Plio-Pleistocene Depositional Sequences of the Southwestern Louisiana Continental Shelf and Slope: Geologic Framework, Sedimentary Facies and Hydrocarbon Distribution

dc.creatorMorton, Robert A.
dc.creatorAyers, Jr., W. B.
dc.date.accessioned2024-04-02T17:51:35Z
dc.date.available2024-04-02T17:51:35Z
dc.date.issued1990
dc.description.abstractThe Plio-Pleistocene hydrocarbon fairway of offshore Louisiana is restricted to the outer continental shelf and upper continental slope where a thick wedge of nearshore and deep marine sediments was deposited. Electric logs, paleontological reports, and seismic profiles form the basis for (1) dividing the wedge of Plio-Pleistocene strata into eight genetic sequences, (2) establishing the structural framework, (3) determining the timing of deformation, and (4) mapping the principal depositional systems of the West Cameron and western Garden Banks areas during the past five million years. Sedimentary facies and structural styles in this part of the basin are highly variable owing to contemporaneous sea-level fluctuations, salt migration, and shifting sites of deltaic, shelf, and slope sedimentation. The resulting complex geologic history of this part of the basin directly controlled the generation, migration, and entrapment of hydrocarbons. The early Pliocene was a period of continental platform inundation and deposition of a thick succession of marine mudstones. About 3 Ma, this monotonous accumulation of deep-water mudstone was interrupted by deposition of sand-rich submarine channels and fans associated with a lowering of sea level. These lowstand deposits extended at least 55 mi (90 km) basinward of the paleomargin. Overlying Pleistocene sediments were deposited mainly by prograding mud-rich fluvial-deltaic systems of moderate size. These rivers and shelf-edge deltas constructed a broad continental platform that buried the submarine fans and prograded the shelf margin approximately 70 mi (110 km) basinward. During this rapid outbuilding, slumping and other gravity-driven mass transport processes removed sand-rich delta-front sediments from unstable shelf margins and redeposited them on the continental slope.
dc.description.departmentBureau of Economic Geology
dc.identifier.urihttps://hdl.handle.net/2152/124591
dc.identifier.urihttps://doi.org/10.26153/tsw/51196
dc.relation.ispartofContract Reports
dc.rights.restrictionOpen
dc.subjectstratigraphy
dc.subjectdepositional systems
dc.subjectPlio-Pleistocene
dc.subjectLouisiana
dc.subjectcontinental shelf
dc.subjectcontinental slope
dc.subjectpetroleum
dc.titlePlio-Pleistocene Depositional Sequences of the Southwestern Louisiana Continental Shelf and Slope: Geologic Framework, Sedimentary Facies and Hydrocarbon Distribution
dc.typeOther

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