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891.
Edmund A. Jarzembowski B. Wang 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(6):673-676
Mayflies are very rare in the British fossil record. The first nymph to be found, Schistonotorum wallisi gen. et sp. nov., is described from the non-marine Lower Cretaceous of southeast England. This Early Barremian find is from the Upper Weald Clay Formation at Smokejacks brickworks, Surrey. It is preserved as an adpression in concretionary sideritic ironstone from the upper insect bed exposed in the northeast face of the pit. The palaeoecological significance of this record is discussed. 相似文献
892.
Saskia Erdmann Rucheng Wang Fangfang Huang Bruno Scaillet Kai Zhao Hongsheng Liu Yan Chen Michel Faure 《Comptes Rendus Geoscience》2019,351(8):551-561
Constraining crystallization pressure and thus intrusion depth of granites in various geodynamic settings remains challenging, yet important to further our understanding of magma system and crustal evolution. We propose that titanite, which is a common accessory in metaluminous and weakly peraluminous granites, can be used as a barometer if it crystallized in magmatic, near-solidus conditions and in equilibrium with amphibole, plagioclase, K-feldspar, quartz, biotite, and magnetite ± ilmenite. Titanite Al2O3 increases with pressure (P) according to: P (in MPa) = 101.66 × Al2O3 in titanite (in wt%) + 59.013 (R2 = 0.83) with estimated uncertainties of ~±60 to ~±100 MPa for crystallization between ~150 and 400 MPa. We highlight that the current calibration dataset is limited, and that systematic experimental studies are needed to rigorously quantify the relation. The most important use of this empirical barometer will be for rocks in which amphibole is present but significantly altered, or in combination with amphibole barometry, as titanite can be easily dated by LA-ICP-MS. 相似文献
893.
This laboratory study seeks to investigate the effect of surface irregularities on the motion characteristics of a falling rock. The irregularly-shaped surfaces of greywacke with a range of joint roughness coefficient (JRC) from 2 to 18 were used in an experimental setup where a falling rock was dropped from a height of 110 cm. A high-speed camera was utilised to capture the trajectory of the falling rock upon its impact with the rock surface. The data from 287 tests were statistically analysed to determine the dominant type of motion and to establish relationships between JRC and the coefficient of restitution (CoR). The effect of surface roughness was seen in different modes of motion of the falling rock with more irregular surfaces often produced ‘sliding’ or ‘rolling’ instead of ‘bouncing’. The obtained data indicated that the rock surface roughness did not seem to have a significant effect on CoR; however, it affected the rebound angle of the falling rock. 相似文献
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Concentrations of ten metals were measured in waters and sediments at 14 sites during four sampling periods (1996–1997). These sites include various marine ecosystems that are highly influenced by industry, tourism and river discharges, nine of which are within the Morrocoy National Park. Spatially, metal concentrations in water were homogenous, whereas in sediments their distributions were related to grain size. Maximum concentrations of cadmium (Cd) and mean concentrations of copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in water were above the guideline values proposed by NOAA, indicating the potential of these metals for producing chronic effects in marine biota. Sheltered sites showed the highest metal concentrations in sediments; with Cd and Zn above these guidelines. Enrichment factors and geo-accumulation indexes suggested that metals in sediments were largely of natural origin except for Pb, Cd and vanadium (V), which were apparently associated with industrial effluents. A disruption of the spatial distribution of metals after heavy rainfall, when exposed sites reached concentrations as high as those in sheltered sites, showed the influence of nearby rivers. The potential increase of such climatic events could represent additional stress for natural protected areas in the Caribbean. 相似文献
899.
冰芯与寒区环境开放研究实验室的回顾与展望 总被引:3,自引:1,他引:2
History and current situations of ice core research in China are reviewed following the establishment of the Laboratory of Ice Core and Cold Regions Environment, CAS. At present, three research foci are mainly carried out in the laboratory, namely: (1) Interaction between glacier and atmosphere; (2) Ice core records; (3) The physics of snow and ice. Within the passing several years. over forty projects have been finished or are being carried out. and about 300 papers were published in various international or domestic scientific journals and 9 monographs were published too. The research results have been awarded two first-class prizes by the Chinese Academy of Sciences, one third-class national prize. and one fourth-class national prize. Intensive cooperation with authoritative research institutions has contributed much to the laboratory. which will be continuously emphasized in the future. 相似文献
900.
日本的国土开发对中国西部大开发的启示 总被引:4,自引:1,他引:3
本文在评述和总结日本国土开发中所取得的成功经验基础上 ,提出了中国在西部大开发中需要注意的四个问题 :一是要制定明确的开发目标和切实可行的开发方式 ,并通过立法的形式保障开发计划的实施 ;二是有效发挥社会资本和民间资本对西部开发的作用 ;三是加大力度促进西部中小城市的发展 ;四是在西部大开发中处理好资源、环境和灾害等问题。 相似文献