Imaging architectural elements of distributary mouth bars using 3D GPR: Examples from cretaceous ferron Sandstone, Notom Delta, South-East Utah

3D ground-penetrating radar (GPR) survey was conducted to image architectural elements of friction dominated distributary mouth bars within proximal delta front deposits in Cretaceous Ferron Sandstone at top of the Notom Delta. Sensor and Software's Noggin Plus SmartCart 250 MHz was used over a 25 m × 5 m grid. We used an orthogonal acquisition geometry and employed a spatial sampling of 0.5 m for the in-line (dip direction) and the cross-line (strike direction). Standard processing flows including deconvolution, dewow, gain, migration, bandpass filtering and background subtraction were used to process the data. The depth of GPR penetration is 3 m. The main objective of the study is to integrate GPR profiles with available plan view and outcrop data to reconstruct a 3D facies architecture model for the distributary mouth bars. Bedding diagrams from local cliff exposures show gently NE dipping accretion of single large foresets that were interpreted as small scale unit bars, which are the building blocks of the large mouth bars. The GPR radargrams are not only capable to image that, but also reveals their 3D shape. A closer look into GPR images also reveals the distinction between various proximal mouth bar facies: upper friction-dominated dune-scale cross beds and bar scale large foresets from lower inertia-dominated basal planar beds.