Phosphorite is one of the most important raw materials for the fertilizer industry. Indias annual production of phosphate from the land-based mines is far less than the domestic needs and thus depends largely on imports. The domestic... more
Phosphorite is one of the most important raw materials for the fertilizer industry. Indias annual production of phosphate from the land-based mines is far less than the domestic needs and thus depends largely on imports. The domestic demand of phosphorite warrants detailed investigations with the aid of high-resolution multibeam bathymetric survey followed by systematic sampling at target locations from selective sectors of the present-day oceans off western margin of India. The present study has yielded phosphorites/phosphatic concretions from two topographic domains of western margin of India, while the third domain was found to be devoid of phosphatic materials. Detailed multibeam bathymetric study of these sites indicates that amongst several factors that controlled phosphorite formation, seabed morphology appears to have played a vital role in phosphatic enrichment in these areas.
A highly altered carbonate rock was recovered from the mount, off Calicut, Kerala. Bulk chemical analysis of the rock showed that it contains ~ 21 % P 2 O 5. The rock consists of fine to coarse lithic and bio-clasts embedded in brown to... more
A highly altered carbonate rock was recovered from the mount, off Calicut, Kerala. Bulk chemical analysis of the rock showed that it contains ~ 21 % P 2 O 5. The rock consists of fine to coarse lithic and bio-clasts embedded in brown to the yellow coloured phosphatic matrix. Detailed SEM-EDS of the rock piece indicates micro-globular and nodular growth of phosphorite around calcite to form a core-rim structure, with P 2 O 5 as high as 31.67 weight percentage. The X-ray elemental mapping carried out using EPMA indicates highest P 2 O 5 (29.87 %) on the altered surfaces. Microstructural and geochemical analyses suggest authigenic/diagenetic precipitation of phosphorite on the carbonate rock.
Evaluation of REE concentration in sediments of different depositional environments like shallow marine, river, estuary and litho units of Tertiary and Quaternary formations along West Coast of India was carried out to identify the zones... more
Evaluation of REE concentration in sediments of different depositional environments like shallow marine, river, estuary and litho units of Tertiary and Quaternary formations along West Coast of India was carried out to identify the zones of REE accumulations. The study showed ∑REE content of 9-319 ppm in shallow marine sediments, 170-5420 ppm in river and estuarine sediments, 25-8179 ppm in Tertiary and Quaternary formations of North Kerala and South Karnataka districts. The study narrowed down the LREE enriched zone to the lateritized Tertiary sediments of Warkallai Formation of Kasaragod and Kannur Districts of North Kerala. ∑REE concentrations upto 8179 ppm with La>2500 ppm, Ce>4400 ppm, Pr>300 ppm and Nd>800 ppm occur within the sandstone and clay units of the Warkallai Formation of Mio-Pliocene age underlying the laterite cappings. Petrographic examination of the REE rich samples have shown abundant heavy minerals like leucoxene, ilmenite and garnet in altered form. XRD studies have shown kaolinite and quartz as the major mineral phases with traces of complex hydroxide minerals like goethite, todorokite, wairakite, dozyite, lawsonite and zinnwaldite indicating intense alteration of minerals under hydrolyzing conditions. In the heavy mineral suites found along the west coast of India, monazite and garnets are known to host REEs. However, the LREE enriched pattern, mineralogy and radionuclide studies rules out monazite and garnet as the source of REE in the samples. It is inferred that the REEs in the lateritized Tertiary sediments have been derived from leaching of monazite bearing placers within the Tertiaries and occurs at present as concentrations within clays in adsorbed state.
Arabian Sea is an excellent repository of past climatic and environmental records of the region and because of this reason it has attracted many geoscientists to explore the past. Vast amount of studies has been carried out in the Arabian... more
Arabian Sea is an excellent repository of past climatic and environmental records of the region and because of this reason it has attracted many geoscientists to explore the past. Vast amount of studies has been carried out in the Arabian Sea to understand the monsoonal impact and its influence on the biological productivity and terrigenous supply, with a special emphasis for the Late Quaternary phase (Sirocko
Pink and grey granites occur as minor, more or less circular bodies at Angadimogal and Kumbdajc areas of Kasaragod district, covering around l0 km2. These granites are emplaced d within the charnockites and gneisses during the Late... more
Pink and grey granites occur as minor, more or less circular bodies at Angadimogal and Kumbdajc areas of Kasaragod district, covering around l0 km2. These granites are emplaced d within the charnockites and gneisses during the Late Precambrian. These granites are coarse-grained and 'traversed by anastomosing patches of aplite. They are in sharp contact with the country rock. The Angadimogar pluton was earlier considered a syenitic body. Normative mineralogy and petrography of'the Angadimogar and Kurnbdaje plutons show high content of silica and other salic minerals and confirm that they are in fact granites. The major oxide chemistry of the plutons is similar to the major granitic plutons of South India. Thus, contrary to the earlier views, we suggest that these bodies are granites.
Arabian Sea is an excellent repository of past climatic and environmental records of the region and because of this reason it has attracted many geoscientists to explore the past. Vast amount of studies has been carried out in the Arabian... more
Arabian Sea is an excellent repository of past climatic and environmental records of the region and because of this reason it has attracted many geoscientists to explore the past. Vast amount of studies has been carried out in the Arabian Sea to understand the monsoonal impact and its influence on the biological productivity and terrigenous supply, with a special emphasis for the Late Quaternary phase (Sirocko
