Salt Tectonics at Passive Margins: Geology Versus Models

Jean-Pierre Brun¹^,² and Xavier Fort²
¹University of Rennes 1, Rennes, France
²g.o. logical consulting, Cesson-Sévigné, France

Numerous passive margins display thick layers of evaporites, among which halite (salt) dominates, that are most often deposited during and/or immediately after continental rifting. They commonly display deformations over periods as long as 100 Ma or more, as recorded by syntectonic sedimentation in extension or contraction. Most often, these deformations are still active. Such salt basins are extremely unstable because salt is a very weak material that is able to flow under very low differential stresses, even at surface temperature conditions. In many salt margins where no regional tectonic effects are recorded, the observed deformations are obviously gravity driven with two ofteninvoked origins of differential stresses, namely margin tilting and/or differential sedimentary loading. Therefore, passive margins are favourable natural laboratories to study the dynamics of salt tectonics, in the absence of crustal-scale tectonics.

AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012