This study demonstrates the compositional and structural analysis of surface sediments in natural depositional environment of the Brahmaputra River using X-ray fluorescence, Raman spectroscopic and Fourier transform infrared spectroscopic techniques. The main peaks in the Raman and infrared spectra reflected Al-OH, Al-O and Si-O functional groups in high frequency stretching and low frequency bending modes. The Raman and infrared spectra reveals the nature of clay (kaolinite) associated with quartz. The infrared spectra are indicative to the weathered metamorphic origin of the silicate minerals. The relative distributions of the contaminations in the sediment are: Si > Al > Fe > Mg > Ca > K > Ti > Mn > Cr >Ni > Zn > Cu > Co. The metal contaminations in the sediments are investigated by calculating the enrichment factor, contamination factor, geo-accumulation index and pollution load index. The relative distributions of the contamination among the samples are: Cu > Si > Mn > Mg > Ni > Cr > Ti > Al > Co > Pb > K > Ca > Zn. The investigating factors suggest the significant contamination in the sediment is due to Cu. The strong positive correlation among Al, Fe, Mg and K suggests association of sediments with clay. The elemental correlation is indicative to the metamorphosed pyrophanite (MnTiO3) deposition.
We report spectroscopic, bulk, trace element and mineralogical composition of a fresh meteorite fall at Bali-Chapori village, near Kamargaon Town, Assam, India (26°37′56″.99 N; 93°46′ 11″.51 E) on November 13 th , 2015. The whole rock analyses and the composition of olivine and pyroxene indicate that the meteorite is an ordinary chondrite belonging to the group L6. The spectroscopic (Raman, FTIR, XRD) and petrographical (HR-ICP-MS, EPMA, XRF) studies reveal that the major constituents of the meteorite is olivine [(Mg, Fe) 2 SiO 4 ], pyroxene, and metal.
We present here the Raman spectroscopic study of silicate and carbonaceous minerals in three ordinary chondrites with the aim to improve our understanding the impact process including the peak metamorphic pressures present in carbon-bearing ordinary chondites. The characteristic Raman vibrational peaks of olivines, pyroxenes, and plagioclase have been determined on three ordinary chondrites from India, Dergaon (H5), Mahadevpur (H4/5), and Kamargaon (L6). The Raman spectra of these meteorite samples show the presence of nanodiamonds at 1334-1345 cm À1 and 1591-1619 cm À1 . The fullwidth at half maximum (FWHM) of Raman peaks for Mahadevpur and Dergaon reflect the nature of shock metamorphism in these meteorites. The frequency shift in Raman spectra might be because of shock effects during the formation of the diamond/graphite grains.
We report here for the first time the possible presence of organic compounds in Sadiya (LL5) ordinary chondrite using micro-Raman and infrared spectroscopic technique. The micro-Raman spectrum exhibits the diamond and graphite peaks correspondingly at 1331 cm-1 , 1349 cm-1 and 1588-1618 cm-1. The full wave at half maximum value of about 18 cm-1 for Sadiya indicating the nature of disordered phase involved shock metamorphism in the meteorite samples. The diamond and graphite peaks intensity ratio (~0.53) indicates the disordered nature of graphite. The infrared spectrum in the range 2700-3000 cm-1 indicates the presence of CH 3 asymmetric stretching, and CH 2 symmetric and asymmetric stretching modes due to aliphatic hydrocarbons. This study has strong implications in understanding of the organic compounds in extra-terrestrial materials.
The presence of microcrystalline quartz particles in fulgurites of Garuamukh and Kimin has been investigated. The compositional and structural studies were carried out at room temperature by using X-ray fluorescence (XRF), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic techniques. The compositional result shows the major constituent of the fulgurites to be SiO 2 with miniature quantities of oxides of Al, Ti, Fe, Ca, and Na. The X-ray diffraction quantified the mixtures of identical amorphous and micro-crystalline phases in the fulgurites samples. Systemetatic investigations of microcrystalline quartz particles have been carried out in midinfrared region of 500 -1000 cm −1 based on the assignment of infrared bands of the structural group SiO 4 tetrahedra. In infrared Si-O-Si bending vibration region of quartz, the octahedral characteristic peak is explored in the fulgurites samples with the variation of the particle sizes which is indicative to the presence of microcrystalline quartz. The distribution of the microcrystalline quartz is ascertained by calculating the extinction coefficient. The present study has significant implications in understanding the thermodynamic properties of naturally occurring glasses, which are formed by shock metamorphism.
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