Particle dynamics simulations of gravitationally driven deep-water fold and thrust belts

Principal Investigators:	Juli Morgan (Rice University)
Collaborators:	Gary Gray (ExxonMobil URC) John Shaw (Harvard University)
Graduate Student:	Scott Maxwell
Funding Sources:	ExxonMobil Exploration Corporation

Figure 1

Sediments accumulated on passive continental margins are subject to gravitational sliding and spreading, leading to coupled regions of up-slope extensional and down-slope contractional deformation. The presence of weak interlayers, such as salt or shale, allows for significant basinward transport of slope sediments leading to the formation of pronounced deep-water fold and/or thrust belts. These features closely resemble fold and thrust belts that form along convergent margins, but result from gravitational rather than tectonic driving forces. High resolution particle dynamics simulations allow the effects of various stratigraphies, strength contrasts, and sediment loading patterns to be explored. The resulting fold and thrust belt geometries compare well to physical analog models and natural systems. The example shown in Figure 1 consists of a broad region of sediment deposition (40% of the domain), upon pre-existing strata containing a weak bed (gray and red particles, respectively). Conjugate normal faults are well-developed upslope, and thrust faults rise from the decollement downslope.

The widths and intensities of the deformed belts are strongly influenced by the thickness, extent, and number of weak interlayers, and their strength contrasts with the surrounding materials. Complex sediment loading patterns produce multiple deformation fronts that interact and eventually merge as displacements increase. The numerical simulations provide preliminary constraints on the mechanical structures and growth histories of documented deep water fold and thrust belts.

Abstracts:

Morgan, J.K., 2006, Particle dynamics simulations of deep-water fold and thrust belts: Coupled extensional and contractional deformation along passive continental margins, AGU, 87, Fall Meet. Suppl., Abstract T51G-05

Page last modified: 29-Dec-2006