--> ABSTRACT: Tectono Sedimentary Evolution of the Cotiella Salt Basins (South-Central Pyrenees of Spain), by Lopez-Mir, Berta; Muñoz, Josep Anton ; García-Senz, Jesus; #90142 (2012)

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Tectono Sedimentary Evolution of the Cotiella Salt Basins (South-Central Pyrenees of Spain)

Lopez-Mir, Berta *1; Muñoz, Josep Anton 1; García-Senz, Jesus 2
(1) Universitat de Barcelona, Barcelona, Spain.
(2) Instituto Geologico y Minero de España, Madrid, Spain.

The Cotiella thrust sheet is a major structural unit of the South-Central Pyrenees. It consists of inverted late Cretaceous extensional basins, which developed in the Bay of Biscay-Pyrenean realm of the Atlantic Ocean during the opening of the Central Atlantic. The internal structure of the Cotiella thrust sheet is dominated by well preserved seismic-scale Middle Coniacian - Early Santonian shallow-dipping extensional listric growth faults detached over Upper Triassic evaporites, displaying spectacular rollover anticlines in their hangingwalls. The Cotiella extensional basins were only partially inverted during the Pyrenean orogeny, although transported for 10’s of kilometres southwards.

The Cotiella basins are interpreted to have been formed by gravity-driven extension and detachment of the postrift platform above Upper Triassic evaporites, in a manner similar to that proposed for the salt basins of the Atlantic passive margins. The Cotiella basins developed at the transition from a shallow carbonate platform to the slope. As a result, the stratigraphic record preserves the tectono-sedimentary relationships between the different carbonate facies and the structural framework of the extensional system. The excellent exposures offers a unique opportunity to investigate in outcrop the carbonate systems that prograde over salt basins and gain insight into the understanding of the tectono-sedimentary evolution of the postrift basins that at present are submerged in the Atlantic Ocean.

We provide new data to better understand the evolution of the Cotiella extensional basins. The structure of the basins has been investigated through geological mapping, integrated with detailed 1:5.000 aerial ortophotographs. Cross-sections and detailed interpretations of oblique photographs are presented to describe the structural framework, the facies distribution and the inversion of the extensional system. 1:5.000 field cartography and a preliminary field data based 3D model have been elaborated to better constrain the cross-sections. New data indicates that salt tectonics played a significant role in the tectono-sedimentary architecture of the extensional basins and a new geological model to constrain the evolution of the Cotiella salt basins is presented.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California