Welcome to Geological Journal of China Universities ! Today is
Share:

J4

• Article • Previous Articles     Next Articles

Cenozoic Extensional Rejuvenation of Salt Structures in the Paradox Basin, Utah and Colorado, USA

GE Hongxing   

  1. ConocoPhillips Company, P.O. Box 2197, Houston, Texas 77252, USA
  • Received:2008-03-20 Revised:2008-03-20 Online:2008-03-20 Published:2008-03-20

Abstract: The famous breached salt anticlines and walls in the northeastern Paradox Basin have previously been considered to be preexisting diapirs amplified by late Cretaceous to Paleocene Laramide regional compression. Similarly, the spectacular arrays of normal faults along the valley sides have been attributed to dissolution of underlying salt. We present evidence that both folding and normal faulting were a response to NE-directed regional extension during late Eocene to Oligocene, which reactivated the preexisting NW-trending salt diapirs. Salt diapirs, which grew mainly by sedimentary differential loading during late Paleozoic and Mesozoic times, localized the Cenozoic extension within the weak diapirs and their thin roofs, resulting in normal faults above the diapir crests. Faults are en echelon because extension was oblique to the trend of the preexisting salt structures. Extension created fault-slip and rollover anticlines separated by listric normal faults. Where the source layer was thick, diapirs reactively rose below the normal faults. Elsewhere, where the source layer was depleted, diapirs subsided as they widened during regional extension.The flanks of tall diapirs subsided, whereas low diapirs entirely subsided. Crestal grabens sank into the widening, subsiding diapirs, creating cusps of salt. Salt locally extruded over extensionally foundered grabens.