Variations in the styles of erosion along the Florida Escarpment, eastern Gulf of Mexico

Twichell, David C.; Parson, L. M.; Paull, C. K.

doi:10.1016/0264-8172(90)90003-y

Cited by 13 publications

(12 citation statements)

References 38 publications

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“…The three canyons have similar trends and morphologies to others surveyed farther north 8 . The EM120 multibeam sonar data exemplify the best available data that can be collected from the sea surface and have a resolution of approximately 100 m. These data show the broad features of three canyons that incise the Florida Escarpment at the study location.…”

Section: Discussionsupporting

confidence: 69%

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AUV and Multibeam Survey on the South Florida Escarpment

Sager

2007

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractFlorida Escarpment is the steep, rugged, western edge of the Florida carbonate platform. It is a poorly-surveyed but geologically complex feature. A small portion of the southern escarpment was surveyed as part of a project funded by the National Oceanic and Atmospheric Administration (NOAA) Office of Ocean Exploration to better understand the geology and habitats of the escarpment. The mapping was carried out by C&C Technologies, Inc., using a surface multibeam echosounder and an Autonomous Underwater Vehicle (AUV), whose instrumentation included a multibeam echosounder, side-scan sonar, and chirp subbottom profiler. Surface multibeam bathymetry data cover 734 km 2 and reveal three northeast-trending canyons incised into the southeast-trending escarpment, which is 750-1300 m in height. Multibeam backscatter data show strong returns from the canyon walls and from talus at the escarpment base. AUV data cover 66 km 2 at the escarpment base and on the platform, the escarpment wall being too steep for the AUV to survey. AUV data show vastly higher resolution with features <5 m in diameter visible in sonar backscatter images. These data indicate that the summit platform is mantled with sediment and contains numerous small mounds similar to carbonate bioherms imaged in other locations. The mounds are typically several tens of meters in diameter or less and can be up to tens of meters in height. Some are isolated, but many occur in clusters and mound fields. AUV data from the platform show a remnant ridge, blocky terrain, and headwall scarps at the platform edge adjacent to the canyons. At the escarpment base, side-scan sonar images show many rock outcrops protruding from sedimentary aprons. These outcrops have a large range in height and complexity, with some barely emergent. Many are linear and nearly perpendicular to the escarpment. Some appear to be piles of rock from masswasting of the escarpment face. On both the platform and at the escarpment base, AUV data show current scour or sediment sorting features trending northwest, indicative of strong currents from the southeast. Acoustic images suggest these currents are particularly strong and potentially erosive at the escarpment base.

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Section: Discussionsupporting

confidence: 69%

“…Outcropping platform interior sediments imply that erosion has cut into the platform edge by several kilometers [5][6] . South of approximately 27°N, the platform edge is incised by numerous canyons that appear to have an erosional origin, perhaps owing to corrosion by groundwater seeping out the platform edge [7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

AUV and Multibeam Survey on the South Florida Escarpment

Sager

2007

All Days

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“…Rather, they share their characteristics with canyons reported on the Florida Escarpment and New Jersey margin. Because of their similarity to subaerial box canyons, such canyons are thought to have been formed by groundwater seepage (Paull and Neumann, 1987;Dunne, 1990;Paull et al, 1990b;Robb, 1990;Twichell et al, 1990;Nagihara, 1996). According to this model, canyons are retrogressively eroded, both mechanically and chemically, into a seepage face.…”

Section: Hydrogeological Processesmentioning

confidence: 99%

“…Carbonate escarpments are submarine limestone and dolomite cliffs with relief in excess of 1 km; they can be up to 650 km long and have average slope gradients exceeding 40° (Schlager and Camber, 1986;Twichell et al, 1990). Their morphologies are complex and variable, comprising scarps, overhangs, vertical walls, terraces and wide canyons (e.g.…”

Section: Introduction 11 the Malta Escarpmentmentioning

confidence: 99%

Geomorphic evolution of the Malta Escarpment and implications for the Messinian evaporative drawdown in the eastern Mediterranean Sea

et al. 2019

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Carbonate escarpments are submarine limestone and dolomite cliffs that have been documented in numerous sites around the world. Their geomorphic evolution is poorly understood due to difficulties in assessing escarpment outcrops and the limited resolution achieved by geophysical techniques across their steep topographies. The geomorphic evolution of carbonate escarpments in the Mediterranean Sea has been influenced by the Messinian salinity crisis (MSC). During the MSC (5.97-5.33 Ma), the Mediterranean Sea became a saline basin due to a temporary restriction of the Atlantic-Mediterranean seaway, resulting in the deposition of more than one million cubic kilometres of salt. The extent and relative chronology of the evaporative drawdown phases associated to the MSC remain poorly constrained. In this paper we combine geophysical and sedimentological data from the central Mediterranean Sea to reconstruct the geomorphic evolution of the Malta Escarpment and infer the extent and timing of evaporative drawdown in the eastern Mediterranean Sea during the MSC. We propose that, during a MSC base-level fall, fluvial erosion formed a dense network of canyons across the Malta Escarpment whilst coastal erosion developed extensive palaeoshorelines and shore platforms. The drivers of geomorphic evolution of the Malta Escarpment after the MSC include: (i) canyon erosion by submarine gravity flows, with the most recent activity taking place <2600 cal. years BP;(ii) deposition by bottom currents across the entire depth range of the Malta Escarpment;(iii) tectonic deformation in the southern Malta Escarpment in association with a wrench zone; (iv) widespread, small-scale sedimentary slope failures preconditioned by oversteepening and loss of support due to canyon erosion, and triggered by earthquakes. 3We carry out an isostatic restoration of the palaeoshorelines and shore platforms on the northern Malta Escarpment to infer an evaporative drawdown of 1800 -2000 m in the eastern Mediterranean Sea during the MSC. We interpret the occurrence of pre-evaporite sedimentary lobes in the western Ionian Basin as suggesting that either evaporative drawdown and canyon formation predominantly occurred before salt deposition, or that only the latest salt deposition at the basin margin occurred after the formation of the sedimentary lobes.

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“…Seismic reflection profiles, dredging, and submersible observations reveal that the Florida Escarpment is associated with a carbonate platform that developed in the Early Cretaceous and continued to grow as the adjacent basin subsided [Antoine et al, 1967;Mitchum, 1978;Corso et al, 1989;Paull et al, 1990;Snedden et al, 2012]. The escarpment later retreated 5-10 km landward in response to erosion [Mitchum, 1978;Freeman-Lynde, 1983;Mullins et al, 1986;Corso et al, 1989;Paull et al, 1990;Twichell et al, 1990], perhaps linked to changes in paleocirculation in the middle to upper Miocene [Snedden et al, 2012]. Average slope along the Florida Escarpment is 40° [Twichell et al, 1991].…”

Section: Eastern Gulf Of Mexico: Florida Marginmentioning

confidence: 99%

Deep crustal structure in the eastern Gulf of Mexico

et al. 2014

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We use air gun data recorded by ocean bottom seismometers to constrain the velocity structure along Gulf of Mexico Basin Opening Line 4, a profile extending from the northwestern Florida peninsula across the Florida Escarpment to the central Gulf of Mexico. Moderately thinned continental crust with a Moho depth of 32-33 km, average sediment thickness of 6 km, and an average crustal thickness of 27 km is interpreted on the northeast end of the profile offshore Florida. Thinned and intruded continental crust is identified over a horizontal distance of 225 km where the crustal layer thins from 25 km to 6-7 km; mean seismic velocities of the crust in this region increase from 6.55 km/s to 6.95 km/s from northeast to southwest and are evidence for increased magmatic input as rifting developed. Oceanic crust with an average thickness of 5.6-5.7 km is observed over a distance of 175 km on the southwest end of the profile, with an extinct spreading ridge with an axial valley morphology imaged on a coincident seismic reflection profile. Anomalously high upper oceanic crust velocities of 6.0-6.7 km/s are interpreted as massive basalt flows and could reflect increased temperatures during emplacement. Integrating well, seismic reflection and our seismic refraction data allow us to estimate a full-spreading rate of 2.2 cm/yr for seafloor spreading along the profile; this indicates that oceanic crust was emplaced at a slow-spreading center.

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Variations in the styles of erosion along the Florida Escarpment, eastern Gulf of Mexico

Cited by 13 publications

References 38 publications

AUV and Multibeam Survey on the South Florida Escarpment

AUV and Multibeam Survey on the South Florida Escarpment

Geomorphic evolution of the Malta Escarpment and implications for the Messinian evaporative drawdown in the eastern Mediterranean Sea

Deep crustal structure in the eastern Gulf of Mexico

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