Analogue models of salt diapirs and seismic interpretation in the Nordkapp Basin, Norway

Abstract: Dynamically scaled analogue models wi th an overburden of cohesive sand and a viscous "salt " layer w e r e deformed in a centrifuge to mimic real salt s t ructures in the Nordkapp Basin. Like their natural prototypes, model diapirs w e r e aligned in rows parallel to the basin margins. In profile, model diapirs w e r e asymmetric, suggesting that the real diapirs will possess asymmetric geometries. Like many of the real salt structures, model diapirs p ierced wi thou t developing a pillow stage because they rose along basin margin faults wh ich propagated u p through the overburden from the basement during thick-skinned extension. Once their overburden was weakened by faulting, differential loading forced model diapirs to rise as long as buoyant material was supplied. Some real salt diapirs initially rose as conformable pillows during the early Triassic, became diapiric during middle Triassic and spread broad overhangs during slow sedimentat ion in late Triassic and Jurassic times. Later, the overhangs reactivated asymmetrically w h e n buried by Cretaceous and Tertiary sediments