The sediments samples were collected from the Dikrong River at various sites to assess the weathering nature and mineral characterization. The Fourier Transform Infrared (FTIR) and X-ray fluorescence (XRF) spectroscop...The sediments samples were collected from the Dikrong River at various sites to assess the weathering nature and mineral characterization. The Fourier Transform Infrared (FTIR) and X-ray fluorescence (XRF) spectroscopic techniques have been used to characterization of minerals in the sediment samples. The plagioclase index of alteration (PIA), chemical index of alteration (CIA) and index of compositional variation (ICV) are investigated for evaluating the weathering nature in the sediment. The obtained results show the presence of quartz, feldspar in different structure and kaolinite as major minerals. Carbonates and organic carbon are found as minor minerals. The correlations of SiO2 with major elements are authenticated the presence of bulk quartz grains and primary depositional environment. The presence of metamorphosed pyrophanite (MnTiO3) in the adjoined areas is reported. The presence of infrared absorption peaks in between 1611 - 1622 cm?1 in this study is indicative to the weathered metamorphic origin of the silicate minerals. The index of compositional variation indicates the presence of less clay minerals and more rock forming minerals such as plagioclase and alkali-feldspar. The obtained results exhibit the area belongs to the intermediate silicate weathering.展开更多
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 (...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 SiO2 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 SiO4 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.展开更多
We present a brief overview of meteorites from the north-eastern India, with a focus on falls, finds, and research developments. To date, out of a total 150 numbers of meteorites fall/find in India (in Meteoritical Bu...We present a brief overview of meteorites from the north-eastern India, with a focus on falls, finds, and research developments. To date, out of a total 150 numbers of meteorites fall/find in India (in Meteoritical Bulletin Database), only six meteorites from north-eastern region have received official international recognition from the Nomenclature Committee of the Meteoritical Society. Among these six meteorites, 2 finds and 4 falls, including one ureilite, two H chondrites and three L chondrites. The first meteorite from north-eastern India (Assam L5, Find) was documented in 1846. After a lack of 153 years, the first fall (Sabrum LL6 chondrite) was documented in 1999. The most recent fall is Kamargaon (L6) chondrite in 2015. Intensively researched meteorites of this region are Goalpara and Dergaon. The reported most massive meteorite of north-eastern India is Mahadevpur (H4/5) chondrite, 70.5 kg of total known weight, and the rest are <13 kg of total known weight. The researches on these meteorites from north-east India can be applied to the newly recovered meteorites to understand the astrophysical enigma.展开更多
文摘The sediments samples were collected from the Dikrong River at various sites to assess the weathering nature and mineral characterization. The Fourier Transform Infrared (FTIR) and X-ray fluorescence (XRF) spectroscopic techniques have been used to characterization of minerals in the sediment samples. The plagioclase index of alteration (PIA), chemical index of alteration (CIA) and index of compositional variation (ICV) are investigated for evaluating the weathering nature in the sediment. The obtained results show the presence of quartz, feldspar in different structure and kaolinite as major minerals. Carbonates and organic carbon are found as minor minerals. The correlations of SiO2 with major elements are authenticated the presence of bulk quartz grains and primary depositional environment. The presence of metamorphosed pyrophanite (MnTiO3) in the adjoined areas is reported. The presence of infrared absorption peaks in between 1611 - 1622 cm?1 in this study is indicative to the weathered metamorphic origin of the silicate minerals. The index of compositional variation indicates the presence of less clay minerals and more rock forming minerals such as plagioclase and alkali-feldspar. The obtained results exhibit the area belongs to the intermediate silicate weathering.
文摘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 SiO2 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 SiO4 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.
文摘We present a brief overview of meteorites from the north-eastern India, with a focus on falls, finds, and research developments. To date, out of a total 150 numbers of meteorites fall/find in India (in Meteoritical Bulletin Database), only six meteorites from north-eastern region have received official international recognition from the Nomenclature Committee of the Meteoritical Society. Among these six meteorites, 2 finds and 4 falls, including one ureilite, two H chondrites and three L chondrites. The first meteorite from north-eastern India (Assam L5, Find) was documented in 1846. After a lack of 153 years, the first fall (Sabrum LL6 chondrite) was documented in 1999. The most recent fall is Kamargaon (L6) chondrite in 2015. Intensively researched meteorites of this region are Goalpara and Dergaon. The reported most massive meteorite of north-eastern India is Mahadevpur (H4/5) chondrite, 70.5 kg of total known weight, and the rest are <13 kg of total known weight. The researches on these meteorites from north-east India can be applied to the newly recovered meteorites to understand the astrophysical enigma.
