Lu-Hf年代学研究——以大别榴辉岩为例   总被引：3，自引：2，他引：3  

袁洪林高山  罗彦宗春蕾  戴梦宁柳小明 第五春荣 《岩石学报》2007,23(2):233-239

本文利用多接收电感耦合等离子体质谱仪(MC-ICP-MS)进行了同位素稀释法Lu-Hf年代学研究,建立了全岩Lu、Hf的分离条件。分离后Lu溶液中~(176)Lu/~(176)Yb大于30,分离后Hf溶液中Lu和Yb对Hf的干扰(~(176)Lu/~(176)Hf和~(176)Yb/~(176)Hf分别小于2×10~(-6)和2×10~(-4))采用指数法则进行校正。建立了MC-ICP-MS进行Lu、Hf同位素高精度准确测试的校正方法。天然样品中Hf同住素~(176)Hf/~(177)Hf的内部测试精度优于0.0015%,外部精密度优于0.0010%。应用本文建立的方法获得大别双河榴辉岩石榴子石-全岩Lu-Hf等时线年龄为254±16Ma(2σ)。年龄误差稍大与该样品石榴子石中较低的Lu含量(1.1μg/g)和石榴子石-全岩的未充分分开的~(176)Lu/~(177)Hf比值(分别为0.05和0.01)有关。  相似文献   

一种快速获取城市地图更新增量的方法   总被引：2，自引：0，他引：2  

张保钢  高莉 《测绘通报》2008,(12)

提出一种利用城市地名审批成果,直接获取城市地图更新增量的方法。该方法省掉了新旧数据比对的工作量,简单、高效、可行,适用于地名审批主管部门的下属单位更新较小比例尺城市地图。建议相关部门加大地名审批管理力度,克服有些地物无名现象,共享地名公共资源,更好地实现城市地图的增量更新。  相似文献   

Place,Learning Progressions,and Progress     

Thomas B. Larsen  John A. Harrington Jr. 《The Journal of geography》2018,117(3):133-136

This commentary response reflects on the thoughts offered by Solem, Mohan, Rawling, and Lambert regarding Larsen and Harrington's article titled “Developing a Learning Progression for Place” (2018).  相似文献   

Alternative and Virtual Rurality: Agriculture and The Countryside as Embodied in American Imagination   总被引：1，自引：0，他引：1       下载免费PDF全文

Lisa M. Butler Harrington 《Geographical review》2018,108(2):250-273

Affection for agrarian livelihoods and rural and small‐town environments has long been held by residents in many of the world's “more developed” countries. Although the rural proportion of the U.S. population has shrunk to a minority over the last century, fondness for rurality continues to manifest itself in a number of ways. Attachment to the rural ideal or rural idyll can be considered as attachment to the idea of a type of place, rather than specific place attachment. Based on literature, field observation, computer searches, and data from the U.S. Census of Agriculture, connections to idea(l)s of rurality apparent in popular culture are identified and illustrated. These include rural and agricultural tourism, small‐scale farming and large‐lot rural subdivisions, urban agriculture, farmers’ markets and community‐supported agriculture, creation of housing developments around farm activities, and rural‐named housing and business developments. Idealized relationships with rurality call upon health and well‐being, connecting to nature, aesthetics, privacy, and respect and nostalgia for rural livelihoods.  相似文献   

A Time-Sensitive Framework for Including Geographic Information Systems (GIS) in Professional Development Activities for Classroom Teachers     

Lisa Tabor Millsaps  John A. Harrington 《The Journal of geography》2017,116(4):152-164

This work shares a time-sensitive framework for teaching GIS to educators of all levels and disciplines. Existing relationships with teachers enabled the addition of GIS content in professional development activities. The amount of time devoted to GIS-related content varied depending on time made available for interaction with the audience. Content audiences included geography, history, social studies, science, agriculture, religion, and math teachers. The framework was developed, tested, and refined over a period of six years, during thirty-six trainings, and with 580 educators. Use of this framework emphasizes that not one size fits all in GIS education and that GIS can work for any teacher, their content, their classroom, and their time availability.  相似文献   

Magnesium Isotopic Compositions of International Geological Reference Materials          下载免费PDF全文

Fang‐Zhen Teng  Wang‐Ye Li  Shan Ke  Wei Yang  Sheng‐Ao Liu  Fatemeh Sedaghatpour  Shui‐Jiong Wang  Kang‐Jun Huang  Yan Hu  Ming‐Xing Ling  Yan Xiao  Xiao‐Ming Liu  Xiao‐Wei Li  Hai‐Ou Gu  Corliss K. Sio  Debra A. Wallace  Ben‐Xun Su  Li Zhao  Johnnie Chamberlin  Melissa Harrington  Aaron Brewer 《Geostandards and Geoanalytical Research》2015,39(3):329-339

Magnesium isotopic compositions are reported for twenty‐four international geological reference materials including igneous, metamorphic and sedimentary rocks, as well as phlogopite and serpentine minerals. The long‐term reproducibility of Mg isotopic determination, based on 4‐year analyses of olivine and seawater samples, was ≤ 0.07‰ (2s) for δ²⁶Mg and ≤ 0.05‰ (2s) for δ²⁵Mg. Accuracy was tested by analysis of synthetic reference materials down to the quoted long‐term reproducibility. This comprehensive dataset, plus seawater data produced in the same laboratory, serves as a reference for quality assurance and inter‐laboratory comparison of high‐precision Mg isotopic data.  相似文献   

Ground truthing groundwater-recharge estimates derived from remotely sensed evapotranspiration: a case in South Australia     

Russell S. Crosbie  Phil Davies  Nikki Harrington  Sebastien Lamontagne 《Hydrogeology Journal》2015,23(2):335-350

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Collapse assessment of moment frame buildings,considering vertical ground shaking          下载免费PDF全文

Cody C. Harrington  Abbie B. Liel 《地震工程与结构动力学》2016,45(15):2475-2493

While many cases of structural damage in past earthquakes have been attributed to strong vertical ground shaking, our understanding of vertical seismic load effects and their influence on collapse mechanisms of buildings is limited. This study quantifies ground motion parameters that are capable of predicting trends in building collapse because of vertical shaking, identifies the types of buildings that are most likely affected by strong vertical ground motions, and investigates the relationship between element level responses and structural collapse under multi‐directional shaking. To do so, two sets of incremental dynamic analyses (IDA) are run on five nonlinear building models of varying height, geometry, and design era. The first IDA is run using the horizontal component alone; the second IDA applies the vertical and horizontal motions simultaneously. When ground motion parameters are considered independently, acceleration‐based measures of the vertical shaking best predict trends in building collapse associated with vertical shaking. When multiple parameters are considered, Housner intensity (SI), computed as a ratio between vertical and horizontal components of a record (SI_V/SI_H), predicts the significance of vertical shaking for collapse. The building with extensive structural cantilevered members is the most influenced by vertical ground shaking, but all frame structures (with either flexural and shear critical columns) are impacted. In addition, the load effect from vertical ground motions is found to be significantly larger than the nominal value used in US building design. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

椭圆展开共反射点叠加方法的应用研究   总被引：4，自引：1，他引：3       下载免费PDF全文

周青春  刘怀山  Kondrashkov V V  李国都  林依华  高静怀 《地球物理学报》2009,52(1):222-232

本文详细介绍了均匀介质条件下椭圆展开共反射点(CRP)叠加原理,并引入双参数(上行波与下行波的速度比和平均速度)来解决非均匀介质条件下的叠加成像,严密论证了所求得的速度是真正的共反射点叠加速度,并结合理论模型计算和地震资料处理证实,利用椭圆展开CRP方法可以对复杂地质剖面求取准确的共反射点叠加速度和正确的零偏移距剖面,得到的成像效果远优于传统共中心点(CMP)方法.  相似文献   

Comment on “Drawdown ‘Triggers’: A Misguided Strategy for Protecting Groundwater‐Fed Streams and Springs,” by Matthew J. Currell, 2016, v. 54, no. 5: 619–622          下载免费PDF全文

Robert Harrington  Keith Rainville  T. Neil Blandford 《Ground water》2017,55(2):152-153

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