Foraminifera as climatic indicators in the sediments of Western Indian continental shelf

M.G.A.P. Setty

Abstract



Foraminifera are the single celled microscopic organisms found abundantly in the seas and oceans. The tests of these organisms are preserved in the present sediments of the ocean as in the past, sometimes constituting extensive deposits as oozes; however they form one of the major constituents of almost all types of sediments. They are not only considered to be the major source of oil and gas but some of the species are also considered as delineators or markers of oil bearing horizons and geological time factors. Thus, they are indicative of various parameters like the environmental conditions of deposition, latitudinal zonation, type of the geosynclinal structural, distance from the shore, rate of sedimentation etc. In fact, they have a story to tell, which can be unravelled by careful analysis and interpretation. Foraminifera are primarily of two kinds-planktonic and benthonic-each having a significant role to play. Therefore, in the study of a sample, the planktonic and benthonic populations should be considered separately. It is so suggested because these two assemblages represent different habitats and environmental conditions. Planktonic foraminifera are distinctly a few in number compared to several thousand benthonic species present. These are about 50 in all but the most characteristic ones are about 30-35 only, however, there are only 8-10 living genera, most of the species of which occur in an extreme abundance of individuals. Individual species are widely distributed by ocean currents and occur, in marine water masses at different depths; thus they are not only pelagic but occur survive, propagate and characterise the distinct parameters of depth distribution, water density, salinity variation, oceanic circulation, temperature gradient or a vertical thermal structure and latitudinal zonation of the seas and the oceans

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