Holocene regional and local vegetation history and lake-level changes in the Torneträsk area, northern Sweden

A combination of pollen and macrofossil analyses from six lakes at altitudes between 370 and 999 m above sea level (a.s.l.) in the Torneträsk area reflect the Holocene vegetation history. The main field study area has been the Abisko valley at altitudes around 400 m a.s.l. The largest lake, Vuolep Njakajaure has annually laminated (varved) sediments. The chronology and sedimentation rates in the pollen-influx calculations are based on varve yrs in this lake and on radiocarbon dated terrestrial plant macrofossils in the other lakes. A strong increase of mountain birch (Betula pubescens ssp. tortuosa) during the early Holocene with a tree-line c. 300 m above the present, indicates that the summer temperature was c. 1.5 °C higher than today, assuming that the land uplift has been 100 m since then. Scattered stands of pine (Pinus sylvestris) may have been growing in the area immediately after the deglaciation but a forest consisting of pine and mountain birch expanded first at low elevations and reached the eastern parts of the Torneträsk area at c. 8300 cal BP and the western parts at c. 7600 cal BP. The highest pine-birch forest limit was not reached until 6300 cal BP (110 m above present pine limit). Warm and dry conditions during the pine forest maximum led to lowering of the water level documented in Lake Badsjön in the Abisko valley about 1-1.5 m lower than today. Pine and mountain birch were growing at the maximum altitude until c. 4500 cal BP. Assuming that land uplift has been in the range of 20-40 m since the mid-Holocene, this implies that the temperature was then c. 1.5-2 °C higher than today. Rising lake-levels and lowering limits of pine and mountain birch since c. 4500 cal BP indicate a more humid and cool climate during the late Holocene.     

中国地质科学50年的简要回顾

在世界之效科学技术大发展的现阶段,中国地质科学必将发展,因为它具箅了社会需求、科学问题和社会基础技术三个科学发展的条件。由于中国地质学奠基者的远见卓识,中国地质学在本世纪２０～３０年代已建立了世界声誉。新中国建立后,５０～７０年代中国地质科学取得迅速工。自７０年代珂至今的改革开放时期更取得了全面的发展。随着地球系统科学的新概念为广大地质学者所接受,地质学各分支学科必将走向互相交驻融合,形成综合的和     

材料科学和地质学的发展及前景(英文)

材料科学可定义为一门涉及化学、物理学、矿物学、地质学、冶金学和合成材料等领域的科学。“工具制造者的人类” ,主要是使用石器 ,并由此而增进了其智能的发育。燧石、石灰岩中氧化硅富集体提供了制作武器和工具的材料 ,土壤则可用于制陶业和陶瓷业。材料科学主要是由研究工业矿物演化而来 ,它与地质学的关系密切 ;合成材料以其特殊的性能满足了人们的需求。火和压力在处理天然材料的工艺发展中起着头等作用 ;金银铜铁及其它金属能用作装饰品、防御武器和制造工具。有些金属的使用显示了人类各历史时期的特点。人们后来发现某些结晶体具有特殊的性质 ,如石英的压电性、红宝石激光 ,钻石和刚玉的高硬度 (可用作磨料 ,将来仍具开发潜力 )。合成材料和在太空合成的材料具有远大前景 (如碳的同素异形体carbyne car bynoid)。在材料科学中 ,特种玻璃 ,硬而防火的陶瓷、磨料、特殊耐火材料 ,只不过是材料科学中业已开发的几种工艺矿物而已。材料科学的发展对于现代文明和解决人类当今和未来所遇到的各种问题都极其重要。与世界人口增长相关的问题 ,可以通过科学、绿色革命和生物技术 ,以及一切天然资源的合理开发来解决 ,这将有助于避免“南北对抗”。肯定地说 ,材料科学及其未来的发展 ,会有助于人类去应付     

OpenGL在三维地质模型可视化中的应用

本文介绍了作者在将ＯｐｅｎＧＬ应用于三维地质模型可视化中的经验与体会。首先介绍了用ＯｐｅｎＧＬ显示三维地质模型的几个技术关键。包括模型绘制、投影变换、取景、ＴＩＮ表面显示、旋转、颜色与材料等。然后介绍了笔者基于ＯｐｅｎＧＬ的剪变换和缓冲区累加功能提出了的”切片合成法”的原理、用途、应用注意事项和应用于煤田地质勘探中煤层底版等高线图制做的实例。     

Growth of Daphnia magna males and females fed with the cyanobacterium Microcystis aeruginosa and the green alga Scenedesmus obliquus in different proportions

Laboratory experiments were used to study the sensitivity of both male and female Daphnia magna to a toxic cyanobacterium, Microcystis aeruginosa. Male and female D. magna were fed with M. aeruginosa and a green alga (Scenedesmus obliquus) in different mixtures that included 0%, 25%, 50%, 75% and 100% Microcystis. Growth of both males and females declined with increasing proportion of Microcystis in the diet. Males were slightly less sensitive to Microcystis than females with EC₅₀ for growth inhibition at 72% and 63% Microcystis in the diet, respectively. On monospecific Microcystis diet, mortality rates for males (0.16 d^–1) and females (0.17 d^–1) were similar. The reproductive rate of females was the most sensitive endpoint with an EC₅₀ of 42% Microcystis in the diet, whereas population growth rates were the least sensitive (EC₅₀ of 74% Microcystis). Microcystis in the diet severely depressed growth and reproduction in Daphnia and poses a severe threat to its survival in which only a switch in reproductive strategy might provide Daphnia a refuge to a Microcystis environment that gradually becomes uninhabitable.     

Modelling considerations in probabilistic performance‐based seismic evaluation: case study of the I‐880 viaduct

Limitations associated with deterministic methods to quantify demands and develop rational acceptance criteria have led to the emergence of probabilistic procedures in performance‐based seismic engineering. The Pacific Earthquake Engineering Research performance‐based methodology is one such approach. In this paper, the impact of certain modelling decisions made at different stages of the evaluation process on the performance assessment of a typical multi‐bent viaduct is examined. Modelling, in the context of this paper, covers hazard modelling, structural modelling and loss modelling. The specific application considered in this study is a section of an existing viaduct in California: the I‐880 interstate highway. Several simulation models of the viaduct are developed, a series of nonlinear time‐history analyses are carried out to predict demands, measures of damage are evaluated and the probability of closure of the viaduct is estimated using the specified hazard for the site. It is concluded that the methodology offers several advantages over existing deterministic performance‐based procedures. Results of the investigation indicate that the assessment methodology is particularly sensitive to the reliability of decisions made by bridge inspectors following a seismic event, and to the dispersion in the demand estimation, which in turn is influenced by several factors including soil–structure interaction effects and ground motion scaling procedures. Copyright © 2005 John Wiley & Sons, Ltd.     

白垩纪地球表层系统重大地质事件与温室气候变化研究

国家重点基础研究发展计划（973）项目“白垩纪地球表层系统重大地质事件与温室气候变化”，将以白垩纪与碳循环相关的重大地质事件和温室气候变化的关系为主线，以大洋缺氧事件—富氧作用转变过程和机制研究为突破口，进行海陆相整合研究，重点追溯东特提斯洋和我国大陆地球表层系统重大地质事件的记录，探讨这些事件与碳循环、快速气候变化的正/负反馈机制。项目将充分利用中国大陆发育完好的白垩纪海相、陆相地层及古生物记录，通过松辽盆地白垩系科学钻探全岩芯取样和多学科综合研究的途径，着眼于厘定反映地质事件和气候变化的层位及标志和时间格架，解决高分辨率海、陆相沉积事件的精确对比，分析地层记录中气候标志和古生物类群的地理分布，集中研究陆地和海洋环境对同一事件的响应机制，重溯白垩纪地球表层系统重大地质事件过程及成因，探究陆相烃源岩大规模形成、陆地生物群更替与温室气候变化和碳循环之间的正/负反馈关系和机制等科学问题，为预测全球长时间尺度上的气候变化趋势提供科学依据。     

基于GIS的滑坡、泥石流灾害危险性区划关键问题研究

随着GIS技术的引入,滑坡、泥石流灾害危险性区划的效率和准确性得以大大提高。依据工程地质类比原则,在灾害学理论指导下,结合专家打分、层次分析、人工神经网络、信息量、Logistic回归、统计量等模型方法,以MAPGIS软件为平台,利用C++语言开发了滑坡、泥石流灾害危险性区划评价分析系统;并重点探讨了GIS支持下的滑坡、泥石流灾害危险性区划过程中的因子分析、模型选取、模型复合、单元划分、系统集成、结果评价等关键问题,建立了一整套基于GIS的滑坡、泥石流灾害评价方法体系。应用该系统对长江三峡库区和辽宁省鞍山市分别开展了滑坡、泥石流灾害危险性区划研究,取得了较好的效果。     

麦兹地区火山沉积岩型铅-锌矿床地质特征与找矿方向

阿尔泰山南缘的铅-锌矿床主要分布于麦兹地区,为了在其找矿空间和找矿类型上有所突破,详细地阐明了麦兹地区铅-锌矿床的主要地质特征、成因类型及其控矿因素,并结合区域构造演化背景,总结了麦兹地区铅-锌矿床的成矿规律,指明了铅-锌矿床的找矿方向。     

云南保山核桃坪铅-锌矿床地质特征

保山核桃坪铅-锌矿为一中型铅-锌矿床。矿体赋存于上寒武统核桃坪组,主要受近SN向的层间断裂(F1)及次级断裂构造控制,岩石(性)控矿也十分明显,成矿作用与矽卡岩化密切相关。通过对该矿床地质特征的系统分析以及对矿床围岩蚀变、控矿因素的深入研究,认为该矿床主要矿化作用是深部高温成矿流体贯入并与围岩发生矽卡岩化蚀变,随后发生矿化作用。矿床应属矽卡岩型铅-锌矿床。