Structural Evolution of Salt-Influenced Fold-and-Thrust Belts: Principles in Salt Basins Containing Isolated Minibasins

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Authors

Oliver B Duffy, Timothy Dooley, Michael R Hudec, Naiara Fernandez , Christopher Aiden-Lee Jackson , Juan I. Soto 

Abstract

Shortening styles in salt-influenced fold-and-thrust belts can vary markedly, with the volume and distribution of salt prior to shortening being a key control. Here we use a suite of physical models to examine styles of thin-skinned shortening in settings where the precursor structure comprised minibasins surrounded by salt (‘isolated-minibasin’ provinces). Our models show that the high volume of mechanically-weak salt localizes shortening and induces salt flow, and that this salt flow contributes to three key processes - translation, tilting and rotation of minibasins. First, we demonstrate that salt flowing around minibasins propels them in the shortening direction, with translation enhanced by fast-flowing salt streams and impeded by basal friction and buttresses. Second, we show how minibasin tilt directions and magnitudes vary spatially and temporally during shortening. Minibasins tilt away from zones of pressurized salt, the locations of which may shift due to changes in salt flow. Tilts may also change as minibasins pivot on primary welds, or due to forces associated with minibasin collision. Third, minibasins can rotate around steep axes during shortening. We speculate that this rotation is caused by a combination of: i) tractions imparted on the minibasin boundary by flow of adjacent salt; and ii) pivoting on welds. We synthesize our results in a series of 3-D conceptual models. Finally, we compare and contrast shortening styles and processes in salt-influenced fold-and-thrust belts with different pre-shortening salt configurations.

DOI

https://doi.org/10.31223/osf.io/n59z4

Subjects

Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

Keywords

salt tectonics; minibasins; shortening; fold-and-thrust belts; welding; structural style

Dates

Published: 2020-07-16 13:55

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License

CC BY Attribution 4.0 International

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