Kindinger, J.L. and
Morton, R.A. .
1999.
Evolution and Holocene stratigraphy of estuarine systems; a conceptual model for the northern Gulf of Mexico..
Annual Meeting Expanded Abstracts - American Association of Petroleum Geologists 1999: A72.
In recent years, many geological studies have been conducted along the coastal embayments and nearshore areas of the Gulf of Mexico, including Tampa Bay, Mobile Bay, Lake Pontchartrain, Calcasieu Lake, Sabine Lake, Nueces Bay, and Corpus Christi Bay. Processes driven by sea-level change during the late Wisconsinan regression and subsequent Holocene transgression have formed the bays and estuaries of the Gulf of Mexico. Erosion by fluvial systems during the late Wisconsinan lowstand cut valleys across the continental shelf. The rapid Holocene transgression forced coastal-plain shorelines landward. As sea-level rise slowed, the incised valleys became estuarine depocenters. Estuarine sediments deposited in the alluvial valley during the initial flooding of the valleys overlie lowstand fluvial and interfluvial deposits. During the present highstand, wave reworking and longshore sediment transport formed shoals or barrier islands across the estuary mouths creating restricted estuaries into which bayhead deltas have prograded. Late Holocene deposition in the estuaries has been dominantly lagoonal sediments. A conceptual model incorporating these erosional and depositional processes with sea-level change has been developed. The model effectively describes the evolutionary succession from incised valley to estuary, exclusive of fluvial source or sediment supply.
Morton, R.A. and
Suter, J.R. .
1999.
Sequence stratigraphy and composition of late Quaternary shelf-margin deltas, northern Gulf of Mexico..
Marine Georesources & Geotechnology 17: 2-3.
High-resolution seismic profiles and foundation borings from the northwestern Gulf of Mexico record the physical attributes and depositional histories of several late Quaternary sequences that were deposited by wave-modified, river-dominated shelf-margin deltas during successive periods of lowered sea level. Each progressively younger deltaic sequence is thinner and exhibits a systematic decrease in the abundance and concentration of sand, which is attributed to a shift in the axis of trunk streams and greater structural influence through time. Our study shows that (1) contemporaneous structural deformation controlled the thickness of each sequence, the oblique directions of delta progradation, the axes of major fluvial channels, and the geometries of delta lobes at the shelf margin, (2) sedimentation was rapid in response to rapid eustatic fluctuations and structural influence, (3) boundaries of these high-frequency sequences are the correlative conformities of updip fluvial incision, and coincide with downlap surfaces at the shelf margin, (4) the downlap surfaces are not true surfaces, but zones of parallel reflections that become progressively higher and younger in the direction of progradation, (5) the downlap zones are composed of marine muds that do not contain high concentrations of shell debris that would be expected in condensed sections, (6) possible paleosols capping the two oldest sequences are regressive surfaces of subaerial exposure that were preserved during transgressions, and (7) no incised valleys or submarine canyons breach the paleoshelf margin, even though incised drainages were present updip and sea-level curves indicate several periods of rapid fall.