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Basement-Rooted Fault Systems of the Midland and Delaware Basins and Their Influence on Early Permian Facies Distributions

Abstract

Using 2D regional seismic lines, high quality 3D seismic volumes, and thousands of well control points from the Midland and Delaware Basins we illustrate that faults directly impact the facies and depositional systems in both basins. Basement-rooted fault-propagation folds with significant offset in the Early Permian created broad areas of uplift and subsidence that altered the base level of key stratigraphic levels in the Midland and Delaware Basins, altering dramatically basin-wide facies distributions. Secondary structures that parallel the orientation of the broad uplifts also developed but at smaller scales, many times becoming three-way fault-controlled traps on the Central Basin Platform. Low offset, oblique-slip fault systems also occur in both basins and were active during the Early Permian affecting facies and depositional patterns within the Wolfcampian and Leonardian intervals. Broad uplifts appear to be associated with the Ancestral Rocky Mountains WSW-ENE orogen whereas the oblique-slip fault systems are best explained by a SE-NW shortening associated with the Ouachitan-Marathon orogenic event. Determining the exact orientation is complicated by pre-existing faults patterns associated with Early Paleozoic rifting. In the Midland Basin, stratal horizon slicing reveals down slope transport systems that are confined by the presence of Wolfcampian-age highs that are developed at the intersection points of both structural styles creating angular fault-controlled folds sometimes referred to as trap-door uplifts. Well control and seismic mapping of horizons illustrate that the movement on faults occurred throughout the Wolfcampian and Leonardian intervals with diminishing effects persisting into the Lower San Andres interval. 3D seismic mapping in the northeastern Delaware Basin reveals a similar age of influence of basement-rooted faults affecting facies distributions and alters basinal slope depositional patterns.