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231.
冬季风异常对西北太平洋海温影响的区域性特征   总被引:10,自引:0,他引:10  
秦正坤  孙照渤 《大气科学》2006,30(2):257-267
分析东亚冬季风异常对西北太平洋海温的影响,结果表明其影响存在显著的区域性特征.冬季风强(弱)年,黑潮流域及我国近海区出现明显的降温(升温),而太平洋暖池区北部和亲潮区海温出现一定的上升(下降)趋势.进一步的物理机制分析和数值模式的结果表明,东亚冬季风对影响西北太平洋海温变化的热力因子与动力因子都有十分显著的影响,区域性特征的成因主要是各海区的大气和海洋对冬季风异常的响应方式存在差异.  相似文献   
232.
长江与汉江现代沉积物元素组成分析   总被引:1,自引:0,他引:1  
梅惠  马振东  李长安 《世界地质》2007,26(2):208-212
长江与汉江表层沉积物常量及微量元素组成特征分析表明,长江沉积物的常量化学组分中CaO、MgO相对较汉江高,汉江沉积物中Fe2O3、Al2O3、K2O相对较长江高;汉江沉积物的微量化学组分中Cr Ni、Mo、As、Sb、F等元素相对长江高;长江沉积物Cd的赋存形式以离子交换态和碳酸盐态为主,汉江沉积物Cd的赋存形式以残余态为主。长江沉积物与汉江沉积物组成的差异是由其源区表壳岩系决定的,前者呈现高CaO、MgO,并呈碱性(pH:8.02)的特点,而后者相对富Fe2O3,并呈中性(pH:6.8)。  相似文献   
233.
论述了湖南省古丈县茄通石灰石矿床的赋存层位,矿体形态、产状及规模,矿石的物质组成、化学成分,矿石的自然类型及质量等地质特征,并概述了矿床成因类型。研究认为,该石灰石矿为产于下粤陶统南津关组中的沉积型石灰石矿床,矿石中w(CaO)、w(MgO)均远远优于工业指标,为优质水泥用石灰石矿。  相似文献   
234.
云南宁洱6.4级地震应急行动及灾害特征   总被引:8,自引:0,他引:8  
云南宁洱6.4级地震是近年来距离城市较近的一次地震事件,造成了较多的人员伤亡和经济损失。震后,地方各级政府和地震部门都迅速启动地震应急预案,周密安排和部署地震应急处置与救灾行动。本文简要介绍了宁洱6.4级地震的应急行动和灾害情况及特征。  相似文献   
235.
A new record of Sebastes koreanus(Kim and Lee,1994) was documented based on morphological characters and DNA barcoding. Fifty-six S ebastes specimens were collected from the coastal waters of northern China. Samples were identified as S. koreanus based on morphological characters. The coloration and morphometric measurements were consistent with those described from specimens collected in South Korea. In this study,specimens had the following morphological characteristics:light brown body with dark stripes and tiny dark spots,4–5 wide indistinct vertical patterns on the side,2 radial stripes behind and below the eyes,1 large dark blotch on the opercle. Additionally,the following meristic characters were recorded:dorsal fin XIV-13,pectoral fin 16,anal fin III-6–7,pelvic fin I-5,lateral line scales 29–30,and vertebrae 26. The fragment of cytochrome oxidase subunit I(C OI) gene of mitochondrial DNA was sequenced for phylogenetic analysis. The mean genetic distance within the species was 0.3%. Net genetic distances between S. koreanus and other S ebastes species ranged from 3.1% to 7.6%,which was greater than the threshold for species delimitation. The phylogenetic analysis strongly supports the validity of S. koreanus in China at the genetic level. The origion,evolution,patterns of speciation and unique features in genome divergence among primate lineages of this species still need future directions of research.  相似文献   
236.
于景维  叶勇  柳妮  朱永才  文华国 《地质学报》2018,92(5):1070-1080
准噶尔盆地是中国西部地区最重要的含油气盆地之一,阜东斜坡区中上侏罗统头屯河组和齐古组是近期勘探重点。根据野外露头、钻井岩芯和分析化验资料,详细分析头屯河组和齐古组储集层特征差异,包括储集层岩矿特征和物性特征差异。岩矿特征中重点对碎屑、填隙物以及孔隙类型和结构特征进行对比分析,物性特征中重点对储集层类型进行研究,发现齐古组储集砂层储集质量总体上要好于头屯河组。通过综合分析,认为阜东斜坡区中上侏罗统储集层特征差异主要受构造、沉积相、异常压力和成岩作用复合控制,构造演化的差异是导致头屯河组和齐古组储集层特征差异的最关键因素,头屯河组物性最好储集层的微相类型为水下分流河道,齐古组物性最好储集层的微相类型为分流河道,异常压力对原生孔隙保存以及黏土矿物发育位置起到重要影响,成岩作用对于重点层位储集层物性好坏起到决定性作用,其中凝灰质的蚀变序列对于后期油气开发有重要参考价值。  相似文献   
237.
广东省泥石流灾害主要分布于粤西、粤东、粤北西部和珠江三角洲北部地区.根据对泥石流历史数据的统计分析研究发现,广东省泥石流灾害虽然发生频率低,但造成的经济损失巨大,明显高于滑坡、崩塌灾害,且呈现频率低、规模大、成灾快、损失严重、时空分布集中、危害范围广等特点.文中最后提出了广东省泥石流防治对策:提高防灾意识,做好防灾规划;注重对低频泥石流的防范;因地制宜采取防治措施;加强预防监督,社绝人为灾害.  相似文献   
238.
彭楠  李家华  陈铭培 《地质与资源》2009,18(4):298-303,255
河北宽城崖门子剖面的高于庄组属于中元古界长城系,下伏长城系大红峪组,上覆中元古界蓟县系杨庄组,沉积年限200 Ma(1800~1600 Ma),共划分为4个亚组,自下而上为官地亚组、桑树鞍亚组、张家峪亚组和环秀寺亚组,为一套厚940 m的碳酸盐岩沉积地层.从常量元素和微量元素2个方面探讨了高于庄组的地球化学特征.通过对岩石样品测试结果的分析,各种元素含量在岩石地层界线附近变化较明显,说明地球化学特征可以辅助划分沉积地层或对已划分的地层界线进行优化.另外,据CaO/MgO、Ca/(Ca+Fe)和Sr/Ba比值及V、Ti元素特征分析,该研究区高于庄组为较干热气候下的海洋环境沉积.  相似文献   
239.
J.M. Buttle  M.C. Eimers   《Journal of Hydrology》2009,374(3-4):360-372
Relationships explaining streamflow behaviour in terms of drainage basin physiography greatly assist efforts to extrapolate streamflow metrics from gauged to ungauged basins in the same landscape. The Dorset Environmental Science Centre (DESC) has monitored streamflow from 22 small basins (3.4–190.5 ha) on the Precambrian Shield in south-central Ontario, in some cases since 1976. The basins exhibit regional coherence in their interannual response to precipitation; however, there is often a poor correlation between streamflow metrics from basins separated by as little as 1 km. This study assesses whether inter-basin variations in such metrics can be explained in terms of basin scale and physiography. Several characteristics (annual maximum, minimum and average flow) exhibited simple scaling with basin area, while magnitude, range and timing of annual maximum daily runoff showed scaling behaviour consistent with the Representative Elementary Area (REA) concept. This REA behaviour is partly attributed to convergence of fractional coverage of the two dominant and hydrologically-contrasting land cover types in the DESC region with increasing basin size. Three Principal Components (PCs) explained 82.4% of the variation among basin physiographic properties, and several runoff metrics (magnitude and timing of annual minimum daily runoff, mean number of days per year with 0 streamflow) exhibited significant relationships with one or more PC. Significant relationships were obtained between basin quickflow (QF) production and the PCs on a seasonal and annual basis, almost all of which were superior to simple area-based relationships. Basin physiography influenced QF generation via its control on slope runoff, water storage and hydrologic connectivity; however, this role was minimized during Spring when QF production in response to large rain-on-snow events was relatively uniform across the DESC basins. The PC-based relationships and inter-seasonal changes in their form were consistent with previous research conducted at point, slope and basin scales in the DESC region, and perceptions of key hydrological processes in these small basins may not have been as readily obtained from scaling studies using streamflow from larger basins. This process understanding provides insights into scaling behaviour beyond those derived from simple scaling and REA analyses. The physiography of the study area is representative of large portions of the Precambrian Shield, such that basin streamflow behaviour could potentially be extended across much of south-central Ontario. This would assist predictions of streamflow conditions at ungauged locations, development and testing of hydrological models for this landscape, and interpretation of inter-basin and intra-annual differences in hydrochemical behaviour on the southern Precambrian Shield.  相似文献   
240.
黄河、长江泥沙特性对比分析*   总被引:10,自引:1,他引:10  
通过对黄河、长江泥沙的粒度分析、矿物分析及石英包裹体分析,揭示了两大河流泥沙的差异性。黄河悬沙粗于长江而底沙比长江为细。重矿物组合中,黄河泥沙黑云母含量远高于长江,粘土矿物中蒙脱石含量约比长江多一倍。反映了两大河流水动力条件及泥沙源区的环境差异。石英包裹体分析,更反映了两大河流泥沙源区的成因环境,为区分河流泥沙来源提供了一种新的方法。  相似文献   
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