Liu B.,China University of Geosciences |
Su X.,China University of Geosciences |
Zheng H.,General Institute of Chemical Geology Survey of China Chemical Geology and Mine Bureau
Chemie der Erde - Geochemistry | Year: 2013
The South China Sea (SCS) is the largest marginal sea in the Western Pacific. A total of 106 sediment core samples was taken from Ocean Drilling Program (ODP) Site 1146 in the SCS and analyzed for major and trace elements. Three stratigraphic sedimentary units (I, II and III) were recognized at this site. Except for the Ca and Na contents, the contents of all the major elements in the sediments taken from Site 1146 were significantly positively correlated with the Al contents, indicating that they were associated with micaceous/clay minerals in the sediments. The sediments were strongly enriched for Ca and Sr in Unit IIA compared to the average upper continental crust (UCC), relative to the other units, while all major elements (except for Na and Ca) were significantly depleted in the unit. High correlations among the contents of Ca, Sr and calcium carbonate suggested that the down-core distribution of most major elements might be affected by the dilution effect of biogenic carbonate. The samples were strongly enriched in transition elements (TTEs) and slightly depleted in high field strength elements (HFSEs) (e.g., Nb and Y), and light rare earth elements (LREEs), such as La and Ce, relative to the UCC. The chemical index of alteration (CIA) in the sediment core ranged between 54 and 72 with an average of 64, reflecting low to intermediate source area weathering intensity. The chemical weathering intensity, in combination with the geochemical proxies of Ti/Na, Al/Na and K/Na, and the mineralogical features of the sediment core, indicated that the climate in the source area had cooled down gradually since the Early Miocene. By comparing the geochemical characteristics of suspended sediments from the Pearl River, the Yangtze River, the Red River, the Chinese Loess and sedimentary rock from Taiwan, we inferred that the sedimentary rock of Taiwan, as well as the suspended sediments from the Yangtze River and the Chinese Loess, might be similar in provenance to the sediments from Site 1146, whereas the Pearl River and the Red River might not play a significant role in contributing detrital material to the site. The detrital material of the northern part of the SCS could be derived from a siliceous igneous source with no major contribution from basic igneous rocks (e.g., the volcanic Taiwan-Luzon Arc). The triangular diagrams of A-CN-K and La-Th-Sc suggested that the samples were not affected by K-metasomatism and came from the same source area; granodiorite was the most likely source rock for these samples. Therefore, the South China craton is believed to be the dominant source of the Site 1146 sediments. © 2012 Elsevier GmbH.
Zhao Z.-Q.,Chinese Academy of science |
Zhao Z.-Q.,CAS Institute of Earth Environment |
Zhao Z.-Q.,Xiamen University |
Zhang W.,Chinese Academy of science |
And 8 more authors.
Atmospheric Environment | Year: 2015
Total suspended particles (TSP) and their source-related samples from Guiyang, Southwest China, were collected and analyzed for their lead (Pb) concentrations and Pb isotopic compositions, to identify the sources of atmosphere lead in urban Guiyang. Coals from Guizhou Province had significantly high radiogenic Pb, different to those from North China. Local vehicle exhaust had similar Pb isotope ratios to those of other areas in China. Pb isotopic compositions of atmospheric aerosols, rainwaters, plant samples, and acid-soluble fraction of street dusts were similar to each other. The results clearly suggest that the Pb-Zn ore-related industrial emission, and/or vehicle exhaust, rather than the local coal combustion, are the main sources of atmospheric Pb in Guiyang. Furthermore, binary mixing model indicates that the contribution of coal combustion to the local atmospheric Pb decreased from about 40% in 1988 to about 10% in 2013. © 2015 Elsevier Ltd.
He X.-H.,CAS Institute of Geology and Geophysics |
He X.-H.,University of Chinese Academy of Sciences |
He X.-H.,General Institute of Chemical Geology Survey of China Chemical Geology and Mine Bureau |
Wang S.-J.,CAS Institute of Geology and Geophysics |
And 3 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013
Since it has insufficient demonstration of theoretical basis of taking the first displacement data as the known condition, the original synergetic model is improved. Based on the improved model, a formula for displacement prediction and landslide time is deduced. In addition, the analysis results indicate that taking the maximum velocity as the forecast criterion of landslide time in the original synergetic model lacks rationality, and taking the maximum acceleration as the forecast criterion is more in accordance with the mechanism of landslides. Then the formula for the forecast value of landslide time based on the maximum acceleration criterion of synergetic model is deduced. Based on the deduced formulas mentioned above, the original and improved synergetic models and the two kinds of criteria are applied to the time forecast of some examples of actual landslides by using MATLAB software. The prediction and forecast results indicate that: (1) the forecast time of the improved synergetic model is closer to the actual occurrence time of landslides, and earlier than that of the original model. The precision of displacement prediction of the improved model is higher than that of the original model; (2) as for the forecast results of two kinds of criteria, the forecast time of the maximum acceleration criterion is earlier than that of the maximum velocity criterion, and its forecast error is smaller than that of the maximum velocity criterion; and (3) the forecast time of the improved model based on the maximum acceleration criterion is very closer and a little earlier than the actual occurrence time of landslides, and it can play a role in early warning. So, the improved model is better than the original one, and the maximum acceleration criterion is better than the maximum velocity one. The application of the improved model based on the maximum acceleration criterion to landslide prediction and forecast is feasible, and its forecast results are much better than those of the original model.
Wang J.-P.,Geological Institute of China Chemical Geology and Mine Bureau |
Shang P.-Q.,Geological Institute of China Chemical Geology and Mine Bureau |
Xiong X.-X.,General Institute of Chemical Geology Survey of China Chemical Geology and Mine Bureau |
Yang H.-Y.,Geological Institute of China Chemical Geology and Mine Bureau |
Tang Y.,General Institute of Chemical Geology Survey of China Chemical Geology and Mine Bureau
Geology in China | Year: 2015
Based on the classification of fluorite deposits, this paper divides the metallogenic units of fluorite deposits, and briefly describes ore-forming features of every unit according to the geotectonic background, distribution features, ore-forming conditions and ore-controlling factors. In addition, the metallogenic regularities of fluorite deposits in China are summarized. Fluorite deposits are mainly distributed in northern and southeastern China. The faulted fractures constitute the common and essential ore-forming factor. The deposition-reformation type fluorite deposits are genetically related to limestone and volcanic rocks. The most intrusive rocks related to the formation of fluorite deposits belong to Yanshanian period. Most deposition-reformation, hydrothermal-reformation, associated, large and gigantic fluorite deposits are genetically related to limestone. The deposits with three ore-forming elements of limestone, Yanshanian intrusive rocks and faulted fractures are generally large or gigantic fluorite deposits. Fluorite deposits in China were mainly formed in Yanshanian period.