Relating orogen width to shortening, erosion, and exhumation during Alpine collision

Rosenberg, C. L.; Berger, Alfons; Bellahsen, N.; Bousquet, R. (2015). Relating orogen width to shortening, erosion, and exhumation during Alpine collision. Tectonics, 34(6), pp. 1306-1328. American Geophysical Union, European Geophysical Society 10.1002/2014TC003736

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We investigate along-strike width changes of the thickened, accreted lower plate (TALP) in the Central and in the Eastern Alps. We set the width of the TALP in relation to the inferred amount of collisional shortening and exhumation along six orogen-scale cross sections. Taking the present-day, along-strike gradients in the amount of collisional shortening to represent the temporal evolution of the collisional wedge, it may be concluded that the cross-sectional area of the TALP diminishes during ongoing shortening, indicating that the erosional flux outpaced the accretionary flux. Higher amounts of collisional shortening systematically coincide with smaller widths of the TALP and dramatic increases of the reconstructed eroded rock column. Higher amounts of shortening also coincide with larger amplitudes of orogen-scale, upright folds, with higher exhumation and with higher exhumation rates. Hence, erosion did play a major role in reducing by >30 km the vertical crustal thickness in order to accommodate and allow shortening by folding. Long-term climate differences cannot explain alternating changes of width by a factor of almost 2 along straight segments of the orogen on length scales less than 200 km, as observed from the western Central Alps to the easternmost Eastern Alps. Sedimentary or paleontological evidences supporting such paleo-climatic differences are lacking, suggesting that erosional processes did not directly control the width of the orogen.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences
08 Faculty of Science > Institute of Geological Sciences > Tectonics

UniBE Contributor:

Berger, Alfons

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0278-7407

Publisher:

American Geophysical Union, European Geophysical Society

Language:

English

Submitter:

Alfons Berger

Date Deposited:

29 Jul 2015 16:04

Last Modified:

01 Jan 2016 02:30

Publisher DOI:

10.1002/2014TC003736

BORIS DOI:

10.7892/boris.70553

URI:

https://boris.unibe.ch/id/eprint/70553

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