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41.
3 富集地幔人们曾经用大陆地壳拼凑和原始的下地幔柱解释所有非大洋中脊玄武岩(即富集玄武岩或来自所谓原生储层的玄武岩)。上地幔被看作是枯竭地幔和洋中脊玄武岩的储层,而仅是洋中脊玄武岩的储藏,它是  相似文献   
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尽管在400km和650km深度附近的地震不整合主要是由于相变,但在均一的地幔中它们却不一定是平衡相的界面。400km附近地震波速的跳跃很小以致不是在橄榄石或者橄榄-斜方辉石类为主的地幔岩中相变的结果。  相似文献   
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加卸载响应比这一新的参数可以定量地刻划构造运动的稳定程度.非稳定的构造运动常引起地质灾害,所以测定与计算响应比就可能预测地质灾害.利用此方法进行了地震预测(后验性的与先验性的),均取得成功.  相似文献   
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The dissolution kinetics of a simulated lunar glass were examined at pH 3, 5, and 7. Additionally, the pH 7 experiments were conducted in the presence of citric and oxalic acid at concentrations of 2 and 20 mM. The organic acids were buffered at pH 7 to examine the effect of each molecule in their dissociated form. At pH 3, 5, and 7, the dissolution of the synthetic lunar glass was observed to proceed via a two-stage process. The first stage involved the parabolic release of Ca, Mg, Al, and Fe, and the linear release of Si. Dissolution was incongruent, creating a leached layer rich in Si and Ti which was verified by transmission electron microscopy (TEM). During the second stage the release of Ca, Mg, Al, and Fe was linear. A coupled diffusion/surface dissolution model was proposed for dissolution of the simulated lunar glass at pH 3, 5, and 7. During the first stage the initial release of mobile cations (i.e., Ca, Mg, Al, Fe) was limited by diffusion through the surface leached layer of the glass (parabolic release), while Si release was controlled by the hydrolysis of the Si-O-Al bonds at the glass surface (linear release). As dissolution continued, the mobile cations diffused from greater depths within the glass surface. A steady-state was then reached where the diffusion rate across the increased path lengths equalled the Si release rate from the surface. In the presence of the organic acids, the dissolution of the synthetic lunar glass proceeded by a one stage process. The release of Ca, Mg, Al, and Fe followed a parabolic relationship, while the release of Si was linear. The relative reactivity of the organic acids used in the experiments was citrate > oxalate. A thinner leached layer rich in Si/Ti, as compared to the pH experiments, was observed using TEM. Rate data suggest that the chemisorption of the organic anion to the surface silanol groups was responsible for enhanced dissolution in the presence of the organic acids. It is proposed that the increased rate of Si release is responsible for the one stage parabolic release of mobile cations and the relatively thin leached layer compared to experiments at pH 3 and 5.  相似文献   
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加卸载响应比20年及其展望   总被引:1,自引:0,他引:1  
地震孕育过程是一个非线性、不可逆的过程,震源区介质的加载响应不同于卸载响应,这种加载响应与卸载响应的差别可以定量地刻画地震的孕育过程。基于这个物理概念,提出了一个新的参数加卸载响应比,作为一类地震前兆,用来定量预测强震的发生。在本文中,首先简单回顾了加卸载响应比的发展历史,然后详细介绍了地震震例检验、数值计算、实验研究、地震预测精度、可信度等方面的内容,最后对加卸载响应比的前景进行了展望。  相似文献   
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A regression model to estimate regional ground water recharge   总被引:1,自引:0,他引:1  
Lorenz DL  Delin GN 《Ground water》2007,45(2):196-208
A regional regression model was developed to estimate the spatial distribution of ground water recharge in subhumid regions. The regional regression recharge (RRR) model was based on a regression of basin-wide estimates of recharge from surface water drainage basins, precipitation, growing degree days (GDD), and average basin specific yield (SY). Decadal average recharge, precipitation, and GDD were used in the RRR model. The RRR estimates were derived from analysis of stream base flow using a computer program that was based on the Rorabaugh method. As expected, there was a strong correlation between recharge and precipitation. The model was applied to statewide data in Minnesota. Where precipitation was least in the western and northwestern parts of the state (50 to 65 cm/year), recharge computed by the RRR model also was lowest (0 to 5 cm/year). A strong correlation also exists between recharge and SY. SY was least in areas where glacial lake clay occurs, primarily in the northwest part of the state; recharge estimates in these areas were in the 0- to 5-cm/year range. In sand-plain areas where SY is greatest, recharge estimates were in the 15- to 29-cm/year range on the basis of the RRR model. Recharge estimates that were based on the RRR model compared favorably with estimates made on the basis of other methods. The RRR model can be applied in other subhumid regions where region wide data sets of precipitation, streamflow, GDD, and soils data are available.  相似文献   
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Ecotoxicological studies, using the tropical marine diatom, Nitzschia closterium (72-h growth rate), were undertaken to assess potential issues relating to the discharge from an alumina refinery in northern Australia. The studies assessed: (i) the species’ upper thermal tolerance; (ii) the effects of three signature metals, aluminium (Al), vanadium (V) and gallium (Ga) (at 32 °C); and (iii) the effects of wastewater (at 27 and 32 °C). The critical thermal maximum and median inhibition temperature for N. closterium were 32.7 °C and 33.1 °C, respectively. Single metal toxicity tests found that N. closterium was more sensitive to Al compared to Ga and V, with IC50s (95% confidence limits) of 190 (140-280), 19,640 (11,600-25,200) and 42,000 (32,770-56,000) μg L−1, respectively. The undiluted wastewater samples were of low toxicity to N. closterium (IC50s > 100% wastewater). Environmental chemistry data suggested that the key metals and discharge are a very low risk to this species.  相似文献   
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