Contractional salt tectonics and role of pre-existing diapiric structures in the Southern Pyrenean foreland fold-thrust belt (Montsec and Serres Marginals)
Burrel Garcia, Laura (Universitat Autònoma de Barcelona. Departament de Geologia)
Teixell Cácharo, Antonio (Universitat Autònoma de Barcelona. Departament de Geologia)

Data:	2021
Resum:	Triassic Keuper evaporites have long been recognized as the main detachment level for thrusting in the Pyrenean fold-thrust belts. The deformed Late Cretaceous-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 and 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 in 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-Paleocene growth strata is taken as marking the onset of contractional folding in the area. During 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 about the role of salt tectonics in the Pyrenees.
Ajuts:	Ministerio de Economía y Competitividad CGL2014-54180-P Agencia Estatal de Investigación PGC2018-093903-B-C21 Ministerio de Economía y Competitividad BES-2015-071786
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Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Boada ; Oblique synclines of Sant Jordi ; Rubió and Montsonís
Publicat a:	Journal of the Geological Society, Vol. 178, Issue 4 (July 2021) , art. jgs2020-085, ISSN 2041-479X

DOI: 10.1144/jgs2020-085

Postprint 54 p, 7.7 MB

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