Palaeomagnetism of Tertiary rocks of Puna jujena (23° S, 66° 30' W): No evidence of vertical axis rotations
Along the central Andes of southern Bolivia, northern Chile and north-western Argentina Tertiary age clockwise vertical axis rotations have been palaeomagnetically determined. Various authors have proposed different mechanisms to explain this observation, but it still remains controversial as to whe...
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| Formato: | JOUR |
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| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_00044822_v54_n4_p407_Prezzi |
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| Sumario: | Along the central Andes of southern Bolivia, northern Chile and north-western Argentina Tertiary age clockwise vertical axis rotations have been palaeomagnetically determined. Various authors have proposed different mechanisms to explain this observation, but it still remains controversial as to whether the rotations are local or regional and how they are related to the main phase of late Cenozoic shortening. In order to contribute to the understanding of the driving process or processes leading to the clockwise vertical axis rotations, 197 oriented cores were obtained from Cenozoic rocks (older than 6.45 ±0.15 Ma) cropping out in the Morro Blanco area (23° 00' S, 66° 30' W, Puna Jujena). Different palaeomagnetic demagnetization techniques were applied to the specimens. The fold test suggests the presence of both, a pre-tectonic rémanent magnetization and a post-tectonic one. These results indicate no evidence of vertical axis rotations in the studied area, at least since Late Miocene. The author considers that this fact could suggest that many of the palaeomagnetically detected rotations along the central Andes might be controlled by local structures. ©1999 Asociacián Gcológica Argentina. |
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