Insight into the Neogene tectonic history of the northern Bolivian Orocline from new paleomagnetic and geochronologic data - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Tectonics Année : 2005

Insight into the Neogene tectonic history of the northern Bolivian Orocline from new paleomagnetic and geochronologic data

Résumé

A paleomagnetic study of 36 sites (315 samples) of Neogene strata from the Peruvian Altiplano and adjacent sub-Andean belt (Pilcopata area), combined with 40Ar/39Ar dating of 13 lava flows, provide new constraints on the Cenozoic deformation history of the northern Bolivian Orocline. In the Peruvian Altiplano, 40Ar/39Ar dating brackets the age of the strata sampled for paleomagnetism between 26.5 and 12.1 Ma for the Huaccochullo basin, 18.6 and 12.1 Ma for the Descanso-Yauri basin, and 16.8 and 15.5 Ma for the Ayaviri basin. Sub-Andean sediments are paleontologically constrained as Miocene, yet pre-9 Ma. Prefolding magnetizations isolated in the Huaccochullo, Descanso-Yauri, and Pilcopata localities indicate significant counterclockwise vertical axis block rotations of 11.3° +/- 5.4°, 31.0° +/- 10.2° and 7.8° +/- 4.8°, respectively. The pattern of rotations together with mapped structures suggest that deformation of the northern Altiplano was partitioned into large regions experiencing relatively minor rotation versus smaller, isolated basins exhibiting high-amplitude counterclockwise rotations that lie in a major left-lateral shear zone. Our new results imply significant transpressional deformation occurred throughout the Peruvian Altiplano since circa 12 Ma and are integrated in a model detailing the tectonic evolution of the northern Bolivian Orocline since 25 Ma.
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Dates et versions

hal-00323003 , version 1 (30-07-2020)

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Sonia Rousse, Stuart A. Gilder, Michel Fornari, Thierry Sempere. Insight into the Neogene tectonic history of the northern Bolivian Orocline from new paleomagnetic and geochronologic data. Tectonics, 2005, 24 (6), pp.6007. ⟨10.1029/2004TC001760⟩. ⟨hal-00323003⟩
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