia properties, metasomatic facies, and the distribution of mineralized zones. These findings can be applied in the prospecting of epithermal and porphyry deposits, as well as in the interpretation of geophysical data.

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