新昌硅化木揭示的早白垩世东南沿海地区古气候特征分析     

薛根元娄伟平  张维祥吴春华 何凤翩 《南京气象学院学报》2005,28(5):666-671

根据浙江省新昌硅化木的分布与特点，应用硅化木记录的可知性和植物学的类比原理，通过该地区硅化木、其他植物化石和岩性组合等综合分析，初步探讨了早白垩世新昌盆地南洋杉型木的生态环境，以此研究该时期东南沿海地区的古气候主要特征。研究表明：该地区早白垩世古气候的主要特点是温暖、湿润及有时存在相对干旱的季节，同时呈现由温湿逐渐转变为干旱炎热的气候变化趋势；新昌硅化木中有明显的树木年轮，表明这种古气候可能存在一定的季节变化。  相似文献   

中国近代气象观测记录特点浅析   总被引：1，自引：0，他引：1       下载免费PDF全文

吴增祥 《气象》2005,31(1):82-85

综合有关中国近代气象观测的史料文献和档案资料，对中国近代气象观测记录的存档现状及主要特点进行初步的论述和分析，对保护和开发利用近代历史气象资料、提供数据共享有一定的参考作用。  相似文献   

Dynamic behavior and applicability of lead alloy absorber     

李亚琦  李小军  刘锡荟 《地震学报(英文版)》2005,18(1):89-98

Introduction As the result of economic development, metropolitans spring out in China. In metropolitans,the cities contact with each other through life line systems, the density of population is larger thanother areas, and social treasure in the unit area is much higher than other cities (GAO, 2003). Atthe same time, the risk of potential earthquake disaster in metropolitans increases greatly. One ofcharacters of metropolitan earthquake damage is that each city in the metropolitan will …  相似文献   

Cosmogenic nuclide chronology of pre-last glacial maximum moraines at Lago Buenos Aires, 46°S, Argentina     

Michael R. Kaplan  Daniel C. Douglass  Bradley S. Singer  Robert P. Ackert  Marc W. Caffee 《Quaternary Research》2005,63(3):636-315

At Lago Buenos Aires, Argentina, ¹⁰Be, ²⁶Al, and ⁴⁰Ar/³⁹Ar ages range from 190,000 to 109,000 yr for two moraines deposited prior to the last glaciation, 23,000–16,000 yr ago. Two approaches, maximum boulder ages assuming no erosion, and the average age of all boulders and an erosion rate of 1.4 mm/10³ yr, both yield a common estimate age of 150,000–140,000 yr for the two moraines. The erosion rate estimate derives from ¹⁰Be and ²⁶Al concentrations in old erratics, deposited on moraines that are >760,000 yr old on the basis of interbedded ⁴⁰Ar/³⁹Ar dated lavas. The new cosmogenic ages indicate that a major glaciation during marine oxygen isotope stage 6 occurred in the mid-latitude Andes. The next five youngest moraines correspond to stage 2. There is no preserved record of a glacial advance during stage 4. The distribution of dated boulders and their ages suggest that at least one major glaciation occurred between 760,000 and >200,000 yr ago. The mid-latitude Patagonian glacial record, which is well preserved because of low erosion rates, indicates that during the last two glacial cycles major glaciations in the southern Andes have been in phase with growth and decay of Northern Hemisphere ice sheets, especially at the 100,000 yr periodicity. Thus, glacial maxima are global in nature and are ultimately paced by small changes in Northern Hemisphere insolation.  相似文献   

渭北东部奥陶灰岩地下水硫酸盐起源的化学同位素研究     

范基姣  马致远  何锦  刘瑞平 《地下水》2005,27(5):344-346

通过对渭北东部奥陶灰岩地下水中SO42-、δD、δ34S、δ18O的分析研究,认为奥陶灰岩地下水中硫酸盐起源主要为海相硫酸盐的溶解,其次为南部古沉积咸水混入.  相似文献   

海原断裂带刺儿沟古地震剖面炭屑~(14)C年龄及其意义          下载免费PDF全文

尹金辉  陈杰  郑勇刚  张克旗  刘粤霞 《地震地质》2005,27(4):578-585

在青藏高原东北缘海原断裂带刺儿沟古地震剖面上不仅保存了地震活动的崩积楔遗迹,还发现多层炭屑以及与人类活动有关的铁渣、陶片等遗物,文中运用14C测年法和经红外释光照射后的绿光释光测年法(Post-IR OSL)分别对剖面上的炭屑、烘烤黏土、沉积物等样品进行年龄测定和比对,获得了各炭屑层和人类活动遗迹的年代。测定的人类活动遗迹年代与海原周缘历史记载的强震发生时间序列比对结果表明,刺儿沟人类活动遗迹的形成可能与历史地震无关,过去以炭屑年代作为地层年代来限定古地震发生的时代,建立的古地震事件时序的结果可能不正确,上述工作为进一步研究海原断裂带的强震复发规律和海原地区考古提供了重要的基础资料  相似文献   

添加钢筋提高隔震结构高宽比限值的研究   总被引：2，自引：0，他引：2  

祁皑  林云腾 《地震工程与工程振动》2005,25(1):120-125

提出了在边支座上添加竖向钢筋以提高隔震结构高宽比限值的构造措施；从方案的构造、添加钢筋的工作状态以及对隔震效果的影响等方面论证了该措施的可行性；基于《建筑抗震设计规范》(GB50011-2001)，推导了添加竖向钢筋后隔震结构高宽比限值的公式；可行性论证和实际算例的计算结果表明，本方案技术可行、效果显著。  相似文献   

The Gambler: (re)placing the desire of money     

Stephen Horton 《New Zealand geographer》2005,61(3):187-202

Abstract:  The Gambler conjures a world of myth: not as a fiction of human consciousness but as unconscious image-language. Its ambition is to write geography as material subject. In tracing the discourse written in the built environment the text ranges over the analyses of Marx and Freud and into the gestural worlds of Kafka and the blood sports of the ancient Colosseum. It discovers the myth of New Zealand horse racing, written in pictures in the local pub where virtual racing, abstracted from the living world, (dis)plays on the television screen. Here, finally, The Gambler comes to terms with loss.  相似文献   

Comparative Accuracy in Four Civil War Maps of the Shenandoah Valley: A GIS Analysis*     

Brooks C. Pearson 《The Professional geographer》2005,57(3):376-394

This study compares the accuracy of four maps available to Union and Confederate officers during the 1862 Shenandoah Valley campaign of the American Civil War. It examines historical maps of the Valley of Virginia by the following cartographers: James W. Abert, Hermann Böÿe and Lewis von Buchholtz, Jedediah Hotchkiss, and Franz Kappner. Both simple and three‐tiered sinuosity measures are derived for reference points along study map representations of the Shenandoah river system. These data are then statistically compared to corresponding sinuosity data from USGS topographic quadrangles to identify the relative accuracies of the historical maps. This article offers evidence to refute the common historical assumption that Hotchkiss provided Maj. Gen. Thomas “Stonewall” Jackson with terrain intelligence that was far superior to that available to his Union opponents. Evidence indicates that maps by Union cartographers as well as the prewar Böÿe‐Buchholtz map were at least as accurate, or superior to, the work of Hotchkiss.  相似文献   

芙蓉洞洞穴演化形成所需历史时间估算方法及其地质意义   总被引：4，自引：0，他引：4  

陈桥  雒昆利  董明星  李会杰  李树文  叶成礼  刘强 《西北地质》2005,38(4):1-7

对芙蓉洞与芙蓉江古水面高程差进行了测量，引用洞穴古老次生化学沉积物同位素地质年代资料，通过和邻区地壳相对抬升速率对比，估算出芙蓉洞洞穴演化形成所需的历史时间约为12～18万a。相对于芙蓉洞古老次生化学沉积物同位素地质年龄（16万a）来说，洞穴演化形成是一个不可忽视的过程，进一步证明了两个清晰的洞穴发育阶段的存在。对于用洞穴古老次生化学沉积物同位素地质年龄代替洞穴发育整个历史过程是需要谨慎的。通过估算方法反演所揭示的该区地壳相对抬升速率与青藏高原相对抬升速率相比，进一步证实了扬子地台和青藏高原虽然具有相同的驱动机制，但扬子地台近代隆升速率远远低于青藏高原的隆升速度。同时，笔者还对扬子地台的隆升趋势作了一定的分析，认为近代扬子地台边缘隆升速度小，中间隆升速度稍大。  相似文献