Physical models of structural patterns above salt diapirs
- Univ. of Alabama, Tuscaloosa (USA)
Dry clay models were used to study fault systems that develop in strata above domal uplifts. Contemporaneous deposition and deformation was modeled by incrementally uplifting a model diapir and depositing additional layers of dry clay on the deformed strata. Variables observed to control structural patterns that developed in the arched and extended strata include: (1) the nature of the contact between the model diapir and the overlying strata, (2) the thickness of the pre-uplift sequence, and (3) the rate of sedimentation with respect to the rate of diapir uplift. Boundary conditions between the model diapir and overlying strata proved very critical in controlling fault patterns. Naturally occurring salt diapir-related faults systems seem best duplicated experimentally by allowing the pre-uplift strata to slide passively along the sides of the uplifting diapir, modeling a non-welded contact. With uplift, two related but distinct systems of extensional faults developed above the crest of the model diapir: (1) a surface-breaking graben complex bounding by inward-dipping normal faults and rooted in the upper levels of the pre-uplift strata, and (2) a blind system of normal faults rooted to the crest of the diapir. The surface-breaking graben complex was observed only in experiments with thin pre-uplift sequences (pre-uplift thickness equaled one-half diapir diameter) and intermediate-thickness pre-uplift sequences (pre-uplift thickness equaled one-and-a-half times diapir diameter). In the thin pre-uplift experiments, the graben complexes were rooted to the top of the diapir. In the intermediate thickness pre-uplift experiments, inwards-dipping, graben-bounding normal faults intersected and diverged at depth, forming conjugate fault sets with grabens situated immediately above pyramid-shaped horsts.
- OSTI ID:
- 5991467
- Report Number(s):
- CONF-9010204-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:9; Conference: Gulf Coast Association of Geological Societies and Gulf Coast Section of SEPM (Society of Economics, Paleontologists, and Mineralogist) meeting, Lafayette, LA (USA), 17-19 Oct 1990; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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