期刊
JOURNAL OF GEODYNAMICS
卷 91, 期 -, 页码 65-88出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jog.2015.08.002
关键词
GOCE; Vertical gravity gradient; Ojos del Salado-San Buenaventura; Lineament; Copiapo aseismic ridge; Chilean-Pampean flat slab
资金
- Ministerio de Ciencia y Tecnica - Agencia de Promocion Cientifica y Tecnologica [PICT07-1903]
- Agenzia Spaziale Italiana for the GOCE-Italy Project
- Ministero dell'Istruzione, dell'Universita' e della Ricerca (MIUR) under project PRIN [2008CR4455_003]
- ESA
Satellite-only gravity measurements and those integrated with terrestrial observations provide global gravity field models of unprecedented precision and spatial resolution, allowing the analysis of the lithospheric structure. We used the model EGM2008 (Earth Gravitational Model) to calculate the gravity anomaly and the vertical gravity gradient in the South Central Andes region, correcting these quantities by the topographic effect, Both quantities show a spatial relationship between the projected subduction of the Copiapo aseismic ridge (located at about 27 degrees-30 degrees S), its potential deformational effects in the overriding plate, and the Ojos del Salado-San Buenaventura volcanic lineament. This volcanic lineament constitutes a projection of the volcanic arc toward the retroarc zone, whose origin and development were not clearly understood. The analysis of the gravity anomalies, at the extrapolated zone of the Copiapo ridge beneath the continent, shows a change in the general NNE-trend of the Andean structures to an ENE-direction coincident with the area of the Ojos del Salado-San Buenaventura volcanic lineament. This anomalous pattern over the upper plate is interpreted to be linked with the subduction of the Copiapo ridge. We explore the relation between deformational effects and volcanism at the northern Chilean-Pampean flat slab and the collision of the Copiapo ridge, on the basis of the Moho geometry and elastic thicknesses calculated from the new satellite GOCE data. Neotectonic deformations interpreted in previous works associated with volcanic eruptions along the Ojos del Salado-San Buenaventura volcanic lineament is interpreted as caused by crustal doming, imprinted by the subduction of the Copiapo ridge, evidenced by crustal thickening at the sites of ridge inception along the trench. Finally, we propose that the Copiapo ridge could have controlled the northern edge of the Chilean-Pampean flat slab, due to higher buoyancy, similarly to the control that the Juan Fernandez ridge exerts in the geometry of the flat slab further south. (C) 2015 Elsevier Ltd. All rights reserved.
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