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971.
碳钠钙铀矿产于我国甘肃某热液铀矿床氧化带内的蚀变角闪岩裂隙面上。该矿物为细小粒状,浅黄绿色,无解理,比重2.83。在长波紫外线照射下,发强篮绿色萤光。微量化学分析结果:Na_2O9.29%,CaO9.30%,UO_346.71%,CO_218.50%(热重分析),H_2O~+15.20%及少量K_2O,MgO,MnO等。X光粉晶分析强线为:13.054(60),7.931(55),5.697(100),5.254(75),5.182(65),4.332(70),4.174(60),3.688(100)。晶胞参数:a=13.0215A(α=86.844°)或α=17.9012A,c=23.7631A。一轴晶,正光性,Ne=1.546,No=1.521。 相似文献
972.
Environmental geology in loess areas of China 总被引:2,自引:0,他引:2
Sun Jianzhong 《Environmental Geology》1988,12(1):49-61
There are several unfavorable geological hazards in the loess area of China. The major purposes of environmental geology studies
in this region are to expound the causes of these hazards and to determine treatments. Geological hazards include endemic
diseases, depletion of groundwater, land subsidence, ground fissures, soil erosion, and collapsibility of loess. This article
is a summary of studies regarding these hazards. Keshan disease and Kaschin-Beck disease, for example, can be prevented and
cured by adding selenates to table salt. Ponds can be constructed on the loess plateau and dikes around farmlands to collect
rainfall to recharge groundwater resources. Excess extraction of groundwater is the major cause of land subsidence. Ground
fissures in Xi'an are primarily caused by tectonics, but over-extraction of ground-water strengthens its activity. Observation
stations should be established in order to forecast and prevent landslides. Planting trees in a regional shelterbelt is the
primary measure necessary to prevent soil erosion. As a result of these geological studies, valuable experience in preventing
collapse of loess in China has been gained. 相似文献
973.
Methodology is described in this paper for investigating biotite reactions in pneumatolyto-hydrothermal solutions rich in
Na, F and Li by using tow buffer systems, NNO and CFG. The results show: (1) Under the experimental conditions biotite is
unstable and different new stable phases will be formed, depending upon the fugacity of oxygen. Na-rich minerals, such as
aegirine and albite, will be produced at low oxygen fugacity, while Li-rich micas are found stable at high oxygen fugacity.
This agrees with the field observation that albitization occurs in general at a lower position than that of Li-rich micas,
suggesting that alkalimetasomatism of biotite may provide the necessary components for subsequent reactions. (2) The stability
of Li-rich micas is dependent on Mg2+ concentration in the medium, which in turn is determined by Mg2+ content in the starting biotite. Li-rich micas are favored by metasomatism of only those biotites that are poor in Mg2+. (3) Unstability of biotite would favor the incorporation of ore-forming elements contained in it as isomorphous impurities
into solutions. 相似文献
974.
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978.
The new concept and analysis method for the rainfall peak are introduced in this paper,and an obser-vational study of a heavy rain case in the Meiyu front has been made with finer radiosonde and precipitationdata.It has found in this case that there are a lot of meso-β scale systems associated with the rainfall peaksin the Meiyu front.Meso-β scale systems can be divided into two kinds,i.e.,the moving and standing types.The moving type is characterized by the unstable gravity wave and has a path corresponding to the meso-α scalerain belts in the direction.The discussion about the meso-β systems is made by using the symmetric andtransversal wave instability theory. 相似文献
979.
通过对桃山、诸广复式岩体的深入研究,得出铀、钍元素在本地区花岗岩中具有以下地球化学特征及地球化学行为:1.岩体的铀、钍丰度与岩体外接触带的变质岩铀,钍丰度具同步增长特点;2.铀与硅、钾、钠关系密切,并有随钾增长,及随铀增长二种趋势,而钍则与TiO_2、FeO、MnO关系密切;3.钍在花岗岩中分布型式为正态分布,变异系数较铀小,而铀在花岗岩中分布型式为正态分布及对数正态分布,变异系数略高,显示了铀有某种富集可能;4.铀在花岗岩中地球化学行为,表现有二个富集高峰,既有在结晶早期富集在各类副矿物中的早富集特征,也有随花岗岩形成和演化富集在晚期的晚富集特征。二个富集途径,即随Si、K增高和随Si、Na增高途径。 相似文献
980.
用扫描电子显微镜研究晋东南太原组下部黄铁矿矿石和煤岩中的黄铁矿,发现许多原始莓体保留着形成时的特征。这些特征反映出原始莓体大多数为硫磺细菌化石,少数由胶体形成。本文对莓体的成因、特征、形成环境等进行了论述。 相似文献