激光显微探针~(40)Ar/~(39)Ar同位素定年   总被引：10，自引：0，他引：10  

穆治国 《地学前缘》2003,10(2):301-307

已有 5 0年历史的K Ar定年法 ,由于过剩Ar和Ar丢失的普遍发现 ,使其最广泛的应用面临着严重挑战。40 Ar/ 3 9Ar分步加热释氩法是常规K Ar定年法的发展 ,它克服了常规K Ar定年法的一些局限 ,又可以测定岩浆构造热事件。激光显微探针40 Ar/ 3 9Ar定年法是在 2 0世纪末把聚焦激光束应用在40 Ar/ 3 9Ar分步加热释氩法中而发展起来的一种定年方法。它既具有常规K Ar定年法和40Ar/ 3 9Ar分步加热释氩法的所有优越性 ,又把定年引入微观领域。特别是在 2 0世纪的最后几年 ,以激光显微探针40 Ar/ 3 9Ar定年方法的完善和精度的提高为标志 ,把K Ar年代学研究推向了一个新的里程碑。微区微量高精度高分辨定年 ,把定年时限扩展到人类历史范畴 ,精细的分析技术拓宽了年代学的应用范围 ,使之解决的地质问题更广泛和深入 ,并且开始冲击着地球科学中的某些热点和难点课题。  相似文献   

Comparing palaeolimnological and instrumental evidence of climate change for remote mountain lakes over the last 200 years   总被引：8，自引：1，他引：7  

Richard W. Battarbee  John-Arvid Grytnes  Roy Thompson  Peter G. Appleby  Jordi Catalan  Atte Korhola  H.J.B. Birks  Einar Heegaard  Andrea Lami 《Journal of Paleolimnology》2002,28(1):161-179

This paper compares the palaeolimnological evidence for climate change over the last 200 years with instrumental climate data for the same period at seven European remote mountain lakes. The sites are Øvre Neådalsvatn (Norway), Saanajärvi (Finland), Gossenköllesee (Austria), Hagelseewli (Switzerland), Jezero v Ledvici (Slovenia), Estany Redó (Spain, Pyrenees), and Niné Terianske Pleso (Slovakia). We used multiple regression analysis to transfer homogenised lowland air temperature records to each of the sites, and these reconstructions were validated using data from on-site automatic weather stations. These data showed that mean annual temperature has varied over the last 200 years at each site by between 1 and 2 °C, typical of the high frequency variability found throughout the Holocene, and appropriate, therefore, to test the sensitivity of the various proxy methods used. Sediment cores from each site were radiometrically dated using ²¹⁰Pb, ¹³⁷Cs and ²⁴¹Am and analysed for loss-on-ignition, C, N, S, pigments, diatoms, chrysophytes, Cladocera and chironomids. Comparisons between the proxy data and the instrumental data were based on linear regression analysis with the proxy data treated as response variables and the instrumental data (after smoothing using LOESS regressions) as predictor variables. The results showed few clear or consistent patterns with generally low or very low r² values. Highest values were found when the data were compared after smoothing using a broad span, indicating that some of the proxy data were capturing climate variability but only at a relatively coarse time resolution. Probable reasons for the weak performance of the methods used include inaccurate dating, especially for earlier time periods, the influence of confounding forcing factors at some sites e.g., air pollution, earthquakes, and the insensitivity of some methods to low amplitude climate forcing. Nevertheless, there were trends in some proxy records at a number of sites that had a relatively unambiguous correspondence with the instrumental climate records. These included organic matter and associated variables (C and N) and planktonic diatom assemblages at the majority of sites and chrysophytes and chironomids at a few sites. Overall for longer term studies of the Holocene, these results indicate the need to be cautious in the interpretation of proxy records, the importance of proxy method validation, the continuing need to use reinforcing multi-proxy approaches, and the need for careful site and method selection.  相似文献   

“新经济地理学”与经济地理学的分异与对立   总被引：22，自引：4，他引：18  

顾朝林  王恩儒  石爱华 《地理学报》2002,57(4):497-504

最近几年来,由于经济全球化的趋势,西方经济学家又开始对经济地理学产生兴趣。“新经济地理学”或“地理经济学”应运而生。首先介绍经济学家克鲁格曼的“新经济地理学”理论框架和方法,综述西方地理学家对所谓“新经济地理学”的评价,最后概述经济地理学最近的发展以及地理学家对新经济地理学理解。  相似文献   

21世纪矿业应向后工业发展势态倾斜--适者生存和可持续发展   总被引：5，自引：0，他引：5  

裴荣富 《地球科学》2002,27(1):72-80

“后工业”（post-industry)是知识经济或曰“新经济”的发展时代。这个时代的自然资源和一般劳动力资源,包括矿产资源在国民经济和社会发展中的基础地位逐渐为知识产权、市场网络、信息、创新环境等后天获得性资源,以及为创新人才的新“认知”（recognized intellect,RI)所代替。然而,据矿产资源分布及其成矿既具有一定的全球统一性又有区域的特殊性,以及不同国家（地区）对矿产资源勘查程度的不均衡性,特别是矿业活动与其他产业性质的不同,如何能按不同国家（地区）的具体发展状况,做好21世纪矿业向“后工业”发展势态的倾斜,达到适者生存和矿业可持续发展的目标是当代探讨的重大问题。在概括阐述了21世纪矿业发展势态、矿业活动特点及其自然属性的基础上,提出了矿业可持续发展的地质勘查和矿业活动决策支持系统的模拟,以及对当前紧缺铜矿资源可持续发展的新“认知”。  相似文献   

地球化学块体——概念和方法学的发展   总被引：55，自引：15，他引：40       下载免费PDF全文

谢学锦刘大文  向运川严光生 《中国地质》2002,29(3):225-233

中国的全国区域化探扫面计划（RGNR）迄今已进行了24年,已经覆盖了全国600余万平方千米的国土面积,获得了高质量元素分析的海量数据,通过对这些数据进行的综合研究,笔者发现了比传统意义的分散晕分散流更为宽广的地球化学模式：区域异常、地球化学省、地球化学巨省和地球化学域。这种更为宽广的所谓套合着的地球化学模式谱系实际上是地球上富含各种金属的巨大岩块的内部结构特征在地表的表现,这种“地球化学块体”是原始地球的不均一性以及地球从起始演化到现在的过程中元素的分布再分配的最终结果的体现,笔者从中得到了这种大的地球化学块体能够为大型巨型矿床的形成提供其所必需的足够的物质供应量的新认识。而追索某元素地球化学块体的内部结构则可揭示该元素在地球化学块体中逐步浓集成矿的轨迹。尽管地球化学块体的理论与方法学研究虽然尚在初期阶段,但已为勘查地球化学、矿床学与成矿学开拓了眼界,并提供了新的研究思路。  相似文献   

European capital cities as political frontiers     

Gertjan Dijkink 《GeoJournal》2000,51(1-2):65-71

The capital is the centre of the established order but it always had to accept a relatively uncontrollable world of individuals redefining urban space in their own way or pioneering new means of support. As their existence is both a political nuisance and a foreshadowing of institutional changes (sometimes revolutionary) of nation-wide importance, I call such ways of life political frontiers. One may wonder what will become of political frontiers in the information society (or postmodern society) that, apart from borderless, has been described as society without a centre as well. Actually information society is the prototype of a frontier society with self-responsible groups and individuals. However, capitals – even stripped of their governmental functions – may offer a symbolical environment (a condensation of space and time) that precisely satisfies the wants of those who wish to politicise a way of life. Niches for pioneering behaviour may get dispersed over a wider territory but new types of political activity will gravitate to the capital even if the capital's official political status has dwindled.  相似文献   

一次台风前部龙卷的多普勒天气雷达分析   总被引：12，自引：3，他引：12       下载免费PDF全文

何彩芬姚秀萍  胡春蕾全彩峰 《应用气象学报》2006,17(3):370-375

通过分析2004年8月25日发生在浙江省宁波市的一次台风前部龙卷发生发展的环境特征, 发现该龙卷发生在台风前部风切变区里, 尽管当时涡度、散度等物理量对于深对流发展不是非常有利, 但下湿中干、强的垂直风切变及地形条件等还是有利于局地弱龙卷的产生; 在宁波新一代天气雷达产品上表现为强的钩状回波, 速度场上有相邻的正负速度中心及强的组合切变值等。通过多个反射率产品、剖面产品等综合分析了该风暴的三维结构, 初步了解此类弱龙卷的发生机理, 为以后的预报提供一些经验。  相似文献   

参考文献著录规则应用及注意的问题     

翟国辉 《黑龙江气象》2006,(4):1-5

通过对《文后参考文献著录规则》的学习和理解,阐明参考文献著录方法,列举了有关著录事例和著录时应注意的问题。为著者撰写学术论文提供参考,以便提高学术论文和科技期刊质量。  相似文献   

Brest sea level record: a time series construction back to the early eighteenth century     

Guy Wöppelmann  Nicolas Pouvreau  Bernard Simon 《Ocean Dynamics》2006,56(5-6):487-497

The completeness and the accuracy of the Brest sea level time series dating from 1807 make it suitable for long-term sea level trend studies. New data sets were recently discovered in the form of handwritten tabulations, including several decades of the eighteenth century. Sea level observations have been made in Brest since 1679. This paper presents the historical data sets which have been assembled so far. These data sets span approximately 300 years and together constitute the longest, near-continuous set of sea level information in France. However, an important question arises: Can we relate the past and the present-day records? We partially provide an answer to this question by analysing the documents of several historical libraries with the tidal data using a ‘data archaeology’ approach advocated by Woodworth (Geophys Res Lett 26:1589–1592, 1999b). A second question arises concerning the accuracy of such records. Careful editing was undertaken by examining the residuals between tidal predictions and observations. It proved useful to remove the worst effects of timing errors, in particular the sundial correction to be applied prior to August 1, 1714. A refined correction based on sundial literature [Savoie, La gnomique, Editions Les Belles Lettres, Paris, 2001] is proposed, which eliminates the systematic offsets seen in the discrepancies in timing of the sea level measurements. The tidal analysis has also shown that shallow-water tidal harmonics at Brest causes a systematic difference of 0.023 m between mean sea level (MSL) and mean tide level (MTL). Thus, MTL should not be mixed with the time series of MSL because of this systematic offset. The study of the trends in MTL and MSL however indicates that MTL can be used as a proxy for MSL. Three linear trend periods are distinguished in the Brest MTL time series over the period 1807–2004. Our results support the recent findings of Holgate and Woodworth (Geophys Res Lett) of an enhanced coastal sea level rise during the last decade compared to the global estimations of about 1.8 mm/year over longer periods (Douglas, J Geophys Res 96:6981–6992, 1991). The onset of the relatively large global sea level trends observed in the twentieth century is an important question in the science of climate change. Our findings point out to an ‘inflexion point’ at around 1890, which is remarkably close to that in 1880 found in the Liverpool record by Woodworth (Geophys Res Lett 26:1589–1592, 1999b).  相似文献   

2O世纪冶金地质化探工作十大创新成果     

李惠 张国义禹斌  李德亮 《地质找矿论丛》2006,21(10):125-130

文章总结了20世纪冶金地质化探工作中的10项有创新、并取得显著找矿效果的成果：找金矿盲矿体的构造叠加晕模式、汞气测量和热释汞测量寻找隐伏矿床、典型有色金属矿床地球化学异常模式研究、中国主要类型金矿找矿模型研究、胶东金矿带盲矿预测的原生地球化学专家系统、包裹体气晕、离子晕及其叠加晕找金新方法、脉钨矿床的“三环一帽式”地球化学异常模式、应用卤素找盲矿和土壤热释卤素新方法、建立优质锰矿床的地球化学找矿模型、区带化探找贵金属及有色金属矿产。  相似文献