Margirier A., Audin Laurence, Robert Xavier, Herman F., Ganne Jérôme, Schwartz S. (2016). Time and mode of exhumation of the Cordillera Blanca batholith (Peruvian Andes). Journal of Geophysical Research : Solid Earth, 121 (8), p. 6235-6249. ISSN 2169-9313.
Titre du document
Time and mode of exhumation of the Cordillera Blanca batholith (Peruvian Andes)
Margirier A., Audin Laurence, Robert Xavier, Herman F., Ganne Jérôme, Schwartz S.
Source
Journal of Geophysical Research : Solid Earth, 2016,
121 (8), p. 6235-6249 ISSN 2169-9313
The Cordillera Blanca batholith (12-5Myr) forms the highest Peruvian summits and builds the footwall of the Cordillera Blanca normal fault (CBNF). Even if several models have been proposed, the processes driving both the exhumation of the Cordillera Blanca and extensional deformation along the CBNF are still debated. Here we quantify the emplacement depth and exhumation of the batholith of the northern Peru arc from the late Miocene to present. Based on a compilation of crystallization ages and new thermobarometry data in the Cordillera Blanca batholith, we propose that the batholith was emplaced at a depth of similar to 3km in successive sills from 14 to 5Ma. By contrast, the younger rocks exposed at the surface were emplaced the deepest (i.e., similar to 6km) and are located close to the CBNF, suggesting post 5Ma tilting. Furthermore, a formal inversion of the thermochronologic data indicates an increase of the exhumation rates in the Cordillera Blanca during the Quaternary. The higher predicted exhumation rates correlate with areas of high relief, both in the northern and central part of the Cordillera Blanca, suggesting that Quaternary valley carving by glaciations have a significant impact on the latest stage of the Cordillera Blanca exhumation (2-0Ma).
