Seismic wavefield calculation for laterally heterogeneous whole earth models using the pseudospectral method   总被引：4，自引：0，他引：4  

T. Furumura  B. L. N. Kennett  & M. Furumura 《Geophysical Journal International》1998,135(3):845-860

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Geographical and vertical variation of the earth's seismicity     

Theodoros M. Tsapanos  Basil C. Papazachos 《Journal of Seismology》1998,2(3):183-192

Information concerning a total number of 13700 instrumentally recorded earthquakes is used to study the geographical and the vertical distribution of the Earth's seismicity. From these earthquakes, which form four complete samples of data (M 7.0, 1894–1992; M 6.5, 1930–1992; M 6.0, 1953–1992; M 5.5, 1966–1992), 11511 are shallow (h 60 km), 2085 are of intermediate focal depth (61 h 300 km) and 564 are deep focus earthquakes (301 h 720 km). The parameters a and b of the frequency-magnitude relationship were calculated in a grid of equally spaced points at 1° by using the data of earthquakes located inside circles centered at each point. The radius of the circles increased from 30 km with a step of 10 km until the information for the earthquakes located inside the circle fulfil three criteria which concern the size of the sample used to compute these parameters at each point of the grid. The results are given in a qualitative way (epicenter maps) as well as in a quantitative way (mean return periods).  相似文献   

A Coupled Riverine-Marine Fractionation Model for Dissolved Rare Earths and Yttrium     

Robert H. Byrne  Xuewu Liu 《Aquatic Geochemistry》1998,4(1):103-121

Fractionation of yttrium (Y) and the rare earth elements (REEs) begins in riverine systems and continues in estuaries and the ocean. Models of yttrium and rare earth (YREE) distributions in seawater must therefore consider the fractionation of these elements in both marine and riverine systems. In this work we develop a coupled riverine/marine fractionation model for dissolved rare earths and yttrium, and apply this model to calculations of marine YREE fractionation for a simple two-box (riverine/marine) geochemical system. Shale-normalized YREE concentrations in seawater can be expressed in terms of fractionation factors ( _ij ) appropriate to riverine environments ( ) and seawater ( ): where and are input-normalized total metal concentrations in seawater and is the ratio of total dissolved Y in riverwater before and after commencement of riverine metal scavenging processes. The fractionation factors ( _ij ) are calculated relative to the reference element, yttrium, and reflect a balance between solution and surface complexation of the rare earths and yttrium.  相似文献   

Analysis of Error Caused by Replacing Spherical Shell with an Elastic Plate Model in Studying Bending Deformation of the Lithosphere     

Wu Hongling Institute of Geomechanics  Chinese Academy of Geological Sciences  Beijing Wang Ren Center for Geodynamics Research  Peking University  Beijing 《中国地质大学学报(英文版)》1998,9(2)

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南京伏牛山铜矿脉状矽卡岩稀土元素地球化学特征   总被引：2，自引：0，他引：2  

张建 《江苏地质》1998,22(1):15-18

介绍了南京伏牛山铜矿与成矿有关的花岗闪长斑岩及脉状矽卡岩的稀土元素组成模式及稀土元素地球化学特征。并据两者的相似性及变异性特征,探讨了脉状矽卡岩的成因。  相似文献   

低温对玉米种子发芽的影响   总被引：9，自引：1，他引：8  

高素华  郭建平  王连敏  王立志  张国民 《气象》1998,24(5):52-55

通过发芽试验研究了东北地区早、中、晚熟３个玉米品种在４℃、８℃、１３℃、１７℃、２１℃和２５℃黑暗条件下的发芽率、发芽势和发芽指数;并求出不同品种的发芽临界温度。结果表明,低温抑制了种子发芽,降低了发芽能力;３个品种发芽的临界温度为３．２￣５．２℃。发芽临界温度愈低,种子的耐低温发芽能力愈强。稀土浸种有提高玉米种子发芽率和促进发芽的作用。  相似文献   

贵州织金地区稀土磷块岩矿床中稀土元素赋存状态   总被引：10，自引：1，他引：9  

张彦斌  龚美菱  李华 《地球科学与环境学报》2007,29(4):362-368

以稀土磷块岩矿床为研究对象,采用电感耦合等离子体光谱法和质谱法研究了3个代表性样品的基本化学组成,分析了40多个元素的含量,确定了矿物质量分数和赋存状态,研究了稀土元素在其中的分布特征。结果表明,97%以上的稀土元素呈类质同象状态部分置换磷灰石晶格中的Ca2 存在,只有小于3%的稀土元素呈被粘土质等吸附状态或离子交换(吸附)状态存在。  相似文献   

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杨兆  孙和平  雷湘鄂 《大地测量与地球动力学》2007,27(4):38-43

??????????????????(Runge??Kutta)????????PREM??????????????????λ??????????????????????????????200 s??????????????????ε??????????????????????????????????仯???????????????о??????λ???????е?仯?????????????:??????????????????????????????仯?????, 20???????????????μ????????????Dziewonski??Anderson??????, ?????????????0.25%?????  相似文献   

On the nutations of a more realistic earth model   总被引：1，自引：0，他引：1  

V. Dehant 《Geophysical Journal International》1990,100(3):477-483

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发光细菌法在环渤海污水样品遗传毒性检测中的应用     

崔志松  栾晓  高伟  李倩  杨官品  郑立 《海洋与湖沼》2015,46(1):228-232

建立了以经过遗传改造的发光细菌Acinetobacter sp.Rec A为受试物种的环境污染物遗传毒性快速检测方法,该方法最快可在3h内得到毒性评价结果。采用该方法评价了环渤海排污口12份污水样品的遗传毒性。环渤海12个排污口的污水样品均表现出了不同水平的遗传毒性,并呈现出一定的分布特征。其中,高毒水质集中出现在山东半岛污水样品中,中毒水质集中出现在辽东半岛地区,而低毒水质主要集中于京津冀地区。综上,在环渤海的污水样品遗传毒性检测中,这种新型发光细菌法具有快速、灵敏、简便等优点,可为以后近海环境的水质生物毒性检测提供参考依据,具有应用于近海环境水质快速监测与评价的潜力。  相似文献