--> ABSTRACT: Rotational Fault-Bend Folds: An Alternative to Kink-Band Models with Implications for Reservoir Geometry and Heterogeneity, by Heather I. Stanton and Eric A. Erslev; #90906(2001)

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Heather I. Stanton1, Eric A. Erslev1

(1) Colorado State University, Fort Collins, CO

ABSTRACT: Rotational Fault-Bend Folds: An Alternative to Kink-Band Models with Implications for Reservoir Geometry and Heterogeneity

Kinematic models of fault-bend folding commonly invoke kink bands, which emanate from hanging-wall and footwall cut-offs defined by the intersection of planar fault segments (e.g., flats and ramps). Many folds in thin-skinned thrust belts display this geometry, where backlimb stratal dips commonly parallel underlying fault ramps. These models predict penetrative or flexural slip deformation in all strata that deviate from the regional dip.

Basement-involved, thick-skinned structures differ in that block rotations over curved faults are commonly invoked to explain tilted domains of minimally deformed strata. New analytical modeling predicts that domains of rotation and translation will remain largely undeformed, and that transitional areas between rotation and translation will be deformed due to localized changes in velocity.

Seismic and field data indicate that Rocky Mountain basement-involved structures are better modeled with rotational fault-bend folding than with current kink-band approximations. On a regional scale, (e.g., the northeastern margin of the Wind River arch), oil-bearing anticlinal traps can be localized over transitional zones of back-limb tightening between translational and rotational domains. At the reservoir scale (e.g., Bighorn Basin oil fields), rotational fault-bend folding provides better predictions of fracture location and density than kink-band models. Worldwide, kink-band and rotational fault-bend fold models represent end-members whose different predictions can be critically important to petroleum exploration and recovery.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado