Ripple Marks Show That Countercurrent Exists in Florida Straits

Hurley, Robert J.; Fink, L. Kenneth

doi:10.1126/science.139.3555.603

Cited by 20 publications

(6 citation statements)

References 2 publications

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“…Thus, the overall southward flow is a counter current rather than a reversing tidal oscillation. These data corroborate previous findings of a regional deep counter current at the base of the Miami Terrace (Hurley and Fink, 1963;Neumann and Ball, 1970;Duing and Johnson, 1971). …”

Section: Southward Bottom Current Throughout the Surveyed Areasupporting

confidence: 94%

“…At the Miami Terrace topographic constriction (~25.5°N), the Florida Current assumes its ultimate meridional orientation. There, the Florida Current reaches speeds of 2 m s −1 at the surface, but is opposed by a southward bottom counter current that reaches velocities of up to 0.50 m s −1 (Hurley and Fink, 1963;Neumann and Ball, 1970;Duing and Johnson, 1971;Wang and Mooers, 1997). This counter current is recognized as a permanent feature, but its horizontal and vertical structure remains poorly resolved.…”

Section: Study Site: the Lower Miami Terracementioning

confidence: 94%

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Genesis and morphology of cold-water coral ridges in a unidirectional current regime

et al. 2012

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Section: Southward Bottom Current Throughout the Surveyed Areasupporting

confidence: 94%

Section: Study Site: the Lower Miami Terracementioning

confidence: 94%

Genesis and morphology of cold-water coral ridges in a unidirectional current regime

et al. 2012

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“…This indication of southward flow was consistent with Hurley (1963), Neumann (1970), Diiing and Johnson (1971).…”

Section: Features Of the Florida Currentsupporting

confidence: 87%

The baroclinic structure of the Florida current

Stubb¹

1971

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“…This strong surface current has a peak average velocity at of 170 cm sec −1 at −32 m water depth and decreases to 100 cm sec −1 at −270 m at 26˚N, and exhibits a large variability across the Upper Miami Terrace where velocities range from 50 to 10 cm sec −1 (Beal et al ., ). Yet, a southward undercurrent across the lower Miami Terrace and its seaward slope at depths of 500 to 800 m flows with a velocity of up to 50 cm sec −1 and produces a moat, separating the northern branch of the Pourtalès Drift from the Terrace (Hurley & Fink, ; Neumann & Ball, ; Correa et al ., 2012a). Here, similar to other places, shallow and deep currents, although decoupled and with opposite flow directions, shape the contourite drift system.…”

Section: Overview Of Currentsmentioning

confidence: 99%

Characteristics of modern carbonate contourite drifts

Eberli

Betzler

2019

Sedimentology

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Carbonate environments inhabit the realm of the surface, intermediate and deep currents of the ocean circulation where they produce and continuously deliver material which is potentially deposited into contourite drifts. In the tropical realm, fine-grained particles produced in shallow water and transported off-bank by tidal, wind-driven, and cascading density currents are a major source for transport and deposition by currents. Sediment production is especially high during interglacial times when sea level is high and is greatly reduced during glacial times of sea-level lowstands. Reduced sedimentation on carbonate contourite drifts leads to early marine cementation and hardened surfaces, which are often reworked when current strength increases. As a result, reworked lithoclasts are a common component in carbonate drifts. In areas of temperate and cool water carbonates, currents are able to flow across carbonate producing areas and incorporate sediment directly to the current. The entrained skeletal carbonate particles have variable bulk density and shapes that lower the prediction of transport rates in energy-based transport models, as well as prediction of current velocity based on grain size. All types of contourite drifts known in clastic environments are found in carbonate environments, but three additional drift types occur in carbonates because of local sources and current flow diversion in the complicated topography inherent to carbonate systems. The periplatform drift is a carbonate-specific plastered drift that is nearly exclusively made of periplatform ooze. Its geometry is built by the interaction of along-slope currents and downslope currents, which deliver sediment from the adjacent shallow-water carbonate realm to the contour current via a line source. Because the periplatform drift is plastered on the slopes of the platforms it is also subject to mass gravity flow and large slope failures. At platform edges, a special type of patch drift develops. These hemiconal platformedge drifts also contain exclusively periplatform ooze but their geometry is controlled by the current around the corner of the platform. At the north-western end of Little and Great Bahama Bank are platform-edge drifts that are over 100 km long and up to 600 m thick. A special type of channel-related drift forms when passages between carbonate buildups or channels within a platform open into deeper water. A current flowing in these channels will entrain material shed from the sediment producing areas. At the channel mouth, the sediment-charged current deposits its sediment load into the deeper basin. With continuous flow, a submarine delta drift is built that progrades into the deep water. The strongly focused current forming the delta drift, is able to rework coarse skeletal grains and clasts, making this type of carbonate drift the coarsest drift type.

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Ripple Marks Show That Countercurrent Exists in Florida Straits

Cited by 20 publications

References 2 publications

Genesis and morphology of cold-water coral ridges in a unidirectional current regime

Genesis and morphology of cold-water coral ridges in a unidirectional current regime

The baroclinic structure of the Florida current

Characteristics of modern carbonate contourite drifts

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