Fracturing along the Grand Hogback, Garfield County, Colorado

摘要: The several sets of fractures found in steeply dipping Mesaverde strata along the Grand Hogback, northwest Colorado, have previously been interpreted to be either (1) entirely pre-uplift origin, or (2) caused by stresses created during folding and uplift. However, based on fracture characteristics measured at 32 locations we suggest that only major set formed prior uplift, corresponds subsurface nearby flat-lying reservoirs. These are oldest fractures, which developed Group lower Wasatch Formation as a west-northwest trending, through-going, regional response horizontal compression. Secondary through northeast cross-cutting post-date can related structural deformation exposure Hogback. suggested resulted from different mechanisms: relaxation subsequent early event, north-south trending section Hogback cross-sectional folding, (3) sinuous east-west sections planarmore » folding. widely but rare subsurface. Conjugate shear compression 17 refs., 12 figs.« less