In the high mountains of the Andes of Chile and Argentina, precious metals are abnormally concentrated in El Indio Belt, which hosts over 45Moz of gold in HS epithermal deposits that were formed very close to the surface, but whose roots lie way into the crust. Within the Andean subduction orogeny, Pascua-Lama, Veladero, El Indio and Tambo were formed only 12 to 6 million years ago, just before the volcanic activity in the area shut down due to the inception of a flat slab associated with the Juan Fernandez Ridge.
In El Indio belt, this project is aiming to decipher the structural architecture that was present before the deposits were being formed, and how it interacted with the geodynamic regime operant in the area at the time of the gold deposition. It is this architecture, which is now concealed below thousands of meters of volcanic material, what is supposed to have controlled the location of the deposits.
By processing aeromagnetic data and analysing geological maps, it has been possible to stipulate that there is an old set of faults that affect the basement existing before the volcanic arc was set. We have been able to map this trend boots-in-the-ground at El Indio Belt as we had our first field season, collecting structural data which interpretation is crucial to the understanding of the architecture and geodynamics of the area.
Also, further state-of-the-art isotopic analysis in zircons (U-Pb ages coupled with O and Lu-Hf isotopes) are being carried out, and will aid to map the fundamental architecture that is even lower, in the mid- to lower crust or maybe even in the lithospheric mantle. By these means, we are aiming to look at the architecture of the deeper magmatic roots responsible of the deposits in El Indio Belt area.
All of the information will be then integrated into what will be the first regional 4D model of the area. By deciphering the intricate intersection in time and space of different main trending faults, and even deeper currently unknown trends, this project is aiming to answer one of the most fundamental questions for economic geology exploration: where is the gold?