东南极格罗夫山萨哈罗夫岭漂砾暴露年龄初探          下载免费PDF全文

李广伟  刘小汉  黄费新  孔屏  David Fink  韦利杰  方爱民 《极地研究》2009,21(4):265-271

首次对格罗夫山地区漂砾的暴露年龄进行的研究表明,萨哈罗夫岭冰原岛峰的两块漂砾样品的 Be最小暴露年龄分别为1．24±0．11Ma和1．37±0．12Ma, 。A1最小暴露年龄分别为0．90 4-0．12Ma和0．44±0．04Ma。萨哈罗夫岭附近冰面上的漂砾样品的 Be和 A1最小暴露年龄分别是0．47±0．3Ma和0．44±0．04Ma。考虑到误差,萨哈罗夫岭三块漂砾的最小暴露年龄与相近高程的基岩样品的最小暴露年龄基本一致。因此,在利用原地生成宇宙成因核素测年技术对东南极内陆格罗夫山地区的冰川消涨历史进行研究时,基岩和漂砾暴露年龄所反映出的冰川演化历史是明显吻合的。  相似文献   

中国对虾黄、渤海沿岸地理群的RAPD分析   总被引：43，自引：1，他引：42  

刘萍  孔杰  石拓  庄志猛  邓景耀  徐怀恕  韩玲玲 《海洋学报》2000,22(5):88-93

采用随机扩增多态DNA(random amplified polymorphic DNA,简称RAPD)技术,对中国对虾的黄、渤海地理群的32个个体遗传多样性进行了检测,使用OPI系列的20个10bp的寡核苷酸随机引物,对每个个体的基因组DNA进行扩增,结果为:17个引物获得了谱带清晰且重复性好的产物,扩增片段的分子量在2000～2000bp之间,共检测106个位点,其中多态位点数为39个,占36.8%;平均遗传距离为0.0941+0.0206,有67个标记(占63.2%)在整个群体的32个个体间表观稳定的一致性.  相似文献   

寻找降雹预报指标集的一种方法:逐步消空法   总被引：2，自引：2，他引：0  

孔燕燕  彭治班  赵秀英  吴宝俊  张纪淮 《气象》2000,26(10):10-14

对于用逐步消空法寻找降雹预报指标集合 ,例如 :寻找指标的步骤 ,从何处入手寻找预报指标 ,预报指标的确认 ,预报指标的总个数等有关问题进行了讨论。  相似文献   

遥感图像几何校正的实现   总被引：15，自引：1，他引：14  

邵鸿飞  孔庆欣 《气象》2000,26(2):41-44

描述了遥感图和何畸变的原因,阐述了几何精校正原理,并在此基础上给出了一个简单衫的精校正方案及其算法。理论上,此校正方法具有小于一个像素点的误差,满足业务上所需的订正精度。  相似文献   

数据表象特征在仪器维护中的应用     

尹传兵  丁雨  陈耿琦  王雪莹  孔丽娜 《地震地磁观测与研究》2012,33(5):279-284

针对地震台站使用的DSQ型水管倾斜仪,对仪器因环境变化、系统故障等原因引起的数据异常表象形态及原因进行剖析总结,提出了观测数据典型异常现象及故障的判定方法和检查思路,对台站做好观测仪器的日常维护维修具有一定的参考意义。  相似文献   

Effect of substrate grain size on the growth and morphology of the submersed macrophyte Vallisneria natans L.     

Z.Q. LiL.Y. Kong  L.F. YangM. Zhang  T. CaoJ. Xu  Z.X. Wang 《Limnologica》2012,42(1):81-85

Experiments were conducted to investigate the growth and morphology of the submersed macrophyte Vallisneria natans in relation to seven substrate types. The study also aims to evaluate the influence of the grain size of the aquatic substrate on the submersed macrophyte. The results show that growth, morphology and biomass accumulation of V. natans were significantly affected by the physical properties of the growth substrate. Compared with V. natans grown in pebble and gravel substrates, V. natans grown in silt and clay substrates had greater height, more ramets and leaves, as well as greater biomass accumulation. No significant differences in biomass allocation patterns were found among the different experimental treatments. The total porosity and dry bulk density of the growth substrate strongly influence plant traits. Substantial positive correlations were observed between total porosity and height and total biomass. Also, negative correlations were observed between dry bulk density and height, number of ramets, total biomass and lacunal volume. These results indicate that at high concentrations of water-column nutrients, V. natans responds to different physical properties of the growth substrate by changing growth and biomass accumulation strategies, rather than by changing biomass allocation patterns. Compared with V. natans grown in substrates with larger grain sizes, V. natans appeared well-adapted to substrates with smaller grain sizes. Thus, the physical properties of the growth substrate could be important in determining submersed macrophyte colonization and distribution in shallow eutrophic lakes. This information may be useful in managing shallow eutrophic lakes wherein rooted submersed macrophytes are declining.  相似文献   

On the transition from the laminar to disordered flow in a precessing spherical-like cylinder     

Dali Kong  Zhen Cui  Xinhao Liao 《地球物理与天体物理流体动力学》2015,109(1):62-83

We investigate, through both asymptotic analysis and direct numerical simulation, precessionally driven flow of a homogeneous fluid confined in a fluid-filled circular cylinder that rotates rapidly about its symmetry axis and precesses about a different axis that is fixed in space. A particular emphasis is placed on a spherical-like cylinder whose diameter is nearly the same as its length. At this special aspect ratio, the strongest direct resonance occurs between the spatially simplest inertial mode and the precessional Poincaré forcing. An asymptotic analytical solution in closed form describing weakly precessing flow is derived in the mantle frame of reference for asymptotically small Ekman numbers. We also construct a nonlinear three-dimensional finite element model – which is validated against both the asymptotic solution and a constructed exact solution – for elucidating the nonlinear transition leading to disordered flow in the precessing spherical-like cylinder. Properties of both weakly and strongly precessing flows are investigated with the aid of a complete inertial-mode decomposition of the fully nonlinear solution. Despite a large effort being made, the well-known triadic resonance is not found in the precessing spherical-like cylinder. The energy contained in the precessionally forced inertial mode is primarily transferred, through nonlinear effects in the viscous boundary layers, to the geostrophic flow that becomes predominant when the precessional Poincaré force is sufficiently large. It is found that the nonlinear flow evolutes gradually and progressively from the laminar to disordered as the precessional force increases.  相似文献   

柴达木盆地鄂博梁Ⅲ号构造新近系沉积环境演化及物源分析   总被引：1，自引：0，他引：1       下载免费PDF全文

孔红喜  赵健  侯泽生  司丹  翟志伟  马进业  申玉山 《古地理学报》2015,17(1):51-62

鄂博梁Ⅲ号构造为柴达木盆地大型构造之一,其中仅新近系下油砂山组圈闭面积即可达470km²。运用近3年来在该构造东西高点钻探的鄂深1、鄂深2及鄂7共3口探井的最新资料,通过岩石学、古生物学及地球化学等综合分析,对鄂博梁Ⅲ号构造沉积环境演化和物源方向进行了系统研究,取得了不同于前人的新认识。鄂博梁Ⅲ号构造新近纪沉积环境自上干柴沟期(N₁)到狮子沟期(N₂³)是一个湖进、水体不断加深的沉积演化过程,与前期所认识的湖泊收缩、水体不断变浅的结论不同。鄂博梁Ⅲ号构造新近系沉积碎屑主要来自于阿尔金山物源区,自下而上具有较强的继承性,浅部地层受冷湖方向物源的影响而具有混源的特点。该研究取得的新成果为该区进一步勘探部署提供了理论依据,并取得了一定的勘探成效。  相似文献   

汉江一级阶地抬升以来北亚热带风尘堆积、发育与东亚季风演变的耦合关系——以郧县段汉江上游谷地为例     

卞鸿雁  庞奖励  黄春长  查小春  孔伟 《中国沙漠》2014,34(3):674-682

风成黄土对东亚冬夏季风优势期转换及起迄时间起到良好指示作用,探究风尘黄土堆积、发育特征与东亚季风演变的耦合关系十分必要。本文通过研究汉江一级阶地上覆黄土-古土壤序列的构型、磁化率、烧失量、粒度、元素组成特征,分析汉江一级阶地抬升以来黄土-古土壤序列的成因及成壤特征,探究东亚冬夏季风的演化序列。结果表明：（1）汉江上游地区黄土-古土壤序列的地层构型为表层土（MS）-近代黄土（L₀）-古土壤（S₀）-过渡层（L_t）-马兰黄土（L₁）,磁化率、粒度、烧失量、元素组成等特征指示各地层成壤强度特征为S₀>L₀/L_t>L₁。（2） 成壤强度指示18000 a BP以来,东亚冬夏季风演替特征为末次盛冰期冬季风强烈→全新世早期冬季风减弱→全新世中期夏季风主导→全新世晚期夏季风减弱~,冬季风强盛,其演变滞后于低纬太阳辐射变化2000~3000 a。（3）该风尘堆积物理化性质对6000~5000a BP的气候恶化期有所响应。总而言之,汉江上游一级阶地上覆黄土为风尘堆积物,指示18000a BP以来东亚季风的变迁规律及季风异常事件,能够体现北亚热带对全球气候变化及极端事件的响应。  相似文献   

污泥沙障对流动沙区植被恢复的作用   总被引：1，自引：0，他引：1  

张军  孔致祥  管东红  任珺  陈明霞  王喜明 《中国沙漠》2014,34(3):747-751

利用城市生活污水处理厂脱水污泥制成成本低、吸水保湿性强和环境友好的污泥方格沙障、沙面上污泥平板沙障和沙面下污泥平板沙障,用于帮助恢复生态极端恶劣的流动沙区植被。调查撒播黄蒿（Artemisia scopara ）种子后试验区沙丘植物的种类、覆盖度、生长状况等植被恢复指标。结果表明：污泥沙障处理下,人工播种的黄蒿、天然的沙米（Agriophyllum squarrosum ）盖度、高度（除沙米）和生物量均显著高于裸沙区（对照）（p <0.05）,雾滨藜（Bassia dasyphylla ）、碱蓬（Suaeda glauca ）和猪毛菜（Salsola ollina ）的盖度、高度、多度、生物量（除雾滨藜）均高于对照;污泥方格沙障区的植物物种丰富度最高,沙面上污泥平板沙障区次之,沙面下污泥平板沙障及对照区较小;Shannon-Wiener多样性指数和Simpson多样性指数均为污泥方格沙障>沙面上污泥平板沙障>沙面下污泥平板沙障>对照;Pielou均匀度指数为污泥方格沙障>沙面下污泥平板沙障>沙面上污泥平板沙障>对照。综合考虑混合污泥成本、用量、植被恢复效果等诸因素,我们推荐采取污泥方格沙障治沙措施,使其在沙地植被恢复工作中发挥作用。  相似文献