Quaternary slope development of the western, leeward margin of the Great Bahama Bank

Author(s): Rendle, R. H.; Reijmer, J. J. G.
Author Affiliation(s): Primary:
GEOMAR, Forschungszentrum für Marine Geowissenschaften, Kiel, Federal Republic of Germany
Volume Title: Carbonate margin development (Bahama Transect, ODP Leg 166)
Volume Author(s): Reijmer, John J. G., editor
Source: Marine Geology, 185(1-2), p.143-164; Paleoceanology of reefs and carbonate platforms; Miocene to modern meeting (PRCP'99), Aix-en-Provence, France, Sept. 27-30, 1999, edited by John J. G. Reijmer. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0025-3227 CODEN: MAGEA6
Note: In English. 99 refs.; illus., incl. 2 tables, sketch map
Summary: To date, work on the Great Bahama Bank's western, leeward margin has centred chiefly on seismic-scale expressions of carbonate sequences and systems tracts. However, periplatform, slope sediments also exhibit very well developed cyclicity on scales of decimetres to several metres. It is these small-scale, high-frequency cycles within the larger-scale facies successions of the Quaternary which form the main topic of this paper. Previous studies have shown that the small-scale cycles correlate to the orbitally forced, high-frequency sea-level changes. Therefore these cycles should indicate how sea level has affected the slope development and thus platform-margin evolution during this period. Through detailed, high-resolution sequence stratigraphy of the Great Bahama Bank"s leeward margin, obtained via δ18O isotope and mineralogical (XRD) analyses, confined by U/Th dating and nannofossil bioevents, a greater understanding of the bedding geometries within the Pleistocene-Holocene seismic sequences and clues as to the nature of the slope development has been achieved. The high-resolution seismic profiles indicate that since the Plio-Pleistocene change in geometry, in which the Great Bahama Bank developed into a rimmed platform, continued steepening and subsequent progradation of the leeward margin has typified slope development during the Quaternary, which is described as an accretionary slope. However, on the basis of our observations we conclude that only the early to lower middle Pleistocene section (isotope stages 45-20) and the Holocene (isotope stage 1) of the leeward margin is accretionary. This indicates that a degree of erosion and/or by-passing has occurred on the leeward margin since the lower middle Pleistocene (isotope stage 19). During the first part of this period (isotope stages 19-12) erosion and/or by-passing occurred in the middle to lower slope regions and toe-of-slope. By the end of the upper middle to late Pleistocene phase (isotope stages 11-2) erosion also occurred on the upper slope. This erosion by currents at the toe-of-slope and oversteepening of the upper and middle slopes have led to back-cutting upslope and resulted in the progressive retreat of the toe-of-slope towards the platform to the east. However, the rise in sea level since the Last Glacial Maximum to its present-day level has allowed high productivity on the platform top during the Holocene and the deposition of a thick sediment wedge on the slope and sedimentation across the entire leeward flanks. This has led to the redevelopment of an accretionary slope and continued westward progradation of the Great Bahama Bank's western, leeward margin. Abstract Copyright (2002) Elsevier, B.V.
Year of Publication: 2002
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Accretionary wedges; Algae; Atlantic Ocean; Bahamas; Bahamas Drilling Project; Bahamas Transect; Carbonate platforms; Carbonate sediments; Caribbean region; Cenozoic; Continental margin; Continental slope; Depositional environment; Erosion; Geotraverses; Great Bahama Bank; Leg 166; Marine sedimentation; Marine sediments; Microfossils; Nannofossils; North Atlantic; Northwest Atlantic; ODP Site 1003; ODP Site 1005; ODP Site 1006; ODP Site 1007; Ocean Drilling Program; Paleogeography; Plantae; Pleistocene; Quaternary; Sea-level changes; Sedimentation; Sediments; Unconformities; West Indies
Coordinates: N242359 N242359 W0792733 W0792733
Record ID: 2002055819
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands