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A total of 24 surface sediment samples were collected from Puravadaiyanar and Vettar estuary. In the Puravadaiyanar estuary, 47 foraminifera and in Vettar estuary, 26 benthic foraminiferal species have been identified. The species, Ammonia beccarii, A. tepida, A. dentata, Nonionoides elongatum, Elphidium advenum, E. discoidale, Cribrononion simplex, Trochammina inflata,and Quinqueloculina seminulumshows a prolific abundance in both region. Puravadaiyanar estuary records comparatively high value of organic matter in most of the stations. The contamination factor of the trace elements of sediment sample from the Puravadaiyanar estuary is Co>Pb>Cu>Zn>Ni>Fe>Mn>Cr and in Vettar estuary Co>Pb>Cu>Zn>Ni>Fe>Mn>Cr. Factor analysis clearly reveals that fine particles and organic matter control the distribution metals in the sediments and organic matter act as a metal carrier in this region. These studies indicate geogenic origin of most of the elements. The impact of heavy metal pollution on benthic foraminifera was very less in the study area.

The present study aims to understand the distribution of benthic foraminifera in surface sediments collected from Kottaipattinam to Kodiyakarai, Palk Strait southeast coast of India. The analysis reveals the presence of 79 species belonging to 42 genera, 24 families, 12 super-families, 19 sub-families, 5 sub-orders and, 5 orders have been reported and illustrated. Out of the total population count of 11,719 specimens, 705 were observed to be Rose Bengal-stained, and are considered to be living at the time of sample collection. Environmental parameters such as water depth, pH, bottom water temperature, dissolved oxygen, salinity, CaCO3, organic matter, sand, silt, and clay contents were determined to adopt standard methodology. Ammonia beccarii (Linnaeus) is the most abundant counterpart in the study area; followed by Asterorotalia trispinosa (Thalmann) and Ammonia tepida (Cushman). Besides that, Spiroloculina corrugata, Spiroloculina angulata, Quinqueloculina bicostata, Quinqueloculina echinata, Pyrgo depressa, Pyrgo laevis, Pseudotriloculina rotunda, Parrina brady, Cancris oblonga, Elphidium hispidulum, Elphidium norvangi, these species were not previously observed in this study site. The textural analysis reveals that the sediments are chiefly composed of sand with less clay and silt. The organic matter content shows a high loading factor in the study site followed by CaCO3. Further, the statistical analysis shows organic matter is major controlling factors in the study site and benthic foraminiferal assemblages are definitely bound to be influenced by the high volume of freshwater influx in the study site.

Pumice clasts, partially and fully coated with ferro-manganese oxide from the Central Indian Ocean Basin (CIOB) were analysed for major, trace and rare earth elements; and glass and mineral grain chemistry to assess their possible source. These pumice clasts have ∼95% glassy matrix with ∼5% of plagioclase, ortho-pyroxene, amphibole, and spinel mineral grains. Pumice is rhyolitic, with high content of silica and total alkalis and show strong light rare earth element enrichment, with La ∼100 times enriched compared to chondritic abundance and exhibits a pronounced negative Eu-anomaly. Both the partially and fully coated pumice clasts have a similar composition, but this, and their, glass and mineral (orthopyroxene) chemistry differs from all tuffs known to have erupted from the Toba Caldera Complex. The partial to complete Fe–Mn oxide coating suggests the pumice probably predates activity from the Toba caldera. Their general composition is consistent with a volcanic arc origin, and show similarities to rhyolitic eruptives from Sumatra. The distribution of partially and fully coated pumice in the CIOB overlaps with that of uncoated pumice from the voluminous YTT eruption, suggesting that other large rhyolitic calderas active in Sumatra/Indonesia. Similarities in composition to ash layers from the CIOB suggest a possible Late Miocene – Late Pleistocene age for these pumices.

The present study encompasses a detailed investigation of downcore Holocene foraminifera and their assemblages to comprehend the ecology of the Bay of Bengal and compare it with that of the South China and Sulu Seas, at the same depth for all the three water bodies. Based on temperature and dissolved oxygen profiles, benthic foraminiferal abundance, and species diversity values, it is inferred that the Bay of Bengal is much better ventilated than either the South China or the Sulu Sea. The planktic/benthic (P/B) ratios are extremely low when compared with those reported elsewhere in the world. The absolute dominance of benthic foraminiferal species over their planktic counterparts is attributed to the effect of fragmentation and dissolution of the latter, as they are relatively more susceptible to this process. The very low P/B values are also indicative of water depth below the lysocline in this part of the Bay of Bengal.

Foraminifera have been successful inhabitants of every aquatic environment from deep oceans to brackish water lagoons, estuaries and even rarely in freshwater streams, lakes, etc. In order to know their distribution in different offshore habitats, the present study has been undertaken between Tuticorin and Tiruchendur, wherein 31 bottom sediment and water samples were collected. Benthic foraminiferal taxa belonging to four suborders (Textulariina, Miliolina, Lagenina and Rotaliina), 14 superfamilies, 25 families, 45 genera and 66 species have been identified; three planktonic species (suborder Globigerinina) have also been identified. An increase in total foraminiferal distribution with depth has been observed, except off Tiruchendur. Living/dead ratios range from 1.57% to 10.02%, indicating a low to moderate rate of sedimentation in this region. Off Punnaikayal and Tiruchendur, the rate of sedimentation is more at greater depths; at other stations, however, it is higher at relatively shallower depths. Based on this study, it is concluded that fluctuations in the distribution of foraminifera are mainly controlled by coastal morphology, wave dynamics, bathymetry and environmental parameters.

The 2004 Indian Ocean tsunami left significant sand deposits along the coastal tract of southeast India (Tamil Nadu state). These deposits serve as a benchmark to understand the effects of present day tsunami on the coastline. Additionally, the geological signatures of tsunami in the coastal stratigraphy can assist in providing modern analogs for identification and interpretation of ancient tsunami. This article presents the field observations of tsunami deposits, their internal stratigraphy and foraminiferal distribution, all of which varied from north to south depending upon coastal geomorphology, near shore bathymetry and sediment sources. In a few places, the tsunami deposits have been reworked due to subsequent events that caused modification in the internal stratigraphy. The tsunami deposits of the northern Tamil Nadu coast comprise at least 50% or more reworked foraminiferal specimens, indicating that the tsunami sediments may have been derived from a paleostrandline from a water depth of at least 45 m

This study deals with the geochemical nature of distribution, enrichment of total trace metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) in bulk sediments and its association with sediment texture, carbonates and organic carbon. Sixty surface sediment samples were collected during two different seasons in 2002 and 2003 along the coastal regions in three transects from Nagapattinam town, north of Point Calimere in southeast coast of India. The sediments are mostly sandy silt and are dominated by the carbonate content. Organic carbon distribution indicates that they are brought in by the minor river input. Enrichment of trace metals is clearly identified by the domination of Pb, Zn, Cd with high values than the average crustal values and comparison of trace metals from other coastal regions in the southeast coast of India. Statistical analysis clearly indicates that Fe and Mn control the distribution of trace metals and are concentrated in the finer particles and organic carbon fraction. The increase in concentration signifies the need for regular monitoring of the offshore coastal region in southeast coast of India which was recently destroyed by the 2004 December tsunami event, and which is also located near the Sethu Samuthram Ship Canal Project.

Detailed examination of inner shelf sediments of the Bay of Bengal, off Karikkattukuppam, south-east coast of India near Madras, revealed quite a few rarely recorded or hitherto unidentified taxa. Of these, one species is a living representative of the genus Cocoarota Loeblich and Tappan, considered to be extinct since the Eocene. The few existing records of this genus from the Upper Eocene, exclusively from the American region, and lack of subsequent ones, raise questions with regard to its geographical distribution and possible migration since the Eocene. Cocoarota madrasensis n. sp. Rajeshwara Rao and Revets is a calcareous, densely perforate (except for the apertural face and sutures), foraminifer characterized by the presence of a series of irregularly shaped bosses clustered in the depressed umbilical area, resembling spiralized ornamentation as a result of thickening of folia and inner ends of sutures of earlier whorls. The flaps or folia on the umbilical side hover over the umbilical aperture that remains open in the earlier parts of the test. It is one of the more abundantly occurring species on the inner shelf off Madras (now Chennai), associated with considerable numbers of Asterorotalia trispinosa (Thalmann) and A. inflata (Millett), particularly at depths between 38 and 55 m, and on substrate with relatively higher mud content. The present discovery necessitates not only extension of the stratigraphic range of the genus Cocoarota but also a thorough review of the existing literature.

Benthic foraminifera have proved to be reliable proxies for understanding paleoenvironmental changes or paleoclimatic changes in the past geological history of the Earth, especially since the Cambrian when these unicellular protozoans began to evolve. Since then, foraminifers have been recorded as fossils and their abundant occurrence in the fossil record has aided in understanding the past history of the Earth. Within the Holocene, this group of microfossils has proved to be of immense utility, as their assemblages could be utilized for understanding past environmental changes, as they are so sensitive to variations in such ecological parameters as pH, depth of the water column, salinity, dissolved oxygen content, nature of substrate calcium carbonate and organic contents, which are the primary controlling factors over their species populations and diversity. The study area is a part of Kannur District, Kerala, India, about 5–7 km from the present-day shoreline. Trench samples (sub-surface) at varying depths up to 3.6 m, at Karakkeezhu and Kuduvathala, yielded a benthic foraminiferal assemblage that is characteristic of modern estuarinelbrackish water environments. This assemblage, typified by the dominance of Ammonia beccarii (Linnaeus) and its associated species, is suggestive of a shallow, probably sheltered, tidal flat environment with a possible connection to the Arabian Sea ∼5,000 to 5,500 years B.P. as revealed by 14C dates of both mollusk shells and sediment samples. The study has thrown open some intriguing questions, particularly with regard to the complete absence of arenaceous, agglutinated forms (Suborder TEXTULARIINA) and the poor representation of calcareous, imperforate taxa (Suborder MILIOLINA).

Raman and infrared intensity analysis of CHCl3 is attempted to determine the bond polarisability derivatives and bond dipole moments and their derivatives respectively, on lines expained in our earlier papers.