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From the Great Bahama Bank into the Straits of Florida; a margin architecture controlled by sea-level fluctuations and ocean currents

Flavio S. Anselmetti, Gregor P. Eberli and Zan-Dong Ding
From the Great Bahama Bank into the Straits of Florida; a margin architecture controlled by sea-level fluctuations and ocean currents
Geological Society of America Bulletin (June 2000) 112 (6): 829-844


High-resolution, multichannel seismic data collected across the Great Bahama Bank margin and the adjacent Straits of Florida indicate that the deposition of Neogene-Quaternary strata in this transect are controlled by two sedimentation mechanisms: (1) west-dipping layers of the platform margin, which are a product of sea-level-controlled, platform-derived downslope sedimentation; and (2) east- or north-dipping drift deposits in the basinal areas, which are deposited by ocean currents. These two sediment systems are active simultaneously and interfinger at the toe-of-slope. The prograding system consists of sigmoidal clinoforms that advanced the margin some 25 km into the Straits of Florida. The foresets of the clinoforms are approximately 600 m high with variable slope angles that steepen significantly in the Pleistocene section. The seismic facies of the prograding clinoforms on the slope is characterized by dominant, partly chaotic, cut-and-fill geometries caused by submarine canyons that are oriented downslope. In the basin axis, seismic geometries and facies document deposition from and by currents. Most impressive is an 800-m-thick drift deposit at the confluence of the Santaren Channel and the Straits of Florida. This "Santaren Drift" is slightly asymmetric, thinning to the north. The drift displays a highly coherent seismic facies characterized by a continuous succession of reflections, indicating very regular sedimentation. Leg 166 of the Ocean Drilling Program (ODP) drilled a transect of five deep holes between 2 and 30 km from the modern platform margin and retrieved the sediments from both the slope and basin systems. The Neogene slope sediments consist of peri-platform oozes intercalated with turbidites, whereas the basinal drift deposits consist of more homogeneous, fine-grained carbonates that were deposited without major hiatuses by the Florida Current starting at approximately 12.4 Ma. Sea-level fluctuations, which controlled the carbonate production on Great Bahama Bank by repeated exposure of the platform top, controlled lithologic alternations and hiatuses in sedimentation across the transect. Both sedimentary systems are contained in 17 seismic sequences that were identified in the Neogene-Quaternary section. Seismic sequence boundaries were identified based on geometric unconformities beneath the Great Bahama Bank. All the sequence boundaries could be traced across the entire transect into the Straits of Florida. Biostratigraphic age determinations of seismic reflections indicate that the seismic reflections of sequence boundaries have chronostratigraphic significance across both depositional environments.

ISSN: 0016-7606
EISSN: 1943-2674
Serial Title: Geological Society of America Bulletin
Serial Volume: 112
Serial Issue: 6
Title: From the Great Bahama Bank into the Straits of Florida; a margin architecture controlled by sea-level fluctuations and ocean currents
Affiliation: Rosenstiel School of Marine and Atmospheric Science, Comparative Sedimentology Laboratory, Miami, FL, United States
Pages: 829-844
Published: 200006
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Accession Number: 2000-040850
Categories: Oceanography
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
N23°30'00" - N24°34'60", W79°28'00" - W79°02'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200014
Program Name: ODPOcean Drilling Program
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