Distribution, ecology and paleoenvironments of Benthic foraminifera - A case study off Manora, Palk Strait, Tamil Nadu

Abstract

A total of 21 benthic foraminiferal species and varieties belonging to 12 genera, 9 families, 6 <b>superfamilies</b>, and 3 suborder have been identified. From the total number of species, <em>Ammonia beccarri</em>, <em>A.tepida,</em> <em>P.calcar</em><em>,</em> <em> P. nipponica</em> shows a higher abundance in this region. The following species are found only in few core samples, namely <em>Elphidium incertum</em>, <em>Spiroloculina communis</em>, <em>Spiroloculina orbis </em> and <em> T. agglutinans,</em>. Size of the foraminifera in this region is very small. It may due to the finer nature of sediments and high rate of sedimentation in this region observed by earlier workers. The OM values ranges from 0.54 to 1.37 %. CaCO₃ value ranges from 1 to 6%. Based on the sand-silt-clay ratio, the study area was predominated with silty sand and sand in majority of the region. From the coastal geomorphological studies it is observed that, the distribution of landforms between near Manora displays a paleo micro deltaic characteristic the beach ridges have width of 200m around Manora. The sediments of beach ridges lie directly above the mudflats suggesting that the beach ridges were deposited later to the formation of mudflats i.e. mudflats are older to beach ridges.