The Wilcox Group in east-central Louisiana consists of a variable sequence of fine-grained sand, mud, and lignite units with a composite thickness of about 3,000 feet. Studies of sand-body geometry, lithologic composition, and facies relationships indicate that the Wilcox Group consists dominantly of deltaic plain deposits (the Holly Springs and an overlying, unnamed delta system) which filled the Mississippi trough during late Paleocene and early Eocene times. Depositional history of these deposits is divided into four phases: (1) a basal progradational phase, characterized by thick bar-finger and upper deltaic plain sequences indicative of delta construction onto a deep and muddy shelf; (2) a thick transgressive deltaic phase including several shoal-water delta lobes with many distributaries separated by destructional phase units; (3) an upper deltaic phase characterized by small shoal-water delta lobes; and (4) a fluvial-transgressive phase consisting of a massive sand unit of coalescing fluvial deposits capped by a veneer of glauconitic, transgressive sands. Deltaic deposits of the lower part of the Wilcox Group closely resemble corresponding facies of the Recent Mississippi River delta system. The deltaic mass of the upper part of the Wilcox Group differs from both in several significant lithologic and geometric parameters, including: (1) an increase in carbonate accumulation; (2) a decrease in thickness and width of the channel sand and related facies; (3) a decrease in sand percentage; and (4) a decrease in the amount of lignite. A shift in paleodrainage from south to southeast accompanies these changes. / text

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Utilizing 887 kilometers of multi-stacked seismic reflection profiles and data from 27 exploratory wells, five salt domes arranged along two intersecting salt ridges, bounding and separating localized depocenters , were delineated by subsurface mapping of the structure, sediment distribution, and major sand trends of a 1621 square kilometer area on the Louisiana continental shelf. Pervasive normal faulting in the study area developed to accommodate lengthening of sedimentary units resulting from relative vertical displacement caused by uneven deposition and salt dome growth. These faults are domal (crestal and radial), bounding, and transverse in geometry. The genesis of the bounding faults can be visualized by two models; hinge faulting and collapse faulting. The dominant structural features of the study area began developing in early Pliocene. These features developed coincident with, and as the result of, a huge influx of paralic sediments associated with the progradation of the shelf edge across the study area between early Pliocene and early Pleistocene. The two major dip-oriented sand trends within this sediment wedge represent high constructive delta systems. The positions of the two systems were locally controlled by growing salt structures and sediments were therefore concentrated in the evolving depocenters . A hint of the deep structure which predated the influx of paralic sediments in Pliocene and early Pleistocene is revealed by a structural reversal present on seismic profiles at about 4.0 seconds in the northwest part of the study area. Reconstruction of the paleostructure of this area reveals the flank of an ancestral structural and stratigraphic basin. This basin may represent an ancestral depocenter which began developing very early on the abyssal plain. / text

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The submerged paleodrainage system of the early Balize delta complex that extended onto the inner continental shelf at 1500 YBP has not been completely studied in great detail. This study interprets the environmental deltaic facies of the Balize Delta, in the Sandy Point region offshore the southeastern Louisiana coast from 120 km of seismic data and 48 vibracores. The stratigraphic and environmental units established in this study provide a geological framework for this area. Overlying Holocene deposits interpreted to be muds of prodelta and lower delta front origin were interpreted as having been deposited from the retreating delta sit atop a transgressive surface, indicated by the toplapping seismic reflectors, the ravinement surface. The deltaic facies below the ravinement surface are of regressive origin an inner shelf delta with widespread delta front sheet sands from a dense group of many distributaries. This research provides a concise methodology adapted from multiple studies for modeling deltaic facies of offshore sand resource targets. / by Zachary Samuel Mester. / Thesis (M.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.