Zircon U–Pb age, trace element and Hf isotope composition of Kongling terrane in the Yangtze Craton: refining the timing of Palaeoproterozoic high-grade metamorphism

U–Pb age, trace element and Hf isotope compositions of zircon were analysed for a metasedimentary rock and two amphibolites from the Kongling terrane in the northern part of the Yangtze Craton. The zircon shows distinct morphological and chemical characteristics. Most zircon in an amphibolite shows oscillatory zoning, high Th/U and ¹⁷⁶Lu/¹⁷⁷Hf ratios, high formation temperature, high trace element contents, clear negative Eu anomaly, as well as HREE-enriched patterns, suggesting that it is igneous. The zircon yields a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 2857 ± 8 Ma, representing the age of the magmatic protolith. The zircon in the other two samples is metamorphic. It has low Th/U ratios, low trace element concentrations, variable HREE contents (33.8 ≥ Lu_N≥2213; 14.7 ≤ Lu_N/Sm_N ≤ 354) and ¹⁷⁶Lu/¹⁷⁷Hf ratios (0.000030–0.001168). The data indicate that the zircon formed in the presence of garnet and under upper amphibolite facies conditions. The metamorphic zircon yields a weighted mean ²⁰⁷Pb/²⁰⁶Pb age of 2010 ± 13 Ma. These results combined with previously obtained Palaeoproterozoic metamorphic ages suggest a c. 2.0 Ga Palaeoproterozoic collisional event in the Yangtze Craton, which may result from the assembly of the supercontinent Columbia. The zircon in two samples yields weighted mean two-stage Hf model ( T _DM2) ages of 3217 ± 110 and 2943 ± 50 Ma, respectively, indicating that their protoliths were mainly derived from Archean crust.     

城市生态景观的构建研究

运用景观生态学、旅游规划学、城市规划理论来认识城市生态景观并分析其具有和谐性、整体性、多样性、畅达性、安全性、可持续性等特点，阐述以人为本、尊重地域和历史文化、生态、满足市民休闲与游憩需求等构建原则，认为重点抓好自然廊道和斑块等自然生态景观的建设、重视人工廊道和城市建筑密集区的景观效果、完善城市生态景观的空间结构体系等是构建和谐城市生态景观的重要途径。     

HHT方法在地震工程中的应用之初步探讨

详细介绍了一种新的非线性、非平稳信号的处理方法-HHT，讨论了其有效性和优越性，简单介绍了其在地震工程中的应用前景，并利用HHT处理了地震工程中常用El Centro地震记录，得到了该记录的振幅-频率-时间分布特性，并将得到的边际谱与傅立叶谱做了对比。     

冀中坳陷-黄骅坳陷馆陶组热储发育差异性及成井条件

本文论述了冀中坳陷-黄骅坳陷馆陶组热储砂岩、底部砾岩、砂砾岩的发育、孔隙度及热水水质的差异性,对热储出水特征进行了探讨,提出了馆陶组热储成井的基本条件,对冀中坳陷-黄骅坳陷馆陶组热储成井具有一定的指导意义。     

河北省物理地层界线厘定

以现代地层学多重划分为理论依据,以岩石地层单元组的密度、磁化率、剩余磁化强度及厚度加权算术平均值等物性参数为研究对象,以有序地质量最优分割方法为数学手段,进行河北省全区综合地层柱物理地层界线的厘定,并对其地质意义进行了初步讨论。     

基于WMS的WebGIS

介绍了Web地图服务规范,通过一种WebGIS的互操作模型实现了WMS,并详细描述了客户端的实现.     

AutoCAD与其他常用软件的数据转换

本文就AutoCAD与生产应用中常用的ARCGIS、ARC／INFO、MicroStation、3DS等软件系统之间的数据转换作一些浅谈。     

山西大同市农村民居震害特征及防震对策

1989年10月18日山西大同-阳高发生了6.1级地震,在这次地震中,倒塌房屋31 348间,其中,倒塌的大部分是土窑洞.可见,减轻地震灾害的关键是提高建筑物的抗震性能.     

三峡库区巫山县城新址岩质库岸再造预测

巫山县城新址位于西坪和大宁河两岸.组成该库段的基岩主要为泥岩、粉砂岩、泥灰岩等,岩性较软弱,且地质构造变动强烈,褶皱、断裂发育,岩层破碎,崩塌、滑坡分布较多,库岸再造问题严重;同时,岸坡再造又严重影响着新县城的规划和库岸的防护.因此把稳态坡形类比法应用于巫山县城新址基岩岸坡的再造预测,定量预测库岸的最终再造宽度,以指导新城的规划与建设.