TOWARD AN UNDERSTANDING OF THE DEVELOPMENT OF SALT-RELATED OVERBURDEN STRUCTURES IN THE SOUTHERN NORTH SEA BASIN, U.K.

Abstract

ABSTRACT The present-day structural configuration of the Mesozoic and younger section in the Southern North Sea (SNS) Basin results from the complex interaction between extension, salt tectonics, inversion, and subsidence, that began in the late Triassic and continued well into the Tertiary. Interpretation of high-resolution 3D seismic data, combined with 2D cross-section restorations and the new insights into salt tectonics derived from scaled analog- and numerical-model experiments, has prompted a reevaluation of the development of salt-related structures in the basin. Several key aspects of the developmental history can be well explained using the concepts derived from experimental data notably diapiric rise and fall and inversion-related diapiric rejuvenation. A wide variety of salt-related structures occurs in the SNS Basin, including graben-diapir systems, salt-walls, and salt swells and troughs. These structures, though physically very different, have similar development histories. Salt-related overburden structures in the basin are considered to result from thin-skinned gravity-driven deformation that was responsible for triggering and controlling graben and diapir growth, and for the selective later inversion of some diapirs. Additional structures were created by bending and vertical movements associated with extensionally-driven diapiric collapse. The development of structures in the overburden was not driven by salt movement; salt structures developed as a simple “reaction” to the thin-skinned extension and subsequent contraction of the overburden.