Journal
JOURNAL OF SOUTH AMERICAN EARTH SCIENCES
Volume 77, Issue -, Pages 58-69Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jsames.2017.04.015
Keywords
Inversion of striated fault planes; Crustal stress field; Mountain building; Peruvian flat-slab; Cordillera Blanca
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Funding
- LabEx OSUG (Observatoire des Sciences de l'Univers de Grenoble, Investissements d'Avenir) [ANR10 LABX56]
- SMINGUE
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In subduction settings, the tectonic regime of the overriding plate is closely related to the geometry of the subducting plate. Flat-slab segments are supposed to increase coupling at the plate interface in the Andes, resulting in an increase and eastward migration of the shortening in the overriding plate. Above the Peruvian flat-slab, a 200 km-long normal fault trend parallel to the range and delimits the western flank of the Cordillera Blanca. In a context of flat subduction, expected to produce shortening, the presence of the Cordillera Blanca normal fault (CBNF) is surprising. We performed a systematic inversion of striated fault planes in the Cordillera Blanca region to better characterize the stress field above the Peruvian flat-slab. It evidences the succession of different tectonic regimes. NE-SW extension is predominant in most of the sites indicating a regional extension. We suggest that the Peruvian flat-slab trigger extension in the Western Cordillera while the shortening migrated eastward. Finally, we propose that flat-slab segments do not increase the coupling at the trench neither the shortening in the overriding plate but only favor shortening migration backward. However, the stress field of the overriding plate arises from the evolution of plate interface properties through time due to bathymetric anomaly migration. (C) 2017 Elsevier Ltd. All rights reserved.
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