--> ABSTRACT: Testing the Concept of Contractional Rejuvenation of Diapirs, by R. J. Hooper, B. C. Vendeville, E. Bergfjord, J. Colleran, C. Gunn, and N. Evans; #91021 (2010)

Datapages, Inc.Print this page

Testing the Concept of Contractional Rejuvenation of Diapirs

HOOPER, R. J., B. C. VENDEVILLE,  E. BERGFJORD,  J. COLLERAN, C. GUNN, and N. EVANS

Structural inversion can exert an important control on diapir development. Salt diapirs represent weak points within the sedimentary cover they intrude. During contraction, deformation is preferentially partitioned into the diapirs, squeezing the diapir stems and thus adding tectonic pressure to the natural buoyant pressure within the diapirs. The net effect is rejuvenation of the diapirs; the cause of the deformation (i.e. contraction), however, often remains cryptic. Contraction may be the cause of rejuvenation even where direct structural evidence for contraction (e.g. folds or contractional faults) is absent: there, contraction is recorded only by the fact that diapirs suddenly start to grow after a long period of immobility, or grow by short pulses interspersed with long periods of immobility.

We will show examples from the Barents Sea, UK and Norwegian Central Graben, southern North Sea, and S.E. Arabian Gulf, where diapirs show evidence of contractional rejuvenation. The examples will illustrate a wide range of structural styles including: low-amplitude, long wavelength swells; long, high-relief walls; graben/diapir systems; low-relief domes; and high relief piercements. All the salt structures show pulsed growth-histories where diapiric rise occurred after long periods of relative diapiric inactivity. In all examples very thick roof-sections have been deformed, some developing large rafted-sections. In some examples the timing of growth can be directly tied to contractional orogenic events; in other cases, the precise source of the contraction is more cryptic and may simply be the result of gravitational gliding.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.