• DEBASHISH SENGUPTA

      Articles written in Journal of Earth System Science

    • Geochemistry of the Heavy Mineral Sands from the Garampeta to the Markandi beach, southern coast of Odisha, India: Implications of high contents of REE and Radioelements attributed to Placer Monazite

      SHAYANTANI GHOSAL SUDHA AGRAHARI SANTANU BANERJEE RAMANANDA CHAKRABARTI DEBASHISH SENGUPTA

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      This study presents major element, radioactive element and rare earth element (REE) concentrations of the Garampeta to Markandi beach along the southern coast of Odisha, India to delineate the source signature and resource potential of the beach placer deposits. Average $\sum$REE concentration of the beach sand samples is about four times higher than the average crustal concentration. The LREE concentration is higher than HREE, with a pronounced negative europium anomaly. The study also discusses about the radioelement $^{238}$U, $^{232}$Th and $^{40}$K concentrations in the study area, and their relationship with REE. Weathering condition of the source rock, based on the major elements and Th$/$U ratio indicated a reasonably high degree of weathering. Major element and the REE composition along with the europium anomaly, relate the beach placers to mainly charnockite and khondalite source. An elevated level of thorium (>60 times than the average UCC values) as exhibited by the samples could be attributed due to the presence of monazites. The high concentration of REEs like Nd and Dy along with La and Ce indicates significant REE resource potential in the beach placers which is important for the resource potential in terms of the strategic mineral reserves of the country.

    • Granulometric analysis of beach sediments enriched in radioactivity along Podampata, east coast of Odisha, India

      SAMIKSHYA MOHANTY SOMNATH ADAK DEBASHISH SENGUPTA

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      The nature and distribution of heavy minerals along beach placers have been studied along the coastal part of Podampata, Eastern Coast of Odisha, India. The primary objective of this study was to assess the heavy mineral placers along the NE–SW direction, the nature of the high background radiation area, and the geomorphic agents controlling the beach sediment distribution. In-situ total radiation counts were obtained using a Micro R survey meter, and the individual activity of $^{232}$U (in $\mu$g/g), $^{234}$Th (in $\mu$g/g), and $^{40}$ K (in %) of the collected samples were measured with Gamma surveyor II instrument. The sediment characterization was undertaken using grain size statistical parameters, which shows dominant influence of river and wind actions on the sediments and their high transportation and modification rates. Nature of radioactive anomalies observed is due to the decays of $^{232}$U and $^{234}$Th. The meandering nature and subsequent erosion, primarily at the outer curvature of the river, seems to have primarily contributed to the heavy mineral deposition. The high wind velocity during the frequent cyclonic events could have a significant influence on distribution and transport of heavy minerals observed. The mixed geomorphic agents operating in the study area influence the distribution of heavy minerals along the NE–SW direction.

      $\bf{Highlights}$

      $\bullet$ The higher abundance of Th is basically along the outer curvature of the meandering part as compared to the U and K occurrences.

      $\bullet$ Fine sand sediments with negatively skewness contains higher abundance of radioactive= elements.

      $\bullet$ The meandering pattern of Rusikulya River along due to beach action, primarily fluvial and aeolian activity plays an important role in the distribution of the sediments along the coast.

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