The origin of salt-encased sediment packages: Observations from the SE Precaspian Basin (Kazakhstan)

This work is divided into three parts. The first part outlines the possible origins of intrasalt sediment packages, as well as criteria to determine if they originated as subsalt, suprasalt or intrasalt sequences. The second part examines how sediment packages that originated on top of salt, such as minibasins, can be encased within salt. Four key encasement processes are proposed: a) salt expulsion from beneath a minibasin experiencing density-driven subsidence; b) salt expulsion from beneath adjacent subsiding minibasins; c) salt expulsion associated with lateral shortening; d) override of minibasins by a salt sheet sourced from elsewhere. The third part of the paper presents a case study from the SE Precaspian Basin, Kazakhstan, where, using a borehole-constrained 3D seismic reflection dataset, the proposed criteria are applied to an area with abundant, newly discovered sediment packages within salt.