Syn-Sedimentary Folds and Associated Structures in Cretaceous Salt Deposits of Sergipe, Brazil

Abstract

ABSTRACT Folds and disturbed bedding are common features in Cretaceous salt deposits of Sergipe, Brazil, and appear to be of syn-sedimentary origin rather than due to tectonic or isostatic forces acting long after lithification and burial. Thick deposits of tachyhydrite, within the evaporite sequence, could only have been preserved in a basin which had a continuous covering of brine and which never reached the dry-lake stage. In such an environment, lack of early cementation may have provided conditions favourable for the formation of syn-sedimentary structures by slumping, compaction and loading. Salt domes are not associated with the Sergipe deposits but unlitlified salt sediments have a low effective density and lack of strength which will facilitate salt flowage and dome formation with a minimum overburden.