Section 6
Chapter 5,181

Distribution of siliceous micro fossils in surficial bottom sediments of the gulf of mexico

Jendrzejewski, J.P.; Hart, G.F.

Palynology 2: 159-166


ISSN/ISBN: 0191-6122
Accession: 005180308

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The major groups of siliceous microfossils found in oceanic surficial bottom sediments of the Gulf of Mexico include: diatoms, radiolaria, sponge spicules and phytoliths. Silicoflagellates, pyrrophytic endoskeletons (Actiniscus), resting spores of diatoms and fresh-water Chrysophyte cysts are present as minor components in the sediments. Throughout most of the Gulf the siliceous forms are subordinate in abundance to calcareous forms (coccolithophytes and foraminifera). Diatoms, radiolaria and sponge spicules display high relative frequencies in the southeastern Gulf, especially off the West Florida and Campeche carbonate platforms. Three groups show low relative frequencies in the northwestern part of the basin and have a patchy distribution in areas of the eastern Gulf on a line from the mouth of the Mississippi River southeastward toward Cuba. This pattern reflects water mass productivity, terrigenous input and silica dissolution in the Gulf. Phytoliths display higher relative frequencies in the western Gulf than in the eastern Gulf reflecting the predominance of terrigenous sedimentation in that part of the basin. Analysis of the displaced (i.e., freshwater, marine benthonic) diatom species depicts the effects of the Mississippi Rio Grande and Mexican rivers into the deep Gulf of Mexico. The silicoflagellates and Actiniscus are present in low relative frequency on the West Florida and Campeche Slopes and are essentially absent from other areas of the Gulf. The distribution patterns of the siliceous microfossils in surficial botton sediments of the Gulf of Mexico provide information concerning plankton productivity, silica dissolution and terrigenous sedimentation in this area.

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