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91.
东岗断裂的能动性问题争议较大 ,在前人研究成果的基础上 ,结合区域构造应力场模拟计算结果 ,对东岗断裂的能动性问题进行研究 ,认为断裂西端存在明显的应力集中现象 ,东岗断裂为能动断层 ,不会对温坨子厂址稳定性构成威胁。 相似文献
92.
《The Professional geographer》2013,65(2):189-193
A population density model is presented for urban areas containing multiple centers. Utilities of this model include evaluating time series for a transformation from monocentricity to polycentricity and testing the assumption of monocentricity at any point in time. Following a discussion of the method of calibrating this model, a case study of Toronto is presented. The major finding from 1971 and 1976 Toronto data is that no transformation is yet detectable. Interpretation of the model is exemplified in this empirical exercise. 相似文献
93.
《Chemie der Erde / Geochemistry》2014,74(4):545-555
The abandoned Sn-W Ribeira mine, northeast of Portugal, contained quartz veins with cassiterite, wolframite, scheelite, pyrite, arsenopyrite, sphalerite, chalcopyrite, manganocolumbite, bismuthinite, native bismuth, phosphates and carbonates. The exploration took place on the northern slope of the Viveiros stream, which is an affluent of the Sabor River. The waste-rock dumps and tailings were deposited on the hillside, close to the mine and are nowadays exposed to significant weathering and erosion, as they are not vegetated. The eroded material is transported by the Viveiros stream toward the Sabor River. A seasonal stream drains the tailings. The stream sediments samples were collected along the Viveiros stream, in the seasonal stream, in a seasonal spring at the bottom of the tailings, in the Sabor River and in other streams not affected by mine workings, following the mine influence along the Viveiros stream and in the Sabor River (1.2 km away from the mine workings). The data show that the degree of pollution increases along the Viveiros stream, especially in winter. The highest degree of pollution is for As, In, W, Sn and Bi. The sediments from the drainage of the main tailings are particularly polluted during winter, by Bi, In and Sn. The sedimentary precipitate from the spring is polluted in Cu, As, In, Sn, Ta, W, Bi, Zn, Nb, Ag, Sb and Ta. The sediments from the Sabor River are significantly polluted by As, Ag, In, Sn, W and Bi. The sediments from the regional streams, Viveiros stream and Sabor River have similar REE (NASC normalized) patterns (ΣREE = 131.7–185.9 mg/kg, LaN/LuN = 1.23–1.42 and Eu/Eu* = 1.02), while those from the seasonal stream, crossing the main tailings, are enriched in REE (ΣREE = 250.3–283.6 mg/kg, LaN/LuN = 1.6–2.09 and Eu/Eu* = 0.96). The general decrease in LaN/LuN values with increase in total Fe2O3 can be explained by the partitioning of HREE to the solid Fe-oxides phase. The sedimentary precipitate and coatings, which are mainly formed by Fe-oxy-hydroxides, but also contain jarosite, are impoverished in all REE. The impoverishment can be explained by the release of REE from the surface of the Fe-oxy-hydroxides, which occurs due to a local lowering of pH, caused by jarosite dissolution. During successive alternate cycles of wet and dry conditions, takes place the formation of Fe-oxy-hydroxides and jarosite in the sedimentary precipitate and coatings. The subsequent dissolution of jarosite releases acidity, thus promoting de-sorption of REE from the Fe-oxy-hydroxides mineral phases. 相似文献
94.
95.
Sediment Phosphorus Chemistry and Microbial Biomass along a Lowland New Zealand Stream 总被引:1,自引:0,他引:1
R. W. McDowell 《Aquatic Geochemistry》2003,9(1):19-40
An evaluation of the distribution of P concentrations in streamflow, P fractions andthe microbial biomass P pool was made of bed and bank sediments along a lowlandstream in New Zealand. Agricultural intensification increased downstream. However,most P fractions decreased downstream (total P decreased from c. 400 to 250 mg kg-1) in bed sediments, while P in streamflow remained relatively constant (generally < 0.005 mg l-1) and sediment microbial P increased from 2 to 8 mg kg-1. An investigation of P release from dried and rewetted sediments showed that solution P (CaCl2-P) increased, on average > 300%, and proportional to the size of the microbial biomass P pool before drying, except in sediments with much organic carbon (OC). When supplied with a P source (1 mg l-1) and then simultaneously with a C source (glucose, 100 mg l-1), all sediment behaved similarly and biotic sorption accounted for, on average, 27 and 34% of the total sediment uptake, respectively (maximum of 58%). The quantity of P taken up was related to the initial size of the microbial biomass P pool, and the availability of P as influenced by organic P complexes and OC. The sediment microbial biomass represents a transient, but small store of P could be useful to indicate bioavailable P inputs. 相似文献
96.
97.
响水砂体是一出露比较完整的中生代的曲流河河道沉积。通过大断面写实的研究方法,运用沉积体系分析、层序地层分析、砂体内部沉积构成分析等方法,比较细致地划分了砂体内部成因单元和储层岩性相,从成因上研究了影响油气运移的沉积因素。通过砂体断面上一定间距的比较均匀的采样,并根据测试成果编图,展示了各种孔沙参数在空间的变化特点及其与各种界面、沉积水动力能量的联系,并依此总结曲流河点坝渗透率的分布模式。 相似文献
98.
P.J. Oonincx 《Computational Geosciences》1999,3(2):111-134
Seismic signals consist of several typically short energy bursts, called phases, exhibiting several patterns in terms of dominant
frequency, amplitude and polarisation. We present a fast algorithm to detect the so‐called S‐phase in a three‐component seismic
signal. This new approach combines traditional S‐phase detection methods and the discrete wavelet transform.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
99.
Pramod Kumar Sharma 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2018,12(3):218-233
Flood hazard evaluation is an important input for Nuclear Power Plants external events safety studies. In the present study, flood hazard at various nuclear sites in India due to rainfall has been evaluated. Hazard estimation is a statistical procedure by which rainfall intensity versus occurrence frequency is estimated from historical records of rainfall data and extrapolated with asymptotic extreme value distribution. Rainfall data needed for flood hazard assessment are daily annual maximum rainfall (24?h data). The observed data points have been fitted using Gumbel, power law and exponential distribution, and return period has been estimated. To study the stationarity of rainfall data, a moving window estimate of the parameters has been performed. The rainfall pattern is stationary in both coastal and inland regions over the period of observation. The coastal regions show intense rainfall and higher variability than inland regions. Based on the plant layout, catchment area and drainage capacity, the prototype fast breeder reactor (PFBR) site is unlikely to be flooded. 相似文献
100.
现阶段,地质灾害评估技术人员在评估实践中,往往不注重各评估对象的差异性,采取同一评估模式,结果达不到评估的目的。在对小型水电站进行评估时,野外调查的重点,评估过程中所使用的方法以及危险性现状、预测及综合分区评估等与大型水电站、路线工程、矿山开采、民用建筑等工程有所不同。湄尼多河小型水电站工程位于云南省怒江州福贡县马吉乡境内,地质环境条件复杂,评估级别综合为二级。文章以该电站建设用地地质灾害危险性评估为例,对小型水电站建设用地地质灾害危险性评估的方法与理论进行探讨。 相似文献