Mineralogy and geochemistry of the four main workable coal seams (No.6, No.7, No.8, and No.11) of Late Permian age from the Songzao Coalfield, Chongqing, Southwest China, were examined using in- ductively coupled plas...Mineralogy and geochemistry of the four main workable coal seams (No.6, No.7, No.8, and No.11) of Late Permian age from the Songzao Coalfield, Chongqing, Southwest China, were examined using in- ductively coupled plasma-mass spectrometry (ICP-MS), X-ray fluorescence spectrometry (XRF), cold-vapor absorption spectrometry (CV-AAS), ion-selective electrode (ISE), scanning electron mi- croscopy equipped with an energy-dispersive X-ray spectrometer (SEM-EDX), and X-ray diffraction analysis (XRD). The results showed that the main workable No.8 Coal that accounts for about 60% of the total coal reserves in the Songzao Coalfield was not enriched in hazardous trace elements. The No.11 Coal has high concentrations of alkaline elements, Be (9.14 μg/g), Sc (12.9 μg/g), Ti (9508 μg/g), Mn (397 μg/g), Co (23.7 μg/g), Cu (108 μg/g), Zn (123 μg/g), Ga (32 μg/g), Zr (1304 μg/g), Nb (169 μg/g), Hf (32.7 μg/g), Ta (11.4 μg/g), W (24.8 μg/g), Hg (0.28 μg/g), Pb (28.1 μg/g), Th (24.1 μg/g), and rare earth elements (509.62 μg/g). The concentration of Nb and Ta in the No. 11 Coal is higher than the industrial grade, and their potential utilization should be further studied. Besides pyrite, quartz, calcite, and clay minerals, trace minerals including chalcopyrite, marcasite, siderite, albite, mixed-layer clay minerals of illite and smectite, monazite, apatite, anatase, chlorite, and gypsum were found in the No.11 Coal. It should be noted that alabandite of hydrothermal origin and anatase occurring as cement were identi- fied in coal. In addition, the clayey microbands derived from alkaline volcanic ashes were identified in the coal. The dominant compositions of these clayey microbands were mixed-layer clay minerals of illite and smectite, which were interlayered with organic bands. The modes of occurrence of alkaline volcanic ash bands indicate that the volcanic activities were characterized by the multiple eruptions, short time interval and small scale for each eruption during peat accumulation. The alkaline volcanic a展开更多
Trace element compositions of garnet, omphacite and apatite in ultrahigh-pressure eclogites from the main hole of the Chinese Continental Scientific Drilling (CCSD) project were in situ analyzed by the LA-ICP-MS metho...Trace element compositions of garnet, omphacite and apatite in ultrahigh-pressure eclogites from the main hole of the Chinese Continental Scientific Drilling (CCSD) project were in situ analyzed by the LA-ICP-MS method. Although both garnet and omphacite have homogeneous major element composi-tions, their trace elements show zonations from core to rim in rare earth elements. In particular, middle rare earth elements in the garnet, heavy rare earth elements in the apatite and all rare earth elements in the omphacite increase from core to rim, respectively. Based on dependence of partition coefficients on temperature and pressure in these minerals, we suggest that the trace elemental zonations in these minerals may record a short-lived heating event during exhumation.展开更多
Emissions of mineral dust and its mixing with anthropogenic air pollutants affect both regional and global climates. Our fieldwork in late spring 2007（April 25-June 15） measured the physical and optical properties o...Emissions of mineral dust and its mixing with anthropogenic air pollutants affect both regional and global climates. Our fieldwork in late spring 2007（April 25-June 15） measured the physical and optical properties of dust storms mixed with local air pollutants at a rural site about 48 km southeast of central Lanzhou. Levels of air pollutants and aerosol optical properties were observed during the experiment, with concentrations of NOx（6.8 ± 3.3 ppb, average ± standard deviation）, CO（694 ± 486 ppb）, SO2（6.2 ±10 ppb）, O3（50.7 ± 13.1 ppb）, and PM10（172 ± 180 μg m-3）, and aerosol scattering coefficient（164 ±89 Mm-1; 1 Mm = 106m） and absorption coefficient（11.7 ± 6.6 Mm-1）, all much lower than the values observed during air pollution episodes in urban areas. During a major dust storm, the mass concentration of PM10 reached 4072 μg m-3, approximately 21-fold higher than in non-dust storm periods. The mixing ratios of trace gases declined noticeably after a cold front passed through. The observed CO/SO2 and CO/NOx ratios during air pollution episodes were 4.2-18.3 and 13.7-80.5, respectively, compared with the corresponding ratios of 38.1-255.7 and 18.0-245.9 during non-pollution periods. Our investigations suggest that dust storms have a significant influence on air quality in areas far from their source, and this large-scale transport of dust and air pollutants produces major uncertainties in the quantification of the global effects of emissions over Northwest China.展开更多
Methods recently advanced for discrimination on the genesis of metamorphic zircon, such as analysis of mineral inclusions and trace elements, provide us powerful means to distinguish zircon overgrowth during high-pres...Methods recently advanced for discrimination on the genesis of metamorphic zircon, such as analysis of mineral inclusions and trace elements, provide us powerful means to distinguish zircon overgrowth during high-pressure metamorphism. Zircons in ultrahigh-pressure eclogite from Qinglongshan in the Sulu terrane were studied by the SHRIMP U-Pb method in combining with trace element and mineral inclusion analyses. No inherited core was identified in the analyzed zircons by means of cathodoluminescence images. The occurrence of high-pressure metamorphic mineral inclusions in zircon, such as garnet, omphacite, rutile, and the flat HREE pattern in zircon indicate that the zircon formed at high-pressure metamorphic conditions. Therefore, a weighted average U-Pb age of 227.4 ± 3.5 Ma obtained from such a kind of zircon is interpreted to represent the timing of peak metamorphism for the Qinglongshan eclogite.展开更多
基金Supported by the National Key Basic Research and Development Program (Grant No. 2006CB202201)the National Natural Science Foundation of China (Grant No. 40472083)the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 200448)
文摘Mineralogy and geochemistry of the four main workable coal seams (No.6, No.7, No.8, and No.11) of Late Permian age from the Songzao Coalfield, Chongqing, Southwest China, were examined using in- ductively coupled plasma-mass spectrometry (ICP-MS), X-ray fluorescence spectrometry (XRF), cold-vapor absorption spectrometry (CV-AAS), ion-selective electrode (ISE), scanning electron mi- croscopy equipped with an energy-dispersive X-ray spectrometer (SEM-EDX), and X-ray diffraction analysis (XRD). The results showed that the main workable No.8 Coal that accounts for about 60% of the total coal reserves in the Songzao Coalfield was not enriched in hazardous trace elements. The No.11 Coal has high concentrations of alkaline elements, Be (9.14 μg/g), Sc (12.9 μg/g), Ti (9508 μg/g), Mn (397 μg/g), Co (23.7 μg/g), Cu (108 μg/g), Zn (123 μg/g), Ga (32 μg/g), Zr (1304 μg/g), Nb (169 μg/g), Hf (32.7 μg/g), Ta (11.4 μg/g), W (24.8 μg/g), Hg (0.28 μg/g), Pb (28.1 μg/g), Th (24.1 μg/g), and rare earth elements (509.62 μg/g). The concentration of Nb and Ta in the No. 11 Coal is higher than the industrial grade, and their potential utilization should be further studied. Besides pyrite, quartz, calcite, and clay minerals, trace minerals including chalcopyrite, marcasite, siderite, albite, mixed-layer clay minerals of illite and smectite, monazite, apatite, anatase, chlorite, and gypsum were found in the No.11 Coal. It should be noted that alabandite of hydrothermal origin and anatase occurring as cement were identi- fied in coal. In addition, the clayey microbands derived from alkaline volcanic ashes were identified in the coal. The dominant compositions of these clayey microbands were mixed-layer clay minerals of illite and smectite, which were interlayered with organic bands. The modes of occurrence of alkaline volcanic ash bands indicate that the volcanic activities were characterized by the multiple eruptions, short time interval and small scale for each eruption during peat accumulation. The alkaline volcanic a
基金Supported by the Ministry of Science and Technology of China (Grant No. 2003CB716501)the National Natural Science Foundation of China (Grant Nos. 40521001 and 40473013)+2 种基金the Program for New Century Excellent Talents in Uni-versity (Grant No. NCET-05-0664)the State Key Laboratory of GPMR, China University of Geosciences (Grant No. GPMR0511)the State Key Laboratory of Continental Dynamics, Northwest University, China
文摘Trace element compositions of garnet, omphacite and apatite in ultrahigh-pressure eclogites from the main hole of the Chinese Continental Scientific Drilling (CCSD) project were in situ analyzed by the LA-ICP-MS method. Although both garnet and omphacite have homogeneous major element composi-tions, their trace elements show zonations from core to rim in rare earth elements. In particular, middle rare earth elements in the garnet, heavy rare earth elements in the apatite and all rare earth elements in the omphacite increase from core to rim, respectively. Based on dependence of partition coefficients on temperature and pressure in these minerals, we suggest that the trace elemental zonations in these minerals may record a short-lived heating event during exhumation.
基金Supported by the National Nature Science Foundation of China(41175134,41105110,and 41305025)Fundamental Research Funds for Central Universities of China(LZUJBKY-2014-110)China 111 Project(B13045)
文摘Emissions of mineral dust and its mixing with anthropogenic air pollutants affect both regional and global climates. Our fieldwork in late spring 2007（April 25-June 15） measured the physical and optical properties of dust storms mixed with local air pollutants at a rural site about 48 km southeast of central Lanzhou. Levels of air pollutants and aerosol optical properties were observed during the experiment, with concentrations of NOx（6.8 ± 3.3 ppb, average ± standard deviation）, CO（694 ± 486 ppb）, SO2（6.2 ±10 ppb）, O3（50.7 ± 13.1 ppb）, and PM10（172 ± 180 μg m-3）, and aerosol scattering coefficient（164 ±89 Mm-1; 1 Mm = 106m） and absorption coefficient（11.7 ± 6.6 Mm-1）, all much lower than the values observed during air pollution episodes in urban areas. During a major dust storm, the mass concentration of PM10 reached 4072 μg m-3, approximately 21-fold higher than in non-dust storm periods. The mixing ratios of trace gases declined noticeably after a cold front passed through. The observed CO/SO2 and CO/NOx ratios during air pollution episodes were 4.2-18.3 and 13.7-80.5, respectively, compared with the corresponding ratios of 38.1-255.7 and 18.0-245.9 during non-pollution periods. Our investigations suggest that dust storms have a significant influence on air quality in areas far from their source, and this large-scale transport of dust and air pollutants produces major uncertainties in the quantification of the global effects of emissions over Northwest China.
基金supported by the“973”Program of the Ministry of Science and Technology of China(Grant No.G1999075503)the National Natural Science Foundation of China(Grant No.40173014)China Postdoctoral Science Founda-tion.
文摘Methods recently advanced for discrimination on the genesis of metamorphic zircon, such as analysis of mineral inclusions and trace elements, provide us powerful means to distinguish zircon overgrowth during high-pressure metamorphism. Zircons in ultrahigh-pressure eclogite from Qinglongshan in the Sulu terrane were studied by the SHRIMP U-Pb method in combining with trace element and mineral inclusion analyses. No inherited core was identified in the analyzed zircons by means of cathodoluminescence images. The occurrence of high-pressure metamorphic mineral inclusions in zircon, such as garnet, omphacite, rutile, and the flat HREE pattern in zircon indicate that the zircon formed at high-pressure metamorphic conditions. Therefore, a weighted average U-Pb age of 227.4 ± 3.5 Ma obtained from such a kind of zircon is interpreted to represent the timing of peak metamorphism for the Qinglongshan eclogite.
