香山绝对点周围的局部地壳变形及其对重力测量结果的影响

为了监视北京地区的地壳稳定性，北京测绘院对10多个基岩点和北京市区进行了多次沉降观测，结果表明香山点近10多年来高程变化只有几毫米，其重力效应可略而不计，但测点东北和东南方有两个较大的下沉区。用线积分法计算了两个局部沉降的重力效应，在沉降区中心其影响可达0.38μms^-2，但对香山点的重力效应非常小，完全可以忽略。因此得出如下结论：香山点观测到的重力变化不是地壳变形引起的。     

A TAXONOMICAL AND ECOLOGICAL SURVEY OF ROTIFER COMMUNITIES IU KROTTENSEE (AUSTRIA)

The composition and distribution of benthic, periphytic and planktonic rotifers in different habitatsin Krottensee were investigated. Sixty-five rotifer taxa were identified, their relative abundance estimated. Classification of the data set by cluster analysis allowed the recognition of distinct habitat groupe con-fined to acid bog ponds, macrophytes, sediments, and open water. Five groups of rotifer taxa were identifiedon the basis of their habitat preferences and the occurrence of the taxa. Highest diversities were found onmacrophytes and in acid bog ponds.     

青藏块体及周缘潜在震源与强震关系研究

利用1993－1999、1999－2001年青藏块体东北以及1991－2000年中国大陆GPS水平运动年速率资料，基于单一力源模型，反演获得了青藏块体及其周缘地区2000－2001年10次地震的震前资料反映的潜在震源参数，所得力源中心位置距实际震中的距离相对较小，其中2000年景泰5．9、2001年宁蒗5．8、昆仑8．1及格尔木3次5．7、5．8级地震均在50km左右；2000年兴海6．6、2001年年施甸5．9、永胜6．0级地震不到100km；2001年雅江6．0级地震最远（121km）。此外，1999－2001年青藏块体东北缘地区的反演结果表明，沿东昆仑构造带的昆仑山口－达日及库玛断裂向东至甘东南、甘青交界区域，可能仍存在潜在震源。     

潮汐形变资料中地震前兆信息的识别与提取

将小波变换的多分辨率分析引入潮汐形变资料处理中，对近年来云南地区的3次强震前的潮汐形变观测资料进行了处理与分析，发现在地震前2～5个月，震中附近的形变台站都接收到一个频段相同的异常信号，且它们之间是相关的，相关系数达80％以上，由此可以确定信号是由同一个源发出来的。出现在多个台站的相同频段的异常信号很可能就是我们想要得到的地震前兆信息。     

GPS-derived horizontal ice flow velocities along the traverse route from Zhongshan Station to Dome-A, East Antarctica

1　IntroductionFromitsoriginalformulationin 1 990 ,theInternationalTrans AntarcticScientificExpedition (ITASE)hashadasitsprimaryaimthecollectionandinterpretationofacon tinental widearrayofenvironmentalparametersassembledthroughthecoordinatedeffortsofscientistsfromseveralnations(Mayewskietal.1 996) .AsaconsequenceITASEhasbeenfocusedtoaddresstwokeyscientificobjectives:1 )Todeterminethespatialvariabil ityofAntarcticclimate (eg.accumulation,airtemperature,atmosphericcirculation)overthelast2…     

渤海湾盆地东营凹陷S6′界面的构造变革意义

以三维地震剖面的解释为基础,在东营凹陷古近纪裂陷期充填序列中识别出了一条在全盆地范围内可以追索对比的区域性不整合界面S6′,该界面构成了盆地沙三段的底界.盆地充填地层的厚度和构造应力场分析揭示,S6′界面将盆地古近纪同裂陷期的演化划分为2个不同构造应力场控制的裂陷幕,即裂陷Ⅰ-Ⅱ幕和裂陷Ⅲ-Ⅳ幕.前者受控于近南北向的拉伸应力场,形成了分别由NWW向的陈南断裂和石村断裂带控制的半地堑式断陷盆地;后者受控于NW-SE向的拉伸应力场,形成了由NE向的断裂系统控制的半地堑式断陷盆地.S6′界面的发育是区域性的,在渤海湾盆地和中国东部的许多盆地中均可追索,其发育的时代为中始新世晚期(43.5 Ma),并且与印度洋板块和太平洋板块新生代期间的一次重大的运动学调整的时间一致,因此,S6′界面的识别有可能为中国东部新生代盆地形成演化的动力学背景的研究提供新的信息.     

3维地理信息系统技术综述

文中对3维地理信息系统技术进行综述性介绍,扼要地讨论了国内外有关3维地球空间信息的获取、管理、分析与可视化等技术的进展与动态,并分别探讨了它们的优势和局限。     

Calculation of the Model of Coesite Inclusions and Analysis of Their Retrometamorphic Paths

The process and path of retrometamorphism of coesite have great significance to our understanding of the P-T tracks of the exhumation of ultrahigh-pressure metamorphic rocks. Most of the coesites in the eclogite from Shima, Anhui Province, the Dabie Mountains, China, are found degraded to quartz partly or wholly, with ruptures occurring in the shells, outside which include the coesite and quartz. According to the microscopic observation, the sample of coesite inclusion is composed of garnet, quartz and coesite, based on which we have built a three-shelled composite sphere model to compute the transition of coesite. Based on the crystal growth formulas and pressure conditions of the ruptures in the garnet, we have calculated the radius of the quartz sphere, which depends on temperature, and eventually drawn the different retrometamorphic paths for different retrometamorphism rates.     

Geochemistry of Ore Fluids and Rb-Sr Isotopic Dating for the Wulong Gold Deposit in Liaoning, China

On the basis of detailed geological studies of the Wulong gold deposit, three metallogenic stages can be identified. With quartz fluid inclusions as an object of study, the authors investigated phase characteristics, compositional variations, temperature and pressure changes, fluid evolution, Pb isotope tracing and Rb-Sr isotopic dating of fluid inclusions entrapped in the above three metallogenic stages. The results show that Na+ is decreased obviously with metallogenic evolution, while K+ and other cations and gas compositions (H2, CO, CH4 and CO2) are increased slightly, and that the temperature and salinity vary in a pulsating manner along with the metallogenic evolution. Inverse calculation of hydrogen and oxygen isotopes indicate that at the first metallogenic stage the fluids were magmatic water, at the second stage they were dominated by magmatic water with a minor amount of meteoric water involved, and at the third stage, i.e., the final stage of metallogenesis, the fluids were composed complete     

当代生物多样性剧减与古-中生代之交生物绝灭的对比

18世纪以来人类活动对环境造成了强烈破坏,给生物多样性带来了巨大损失.为了了解生物多样性的变化趋势,利用"绝灭物种统计法"、"种-区曲线法"和化石记录对400年以来的生物多样性和古-中生代之交的生物绝灭进行了分析.当代生物多样性剧减表现为物种的快速绝灭(从8×104种/Ma增大到1.2×106种/Ma),而属的绝灭几乎为0;古-中生代之交生物绝灭的初始阶段也表现为物种的快速绝灭(从40种/Ma增大到150种/Ma),并且这个阶段的属的绝灭速率远低于绝灭高峰阶段的相应值(即66属/Ma远小于465属/Ma),可见当代生物多样性剧减相当于二叠-三叠系之交生物绝灭的初始阶段.