San Agustín Project

The San Agustin project is located in the western part of the Deseado Massif, and covers an area of almost 6000 ha. In 2022, Fomicruz decided to focus on this project since it showed to be highly prospective.

Fomicruz has mapped the geology of the project, it has collected 330 rock chip and channel samples for geochemistry, and more than 3000 small samples for being analyzed by reflectance spectroscopy and portable XRF, to determine alteration minerals and chemical composition. In addition, a magnetometric survey has registered data over 70 % of the project's area.

A variety of evidence observed in the project, indicate the presence of the upper parts of a large epithermal paleosystem. These evidence include a siliceous sub-horizontal layer, which shows clear evidence of biologic activity. This siliceous layer is partially surrounded by carbonates, and is interpreted as a silica sinter.

In addition, areas with large outcrops of siliceous rocks were detected. Those rocks seem to represent a subhorizontal layer that suffered pervasive silicification, and locally subsequent fracturing, generating breccias with fragments of the silicified rocks cemented by fine grained silica.

The project includes numerous siliceous hydrothermal structures mainly hosted by crystal-rich tuffs and with a total summed length of approximately 7000 m; they are veins, veinlets, stockworks, hydrothermal breccias, and silicified rocks, which are composed of quartz, chalcedony, Fe-oxides, and locally some sulfides. In general, the veins are more abundant in the western sector of the project, and their dominant orientation is NW-SE, but some of them are oriented SSW-NNE. Their maximum length is of about 800 m, and their maximum thickness is 4 m, although the average is closer to 80 cm.

All of the data recently collected by Fomicruz, are currently being interpreted for generating drilling targets. Assays from the rock samples returned a maximum gold concentration of 2.24 ppm. Arsenic and antimony are anomalous in most of the samples, with maximum concentrations of 4620 ppm and 690 ppm respectively. The concentrations of Ag, Cu, Pb and Zn are low in most of the samples, with maximum of 224, 31, 140 and 152 ppm respectively. The preliminary interpretations of the geology and geochemistry indicate that the erosion has only uncovered the superficial portion of an epithermal paleo-system, and therefore, most of the mineralized rocks may be preserved at depth.