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Evgueni Jak - One of the best experts on this subject based on the ideXlab platform.
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the effect of sulfur dioxide partial pressure on gas slag matte Tridymite equilibria in the cu fe o s si system at 1200 c
Mineral Processing and Extractive Metallurgy, 2020Co-Authors: Ata Fallahmehrjardi, P C Hayes, Taufiq Hidayat, Evgueni JakAbstract:The gas-slag-matte-Tridymite equilibria in the Cu–Fe–O–S–Si system at 1200°C have been experimentally studied. An improved experimental technique was used, which includes high temperature equilibration of sulfide-oxide mixtures on silica substrates at p(SO) = 0.6 atm, preservation of the equilibrium phases by rapid quenching, and direct compositional analysis of the phases using microanalysis techniques. The new data have enabled the effects of sulfur dioxide partial pressure between 0.1 and 0.6 atm on the equilibria to be accurately determined. Whilst, for a given matte grade, the dissolved copper in slag is not sensitive to sulfur dioxide partial pressure, the Fe/SiO in slag in equilibrium with Tridymite was found to increase with increasing p(SO). This latter observation has implications for fluxing practice in industrial copper smelting operations.
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the effect of al2o3 on fayalite based copper smelting slags in equilibrium with matte and Tridymite at 1 200 c and p so2 0 25 atm
International Journal of Materials Research, 2020Co-Authors: Ata Fallahmehrjardi, P C Hayes, Taufiq Hidayat, Evgueni JakAbstract:Experimental investigations have been undertaken to determine the effect of Al2O3 in slag on the gas/slag/matte/Tridymite equilibria in the multi-component Cu-Fe-O-S-Si-Al system at 1 200 degrees C, and P(SO2) = 0.25 atm. The experimental technique involves high temperature equilibration of synthetic samples on the open silica substrate in controlled gas atmospheres (CO/CO2/SO2/Ar), rapid quenching after a designated equilibration time followed by the compositional analysis of the condensed phases with electron probe X-ray microanalyzer. The experimental data of the present study provide information on the effect of alumina on the slag composition, such as the chemically dissolved copper, dissolved sulphur, and Fe/SiO2 ratio in slag at Tridymite saturation at different Cu in matte. The new data have been used as inputs for the optimization of the thermodynamic databases for the copper-containing systems and can also be used to evaluate the fluxing strategy in the copper smelting operation.
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experimental study of gas slag matte Tridymite equilibria in the cu fe o s si al system at 1573 k 1300 c and p so 2 0 25 atm
Journal of Phase Equilibria and Diffusion, 2020Co-Authors: Hamed Abdeyazdan, Ata Fallahmehrjardi, P C Hayes, M A Shevchenko, Taufiq Hidayat, Evgueni JakAbstract:Fundamental experimental investigations have been conducted to study the effect of Al2O3 on the equilibria between the gas phase (CO-CO2-SO2-Ar) and slag-matte-Tridymite phases in the Cu-Fe-O-S-Si-Al system at 1573 K (1300 °C) and P(SO2) = 0.25 atm. The experimental technique used is based on equilibration, rapid quenching and electron probe x-ray microanalysis. New experimental data have been obtained for the four-phase gas-slag-matte-Tridymite equilibria system for a range of alumina concentrations up to 20.4 mass% in the slag phase as a function of matte grade, including the concentrations of dissolved sulphur and copper in slag, and Fe/SiO2 ratios in slag. The results obtained for 1573 K (1300 °C) are also used to analyse the effect of temperature on phase equilibria in the range of conditions investigated to that of reported for 1473 K (1200 °C) in the literature. The results obtained show that the concentrations of sulphur, copper and “FeO” in slag decrease with increase of Al2O3 concentration in slag while it has no detectable effect on concentration of sulphur in matte for a given matte grade. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input for optimisation of the FactSage thermodynamic database for the copper-containing, multi-component multi-phase system.
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experimental investigation of gas slag matte Tridymite equilibria in the cu fe o s si al ca mg system in controlled gas atmosphere experimental results at 1473 k 1200 c 1573 k 1300 c and p so2 0 25 atm
Journal of Phase Equilibria and Diffusion, 2020Co-Authors: Svetlana Sineva, Ata Fallahmehrjardi, P C Hayes, M A Shevchenko, Taufiq Hidayat, Denis Shishin, Evgueni JakAbstract:The effect of temperature, CaO, MgO and Al2O3 on important technological copper smelting parameters, such as the chemically dissolved copper in slag and the composition of the liquid phase in equilibrium with Tridymite, are experimentally characterised as a function of copper concentration in matte. Two series of experiments for the gas/slag/matte/Tridymite equilibria in the Cu-Fe-O-S-Si system at p(SO2) = 0.25 atm have been carried out. The effect of CaO at 1573 K (1300 °C), and the combined effect of Al2O3 + CaO + MgO at 1473 K (1200 °C) and 1573 K (1300 °C) have been measured in the first and second series of experiments respectively. The experimental methodology involves high temperature equilibration of samples on a substrate made from the primary phase under controlled gas atmosphere (CO/CO2/SO2/Ar), followed by rapid quenching of the equilibrium condensed phases and direct measurement of the phase compositions using the Electron Probe x-ray Microanalysis. The resulting data are used in the optimization of the thermodynamic database for the copper-containing systems.
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the effect of cao on gas slag matte Tridymite equilibria in fayalite based copper smelting slags at 1473 k 1200 c and p so 2 0 25 atm
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2018Co-Authors: Ata Fallahmehrjardi, P C Hayes, Evgueni JakAbstract:Fundamental experimental studies have been undertaken to determine the effect of CaO on the equilibria between the gas phase (CO/CO2/SO2/Ar) and slag/matte/Tridymite phases in the Cu-Fe-O-S-Si-Ca system at 1473 K (1200 °C) and P(SO2) = 0.25 atm. The experimental methodology developed in the Pyrometallurgy Innovation Centre was used. New experimental data have been obtained for the four-phase equilibria system for fixed concentrations of CaO (up to 4 wt pct) in the slag phase as a function of copper concentration in matte, including the concentrations of dissolved sulfur and copper in slag, and Fe/SiO2 ratios in slag at Tridymite saturation. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input to optimize the thermodynamic database for the copper-containing multi-component multi-phase system.
Heribert A Graetsch - One of the best experts on this subject based on the ideXlab platform.
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monoclinic alpo4 Tridymite at 473 and 463 k from x ray powder data
ChemInform, 2010Co-Authors: Heribert A GraetschAbstract:Upon cooling from its hexagonal high-temperature modification, AlPO4 (aluminium phosphate) Tridymite successively transforms to several displacively distorted forms, including a normal structure–incommensurate–lock-in phase transition sequence. The space-group symmetries in this series are P1121, P1121(αβ0) and P212121, respectively. The distortion pattern of the intermediate P1121 phase can be described as alternate shifts of adjacent layers of tetrahedra coupled with tilting of the tetrahedra. The symmetry and direction of the shifts are different from the analogous SiO2 Tridymite modification. The atomic displacement parameters of the O atoms are strongly anisotropic due to thermal motions of the rigid tetrahedra. Condensation of a lattice vibration mode results in the formation of an incommensurate structural modulation below 473 K. The 3+1 superspace-group symmetry of the modulated phase is P1121(αβ0).
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modulated crystal structure of incommensurate low Tridymite
Acta Crystallographica Section B-structural Science, 2009Co-Authors: Heribert A GraetschAbstract:The incommensurately modulated crystal structure of low SiO2 Tridymite was refined based on single-crystal X-ray diffraction data in the superspace group Cc(α0γ)0. The data set consists of 885 main reflections, 1751 first-order, 924 second-order and 119 third-order satellite reflections with I > 3σ(I). The modulation is mainly made up from cooperative twistings of the rigid SiO4 tetrahedra. Two orders of displacement waves are used to describe the modulation of the Si atoms and three orders for the O atoms. The maximal amplitudes are ca 0.6 A. O atoms bridging pairs of tetrahedra in cis and trans configurations show different positional modulation patterns. The anisotropic displacement parameters (ADPs) are also modulated. A correlation between ADP modulations and positional modulations was found.
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incommensurate modulation at 165 c of intermediate Tridymite
Zeitschrift Fur Kristallographie, 2005Co-Authors: Heribert A Graetsch, Michela BrunelliAbstract:The crystal structure of the incommensurate modification of SiO 2 Tridymite existing between 150 and 200 °C was refined in the 3 + 1 dimensional superspace group P2 1 (α β 0) from synchrotron powder diffraction data. The modulation consists of rotations and tiltings of rigid SiO 4/2 tetrahedra with mainly transversal displacements of the atoms. At 165 °C the wave vector is r = 0.054a* + 0.004b*. The largest amplitude is ca. 0.4 A for oxygen and ca. 0.2 A for silicon. Si-O-Si intertetrahedral and O-Si...Si-O torsion angles vary by more than 10°. The torsion rotations are larger for pairs of adjacent tetrahedra in trans-configuration than for those in cis-configuration. The shape of six-membered rings of tetrahedra change from almost hexagonal to ditrigonal along the modulation vector.
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hexagonal high temperature form of aluminium phosphate Tridymite from x ray powder data
Acta Crystallographica Section C-crystal Structure Communications, 2001Co-Authors: Heribert A GraetschAbstract:Similar to silica Tridymite, AlPO4 Tridymite shows a sequence of displacive phase transitions resulting in a dynamically disordered hexagonal high-temperature modification. Rietveld refinement reveals that the thermal motions of the tetrahedra can be described either by strongly anisotropic displacement parameters for oxygen or by split O atoms. Due to the ordered distribution of aluminium and phosphorus over alternating tetrahedra, the space group symmetry of high-temperature AlPO4 Tridymite is reduced with respect to SiO2 Tridymite from P63/mmc to P63mc.
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x ray powder diffraction study on the modulated high temperature forms of sio 2 Tridymite between 110 and 220 c
Physics and Chemistry of Minerals, 2001Co-Authors: Heribert A GraetschAbstract:The crystal structure of intermediate incommensurate Tridymite was refined at 150 °C from powder data. Upon cooling from above 220 °C, the basic structure with space group symmetry C2221 is gradually distorted from orthorhombic to monoclinic symmetry. With decreasing temperature, the monoclinic angle γ smoothly opens up to 90.3°, while a displacive modulation with temperature-dependent wavelength develops. The 3 + 1 dimensional superspace group of the incommensurate phase is C1121(αβ0). The modulation mainly consists of two sinusoidal transverse displacement waves for the silicon atoms coupled to rotations of the rigid SiO4/2 tetrahedra. The wave vector is r=0.1192(1)a* − 0.0043(1)b* at 150 °C. Below 150 °C Tridymite discontinuously transforms to another orthorhombic phase and the modulation partially locks in at the wave vector r 1=1/3a*. Simultaneously, an additional incommensurate modulation with r 2= 0.0395(1)b* − 0.3882(1)c* is formed. The two-dimensional modulation does not vary significantly with the temperature.
Jak Evgueni - One of the best experts on this subject based on the ideXlab platform.
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The effect of Al2O3 on fayalite-based copper smelting slags in equilibrium with matte and Tridymite at 1 200 degrees C and P(SO2)=0.25 atm
'Carl Hanser Verlag', 2020Co-Authors: Fallah-mehrjardi Ata, Hayes, Peter C., Hidayat Taufiq, Jak EvgueniAbstract:Experimental investigations have been undertaken to determine the effect of Al2O3 in slag on the gas/slag/matte/Tridymite equilibria in the multi-component Cu-Fe-O-S-Si-Al system at 1 200 degrees C, and P(SO2) = 0.25 atm. The experimental technique involves high temperature equilibration of synthetic samples on the open silica substrate in controlled gas atmospheres (CO/CO2/SO2/Ar), rapid quenching after a designated equilibration time followed by the compositional analysis of the condensed phases with electron probe X-ray microanalyzer. The experimental data of the present study provide information on the effect of alumina on the slag composition, such as the chemically dissolved copper, dissolved sulphur, and Fe/SiO2 ratio in slag at Tridymite saturation at different Cu in matte. The new data have been used as inputs for the optimization of the thermodynamic databases for the copper-containing systems and can also be used to evaluate the fluxing strategy in the copper smelting operation
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Experimental Study of Gas-Slag-Matte-Tridymite Equilibria in the Cu-Fe-O-S-Si-Al System at 1573 K (1300 degrees C) and P(SO2)=0.25 atm
'Springer Science and Business Media LLC', 2020Co-Authors: Abdeyazdan Hamed, Fallah-mehrjardi Ata, Hayes, Peter C., Hidayat Taufiq, Shevchenko Maksym, Jak EvgueniAbstract:Fundamental experimental investigations have been conducted to study the effect of Al2O3 on the equilibria between the gas phase (CO-CO2-SO2-Ar) and slag-matte-Tridymite phases in the Cu-Fe-O-S-Si-Al system at 1573 K (1300 degrees C) and P(SO2) = 0.25 atm. The experimental technique used is based on equilibration, rapid quenching and electron probe x-ray microanalysis. New experimental data have been obtained for the four-phase gas-slag-matte-Tridymite equilibria system for a range of alumina concentrations up to 20.4 mass% in the slag phase as a function of matte grade, including the concentrations of dissolved sulphur and copper in slag, and Fe/SiO2 ratios in slag. The results obtained for 1573 K (1300 degrees C) are also used to analyse the effect of temperature on phase equilibria in the range of conditions investigated to that of reported for 1473 K (1200 degrees C) in the literature. The results obtained show that the concentrations of sulphur, copper and "FeO" in slag decrease with increase of Al2O3 concentration in slag while it has no detectable effect on concentration of sulphur in matte for a given matte grade. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input for optimisation of the FactSage thermodynamic database for the copper-containing, multi-component multi-phase system
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The effect of sulfur dioxide partial pressure on gas-slag-matte-Tridymite equilibria in the Cu-Fe-O-S-Si system at 1200°C
'Informa UK Limited', 2020Co-Authors: Fallah-mehrjardi Ata, Hayes, Peter C., Hidayat Taufiq, Jak EvgueniAbstract:The gas-slag-matte-Tridymite equilibria in the Cu–Fe–O–S–Si system at 1200°C have been experimentally studied. An improved experimental technique was used, which includes high temperature equilibration of sulfide-oxide mixtures on silica substrates at p(SO) = 0.6 atm, preservation of the equilibrium phases by rapid quenching, and direct compositional analysis of the phases using microanalysis techniques. The new data have enabled the effects of sulfur dioxide partial pressure between 0.1 and 0.6 atm on the equilibria to be accurately determined. Whilst, for a given matte grade, the dissolved copper in slag is not sensitive to sulfur dioxide partial pressure, the Fe/SiO in slag in equilibrium with Tridymite was found to increase with increasing p(SO). This latter observation has implications for fluxing practice in industrial copper smelting operations
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Experimental investigation of gas/slag/matte/Tridymite equilibria in the Cu-Fe-O-S-Si-Al-Ca-Mg system in controlled gas atmosphere: experimental results at 1473\ua0K (1200\ua0°C), 1573\ua0K (1300\ua0°C) and p(SO2) = 0.25\ua0atm
'Springer Science and Business Media LLC', 2020Co-Authors: Sineva Svetlana, Fallah-mehrjardi Ata, Hayes, Peter C., Hidayat Taufiq, Shevchenko Maksym, Shishin Denis, Jak EvgueniAbstract:The effect of temperature, CaO, MgO and AlO on important technological copper smelting parameters, such as the chemically dissolved copper in slag and the composition of the liquid phase in equilibrium with Tridymite, are experimentally characterised as a function of copper concentration in matte. Two series of experiments for the gas/slag/matte/Tridymite equilibria in the Cu-Fe-O-S-Si system at p(SO) = 0.25\ua0atm have been carried out. The effect of CaO at 1573\ua0K (1300\ua0°C), and the combined effect of AlO + CaO + MgO at 1473\ua0K (1200\ua0°C) and 1573\ua0K (1300\ua0°C) have been measured in the first and second series of experiments respectively. The experimental methodology involves high temperature equilibration of samples on a substrate made from the primary phase under controlled gas atmosphere (CO/CO/SO/Ar), followed by rapid quenching of the equilibrium condensed phases and direct measurement of the phase compositions using the Electron Probe x-ray Microanalysis. The resulting data are used in the optimization of the thermodynamic database for the copper-containing systems
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The Effect of CaO on Gas/Slag/Matte/Tridymite Equilibria in Fayalite-Based Copper Smelting Slags at 1473 K (1200 °C) and P(SO2) = 0.25 Atm
'Springer Science and Business Media LLC', 2018Co-Authors: Fallah-mehrjardi Ata, Hayes, Peter C., Jak EvgueniAbstract:Fundamental experimental studies have been undertaken to determine the effect of CaO on the equilibria between the gas phase (CO/CO/SO/Ar) and slag/matte/Tridymite phases in the Cu-Fe-O-S-Si-Ca system at 1473 K (1200 °C) and P(SO) = 0.25 atm. The experimental methodology developed in the Pyrometallurgy Innovation Centre was used. New experimental data have been obtained for the four-phase equilibria system for fixed concentrations of CaO (up to 4 wt pct) in the slag phase as a function of copper concentration in matte, including the concentrations of dissolved sulfur and copper in slag, and Fe/SiO ratios in slag at Tridymite saturation. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input to optimize the thermodynamic database for the copper-containing multi-component multi-phase system
P C Hayes - One of the best experts on this subject based on the ideXlab platform.
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the effect of sulfur dioxide partial pressure on gas slag matte Tridymite equilibria in the cu fe o s si system at 1200 c
Mineral Processing and Extractive Metallurgy, 2020Co-Authors: Ata Fallahmehrjardi, P C Hayes, Taufiq Hidayat, Evgueni JakAbstract:The gas-slag-matte-Tridymite equilibria in the Cu–Fe–O–S–Si system at 1200°C have been experimentally studied. An improved experimental technique was used, which includes high temperature equilibration of sulfide-oxide mixtures on silica substrates at p(SO) = 0.6 atm, preservation of the equilibrium phases by rapid quenching, and direct compositional analysis of the phases using microanalysis techniques. The new data have enabled the effects of sulfur dioxide partial pressure between 0.1 and 0.6 atm on the equilibria to be accurately determined. Whilst, for a given matte grade, the dissolved copper in slag is not sensitive to sulfur dioxide partial pressure, the Fe/SiO in slag in equilibrium with Tridymite was found to increase with increasing p(SO). This latter observation has implications for fluxing practice in industrial copper smelting operations.
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the effect of al2o3 on fayalite based copper smelting slags in equilibrium with matte and Tridymite at 1 200 c and p so2 0 25 atm
International Journal of Materials Research, 2020Co-Authors: Ata Fallahmehrjardi, P C Hayes, Taufiq Hidayat, Evgueni JakAbstract:Experimental investigations have been undertaken to determine the effect of Al2O3 in slag on the gas/slag/matte/Tridymite equilibria in the multi-component Cu-Fe-O-S-Si-Al system at 1 200 degrees C, and P(SO2) = 0.25 atm. The experimental technique involves high temperature equilibration of synthetic samples on the open silica substrate in controlled gas atmospheres (CO/CO2/SO2/Ar), rapid quenching after a designated equilibration time followed by the compositional analysis of the condensed phases with electron probe X-ray microanalyzer. The experimental data of the present study provide information on the effect of alumina on the slag composition, such as the chemically dissolved copper, dissolved sulphur, and Fe/SiO2 ratio in slag at Tridymite saturation at different Cu in matte. The new data have been used as inputs for the optimization of the thermodynamic databases for the copper-containing systems and can also be used to evaluate the fluxing strategy in the copper smelting operation.
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experimental study of gas slag matte Tridymite equilibria in the cu fe o s si al system at 1573 k 1300 c and p so 2 0 25 atm
Journal of Phase Equilibria and Diffusion, 2020Co-Authors: Hamed Abdeyazdan, Ata Fallahmehrjardi, P C Hayes, M A Shevchenko, Taufiq Hidayat, Evgueni JakAbstract:Fundamental experimental investigations have been conducted to study the effect of Al2O3 on the equilibria between the gas phase (CO-CO2-SO2-Ar) and slag-matte-Tridymite phases in the Cu-Fe-O-S-Si-Al system at 1573 K (1300 °C) and P(SO2) = 0.25 atm. The experimental technique used is based on equilibration, rapid quenching and electron probe x-ray microanalysis. New experimental data have been obtained for the four-phase gas-slag-matte-Tridymite equilibria system for a range of alumina concentrations up to 20.4 mass% in the slag phase as a function of matte grade, including the concentrations of dissolved sulphur and copper in slag, and Fe/SiO2 ratios in slag. The results obtained for 1573 K (1300 °C) are also used to analyse the effect of temperature on phase equilibria in the range of conditions investigated to that of reported for 1473 K (1200 °C) in the literature. The results obtained show that the concentrations of sulphur, copper and “FeO” in slag decrease with increase of Al2O3 concentration in slag while it has no detectable effect on concentration of sulphur in matte for a given matte grade. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input for optimisation of the FactSage thermodynamic database for the copper-containing, multi-component multi-phase system.
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experimental investigation of gas slag matte Tridymite equilibria in the cu fe o s si al ca mg system in controlled gas atmosphere experimental results at 1473 k 1200 c 1573 k 1300 c and p so2 0 25 atm
Journal of Phase Equilibria and Diffusion, 2020Co-Authors: Svetlana Sineva, Ata Fallahmehrjardi, P C Hayes, M A Shevchenko, Taufiq Hidayat, Denis Shishin, Evgueni JakAbstract:The effect of temperature, CaO, MgO and Al2O3 on important technological copper smelting parameters, such as the chemically dissolved copper in slag and the composition of the liquid phase in equilibrium with Tridymite, are experimentally characterised as a function of copper concentration in matte. Two series of experiments for the gas/slag/matte/Tridymite equilibria in the Cu-Fe-O-S-Si system at p(SO2) = 0.25 atm have been carried out. The effect of CaO at 1573 K (1300 °C), and the combined effect of Al2O3 + CaO + MgO at 1473 K (1200 °C) and 1573 K (1300 °C) have been measured in the first and second series of experiments respectively. The experimental methodology involves high temperature equilibration of samples on a substrate made from the primary phase under controlled gas atmosphere (CO/CO2/SO2/Ar), followed by rapid quenching of the equilibrium condensed phases and direct measurement of the phase compositions using the Electron Probe x-ray Microanalysis. The resulting data are used in the optimization of the thermodynamic database for the copper-containing systems.
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the effect of cao on gas slag matte Tridymite equilibria in fayalite based copper smelting slags at 1473 k 1200 c and p so 2 0 25 atm
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2018Co-Authors: Ata Fallahmehrjardi, P C Hayes, Evgueni JakAbstract:Fundamental experimental studies have been undertaken to determine the effect of CaO on the equilibria between the gas phase (CO/CO2/SO2/Ar) and slag/matte/Tridymite phases in the Cu-Fe-O-S-Si-Ca system at 1473 K (1200 °C) and P(SO2) = 0.25 atm. The experimental methodology developed in the Pyrometallurgy Innovation Centre was used. New experimental data have been obtained for the four-phase equilibria system for fixed concentrations of CaO (up to 4 wt pct) in the slag phase as a function of copper concentration in matte, including the concentrations of dissolved sulfur and copper in slag, and Fe/SiO2 ratios in slag at Tridymite saturation. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input to optimize the thermodynamic database for the copper-containing multi-component multi-phase system.
Haibo Zou - One of the best experts on this subject based on the ideXlab platform.
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Fe-Al-rich Tridymite-hercynite xenoliths with positive cerium anomalies: preserved lateritic paleosols and implications for Miocene climate
2020Co-Authors: Haibo Zou, Kevin D Mckeegan, Alan ZindlerAbstract:Abstract We report isotopic and chemical compositions of unusual Tridymite -hercynite xenoliths in middle Miocene Niutoushan tholeiites from the southeast coastal area of China. These xenoliths are characterized by positive cerium (Ce) anomalies and extremely high Al 2 O 3 (32 -34 wt.%) and total iron oxide (20 -22%). . Their chemical and isotopic compositions suggest that these xenoliths represent preserved aluminous lateritic paleosols that are not genetically related to host tholeiites. These lateritic paleosols with strongly desilicated minerals were formed by intense chemical weathering under warm and humid tropical conditions (with annual average temperature of >19 jC and the annual rainfall of >165 cm) in SE China during the interval from 17 to 15 Ma. The formation age of the paleosols corresponds to a period characterized by slow uplift of the Himalayan -Tibetan Plateau region (and thus less consumption of CO 2 ) after 17 Ma, and eruptions of 17 -15 Ma Columbia River flood basalts, the Vogelsberg basalts, and eastern China basalts (and thus more input of CO 2 into the atmosphere). The Tridymite -hercynite xenoliths in the Niutoushan basalts thus preserve evidence of extraordinary climatic greenhouse conditions in the middle Miocene that would otherwise have been lost by the erosion of paleosols.
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fe al rich Tridymite hercynite xenoliths with positive cerium anomalies preserved lateritic paleosols and implications for miocene climate
Chemical Geology, 2004Co-Authors: Haibo Zou, Kevin D Mckeegan, Alan ZindlerAbstract:We report isotopic and chemical compositions of unusual Tridymite–hercynite xenoliths in middle Miocene Niutoushan tholeiites from the southeast coastal area of China. These xenoliths are characterized by positive cerium (Ce) anomalies and extremely high Al2O3 (32–34 wt.%) and total iron oxide (20–22%). They have 87 Sr/ 86 Sr of 0.7050–0.7058, eNd(0) values of +3.2 to +4.2, 206 Pb/ 204 Pb ratios of 18.8–19.1, and d 18 O values of +5.2xto +6.1x. Their chemical and isotopic compositions suggest that these xenoliths represent preserved aluminous lateritic paleosols that are not genetically related to host tholeiites. These lateritic paleosols with strongly desilicated minerals were formed by intense chemical weathering under warm and humid tropical conditions (with annual average temperature of >19 jC and the annual rainfall of >165 cm) in SE China during the interval from 17 to 15 Ma. The formation age of the paleosols corresponds to a period characterized by slow uplift of the Himalayan–Tibetan Plateau region (and thus less consumption of CO2) after 17 Ma, and eruptions of 17–15 Ma Columbia River flood basalts, the Vogelsberg basalts, and eastern China basalts (and thus more input of CO2 into the atmosphere). The Tridymite–hercynite xenoliths in the Niutoushan basalts thus preserve evidence of extraordinary climatic greenhouse conditions in the middle Miocene that would otherwise have been lost by the erosion of paleosols. D 2004 Elsevier B.V. All rights reserved.
