| 1 | Provenance studies on the heavy mineral placers along the coastal deposits of Odisha,eastern India显示文摘The coastal deposits along the eastern part of the Indian Peninsula are known for the high abundance of heavy minerals. The present study, as discussed here, has been undertaken along the southwestern coastal part of Odisha, India, adjoining the charnockite-migmatite zone of the Eastern Ghat Mobile Belt(EGMB). The composition of the placers along the study area is primarily controlled by the detritus from the proximal hinterland rock type(s). The weathering index has been established based on the grain morphology, major element concentration and radioelement ratios. Petrological characteristics and grain morphology of monazite, zircon, ilmenite and rutile have been presented respectively, and their implications are discussed. The provenance study of these coastal placers is based on the abundance of rare earth elements(REE) and radioactive elements in the placer sands and the rock types in the study area. The tectonic implications are based on the major element abundance of the beach sands. | Shayantani Ghosal Sudha Agrahari Debashish Sengupta | 2022 | Journal of Palaeogeography2022，11，2： | 1 |
| 2 | Geochemical,mineralogical and textural nature of beach placers,north-east Sri Lanka:Implications for provenance and potential resource显示文摘The Pulmoddai placer sands in Sri Lanka(9°3’23.65’’-8°51’38.83’’N and 80°55’22.91’’-81°3’32.65’’E)is considered to be one of the major rare earth element(REE)prospects world-wide.This deposit has a global significance in terms of strategic economic resources and can provide valuable insight for resource estimation and for its economic use.A detailed study of the geochemical,mineralogical,and textural properties of the heavy minerals of this region is undertaken applying the scanning electron microscopy-electron dispersive X-ray spectroscopy(SEM-EDS),inductively coupled plasma-optical emission spectroscopy(ICP-OES),X-Ray diffraction(XRD),and X-Ray fluorescence(XRF)techniques.The results from these analyses are modeled to delineate the source(s)which contribute to the formation of the mineral deposits and their subsequent enrichment.The beach sediment from this region,exhibited elevated concentrations of major elements like silicon(Si)and manganese(Mn)and high abundance of minor and trace elements like yttrium(Y),strontium(Sr),lanthanum(La),barium(Ba),which indicates that the provenance is similar to calcium-silicate rocks.The highest(total)concentration of Y,La,scandium(Sc)and cerium(Ce)are mainly associated to fine grained sediment,signifying that their occurrences are governed by the grain size distribution and ambient hydrodynamic conditions primarily from lagoonal input.Monazite,zircon,ilmenite,rutile,and xenotime are more abundant than garnet in the study area,as is evident from the higher abundance of thorium(Th)and uranium(U)and the enrichment of zirconium(Zr),Ce,vanadium(V),chromium(Cr),and Y.Textural analysis of sediment shows sediment particles are poorly sorted and have more angular grain boundaries,indicating their lower textural maturity.This suggests that the sediment is fluvially derived from a close source rock of charnockite specific to the hinterland lithology.The sediment transported by perennial rivers and the hydrodynamic conditions of the Kokkilai Lagoon estuary,are the two primary sources of heavy mineral enrichment in the study area,which is quite unique in terms of the placer formation.Subsequently,these sediment particles formed the beach placer deposits enriched in REE-Th rich heavy minerals,which are of immense strategic importance. | Samikshya Mohanty Madurya Adikaram Debashish Sengupta Nishara Madhubashini Chelaka Wijesiri Somnath Adak Biswajit Bera | 2023 | International Journal of Sediment Research2023，38，2： | 0 |
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