Published 1995 as part of Memoir 65
Copyright © 1995 The American Association of Petroleum Geologists.   All Rights Reserved.
 

The influence of tectonic stress on the initiation and development of evaporite diapirs is of great importance in the interpretation of diapiric structures and associated sediments. The eastern Prebetic foldbelt in southeastern Spain contains many diapirs that provide excellent examples of tectonically controlled diapirism. These diapirs are mainly composed of Triassic evaporite and shale that have pierced their overburden along extensional faults and in releasing oversteps along strike-slip faults. They occur as highly elongated diapiric walls or as large, fault-bounded bodies that can cover several tens of square kilometers at the center of grabens. Most of these diapirs reached the surface in Neogene times, constituting local depocenters for Miocene sediments. Outcrop and well data suggest that their source layer consists mainly of interbedded shale and anhydrite, which are denser than their carbonate overburden and thus preclude piercement diapirism driven by buoyancy. The external geometry of these diapirs and a variety of kinematic indicators in surrounding overburden suggest that their location and initiation was primarily controlled by (trans)tensional faulting. It is therefore concluded that the Prebetic diapirs formed in response to thin-skinned extension of their overburden, which induced differential loading and viscous flow of the Triassic evaporites. Regional paleostress analysis and chronostratigraphic correlation suggest that diapirism was triggered by rifting in the adjacent Western Mediterranean Basin.