| Fold - Fracture Relationships: Application at Sheep Mountain Anticline, Bighorn Basin, Wyoming | |
| Personnel: N. Bellahsen, P. Fiore and D. D. Pollard Sponsor: NSF Tectonics Program EAR-0125935; NSF Collaboration in Mathematical Geosciences EAR-0417521; Stanford Rock Fracture Project; Institut Français du Pétrole | |
Description:
This project examines the relationship between the folding and fracturing of a Laramide, asymmetric, fault-cored fold of the Bighorn
Basin in Wyoming. Field and thin section observations of fracture orientation, mode of deformation (opening or shear), termination
relationships, and evidence for reactivation have been synthesized into a fracture evolution history that constrains the kinematics of
the fold evolution. Analyses to date suggest that there was no lateral fold propagation and no hinge migration, and that limb rotation
or limb flexure operated at different structural locations during folding. Further work will focus on (1) mechanical models that
investigate the relationship between the heterogeneous distribution of certain fracture sets and stress field perturbations due to
slip along the underlying thrust fault; (2) geochemical analyses of fracture cements to determine how cements within various fracture
sets vary and what this may imply about fluid migration and the relative age relationships and regionality of the fracture sets; and
(3) reprocessing three two dimensional seismic profiles located near Sheep Mountain to better constrain the subsurface fault geometry.
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| Selected Publications: Bellahsen, N., Fiore, P., and Pollard, D. D., The role of fractures in the structural interpretation of Sheep Mountain anticline, Wyoming. Submitted to the Journal of Structural Geology. | |