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Basin stratigraphic response to variable fault geometry and tectonic kinematics: An investigation of extensional basin development

Todd Engelder,

The Indiana University,

Department of Geological Sciences, Bloomington In.,

[email protected]

Fault geometry and tectonic rate impose a significant impact on the transverse distribution of stratigraphic facies with respect to the main basin-bounding fault. Half-graben basins with relatively large basin-bounding fault dips and slow subsidence rates are generally dominated by footwall fans. However, basins with relatively small basin-bounding fault dips and fast extension rates expose a greater surface area within the footwall. Increased area for potential erosion allows a more significant sediment flux to enter the basin from the footwall.

During the Miocene, rapid extension within the Socorro and La Jencia sub-basins of the Rio Grande Rift Basin induced significant footwall uplift. Syn-rift facies (Santa Fe Group) that were deposited during this event are present within the Lemitar Mountains as well as within core that was collected from the Albuquerque, Espanola, and San Luis basins. Coarse-grained alluvial fan facies located adjacent to the Magdelina Mountains (footwall) are inter-tongued with finer-grained playa lake facies that extend into the remainder of the basin. Field work this fall will be focused on further constraining the rates of tectonic extension and the distribution of facies within the Socorro and La Jencia sub-basins during the Miocene. Extension data will then be implemented as a parameter for a sediment transport model that will be utilized to test the effect that fault geometry imposes on the distribution of depositional facies.

AAPG Search and Discovery Article #90060©2006 AAPG Foundation Grants-in-Aid