Tectonic signatures in the Triassic sediments of the Betic External Zone (southern Spain) as possible evidence of rifting related to the Pangaea breakup
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Academie des sciences
Materia
Muschelkalk Keuper Seismite Soft-sediment deformation structures Volcaniclastics
Date
2021-10-15Referencia bibliográfica
Alberto Pérez-López; Fernando Pérez-Valera. Tectonic signatures in the Triassic sediments of the Betic External Zone (southern Spain) as possible evidence of rifting related to the Pangaea breakup. Comptes Rendus. Géoscience, Tome 353 (2021) no. 1, pp. 355-376. [doi : 10.5802/crgeos.85]
Sponsorship
Secretaría de Estado de I+D+I B-RNM-072-UGR18; European Regional Development Fund P18-RT-4074, RNM-208; Junta de AndalucíaAbstract
This paper describes various soft-sediment deformation structures present in the Triassic
deposits of the Betic External Zone (Southern Iberian). These structures, together with variations in
deposit thicknesses, internal angular unconformities, and synsedimentary faults, point to intense tectonic activity from the Middle to Late Triassic related to a stage of rifting. The Middle–Late Triassic in
the Betic External Zone shows a sedimentary record represented by Muschelkalk and Keuper facies. In
the Ladinian Muschelkalk, carbonates appear slumps, breccias, load casts, slide and parallel shear sur faces, and tsunamites. In the sandstones of the Carnian Keuper facies, different seismite beds and ball
and pillow structures can be discerned. Above these deposits, the carbonate Zamoranos Formation
of the Rhaetian displays volcaniclastic rocks with conglomerates, slumps and synsedimentary faults.
All these features and magmatism suggest some tectonic activity, possibly related to the breakup of
Pangaea, especially at the end Triassic. We highlight the features that indicate this tectonic activity
over time and discuss the factors that triggered the development of these structures, along with the
conditions that made this possible.