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Phase equilibria modelling coupled with U–Pb zircon and monazite ages of garnet–cordierite gneiss from Vallikodu Kottayam in the Kerala Khondalite Belt,southern India are presented here.The results suggest that the area attained peak P–T conditions of^900C at 7.5–8 kbar,followed by decompression to 3.5–5 kbar and cooling to 450–480C,preserving signatures of the partial melting event in the field of high to ultra-high temperature metamorphism.Melt reintegration models suggest that up to 35%granitic melt could have been produced during metamorphism at^950C.The U–Pb age data from zircons(~1.0–~0.7 Ga)and chemical ages from monazites(~540 Ma and^941 Ma)reflect a complex tectonometamorphic evolution of the terrain.The^941 Ma age reported from these monazites indicate a Tonian ultra-high temperature event,linked to juvenile magmatism/deformation episodes reported from the Southern Granulite Terrane and associated fragments in Rodinia,which were subsequently overprinted by the Cambrian(~540 Ma)tectonothermal episode. 相似文献
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GeoJournal - Application of geospatial technologies in criminological study is most relevant in present day context. Crime mapping with the help of Geographical Information System is being a very... 相似文献
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High-temperature cooling histories of migmatites from the High Himalayan Crystallines in Sikkim, India: rapid cooling unrelated to exhumation? 总被引：1，自引：0，他引：1
Nilanjana Sorcar Ulrich Hoppe Somnath Dasgupta Sumit Chakraborty 《Contributions to Mineralogy and Petrology》2014,167(2):1-34
The High Himalayan Crystallines (HHCs) provide an excellent natural laboratory to study processes related to crustal melting, crustal differentiation, and the tectonic evolution of mountain belts because partial melting in these rocks occurred under well-defined tectonic boundary conditions (N–S collision of the Indian and the Eurasian plates) and the rocks have not been modified by subsequent metamorphic overprinting. We have used petrogenetic grids, kinetically constrained individual thermobarometry, pseudosection calculations, and reaction histories constrained by textural evidence to determine that the migmatites in the HHC of Sikkim attained peak P–T conditions of 750–800 °C, 9–12 kbar, followed by steep isothermal decompression to 3–5 kbar, and then isobaric cooling to ~600 °C. There may be a trend where rocks to the north [closer to the South Tibetan detachment system (STDS)] attained somewhat higher maximum pressures. The decompression may have been triggered by a reduction in density due to the production of melt (~20 vol%); minor amounts of additional melt may have been produced in individual packages of rock during decompression itself, depending on the exact geometry of the P–T path and the bulk composition of the rock. The stalling of rapid, isothermal exhumation at depths of 10–18 km (3–5 kbar) is related to metamorphic reactions that occur in these rocks. Geospeedometry indicates that at least a two-stage cooling history is required to describe the compositional zoning in all garnets. Both of these stages are rapid (several 100’s °C/my between 800 and 600 °C, followed by several 10’s °C/my between 600 and 500 °C), but there appears to be a spatial discontinuity in cooling history: Rocks to the south (closer to main central thrust) cooled more slowly than rocks to the north (closer to STDS). The boundary between these domains coincides with the discontinuity in age found in the same area by Rubatto et al. (Contrib Mineral Petrol 165:349–372, 2013). Combined with the information on petrologic phase relations, the data reveal the remarkable aspect that the rapid cooling and change of cooling rates all occurred after, rather than during, the rapid exhumation. This result underscores that high-temperature (e.g., >550 °C) cooling is a result of several processes in addition to exhumation and a one-to-one correlation of cooling and exhumation may sometimes be misplaced. Moreover, average cooling rates inferred from the closure temperatures of two isotopic systems should be interpreted judiciously in such nonlinearly cooling systems. While many aspects (e.g., isothermal decompression, isobaric cooling, duration of metamorphism, and cooling rates) of the pressure–temperature history inferred by us are consistent with the predictions of thermomechanical models that produce midcrustal channel flow, the occurrence of blocks with two different cooling histories within the HHC is not explained by currently available models. It is found that while exhumation may be initiated by surface processes such as erosion, the course of exhumation and its rate, at least below depths of ~15 km, is mostly controlled by a coupling between mechanical (density gain/loss) and chemical (metamorphic reactions) processes at depth. 相似文献
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Nilanjana Das 《洁净——土壤、空气、水》2012,40(1):16-23
The development of nuclear science and technology has led to the increase of nuclear wastes containing radionuclides to be released and disposed in the environment. Pollution caused by radionuclides is a serious problem throughout the world. To solve the problem, substantial research efforts have been directed worldwide to adopt sustainable technologies for the treatment of radionuclide containing wastes. Biosorption represents a technological innovation as well as a cost effective excellent remediation technology for cleaning up radionuclides from aqueous environment. A variety of biomaterials viz. algae, fungi, bacteria, plant biomass, etc. have been reported for radionuclide remediation with encouraging results. This paper reviews the achievements and current status of radionuclide remediation through biosorption which will provide insights into this research frontier. 相似文献
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Nilanjana Sorcar Kumar Batuk Joshi Elson P. Oliveira J.K. Tomson V. Nandakumar 《地学前缘(英文版)》2021,12(2):693-694
The sample location in our paper(Sorcar et al.,2020)was incorrectly marked in Fig.1,although the GPS location was reported correctly.The corrected sample location of garnet-cordierite gneiss is shown in Fig.1.The sample location falls within the Achankovil Shear Zone(ASZ)and not in the Trivandrum Block as stated in our paper.Thus,the Tonian ultrahigh-temperature(UHT)metamorphic event reported in our paper is applicable to ASZ,and not for the Trivandrum Block.The related discussion on Gondwana correlation in our paper may be viewed and read in that context. 相似文献
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Response surface methodology (RSM) employing the three‐level Box–Behnken factorial design was used to optimize the biosorption of Ag(I) by the macrofungus Pleurotus platypus. The initial Ag(I) concentration (100–300 mg/L), pH (3.0–9.0), and biomass dosage (1.0–5.0 g/L) were chosen as the process variables for the optimization. A coefficient of determination (R2) value (0.99), model F value (234.18), and its low p‐value (F < 0.0001) along with the lower value of coefficient of variation (2.44%) indicated the fitness of response surface quadratic model during the present study. At the optimum pH (6.0), initial metal concentration (220 mg/L), and biomass dosage (3.0 g/L), the model predicted 46.7 mg/g Ag(I) uptake and an experimental 46.77 mg/g Ag(I) uptake by P. platypus was obtained. This is the first report on Ag(I) sorption by P. platypus using statistical experimental design employing RSM which may be helpful towards the treatment of industrial effluent containing silver. 相似文献
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