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International Journal of Geophysics
Volume 2009, Article ID 607458, 8 pages
http://dx.doi.org/10.1155/2009/607458
Research Article

A Comparative Analysis of Seismological and Gravimetric Crustal Thicknesses below the Andean Region with Flat Subduction of the Nazca Plate

1CONICET, Universidad Nacional de San Juan, IGSV-M├ętodos Potenciales, San Juan CP. 5400, Argentina
2Department of Earth Sciences, University Trieste, Via Weiss 1, 34100 Trieste, Italy
3CONICET, Universidad Nacional de Rosario, Rosario CP. 2000, Argentina

Received 18 December 2008; Revised 3 April 2009; Accepted 4 June 2009

Academic Editor: John F. Cassidy

Copyright © 2009 Mario E. Gimenez et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A gravimetric study was carried out in a region of the Central Andean Range between and south latitudes and from and west longitudes. The seismological and gravimetrical Moho models were compared in a sector which coincides with the seismological stations of the CHARGE project. The comparison reveals discrepancies between the gravity Moho depths and those obtained from seismological investigations (CHARGE project), the latter giving deeper values than those resulting from the gravimetric inversion. These discrepancies are attenuated when the positive gravimetric effect of the Nazca plate is considered. Nonetheless, a small residuum of about 5 km remains beneath the Cuyania terrane region, to the east of the main Andean chain. This residuum could be gravimetrically justified if the existence of a high density or eclogitized portion of the lower crust is considered. This result differed from the interpretations from Project “CHARGE” which revealed that the entire inferior crust extending from the Precordillera to the occidental “Sierras Pampeanas” could be “eclogitized”. In this same sector, we calculated the effective elastic thickness (Te) of the crust. These results indicated an anomalous value of Te = 30 km below the Cuyania terrane. This is further conclusive evidence of the fact that the Cuyania terrane is allochthonous, for which also geological evidences exist.