The open scars of Latin America: The Bolivian Orocline as a basament-related hinge, and the influence of accreted terranes on the paleomagnetic rotational patterns of the Chilean forearc - INSU - Institut national des sciences de l'Univers Access content directly
Conference Poster Year : 2015

The open scars of Latin America: The Bolivian Orocline as a basament-related hinge, and the influence of accreted terranes on the paleomagnetic rotational patterns of the Chilean forearc

Abstract

We made a paleomagnetic study in two separate zones of the Chilean forearc, between 18-22ºS and between 28-32ºS, sampling igneous and sedimentary rocks with ages ranging from Triassic to Miocene. More than 500 samples showed a stable magnetization, with hematite and magnetite being the principal carriers of magnetism. The rotation pattern obtained, added to previously published paleomagnetic data, show a continuous database for the Chilean forearc, between 19 and 35ºS, allowing us to separate distinct patterns in 4 major rotational zones: (1) Between 18-19.5ºS there is a strong anticlockwise rotational pattern, in agreement with the data known in southern Peru. (2) Between 19.5-22.5ºS, there is little to no rotation, with the southern limit being related to a major structural feature: The Antofagasta–Calama Lineament. (3) Between 22.5-29ºS there is a strong clockwise rotation pattern of nearly 30º. (4) Between 29-32ºS there is again a little to non-rotational pattern, in the area of the Pampean flat-slab. Overlapping these zones and the recognized accreted terranes boundaries shows a clear spatial relation between these and the limits of the rotated zones. We propose that the limits of this rotational domains can be linked to basament hinge-like weakness zones that helped to create the margin curvatures observed today. Under this model, the bolivian orocline would be the result of the opening of a hinge, helped by other geodynamics features like sea mountains and ridges, at the limit between the old accreted paleozoic terranes of Antofalla and Arequipa.
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insu-01265813 , version 1 (01-02-2016)

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  • HAL Id : insu-01265813 , version 1

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Matias Pena Gomez, Cesar Arriagada, Ivan Gomez, Pierrick Roperch. The open scars of Latin America: The Bolivian Orocline as a basament-related hinge, and the influence of accreted terranes on the paleomagnetic rotational patterns of the Chilean forearc . AGU Fall Meeting 2015, Dec 2015, San Francisco, United States. pp.T23A-2909, 2015. ⟨insu-01265813⟩
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