12/16/2023 0 Comments Continental shelf gulf of mexico![]() ![]() The multibeam bathymetry and acoustic backscatter data are available on this Open-File Report in two formats ASCII XYZ and ArcInfo GRID. Report RV Ocean Surveyor Cruise O-1-00-GM, The Bathymetry andĪcoustic Backscatter of the Pinnacles Area, Northern Gulf of Outer continental shelf off Mississippi and Alabama. Quaternary-Holocene processes of northeastern Gulf of Mexico Sulak, BrianĬalder, and Laurent Hellequin. Gardner, James V., Peter Dartnell, Kenneth J. Ludwig, J.C and Walton, W.R., 1957, Shelf-edge calcareousīrominences in northeastern Gulf of Mexico. This Open-File Report publishes the multibeam bathymetry and acoustic backscatter data, along with images and a GIS of the data. These data should prove extremely useful in relating dominant species groups (which display highly specific biotope affinities) to the geomorphology ( e.g., reef flattop, forereef crest, reef wall, reef base,Ĭircum-reef talus zone, circum-reef, high-reflectivity sedimentįor more information, see the West Florida Shelf Multibeam Cruise Report, or visit our Pacific Seafloor Mapping website. The signal can give an indication of the type of material exposed on the ocean floor (i.e. Acoustic backscatter is the intensity of an acoustic pulse that is backscattered off the seafloor back to the transducer. The EM1002 produces both geodetically accurate georeferenced bathymetry and coregistered, calibrated, acoustic backscatter. The cruise used a Kongsberg Simrad EM1002 MBES, the latest generation of high-resolution mapping systems. Our objective was to map the region between the 50 to 150-m isobaths south from the eastern edge of De Soto Canyon as far as Steamboat Lumps using a state-of-the-art multibeam mapping system (MBES)(red polygons labeled 2001 on Figure 1). Thus, one of the principle uses of the morphology data will be to identify whether any reefs found are hermatypic or ahermatypic in origin. ![]() Instead, exogenous plankton, transported to the reef by currents, serves as the primary carbon source. The ecology of deep-water ahermatypic reefs is fundamentally different from hermatypic reefs because autochthonous intracellular symbiotic zooxanthellae (the carbon source for hermatypic corals) do not form the base of the trophic web in ahermatypic reefs. Fish faunas of shallow hermatypic reefs have been well studied, but those of deep ahermatypic reefs have been relatively ignored. Morphology is thought to be critical to defining the distribution of dominant demersal plankton/planktivores communities. Georeferenced high-resolution mapping of bathymetry is a fundamental first step in the study of areas suspected to be critical habitats. Location map showing northwest Florida shelf area mapped in 2001 (red rectangles) and area mapped in 2000 on Mississippi-Alabama shelf and slope (green rectangle). A comparison of the heavy mineral suites of the modern and relict Rio Grande delta sediments, which are derived from a common provenance, also shows mineral variations resulting from factors other than provenance.Figure 1. The differential effects of these processes on the sediments have resulted in local variations that contribute to the total mineralogical variability. These factors have operated at varying degrees on the relict, palimpsest, and modern sediment populations of the sedimentary provinces since the end of Pleistocene time. Analysis of variance, correlation, and regression methods indicate that heavy-mineral variations in each sedimentary province have been significantly influenced by hydraulic fractionation by size, shape, and density, and by a selective chemical decomposition of unstable minerals. An interdelta region contains a heavy mineral suite that is mixed owing to contributions from both ancestral deltas. The southern ancestral Rio Grande delta sediments contain a distinct opaque-pyroxene-garnet suite, whereas the northern ancestral Brazes-Colorado delta sediments contain a tourmaline-green hornblende suite. Q-mode factor analysis showed that three suites of heavy minerals are present. Heavy-mineral distribution on the outer continental shelf off the southern coast of Texas shows regional variability induced by provenance and local variability reflecting genetic differences in sea-floor sediments. ![]()
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