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431.
432.
BARBARA WOHLFARTH SVANTE BJÖRCK GÖRAN POSSNERT BJÖRN HOLMQUIST 《Boreas: An International Journal of Quaternary Research》1998,27(4):243-257
More than 50 varve-thickness diagrams, which were established from glacial varved clays in south-eastern Sweden were correlated with each other to form an 800-year long floating varve chronology. AMS |214|0C measurements on terrestrial macrofossils from the varved clays enabled synchronization of the record with other high-resolution archives. The synchronization indicates that the chronology spans between c. 13 150 and c. 12 350 calendar years BP and covers the later part of the Allerørd and the early part of the Younger Dryas. Calibrated radiocarbon dates, which were obtained on varved clays south of the floating chronology, indicate that the ice recession in south-eastern Sweden may have started during late Bølling. Our results indicate a longer time-span in varve years for the deglaciation than has been previously estimated 相似文献
433.
An idealised two-basin model is used to investigate the impact of the wind field on the heat exchange between the ocean basins. The scalar potential of the divergent component of the horizontal heat flux is computed, which gives a 'coarse-grained' image of the surface heat flux that captures the large-scale structure of the horizontal heat transport. Further the non-divergent component is examined, as well as the meridional heat transport and the temperature–latitude overturning stream function. A sensitivity analysis examines the heat transport response to changes in wind stress at different latitudes. The results are compared with results from an eddy-permitting global circulation model. The westerly wind stress over the Southern Ocean has two effects: a local reduction of the surface heat loss in response to the equatorward surface Ekman drift, and a global re-routing of the heat export from the Indo-Pacific. Without wind forcing, the Indo-Pacific heat export is released to the atmosphere in the Southern Ocean, and the net heat transport in the southern Atlantic is southward. With wind forcing, the Indo-Pacific export enters the Atlantic through the Aghulas and is released in the Northern Hemisphere. The easterlies enhance the poleward heat transport in both basins. 相似文献
434.
经过4年的攻关,国家“863”计划重点项目“2000m地质岩心钻探关键技术与装备”研制取得了多项创新成果,主要包括:完成了地面钻探设备及孔内钻探取心器具集成配套,形成了深部岩心钻探施工和示范能力;完成了山东金青顶矿区危矿专项ZK43—1钻孔施工,终孔深度2212.80m。全孔平均钻进时效为1.65m,岩心采取率为98.6%,钻孔质量优良;创造了3项钻深和套管下入深度全国记录;在大项目运作机制、产学研合作模式及钻探技术示范方式等方面积累了一些经验。详细介绍了项目的研制情况及取得的主要成果。 相似文献
435.
The Qulong deposit in Tibet is one of the largest porphyry copper-molybdenum deposits in China. We used short-wave infrared (SWIR) spectroscopy to examine the spectral characteristics of the extensively developed chlorite in this deposit. X-ray diffraction and electron microprobe analyses were used for phase identification and to obtain the chemical composition, ion substitution relationships, and formation environment of the chlorite. SWIR spectral parameters were applied to detect the hydrothermal centers. The results indicate that the wavelength of the absorption feature for Qulong chlorite Fe-OH (Pos2250) range from 2240 to 2268.4 nm; the chlorite substitution relationships are dominated by Mg-Fe substitution at the octahedral sites together with AlⅣ-Si substitution at the tetrahedral sites; the chlorite formation temperatures range within the medium-low temperature hydrothermal alteration range from 164 to 281°C, with an average value of 264°C; the wavelength of the chlorite peak position for Fe-OH (2250 nm) absorption and its chemical composition are positively correlated with AlⅥ, Fe + AlⅥ, Fe/(Fe + Mg), Fe, and Fe + AlⅣ but negatively correlated with Mg and Mg/(Fe + Mg); and the wavelength associated with the chlorite Fe-OH (2250 nm) absorption feature is positively correlated with the temperature at which the chlorite formed. These correlations indicate that more Fe and AlⅥ ions and fewer Mg ions at the octahedral sites of chlorite lead to a longer the wavelength of the chlorite Fe-OH (2250 nm) absorption feature and a higher chlorite formation temperature. The wavelength of the Qulong chlorite Fe-OH (2250 nm) absorption feature (>2252 nm) can thus serve as an exploration indicator to guide the detection of hydrothermal centers in porphyry copper deposits. The results of the study indicate that the mineralogical and SWIR spectral characteristics of chlorite are significant indicators for locating hydrothermal centers within porphyry deposits. 相似文献
436.
437.
The deformation parameter (DP), which is defined as the product of shear deformation and stretching deformation of moisture flux circulation, is introduced. The tendency equation of DP is derived in pressure coordinates. Furthermore, DP is used to diagnose the deformation character of moisture flux circulation in the periphery of Bilis. The analysis showed that before Bilis landed, DP presented eight abnormal areas, which distributed alternately and closely encircled the low-pressure center. This indicated that the moisture flux circulation in the periphery of Bilis rotated counterclockwise and stretched longitudinally and latitudinally to deform. After Bilis landed, DP weakened gradually and its regular pattern of horizontal distribution loosened. The shear and stretching deformations of moisture flux circulation surrounding Bilis weakened after the typhoon landed. The deformation of moisture flux circulation in the periphery of Bilis mainly appeared in the middle-lower troposphere. There existed 1/2 phase difference between the shear and stretching deformations in the vertical-latitudinal cross section and aπ/4 phase difference between them on the horizontal plane. As Bilis landed and further moved inland of China, the intensities of DP, shear and stretching deformations decreased, meanwhile their vertical and horizontal structures became irregular. The chief dynamic factors responsible for the deformation of moisture flux circulation in the periphery of Bilis were the three terms associated with the three-dimensional advection transportation of DP, square difference between shear and stretching deformations coupling with Coriolis parameter, and horizontal gradient of geopotential height before Bilis landed. The last two dynamic factors impacted jointly on the deformation of moisture flux circulation after Bilis landed. 相似文献
438.
XU Xiwei YU Guihua CHEN Guihua RAN Yongkang LI Chenxia CHEN Yuegau CHANG Chungpai Institute of Geology China Eathquake Administrative Beijing 《《地质学报》英文版》2009,83(4)
On May 12th,2008,the M_w7.9 Wenchuan earthquake ruptured the Beichuan,Pengguan and Xiaoyudong faults simultaneously along the middle segment of the Longmenshan thrust belt at the eastern margin of the Tibetan plateau.Field investigations constrain the surface rupture pattern, length and offsets related to the Wenchuan earthquake.The Beichuan fault has a NE-trending rightlateral reverse rupture with a total length of 240 km.Reassessment yields a maximum vertical offset of 6.5±0.5 m and a maximum right-lat... 相似文献
439.
440.
基于斐索干涉仪的直接探测多普勒测风激光雷达 总被引:5,自引:0,他引:5
提出结合多光束斐索(Fizeau)干涉仪和CCD探测器的条纹图像技术,测量地球边界层下的三维风场的直接探测多普勒激光雷达技术.在分析Fizeau干涉仪的物理特性和光谱特性以及影响测量多普勒频移的因数和改进方法的基础上,提出一套切合实际的直接探测多普勒激光雷达系统参数.并利用该参数进行性能评估分析,模拟不同干涉仪参数对风速精度的影响,得出一个优化的干涉仪物理参数.模拟结果显示,系统可以获得小于1 m s-1的水平风速精度.这些分析,为建立实际的激光雷达系统提供设计依据. 相似文献