The fate of the Copiapo ridge beneath South America, and its connection with the Pampean-Chilean flat subduction zone, tracked by GOCE satellite and EGM2008 models.

ALVAREZ ORLANDO; GIMENEZ MARIO; FOLGUERA ANDRES; SPAGNOTTO SILVANA

JOURNAL OF GEODYNAMICS

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 1 p. 1 - 20

0264-3707

Satellite-only gravity measurements and those integrated with terrestrial observations27 provide global gravity field models of unprecedented precision and spatial resolution,28 which allow analyzing lithospheric structure allowing the analysis of the lithospheric29 structure. We used the model EGM2008 (Earth Gravitational Model) to calculate the30 gravity anomaly and the vertical gravity gradient in the South Central Andes region,31 correcting these quantities by the topographic effect. Both quantities show a spatial32 relationship between the projected subduction of the Copiapó aseismic ridge (located at33 about 27º 30? S), its potential deformational effects in the overriding plate, and the Ojos34 del Salado-San Buenaventura volcanic lineament. This volcanic lineament constitutes a35 projection of the volcanic arc towards the retroarc zone, whose origin and development36 were not clearly understood. The analysis of the gravity anomalies, at the extrapolated37 zone of the Copiapó ridge beneath the continent, shows a change in the general NNE38trend of the Andean structures to an ENE-direction coincident with the area of the Ojos39 del Salado-San Buenaventura volcanic lineament. This anomalous pattern over the40 upper plate is interpreted to be linked with the subduction of the Copiapó ridge.41 We explore the relation between deformational effects and volcanism at the northern42 Chilean-Pampean flat slab and the collision of the Copiapó ridge, on the basis of thePage 3 of 89Accepted Manuscript343 Moho geometry and elastic thicknesses calculated from the new satellite GOCE data.44 Neotectonic deformations interpreted in previous works associated with volcanic45 eruptions along the Ojos del Salado-San Buenaventura volcanic lineament is interpreted46 as caused by crustal doming, imprinted by the subduction of the Copiapó ridge,47 evidenced by crustal thickening at the sites of ridge inception along the trench.48 Finally, we propose that the Copiapó ridge could have controlled the northern edge of49 the Chilean-Pampean flat slab, due to higher buoyancy, similarly to the control that the50 Juan Fernandez ridge exerts in the geometry of the flat slab further south