福建省古田小溪组早白垩世孢粉植物群   总被引：1，自引：0，他引：1  

郑芬 《福建地质》1993,12(3):210-217

福建省古田小溪组下段含丰富的孢粉化石,其组合特征是以裸子植物花粉为主,蕨类植物孢子其次,被子植物花粉极少。主要成分有:Classopollis、Exesipollenites、Cicatricosisporites、Jugella、Tricolpopollenites等。它和中国南方白垩纪孢粉组合序列中的Classopollis-Cicatricosisporites-Tricolpoppllenites带相当。地质时代为早白垩世的巴列姆期。  相似文献   

华北克拉通若干脉状金矿的黄铁矿标型特征与流体成矿过程   总被引：15，自引：6，他引：15  

李晶  陈衍景  刘迎新 《矿物岩石》2004,24(3):93-102

通过对华北克拉通若干典型脉状(造山型)金矿流体成矿过程的研究分析发现：其可分为3个阶段，对比不同阶段黄铁矿的矿物学、微量元素和热电性等方面的特征，显示中阶段细粒黄铁矿(烟灰状黄铁矿)微量元素成分复杂，含量较高，金含量也明显较高，相应的金矿石品位较高；中阶段黄铁矿多呈灰绿-黄绿色，晶形常为五角十二面体，自形程度低(他形-半自形)，粒度细小，晶体表面平滑度差，凹入角发育，表面自由能高，吸附金的能力强，载金能力增强；中阶段黄铁矿热电性较强。结合理论和实验研究成果，认为杂质元素加入导致黄铁矿晶格畸变，电荷不平衡，热电性增强等一系列现象；使黄铁矿的结晶学特征、成分和热电性构成了“三位一体”的标型特征，可作为有效的金矿勘查的直接标志。富金的烟灰状黄铁矿快速沉淀于热液瞬时过饱和或物理化学性质瞬时巨变的条件下，流体沸腾和混合是最重要机制。鉴于黄铁矿标型特征的演化和形成机制与陆陆碰撞体制流体成矿作用的3阶段模式(即CMF模式)完全吻合，借助CMF模式进一步分析烟灰状黄铁矿在脉状造山型金矿床中的发育时间和空间，为CMF模式补充了矿物学方面的支持，同时，赋矿断裂带的脆韧性转变带、挤压向伸展转变期最有利于流体沸腾和混合，是高品位脉状金矿床形成的最佳空间和时间。  相似文献   

新疆塔里木河下游(上段)地区天然草地生态脆弱性研究   总被引：3，自引：0，他引：3  

龚新梅  汪溪远  潘晓玲  师庆东 《干旱区地理》2006,29(2):230-236

塔里木河(以下简称塔河)流域是我国生态脆弱地区之一,其中塔河下游地区为严重脆弱地区。塔河下游地区广大的天然草地主要分布在绿洲-荒漠过渡带,该地带也是一个典型的生态脆弱带。依据有关生态脆弱带评价方法,结合塔河下游天然草地分布的实际状况,建立生态脆弱性评价体系。对垂直于塔河河道不同距离上的草地生态环境进行了分析,得出在距离河道500 m以上的地带草地生态环境表现为中度生态脆弱,<350 m的草地生态环境表现为一般脆弱。评价结果基本符合实际情况,对指导当地合理开发和利用草地资源具有一定的价值。  相似文献   

东天山成矿带斑岩铜矿和其他类型矿床找矿勘查   总被引：4，自引：0，他引：4  

王庆明  赵仁夫  屈迅  程晓红  袁永江 《西北地质》2006,39(2):57-77

东天山地区横跨哈萨克斯坦与塔里木两大板块,是新疆最重要的有色金属、黑色金属和贵金属矿产地之一。经历了前震旦纪基底形成→震旦-泥盆纪古亚洲洋形成、消亡→石炭纪-早二叠世后碰撞造山→晚二叠世至今的陆内造山等阶段。主要成矿期为晚古生代早期(泥盆纪-二叠纪),成矿作用复杂、类型繁多。其中,北部形成岛弧斑岩型和火山岩型铜、钼、金矿,中部形成拉张火山岩型和矽卡岩型金、铜、镍、银矿,中南部形成前寒武纪结晶基底叠加改造的层控-热液型铅、锌、银矿,南部库鲁克塔格和北山地区形成拉张铜、镍、金矿。通过研究认为,东天山地区尤以铜、镍、钼矿产资源潜力很大,优选出28个矿找矿靶区。  相似文献   

Comparison of CO2 Effluxes and Their Driving Factors Between Two Temperate Steppes in Inner Mongolia, China     

齐玉春  董云社  耿元波  刘立新 《大气科学进展》2006,23(5):726-736

Soil respiration is a key component of the global terrestrial ecosystem carbon cycle. The static opaque chamber method was used to measure the CO2 effluxes from soil of a semiarid Aneurolepidium chinense steppe and a Stipa krylovii steppe in the Xilin River Basin of Inner Mongolia, China from March 2002 to December 2004. The results indicated that the soil respiration rates of the semiarid Aneurolepidium chinense steppe and the Stipa krylovii steppe were both relatively high from mid-May to mid-September of each year and remained low during the rest of the year. The minimum value of soil respiration occurred in December or January and negative effluxes of CO2 appeared for several days during the non-growing season of individual years at the two sampling sites. A high annual variation was found in the two steppes with the coefficients of variance (CV) being over 94%, even high to 131%. The annual sums of soil CO2 efflux of the Aneurolepidium chinense steppe varied between 356.4 gC m?2 yr?1 and 408.8 gC m?2 yr?1, while those of the Stipa krylovii steppe in the three years were in the range of 110.6 gC m?2 yr?1 to 148.6 gC m?2 yr?1. The mean respiration rates of the Aneurolepidium chinense steppe were significantly higher than those of the Stipa krylovii steppe in different statistical periods with the exception of the non-growing season. About 59.9% and 80.6% of the soil respiration variations in both steppes for the whole sampling period were caused by the changes of temperature and soil water content. In the Aneurolepidium chinense steppe, the soil respiration rate has significant or extremely significant positive correlation (r = 0.58 ? 0.85, p < 0.05 or p < 0.01) with air temperature and ground temperature of the topsoil except in 2002; the unique contributions of temperature change to the soil respiration variation of the three years were 53.3%, 81.0% and 58.6%, respectively. But, for the Stipa krylovii steppe in the same time interval, the soil water content (especially that of the 10–20 cm layer) has a greater effect on the change of soil respiration, and the unique contributions of the change of the 10–20 cm soil water content to the variations of soil respiration in 2002 and 2003 were 60.0% and 54.3%, respectively. In 2004, in spite of the higher contribution of temperature than soil water content, the contribution of ground temperature at a depth of 10 cm was only 46.2%, much weaker than that of any single year in the Aneurolepidium chinense steppe.  相似文献   

Vegetation analysis of a typical mangrove swamp—Lai Chi Wo coast of Hong Kong     

Lu Chang-yi  Wong Yuk-shan  F. Y. Tam Nora  Berry Richard 《中国海洋湖沼学报》1998,16(1):72-77

A vegetation analysis reveals that the Lai Chi Wo mangrove swamp in Hong Kong has 10 mangrove species comprising 76.9% of the total number of mangrove species in Hong Kong. This swamp is a mixed community dominated byAegiceras corniculatum, Heritiera littoralis, Excoecaria agallocha, Kandelia candel, Bruguiera gymnorrhiza, with importance values of 37.88, 28.19, 14.33, 11.33 and 8.27 respectively. The community’s mangrove species diversity and evenness, as based on the Shannon-Wiener Function, were 1.44 and 62.01%, which were lower than those of the south su-tropical evergreen broad-leaf forest community but its ecological dominance (0.26) was higher. The correlation information field (CIF) method, a useful analytical method for complex forest community, was adopted in the present mangrove analysis. The species correlation information was:Aegiceras corniculatum (0.268)>Heritiera littoralis (0.250)>Kandelia candel (0.220)>Excoecaria agallocha (0.169)>Bruguiera gymnorrhiza (0.101). The correlation information of the mangrove community was 1.008. This work was financially supported by the Agriculture and Fisheries Department of The Hong Kong Government and The Hong Kong University of Science & Technology.  相似文献   

新疆典型流域多卫星积雪遥感监测信息系统的设计与实践     

马虹  姜小光 《干旱区地理》1998,21(4):79-87

本文介绍了新疆典型流域多卫星积雪遥感监测信息系统的设计与实现。除了系统的构成和主要功能外,也较为详细的介绍了不同类型数据的处理,转换的综合分析的方法。在文章的最后,举例说明了系统的几个应用方面。  相似文献   

我国旬降水年变化特征的区域分布   总被引：2，自引：1，他引：2  

王小玲  屠其璞 《南京气象学院学报》2002,25(4):518-524

利用全国多年平均旬降水资料，通过旋转EOF分解，将全国各地旬降水的年变化特征划分为6大类别，在地理分布上归属为8个区域，各区域的降水除了夏季多，冬季少的共同特征外，还有其地域性特点。各区域特征时段降水量间的显著统计相关有一定的中期天气预报意义。各区域特征时段降水量和年降水量近44a来有不同的趋势变化，部分区域可用特征时段的降水变化特征表示年降水的变化特征。  相似文献   

城市典型建筑的地震损失预测方法I：结构易损性分析     

侯爽 郭安薪李惠  欧进萍 《地震工程与工程振动》2007,27(6):64-69

地震作用下结构的易损性分析是地震灾害损失预测方法的重要组成部分。本文针对多层砌体房屋结构、排架结构和多层钢筋混凝土结构等3种城市典型建筑，首先给出了该类单体建筑的地震结构易损性分析方法，然后对群体建筑的地震易损性分析方法，以及群体建筑的易损性分类方法进行了探讨，为城市典型建筑的地震灾害损失预测和评估提供参考，并为宁波市抗震防灾规划的地震损失预测提供基础。  相似文献   

Evapotranspiration from a Mongolian steppe under grazing and its environmental constraints     

Sheng-Gong Li  Jun Asanuma  Gombo Davaa 《Journal of Hydrology》2007,333(1):133-143

  相似文献