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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 byMuschelkalk and Keuper facies. In the LadinianMuschelkalk, carbonates appear slumps, breccias, load casts, slide and parallel shear surfaces, 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. [ABSTRACT FROM AUTHOR]

Five successive fossil submarine slides have been mapped and described in the Sobrarbe deltaic complex (Ainsa Basin, Spanish Pyrenees). These slides affect and remove up to 15% of the delta front. The head of the scar surfaces is recognized clearly in the field due to the angular unconformity between the infilling sediments and the underlying layers. Most of the slide scarps trend 55°N with 20° to 40° dips indicating north-westward sliding. Downslope, traces of the sliding surfaces parallel stratification. However, these surfaces can be identified by displaced masses, resedimented sandstones and soft-sediment deformation features such as metre-scale half-grabens, normal faults and tension cracks; all the surfaces indicate a sliding displacement toward the north-west. A three-dimensional model built from topographic data with Earth Vision® software shows the architecture of the slide surfaces and provides an estimation of the volume of each sedimentary body within the limit of the studied area. This study also indicates that: (i) the sediments have been cut and carried away before their lithification; (ii) the sedimentation rate infilling a single slump scar is estimated to be about 8 m per 1000 years, i.e. 10 times higher than in the overall area of the Sobrarbe deltaic complex; (iii) each composite scar progressively develops and infills by retrogressive slumps; (iv) the successive slide surfaces stack vertically in a collapse complex structure and migrate downward to follow the sea-level drop between two successive collapse complex structures; (v) the development of the scars in the Sobrarbe delta is described from a seven-stage conceptual model starting with a regressive event; and (vi) the triggering of the Sobrarbe instabilities is controlled by high values of sedimentation rate, relative sea-level falls mainly controlled by tectonic uplift, and likely seismic activity. [ABSTRACT FROM AUTHOR]