The subduction of the Copiapó aseismic ridge, is the causing of the formation of metallic minerals deposits in north of Chile and Argentina?

• Main Authors: Mario Gimenez, Gemma Acosta, Orlando Alvarez, Agustina Pesce, Federico Lince Kinger, Andres Folguera
• Format: Article
• Language: English
• Published: KeAi Communications Co., Ltd. 2019-11-01
• Series: Geodesy and Geodynamics
• Online Access: http://www.sciencedirect.com/science/article/pii/S1674984719300308

The results obtained in this work evince that the metallic mineral deposits located in the northern region of the Chilean-Pampean flat slab (in northern Chile and north-western Argentina), at approximately 27° 30′S, would be related to the subduction of the Copiapó aseismic ridge. The analysis of the gravity anomalies and vertical gravity gradient allows inferring a deflection and truncation of the main trend of the Andean structures at the extrapolated zone of the Copiapó ridge beneath South America. Thus, the general NNE-trend of the Andean structures are rotated locally to an ENE-strike within the area of the Ojos del Salado – San Buena Ventura lineament. We explain that this anomalous behavior of the gravity derived anomalies is related to the deformational effects imprinted by the ridge subduction. Regions with a low subduction angle (<30° to horizontal) are related to large mineralization due to fluids released by dehydration of the subducting crust. In addition, a higher degree of mantle melting could be produced by a thicker oceanic crust. Therefore, we interpret that the processes associated to the subduction of the Copiapó aseismic ridge (emplaced on a thickened oceanic crust due to a local compensation of the seamounts) are the cause of formation and emplacement of big metallic mineral deposits in this region of Chile and Argentina. Keywords: Aseismic ridge, Satellite gravity, Ojos del Salado-San Buena Ventura lineament, Metallic mineral deposits