Elements of High Constructive Deltaic Sedimentation, Lower Frio Formation, Brazoria County, Texas

ABSTRACT The lower Frio Formation in eastern Brazoria County, upper Texas Gulf Coast, was deposited in a high constructive deltaic environment in the Houston Delta System. Constructive elements of the stacked, elongate to lobate deltas, intersected in three cores through the lower Frio Formation, are storm-induced delta-front splays, delta-front slump deposits, distributary mouth bar, distributary channel, and delta-plain assemblages. Reworked and winnowed abandonment facies are volumetrically insignificant relative to constructive elements, are subdivided into a crossbedded shoreface-foreshore subfacies and a cyclic sequence of fine-grained storm deposits on the distal delta front. Micropaleontological evidence indicates that deposition of constructive and abandonment facies took place in water depths of less than 120 feet.