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正The 2017 Geoscience Frontiers Annual Convention was held in Beijing,China during October 19-21,2017 hosted by China University of Geosciences,Beijing(Fig.1).This convention assembled earth scientists from seven countries,including Australia(Dr.Christopher Spencer and Dr.Stijn Glorie),Korea(Dr.S.Kwon),India(Dr.Shaji Erath),Japan(Dr.Toshiaki Tsunogae and Dr.Masaki Yoshida),Russia(Dr.Inna Safonova),UK(Dr.Nick Roberts),China,and also 相似文献
166.
Jin-wang Zhang Jia-chen Wang Wei-jie Wei Yi Chen Zheng-yang Song 《Arabian Journal of Geosciences》2018,11(5):96
Steep coal seam mining activities will frequently occur during the next few decades in China. In this study, both experimental and numerical methods are employed to investigate the coal drawing from thick steep seam with longwall top coal caving mining. A series of analyses is performed to investigate the features of the drawing body, the distribution of top coal recovery ratio and the shape of the rock flow under steep conditions. The results indicate that the drawing body of top coal develops prior to upper side of the panel face obviously, and the top coal in the central part of the panel has a higher recovery ratio than that in the lower and upper parts in steep coal seam with caving mining method. The flow paths of the fragmented top coal are nearly straight lines moving towards the drawing window, and the fastest path maintains a constant angle with the plumb line. The spatial shape of the rock flow indicates “bidirectional asymmetry,” which results from the presence of the shield beam and dip angle of the coal seam; thus, this is the root cause of the appearance of the drawing body’s prior development towards the upper side of the panel. The field observation data indicates the same distribution of top coal recovery as that in the physical experiment and numerical simulation. Furthermore, suggested measurements are proposed to improve top coal recovery in steep seam mining based on the engineering practice of Dayuan coal mine. 相似文献
167.
Kun?Wang Christina?Yan?WangEmail author Zhong-Yuan?RenEmail author 《Contributions to Mineralogy and Petrology》2018,173(7):59
The ~?2-km-thick Panzhihua gabbroic-layered intrusion in SW China is unusual because it hosts a giant Fe–Ti oxide deposit in its lower zone. The deposit consists of laterally extensive net-textured and massive Fe–Ti oxide ore layers, the thickest of which is ~?60 m. To examine the magmatic processes that resulted in the Fe enrichment of parental high-Ti basaltic magma and the formation of thick, Fe–Ti oxide ore layers, we carried out a detailed study of melt inclusions in apatite from a ~?500-m-thick profile of apatite-bearing leucogabbro in the middle zone of the intrusion. The apatite-hosted melt inclusions are light to dark brown in color and appear as polygonal, rounded, oval and negative crystal shapes, which range from ~?5 to ~?50 µm in width and from ~?5 to ~?100 µm in length. They have highly variable compositions and show a large and continuous range of SiO2 and FeOt with contrasting end-members; one end-member being Fe-rich and Si-poor (40.2 wt% FeOt and 17.7 wt% SiO2) and the other being Si-rich and Fe-poor (74.0 wt% SiO2 and 1.20 wt% FeOt). This range in composition may be attributed to entrapment of the melt inclusions over a range of temperature and may reflect the presence of µm-scale and immiscible Fe-rich and Si-rich components in different proportions. Simulating results for the motion of Si-rich droplets within a crystal mush indicate that Si-rich droplets would be separated from Fe-rich melt and migrate upward due to density differences in the interstitial liquid when the magma unmixed. Migration of the Si-rich, immiscible liquid component from the interstitial liquid caused the remaining Fe-rich melt in the lower part to react with plagioclase primocrysts (An59–60), as evidenced by fine-grained lamellar intergrowth of An-rich plagioclase (An79–84)?+?clinopyroxene in the oxide gabbro of the lower zone. Therefore, magma unmixing within a crystal mush, combined with gravitationally driven loss of the Si-rich component, resulted in the formation of Fe-rich, melagabbro and major Fe–Ti oxide ores in the lower part and Si-rich, leucogabbro in the upper part of the intrusion. 相似文献
168.
L. Z. Reznitskii V. P. Kovach I. G. Barash Yu. V. Plotkina K. -L. Wang H. -Y. Chiu 《Stratigraphy and Geological Correlation》2018,26(5):489-513
The results of U—Th—Pb (LA-ICP-MS) geochronological studies of detrital zircons from terrigenous rocks of the Dzhida terrane of the Central Asian Fold Belt (CAFB) are presented. The data obtained allow us to distinguish the following age maxima (Ma): 578 and 634 (Vendian); 720, 823, and 919 (Late Riphean); 1922, 2090, 2225, and 2321 (Early Proterozoic). A number of zircons have Late Archean age in the interval of 2670–2980 Ma. Taking into account Late Cambrian age (504–506 Ma) of intrusive rocks that intruded the Dzhida terrane, a possible sedimentation period of sequences of this terrane is estimated to be in the interval of 580–510 Ma (from Vendian to Late Cambrian). The possible provenance areas of terrigenous sediments are proposed and the previously proposed models of geodynamic evolution of the Dzhida terrane are correlated with new geochronological data. 相似文献
169.
Windblown dust originating in China and Mongolia causes health effects and agricultural damage in its source areas and causes Asian dust events in Japan. An early warning system that could be combined with weather forecasts would be helpful in preventing serious damage. However, it is difficult to specify source areas of dust with current dust modeling systems because land surface information, including vegetation coverage and land surface soil water content, is inadequate. To find and monitor dust source regions, a semi-real-time dust erodibility map was developed based on MODIS satellite data that focuses particularly on the threshold wind speed in a target area of northeast Asia including China and Mongolia (35°–50°N, 75°–120°E). The mapping system incorporates satellite data on snow cover, areas of frozen soil, surface soil water content, and vegetation cover. 相似文献
170.
Wang Minfang Zhang Xubo Guo Xiaonan Pi Daohui Yang Meijun 《Mineralogy and Petrology》2018,112(1):85-103
Mineralogy and Petrology - Electron probe microanalysis (EPMA) results are reported for newly identified silver–bearing minerals from the Xinhua deposit, Yunkaidashan area, South China. The... 相似文献