The Sicilian gateway: anatomy of the deep-water connection between East and West Mediterranean basins
Published:January 01, 2002
Michael S. Reeder, Guy Rothwell, Dorrik A. V. Stow, 2002. "The Sicilian gateway: anatomy of the deep-water connection between East and West Mediterranean basins", Deep-Water Contourite Systems: Modern Drifts and Ancient Series, Seismic and Sedimentary Characteristics, D. A. V. Stow, C. J. Pudsey, J. A. Howe, J.-C. Faugères, A. R. Viana
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The Sicilian gateway is a narrow, deep, interconnected series of basins, sill valleys and passageways that cuts across the broad, shallow Sicilian–Tunisian Platform in the Central Mediterranean. This deep connection allows dense Levantine Intermediate Water (LIW) formed in the Eastern Mediterranean to flow in a westerly direction through the gateway and exit into the Tyrrhenian and Balearic basins of the Western Mediterranean. LIW is replaced by a strong surface flow of Modified Atlantic Water (MAW). A complex and still active tectonic regime has been an important control on the development of physiography and on the style and distribution of sediments across the Platform.
Within the deep gateway basins, turbidites, debrites and megabeds are intercalated with a background of predominantly muddy and calcareous, hemipelagic and contourite sediments. Evidence for the influence of bottom currents on sedimentation is seen in the construction of small mounded drifts and irregular patch drifts, in zones of scouring and non-deposition, in local photographic evidence of a current-smoothed or rippled seafloor, and as a subtle combination of features present in the background sediments. These include: extensively reworked microfossil assemblages, rare diffuse lamination, coarse lenses of mixed composition within a pervasively bioturbated sediment, and relatively high rates of accumulation.
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Deep-Water Contourite Systems: Modern Drifts and Ancient Series, Seismic and Sedimentary Characteristics
Countourites are a widespread but poorly known group of sediments linked to the action of powerful bottom currents in deep water. Although we know they are especially common along continental margins and through oceanic gateways, they have been surrounded by contoversy since they were first recognized in the early 1960s. Where correctly recognized and decoded they can provide one of the keys to our better understanding of bottom water circulation and of the ocean–climate link. They are part of the spectrum of deposits that confronts the oil industry as exploration moves into progressively greater water depths.
This memoir is an important outcome of the International Geological Correlation Project 432 on Bottom Currents, Contourites and Palaeocirculation. It includes 30 papers involving over 75 key scientists from around the world. Following an introductory state–of–the–art paper by the editors, there are 25 separate case studies on modern drifts and four on ancient contourite series. Each contribution highlights the specific geological and oceanographic setting, bathymetry, physiographic and stratigraphic context, seismic attributes and sedimentary characteristics of that drift. Case studies range from some of the well-documented North Atlantic drifts to those much less known from the Mediterrenean, from important syntheses of the Gulf of Cadiz and Vema Channel Gateway, to completely new data on South Atlantic, Pacific and Antartic margin systems. The four papers on ancient series from Japan, China and Cyprus serve to emphasise the complex nature and subtle characteristics of contourites, which make their identification a scientific challenge.
This volume is dedicated to the memory of Charlie Hollister (1936–1999), one of the founding fathers and pioneers of countourite research.