The competition for salt and kinematic interactions between minibasins during density-driven subsidence: observations from numerical models

摘要

Stratal geometries of salt-floored minibasins provide a record of the interplay between minibasin subsidence and sedimentation. Minibasin subsidence and resulting stratal geometries are frequently interpreted by considering the minibasins in isolation and implicitly assuming that internal geometries are the result of purely vertical halokinetic processes. However, minibasins rarely form in isolation and may record complex subsidence histories even in the absence of tectonic forces. In this study we use numerical models to investigate how minibasins subside in response to density-driven downbuilding. We show that minibasins subsiding in isolation result in simple symmetrical minibasins with relatively simple internal stratigraphic patterns. In contrast, where minibasins form in closely spaced arrays and subside at different rates, minibasins can kinematically interact due to complex patterns of flow in the encasing salt, even during simple density-driven subsidence. More specifically, we show that minibasins can: (1) prevent nearby minibasins from subsiding; (2) induce lateral translation of nearby minibasins; and (3) induce tilting and asymmetrical subsidence of nearby minibasins. We conclude that even in areas where no regional or dominant salt flow regime exists, minibasins can still be genetically related and the minibasin subsidence histories cannot be fully understood if considered in isolation.