Trench migration and slab buckling control the formation of the Central Andes

This is a Preprint and has not been peer reviewed. This is version 1 of this Preprint.

Add a Comment

You must log in to post a comment.


Comments

There are no comments or no comments have been made public for this article.

Downloads

Download Preprint

Supplementary Files
Authors

Michaël Pons, Stephan V. Sobolev, Sibiao Liu , Derek Neuharth 

Abstract

The formation of the Central Andes dates back to ~50 Ma, but its most pronounced phase, including the growth of the Altiplano-Puna Plateau and pulsatile tectonic shortening phases, occurred within the last 25 Ma. The reason for this evolution remains unexplained. Using geodynamic numerical modeling we infer that the primary cause of the pulses of tectonic shortening and growth of Central Andes is the changing geometry of the subducted Nazca plate, and particularly the steepening of the mid-mantle slab segment which results in a slowing down of the trench retreat and subsequent shortening of the advancing South America plate. This steepening first happens after the end of the flat slab episode at ~25 Ma, and later during the buckling and stagnation of the slab in the mantle transition zone. The Intensity of the shortening events is enhanced by the processes that mechanically weaken the lithosphere of the South America plate, which were suggested in previous studies. These processes include delamination of the mantle lithosphere and weakening of the foreland sediments. Our new modeling results are consistent with the timing and amplitude of the deformation from geological data in the Central Andes at the Altiplano latitude.

DOI

https://doi.org/10.31223/X5Z34N

Subjects

Geophysics and Seismology, Other Earth Sciences, Tectonics and Structure

Keywords

Andes, Altiplano, subduction, shortening, buckling, trench, geodynamic, plateau, uplift, weakening, delamination

Dates

Published: 2022-02-03 15:29

License

CC BY Attribution 4.0 International