A review about the quaternary upper-plate deformation in the Southern Central Andes (36–38°S): A plausible interaction between mantle dynamics and tectonics

SAGRIPANTI, LUCÍA; COLAVITTO, BRUNO; JAGOE, LUCÍA; ANDRÉS, FOLGUERA; COSTA, CARLOS

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2017

0895-9811

Quaternary deformation in the Southern Central Andes between 36° and 38ºS isdisconnected, noncontinuous and not particularly tracing the main mountain topographicfronts. This pattern contrasts to the one to the north through the Chilean-Pampean flatsubduction system, where continuous neotectonic structures develop at the feet of themain active structures. Instead, in the Southern Central Andes, two active deformationalsystems are developed: a western one acting as an out-of-sequence belt with respect tothe eastern-frontal structures developed through Cretaceous and Cenozoic times, and aneastern one associated with different individual structures. While the westerndeformational belt constitutes the continuation to the north of an intra-arc fault systemassociated with dip- and strike-slip displacements in a strain partitioned regime, theeastern sector cannot be directly related to other deformational systems neither to thenorth nor south. However, a strong correlation exists between areas that show evidenceof Quaternary deformation and a complex pattern of mantle anomalies affecting thelower lithosphere determined in previous magnetotelluric surveys. We suggest that thethermally weakened crust at these latitudes could be the main control focalizingdeformation, which would explain this contrasting pattern of young deformations in theSouthern Central Andes.