MS2000激光粒度仪测量第四纪沉积物粒度的定量进样研究

粒度是第四纪古气候与古环境重建的常用替代指标,目前通常采用Mastersizer2000激光粒度仪进行分析,该测试仪器优点是速度快、精度高、重复性好,缺点是进样过程未实现定量化,对部分沉积样品的分析结果出现一定的随机性和不确定性,分析结果易产生人为误差。为探究样品量和进样方法对测试结果可能造成的影响,本研究选取6类代表性第四纪松散沉积物,预处理后分别采用倾倒法、吸管法及定量进样法进行多次重复实验。结果显示:粒度组分越单一,不同进样方法造成的结果误差越小;如果沉积物含有多个粒度组分,而预处理样品量过多,倾倒法容易造成粒度结果偏细,吸管法往往造成实验结果偏粗,定量进样法实验结果居于前两者之间。采用烧失量法计算沉积物中碳酸盐、有机质含量,结合马尔文激光粒度仪测试原理及多次定量重复实验结果,计算了一次实验所需样品量,发现其与中值粒径和碳酸盐、有机质(合称杂质)含量呈线性正相关。根据该线性关系式,在分析第四纪沉积物中值粒径范围及杂质含量的前提下,可计算一次测试所需样品量,将全部预处理后样品倒入测试烧杯中,可有效避免样品量和进样方法对样品粒度实验结果造成的误差。     

Shear-wave splitting in the southeast of Cathaysia block, South China

This study is focused on Fujing Province in China, southeast of Cathaysia block (SECB). The present work benefits from the data provided by the Fujian Seismic Network (FJSN) to study the seismic anisotropy in the crust. By means of a systematic analysis and adequate software package, we examine shear-wave splitting from data recorded at ten FJSN stations during the period January 1999 to December 2003. The results demonstrate that the average fast wave polarization is N109.4° E ± 42.6°, corresponding to the horizontal principal compressive stress in the test zone, and the average normalized slow wave time delay is 2.5 ± 1.5 ms/km. The predominant polarizations at stations in the eastern part of SECB are in the N–W direction, which suggests that they are related to the regional horizontal principal compressive stress and also to the strikes of faults. In contrast, the predominant polarizations at two stations in the western part of SECB are in the N–E direction. This polarization direction does not coincide with the direction of the horizontal principal compressive stress, but it follows the strikes of near faults, thus suggesting the influence of the local tectonics and a change in the stress field. The results prove that the predominant polarizations are parallel to the strikes of faults whenever the stations are on active faults. At a few stations near the coastal line, some polarizations show a certain amount of scatter which may be caused by crossing faults and irregular topography. Finally, the spatial distribution of time delays depicts strong lateral variations near the coast just where the seismic activity is comparatively bigger, so that the magnitude of anisotropy seems to be consistent with the most seismically active area.     

小江断裂带周边地区三维P波速度结构及其构造意义

作为青藏高原的东南边界,小江断裂带在高原物质的侧向逃逸中发挥着重要的作用.本文利用流动地震台阵及固定台站的走时观测资料,对小江断裂带及周边区域的壳幔三维P波速度结构进行了研究.结果表明,在中上地壳,小江断裂带内部主要为低速异常,其东侧主要为高速异常.在中下地壳,小江断裂带中部为低速异常,北部和南部主要为高速异常,其中北部的高速异常可延伸到地表附近,南部的高速异常可一直延伸到上地幔.我们推测,小江断裂带中部的低速异常与深部热作用有关;北部的高速异常可能是晚古生代地幔柱活动导致大量基性和超基性幔源物质侵入地壳引起的,它的存在对青藏高原物质向南逃逸起到了一定的阻挡作用,可能是导致川滇活动块体北部次级块体快速抬升的重要因素;南部顶界面向北倾斜的高速异常体对川滇活动块体向南滑移起到了进一步的阻挡作用,导致其上覆的中上地壳低速异常区发生较强的变形和强烈的地震活动,同时在上地幔深度范围起到了稳定的作用,使其南部区域的介质受青藏高原物质向南挤出的影响明显减小.     

澳大利亚稀土矿床主要类型及其成矿特征

澳大利亚稀土矿资源丰富,类型多样。通过对澳大利亚170余处稀土矿床地质特征的总结,将澳大利亚稀土矿床划分为4个主要类型和13个亚类。主要类型为与岩浆活动有关的稀土矿床、与沉积盆地有关的稀土矿床、与近代河流和滨海砂矿有关的稀土矿床和与表生风化作用有关的稀土矿床,并对每个亚类型矿床的分布特征、成矿时代和地质特征进行了总结。在此基础上,根据澳大利亚稀土矿床的地质背景、成矿特征等因素,初步划分出9个主要的稀土矿床矿集区,并从商业价值和资源潜力角度分别对矿集区的找矿潜力进行分析,综合认为H和E区是下一步进行矿业投资的良好对象。     

Laboratory study of wave and turbulence velocities in a broad-banded irregular wave surf zone

The characteristics of wave and turbulence velocities created by a broad-banded irregular wave train breaking on a 1:35 slope were studied in a laboratory wave flume. Water particle velocities were measured simultaneously with wave elevations at three cross-shore locations inside the surf zone. The measured data were separated into low-frequency and high-frequency time series using a Fourier filter. The measured velocities were further separated into organized wave-induced velocities and turbulent velocity fluctuations by ensemble averaging. The broad-banded irregular waves created a wide surf zone that was dominated by spilling type breakers. A wave-by-wave analysis was carried out to obtain the probability distributions of individual wave heights, wave periods, peak wave velocities, and wave-averaged turbulent kinetic energies and Reynolds stresses. The results showed that there was a consistent increase in the kurtosis of the vertical velocity distribution from the surface to the bottom. The abnormally large downward velocities were produced by plunging breakers that occurred from time to time. It was found that the mean of the highest one-third wave-averaged turbulent kinetic energy values in the irregular waves was about the same as the time-averaged turbulent kinetic energy in a regular wave with similar deep-water wave height to wavelength ratio. It was also found that the correlation coefficient of the Reynolds stress varied strongly with turbulence intensity. Good correlation between u′ and w′ was obtained when the turbulence intensity was high; the correlation coefficient was about 0.3–0.5. The Reynolds stress correlation coefficient decreased over a wave cycle, and with distance from the water surface. Under the irregular breaking waves, turbulent kinetic energy was transported downward and landward by turbulent velocity fluctuations and wave velocities, and upward and seaward by the undertow. The undertow in the irregular waves was similar in vertical structure but lower in magnitude than in regular waves, and the horizontal velocity profiles under the low-frequency waves were approximately uniform.     

藏东南波堆藏布江谷地古冰碛堰塞湖初步研究

藏东南作为青藏高原内外动力作用最强烈的地区之一,是河流堰塞-溃决洪水链式灾害频发地区。研究该区域古堰塞湖的形成与演化,对认识、评估灾害风险具有重要意义。研究结果表明,波堆藏布江谷地保存有一套湖相沉积地层,通过地貌填图和光释光测年等手段,并结合前人研究成果,推测海因里希事件1(H1)以来波堆藏布江谷地可能发生了一期古堰塞湖事件。该古堰塞湖可能是由波堆藏布江侧蚀白玉沟沟口冰碛垄,致使冰碛物滑塌并阻江形成的,古湖的最大湖面面积约为18.8km2,库容蓄水量约为0.13km3。该古堰塞湖的形成时间可能介于H1～10ka之间,其溃决时间可能在～6ka之后,后期河流溯源侵蚀及下切作用形成了多级以湖相地层为基座的阶地。     

塔里木河下游生态输水后植被景观格局动态变化研究

2000-2005年, 塔里木河流域管理局先后7次向塔里木河下游断流区进行了生态输水, 输水河道两岸的植被得到了一定的恢复. 以2000-2005的中巴资源卫星CCD影像为主要数据源, 获得了6 a的植被/非植被二值图, 并计算各年的景观格局指数, 分析了6 a植被景观格局的变化. 结果表明: 植被景观动态度在第四时段(2003-2004年)最大, 为47.83%; 在第三时段(2002-2003年)最小, 为-1.39%; 2000-2005年植被景观的动态变化呈正向趋势. 2000-2005年, 植被景观斑块个数与景观形状指数增加, 蔓延度指数下降了36.9, 斑块结合度指数均高于99, 表明研究区的植被景观破碎化程度、分离程度增加, 而景观类型联通性较高. 植被斑块面积均处于增加趋势且远离河道植被恢复率越小, 但植被景观的比重仍小于50%, 说明非植被类型是研究区的基质类型, 组成了景观的最大斑块. 针对缓冲区Zone 1, 植被景观的平均分维数处于减小趋势且2005年的斑块个数最小, 斑块结合度指数处于增加趋势, 表明近河道区域植被较为稳定, 受生态输水的干扰度较小, 植被景观斑块之间越来越聚集. 6 a间Zone 1的植被最大斑块指数均大于10%, 远高于其它5个缓冲带, 表明离河道越近植被景观的优势度最大.     

MySQL集群与MPI的并行空间分析系统设计与实验

GIS应用正面对空间数据规模日益增加和空间分析算法复杂度逐渐提高的挑战,本文提出一种基于MySQL空间数据库集群与MPI的并行计算库分布式空间分析框架的解决方案.该框架使用MySQL空间数据库集群解决大量空间数据存储与管理问题,利用MySQL Spatial的Replication机制加强空间数据的冗余备份和并发访问控制,同时使用MPI负责分布式计算节点间的通信减少人工控制通信的开发成本.并行框架的任务管理与调度系统采用优先队列式管理,通过Master节点监控集群状态,合理分发计算任务实现负载均衡和容错.最后,以多边形Overlay算法为例,研究其在该并行空间分析系统下的并行策略,采用数据并行的管道流水线作业方式在框架中运行测试,结果表明,该并行框架相比串行算法可以得到可靠的加速比.     

原位低温拉曼光谱技术在人工合成CaCl_2-H_2O和MgCl_2-H_2O体系流体包裹体分析中的应用Ⅰ:低温拉曼光谱研究

利用原位低温拉曼光谱分析技术,对在设定的实验条件下合成的CaCl2-H2O体系和MgCl2-H2O体系的流体包裹体进行分析研究,结果表明低温下CaCl2水溶液和MgCl2水溶液形成的盐水合物具有各自不同的特征拉曼光谱,通过测定特征光谱,能够简易直接的鉴定这些物质,进而确定盐水体系包裹体的成分.因此,原位低温拉曼光谱技术,能够有效地测定Ca2+和Mg2+这两种盐水体系包裹体流体中常见,但显微测温过程难以观察和判别的二价阳离子.实践表明,原位低温拉曼光谱分析技术是对传统的流体包裹体显微测温技术的一个十分有效的补充,在包裹体研究领域会得到越来越广泛的应用.     

气相色谱-质谱法分析土壤中十溴联苯醚

通过优化分析仪器的条件设置,建立了使用气相色谱-质谱技术分析十溴联苯醚(BDE 209)的仪器分析方法。通过实施严格的质量控制和质量保证(QA/QC)措施,建立了使用加速溶剂萃取(ASE)技术测试土壤中十溴联苯醚的分析检测方法。该方法的仪器检出限为9.75pg,方法检出限3.25ng/g,方法的精密度为5.56%,平均回收率为86.8%。比较了加速溶剂萃取、微波萃取、超声萃取、索氏抽提等方法的萃取回收效率,实验结果表明,四种方法的萃取回收率在97.7%~108%,都可以作为分析检测土壤中BDE 209的萃取方法。