Publication Date:
2021-02-04
Description:
Triassic Keuper evaporites have long been recognized as the main detachment level for thrusting in the Pyrenean fold-and-thrust belts. The deformed Late Cretaceous to Eocene foreland basin of the Southern Pyrenees has structures and stratal geometries that can be interpreted as related to salt tectonics (e.g. unconformities, rapid thickness variations, long-lived growth fans, overturned flaps), although they have been overprinted by shortening and thrusting. Based on field observations and published maps, we build new structural cross-sections reinterpreting two classic transects of the Southern Pyrenees (Noguera Ribagorçana and Noguera Pallaresa river transects). The sequential restoration of the sections explores the variations of structural style, addressing the role of halokinesis in the tectonic and sedimentary development. In the Serres Marginals area, we propose that salt pillows and diapirs started developing locally during the Mesozoic pre-orogenic episode, evolving into a system of salt ridges and intervening synclines filled with early synorogenic sediments. Rapid amplification of folds recorded by widespread latest Cretaceous-Palaeocene growth strata is taken as marking the onset of contractional folding in the area. During the Pyrenean compression, folding mechanisms transitioned from dominantly halokinetic, to a combination of buckling and differential sedimentary loading. Squeezing of salt diapirs and thrust welding occurred as salt ridges were unroofed. We provide new field observations that lead to a reinterpretation of the regional structural development and contribute to the debate of the role of salt tectonics in the Pyrenees.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5287737
Print ISSN:
0016-7649
Topics:
Geosciences
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