Abstract

The Bicorb–Quesa diapir belongs to a complex system of evaporite diapirs located in the SE Iberian Peninsula. It was emplaced along the axis of a graben system flanked by two syn-diapir growth basins filled by Miocene sediments. The Miocene evolution of the diapir may be divided into three major phases: an initial extensional phase during which the graben system formed and the diapir rose; a second phase during which regional shortening closed the diapir; and a third phase characterized by normal faulting during which diapirism was reactivated, cutting the previously-formed thrusts and folds. This evolutionary trend demonstrates that diapirism was initiated and promoted by regional extension.

During the two extensional phases, the diapir grew by reactive, active and passive rise. Sedimentation during the reactive stage was characterized by strong basin subsidence, sharp changes in sediment thicknesses, and major coarse-grained sediment input. During the active stage, the coeval basin-fill sequence displays progressive angular unconformities, gravitational deposits and subtle changes in thickness with the sediments unconformably overlying most of the earlier-formed faults. Finally, during the passive stage, the sediments synchronous with diapir formation include abundant components from the extruding rocks, and show gentler changes in thicknesses, a progressive decrease in the input of coarse sediments, and the deposition of mudstones and/or lacustrine carbonates that clearly extend onto the faulted basin margins.

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