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排序方式: 共有1556条查询结果,搜索用时 31 毫秒
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M. L. Demidov 《Solar physics》1996,164(1-2):381-388
The zero level problem of solar magnetographs is particularly important for observations of large-scale magnetic fields on the Sun. Experiments conducted at the STOP telescope of the Sayan observatory show that, in addition to adjustment errors of the polarization analyzer and the spectrograph focusing, spurious signals of the magnetograph are caused by polarization effects in optical components preceding the polarization analyzer and aberration errors of the spectrograph. 相似文献
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水成沉积与风成沉积及古土壤的磁组构特征 总被引:14,自引:2,他引:14
晚第四纪水成沉积、风成沉积、古土壤等的磁组构研究表明,不同成因的沉积物具有明显不同的磁组构特征。一般地,水成沉积的体积磁化率K受物源和水动力因素控制,P和F均>1.02,q<0.5;风成沉积的K受物源控制,内陆黄土的K明显高于沿海黄土及海岸风沙K,P和F均<1.02,q的平均值>0.55;古土壤的K受母质沉积类型和成土环境的氧化还原条件控制,内陆古土壤的K偏高,沿海古土壤的K偏低,内陆古土壤的K远高于沿海古土壤的K,P和F均<1.02,q的平均值在0.5左右。运用典型沉积的磁组构特征对比分析未知沉积物,可以得到未知沉积物的物源、沉积过程和环境信息。 相似文献
5.
The Blake Outer Ridge is a 480–kilometer long linear sedimentary drift ridge striking perpendicular to the North American
coastline. By modeling free-air gravity anomalies we tested for the presence of a crustal feature that may control the location
and orientation of the Blake Outer Ridge. Most of our crustal density models that match observed gravity anomalies require
an increase in oceanic crustal thickness of 1–3 km on the southwest side of the Blake Outer Ridge relative to the northeast
side. Most of these models also require 1–4 km of crustal thinning in zone 20–30 km southwest of the crest of the Blake Outer
Ridge. Although these features are consistent with the structure of oceanic fracture zones, the Blake Outer Ridge is not parallel
to adjacent known fracture zones. Magnetic anomalies suggest that the ocean crust beneath this feature formed during a period
of mid-ocean ridge reorganization, and that the Blake Outer Ridge may be built upon the bathymetric expression of an oblique
extensional feature associated with ridge propagation. It is likely that the orientation of this trough acted as a catalyst
for sediment deposition with the start of the Western Boundary Undercurrent in the mid-Oligocene. 相似文献
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哀牢山-红河断裂带中段应变分析 总被引:1,自引:0,他引:1
对哀牢山—红河断裂带中段和平—水塘剖面、墨江—元江剖面和其它地段的岩石应变及磁组构进行了分析,表明应变强度的校正磁各向异性度PJ从断裂带向西至三叠系明显降低,变形强度向西迅速减弱。磁化率椭球体主轴展布反映出剪切带内、外变形方式的改变。剪切带内,以水平走滑运动为主;向西则以水平缩短为主。在应变分析中,对断裂带内的S—C组构两组面理夹角、杏仁体和石榴石应变标志体进行了测量,结果显示,剪切带内的磁组构和岩石组构间关系较差。此外,还对这两条剖面中的三叠系进行了应变和磁组构分析,找出了它们与磁化率椭球体对应轴率间的相关性。 相似文献
8.
S. I. Mayr H. Burkhardt Yu. Popov A. Wittmann 《International Journal of Earth Sciences》2008,97(2):385-399
Internal surface, formation factor, Nuclear Magnetic Resonance (NMR)-T2 relaxation times and pore radius distributions were
measured on representative core samples for the estimation of hydraulic permeability. Permeability is estimated using various
versions of the classic Kozeny–Carman-equation (K–C) and a further development of K–C, the fractal PaRiS-model, taking into
account the internal surface. In addition to grain and pore size distribution, directly connected to permeability, internal
surface reflects the internal structure (“micro morphology”). Lithologies could be grouped with respect to differences in
internal surface. Most melt rich impact breccia lithologies exhibit large internal surfaces, while Tertiary post-impact sediments
and Cretaceous lithologies in displaced megablocks display smaller internal surfaces. Investigations with scanning electron
microscopy confirm the correlation between internal surface and micro morphology. In addition to different versions of K–C,
estimations by means of NMR, pore radius distributions and some gas permeability measurements serve for cross-checking and
calibration. In general, the different estimations from the independent methods and the measurements are in satisfactory accordance.
For Tertiary limestones and Suevites bulk with very high porosities (up to 35%) permeabilites between 10−14 and 10−16 m2 are found, whereas in lower Suevite, Cretaceous anhydrites and dolomites, bulk permeabilites are between 10−15 and 10−23 m2. 相似文献
9.
俯冲带榴辉岩的变形作用及其对俯冲-折返过程的意义 总被引:1,自引:0,他引:1
榴辉岩是大洋和大陆俯冲带的重要岩石类型,在研究俯冲带的形成过程、热结构、壳幔相互作用等方面有重要意义。通过对天然和实验样品中石榴子石、绿辉石等矿物的变形特征、变形机制、变形的影响因素等的综合分析,系统总结了高压变质带中榴辉岩矿物显微和超微变形研究的进展,探讨了榴辉岩的变形特征在恢复俯冲与折返过程研究中的意义及一些尚待解决的一些问题。 相似文献
10.
On the use of gravity and magnetic anomalies for locating probable areas of metallic mineralization in South Sinai, Egypt 总被引:1,自引:0,他引:1
The present study deals with processing and interpreting the potential gravity and magnetic data in order to locate promising
sites for metallic mineral occurrences in the basement rocks of South Sinai. Two promising sites were anticipated by combining
the geophysical results and the available geological information. Each site was profiled and interpreted to the nearly approximated
subsurface feature model, and the geometrical parameters of the expected subsurface structures may form mineralized bodies
such as depth, thickness, width, dipping, density contrast, and magnetic susceptibility contrast could be delineated. Detailed
ground Very Low Frequency (VLF) and Vertical Magnetic Gradient (VMG) methods were carried out in the site A2, eight VLF and
VMG anomalies were determined, and their depths were calculated. 相似文献