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71.
The pyroxenite xenoliths in the volcanic rocks of Hoh Xil consist of clinopyroxenes and orthopyroxenes. The mineral composition of these pyroxenes is similar to that of mantle xenoliths including peridotite and pyroxenite from China and abroad, and different from that of granulites. The pyroxenes formed at 1101–1400°C (averaging 1250°C) and under 30–60 kb (averaging 46 kb). We deduced that the magma was derived from the mantle at a depth of more than 150 km, which fits in with the geophysical conclusion that the low-velocity layer existed in the mantle under 150 km.
相似文献72.
73.
We study a model of mergers affecting only the progenitors of present E/SO. We adopt the standard scenarios of star formation as prescribed by Guiderdoni & Rocca-Volmerange. The merging process is parametrized under the assumptions of(1) self-similarity of the Schechter MF and(2) mass conservation. Nine models are discussed. The predictions are compared with counts ofB
J
,U
+,F
+,N
+ bands. E/SO mergers account for the excess of the faintest blue galaxies without causing excess in redder bands. However, as we no longer have enough mergers at brighter magnitudes, a plain E/SO merging model fits less tightly for the redshift and the colour distributions. Detection effect, a steeper slope of LF may be ways to improve. Our models predict acceptable merger frequencies atz = 0.5 although some models predict more interacting galaxies than observation atz = 0. 相似文献
74.
本文根据石油地质勘探的最新资料和元-济人工地震地壳测深剖面相应地段重新解释的结果,分析了邢台7.2级地震的构造背景和发震断裂。研究结果表明,7.2级地震震中位于束鹿断陷盆地南部次凹的东缘,该次凹发育在由新河断裂等4条缓倾铲形正断裂分制围限地台盖层而成的“斛”状构造块体上,块体之下的地壳中存在两条倾向相反的高角度断裂;地震与断陷主断裂及其控制的断陷盆地并非是简单的对应关系,7.2级地震的发震断裂不是单一的缓倾铲形新河断裂或其下方的高角度的F_3断裂和深部的东断裂,而是它们的组合,且高角度断裂是发震断裂的主要部分 相似文献
75.
76.
Energy is stored when the force-free magnetic field in an active region departs from a potential field, the departure showing up as a shear in the field. As soon as the field untwists, energy will be released to produce flares. Based on this idea, we derived an analytical solution of the equation of force-free field under the assumption of a constant force-free factor, and found expressions for seven important quantities for quadrupolar sunspots: the magnetic energy of the twisted field, that of potential field, the extractable free energy ΔM, the magnetic flux, the total current, the force-free factor and the field decay factor, in terms of three observables: the field intensity, the twist angle and the distance between two spots of the same polarity. The expression for ΔM can be useful in solar prediction work. For the active region of August, 1972, we found ΔM up to 6 × 1032 erg, sufficient to supply the energy of the observed flare activity. Observations of this active region are in good general agreement with our theoretical expectations: in the entire twisting of the quadrupolar sunspot group, each spot assumes the form of a complete spiral in the clockwise direction for each of the four spots. 相似文献
77.
江西省德兴铜矿矿区重金属元素的环境效应 总被引:6,自引:0,他引:6
本文系统研究了德兴铜矿排石场和尾砂库的环境问题,以环境介质(水土植物)中重金属元素含量为研究对象,论述矿区重金属的环境效应。研究结果表明祝家村低品位矿石堆浸场淋滤产生的酸性废水是造成大坞河流域重金属污染的主要来源。大坞河上游水体中Cu元素含量高达14506μg/L,是国家Ⅲ级水标准的14倍之多,Zn元素含量高达2938μg/L,是国家Ⅲ级水标准的2.9倍,同时pH值在3~4范围内;到中下游水体中Cu元素含量减小到几千到几百μg/L,水质有所改善。大坞河沿岸上游和中游土壤重金属含量受河水影响,随着与河岸距离的增加而减小。同时水稻中Pb元素含量是国家粮食标准的2倍。推测4#尾砂库尾砂表层氧化带深度大于80cm;而1#尾砂库库内尾砂中氧化带估计在0~25cm处。推测两个尾砂库产酸能力小于酸中和能力,故坝底水中pH值在7左右,对周围水体影响较小。与4#尾砂库距离近的石墩头村稻田表层土壤中Cu、Mo元素含量较高,远离尾砂库土壤中重金属含量降低。同时4#尾砂库周围土壤中Cd、Pb、Cu元素的吸附态、碳酸盐态比例在20%左右,因而在酸性环境下较容易被植物吸收。1#尾砂库矿建村种植的小白菜中Pb元素含量超过国家蔬菜标准的4倍,Cu、Pb、Zn元素含量严重超过背景值。 相似文献
78.
Development of a 3D GIS and its application to karst areas 总被引:1,自引:0,他引:1
There is a growing interest in modeling and analyzing karst phenomena in three dimensions. This paper integrates geology,
groundwater hydrology, geographic information system (GIS), database management system (DBMS), visualization and data mining
to study karst features in Huaibei, China. The 3D geo-objects retrieved from the karst area are analyzed and mapped into different
abstract levels. The spatial relationships among the objects are constructed by a dual-linker. The shapes of the 3D objects
and the topological models with attributes are stored and maintained in the DBMS. Spatial analysis was then used to integrate
the data in the DBMS and the 3D model to form a virtual reality (VR) to provide analytical functions such as distribution
analysis, correlation query, and probability assessment. The research successfully implements 3D modeling and analyses in
the karst area, and meanwhile provides an efficient tool for government policy-makers to set out restrictions on water resource
development in the area. 相似文献
79.
Concentrations of trace elements and heavy metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Se, Sr, V and Zn) in
the Danjiangkou Reservoir, the water source area of the Middle Route of China’s interbasin South to North Water Transfer Project,
were analyzed using an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) and compared with the national and
international standards for drinking water. The results indicated that concentrations of As, Pb, Sb and Se in the Reservoir
exceeded the standards and they would pose health risk for residents in the region and the water receiving areas of the interbasin
water transfer project. Spatial and temporal variability of the trace elements and heavy metals in the Reservoir implies their
mixed sources of natural processing and anthropogenic activities in the upper drainage of the Reservoir. The research results
would help develop water resource management and conservation strategy for the interbasin water transfer project. 相似文献
80.
Glacier change and glacier runoff variation in the Tuotuo River basin,the source region of Yangtze River in western China 总被引:3,自引:0,他引:3
Glaciers in the Tuotuo River basin, western China, have been monitored in recent decades by applying topographical maps and
high-resolution satellite images. Results indicate that most of glaciers in the Tuotuo River basin have retreated in the period
from 1968/1971 to 2001/2002, and their shrinkage area is 3.2% of the total area in the late 1960s. To assess the influence
of glacier runoff on river runoff, a modified degree–day model including potential clear-sky direct solar radiation has been
applied to the glaciated regions of the river basin over the period 1961–2004. It was found that glacier runoff has increased
in the last 44 years, especially in the 1990s when a two-thirds increase in river runoff was derived from the increase in
glacier runoff caused by loss of ice mass in the entire Tuotuo River basin. 相似文献