华南壳幔结构与动力学的宽频地震观测研究   总被引：1，自引：0，他引：1       下载免费PDF全文

于大勇  米宁  黄晖  黄周传  李华  王良书  徐鸣洁 《地质科学》2016,(1):99-115

了解华南各岩石圈块体壳幔结构和各向异性方面的差异是揭示华南深部构造演化的基础。本文利用布设于华南的两条宽频地震测线观测数据,采用多种地震学方法对华南的地壳上地幔结构和各向异性进行了研究。接收函数结果表明,华南地区地壳厚度和岩石圈厚度都较薄,地壳厚度自东南沿海向西北内陆增厚,扬子克拉通的泊松比(波速比)低于华夏块体,表明扬子克拉通地壳较华夏块体更偏长英质。约北纬29°以北的扬子克拉通地幔转换带厚度明显增厚,可能是由地幔转换带底部停滞的冷的古太平洋板片或中生代克拉通碰撞残留造成的。层析成像结果显示华南上地幔具有很强的横向差异性,上地幔中的强烈低速异常体可能对应了晚中生代发生广泛岩浆作用时的岩浆房和岩浆通道。台湾下方的上地幔存在南北横向差异明显的高速异常,分别对应台湾南部向东俯冲的欧亚板块及台湾北部向北俯冲的菲律宾海板块。俯冲的欧亚板块在台湾南部是连续的,而在台湾中北部,由于与菲律宾海板块的相互作用,俯冲的欧亚板块被折断。剪切波分裂结果显示,以江绍断裂为界,华夏块体与扬子克拉通的岩石圈地幔各向异性存在明显的横向变化,表明两者的构造演化过程有显著差异。  相似文献   

干涉图像第二类统计Goldstein自适应滤波方法   总被引：1，自引：1，他引：0  

赵文胜  蒋弥  何秀凤 《测绘学报》2016,45(10):1200-1209

干涉图滤波是InSAR数据处理中的关键步骤之一,滤波结果的优劣会直接影响到相位观测的质量和最终产品精度。本文结合干涉图滤波算法的研究进展,对Goldstein频率域滤波及其经典改进算法进行了系统分析和比较,在此基础上提出了一种基于第二类统计的稳健相干性估计量的Goldstein自适应滤波方法。本文采用模拟数据和Envisat ASAR真实数据与现有方法进行了验证,试验结果表明,新的滤波方法在保持细节和抑制噪声方面优势更加明显。  相似文献   

冰盖下矩形河道的综合糙率          下载免费PDF全文

陈刚  张玉蓉  周密  顾世祥 《水科学进展》2016,27(2):290-298

综合糙率是采用曼宁公式确定河道水位和流量关系的关键参数。在河道冰封期,冰盖的出现增加了流动的阻力,明流条件下确定的综合糙率不再适用,需要重新估算。基于Einstein阻力划分过流断面的原理,冰盖下矩形河道的过水断面可划分为冰盖区、河床区和边壁区。根据总流的连续性方程,在确定各分区糙率系数、水力半径和断面面积的基础上,提出了冰盖下矩形河道综合糙率的计算公式。采用已有的试验水槽测量数据和天然河道实测资料对公式进行了验证,结果表明:公式计算的综合糙率与实测值吻合较好,与Einstein公式和Sabaneev公式相比,计算精度更高;对于冰封水流,宽浅河道采用分区水深代替水力半径进行简化计算的条件有别于明渠水流,在宽深比大于20时,计算结果才满足精度要求。  相似文献   

Variations of Hydrodynamics and Submarine Groundwater Discharge in the Yellow River Estuary Under the Influence of the Water-Sediment Regulation Scheme   总被引：1，自引：0，他引：1  

Dong Xia  Zhigang Yu  Bochao Xu  Maosheng Gao  Tiezhu Mi  Xueyan Jiang  Peng Yao 《Estuaries and Coasts》2016,39(2):333-343

The “Water-Sediment Regulation Scheme” (WSRS) is critically important to the hydrologic evaluation of the Yellow River estuary since a huge pulse of water and sediment are delivered into the sea during a short period. We used the natural geochemical tracers radium (²²³Ra, ²²⁴Ra, ²²⁶Ra) and radon (²²²Rn) isotopes as well as other hydrological parameters to investigate the mixing variations and submarine groundwater discharge (SGD) in the Yellow River estuary under the influence of the 2013 WSRS. Dramatically elevated radium and radon isotopic activities were observed during this WSRS compared with activities measured during a non-WSRS period. Radium “water ages” indicated that the offshore transport rate nearly tripled when the river discharge increased from 400 to 3400 m³/s. We calculated the SGD flux in the Yellow River estuary based on a radium mass balance model as well as radium and radon time-series models. The SGD flux was estimated at 0.02~0.20 m/day during a non-WSRS period and 0.67~1.22 m/day during the 2013 WSRS period. The results also indicate that large river discharge tends to lead more intense SGD along the river channel direction with a large amount of fresh SGD.  相似文献   

Representation and discovery of building patterns: a three-level relational approach     

Shihong Du  Mi Shu  Chen-Chieh Feng 《International journal of geographical information science》2016,30(6):1161-1186

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Bias estimation and correction for triangle-based surface area calculations     

Shuqiang Xue  Jiping Liu  Jinzhong Mi  Chun Dong  Yingyan Cheng 《International journal of geographical information science》2016,30(11):2155-2170

The calculation of surface area is meaningful for a variety of space-filling phenomena, e.g., the packing of plants or animals within an area of land. With Digital Elevation Model (DEM) data we can calculate the surface area by using a continuous surface model, such as by the Triangulated Irregular Network (TIN). However, just as the triangle-based surface area discussed in this paper, the surface area is generally biased because it is a nonlinear mapping about the DEM data which contain measurement errors. To reduce the bias in the surface area, we propose a second-order bias correction by applying nonlinear error propagation to the triangle-based surface area. This process reveals that the random errors in the DEM data result in a bias in the triangle-based surface area while the systematic errors in the DEM data can be reduced by using the height differences. The bias is theoretically given by a probability integral which can be approximated by numerical approaches including the numerical integral and the Monte Carlo method; but these approaches need a theoretical distribution assumption about the DEM measurement errors, and have a very high computational cost. In most cases, we only have variance information on the measurement errors; thus, a bias estimation based on nonlinear error propagation is proposed. Based on the second-order bias estimation proposed, the variance of the surface area can be improved immediately by removing the bias from the original variance estimation. The main results are verified by the Monte Carlo method and by the numerical integral. They show that an unbiased surface area can be obtained by removing the proposed bias estimation from the triangle-based surface area originally calculated from the DEM data.  相似文献   

Molecular characterization of sulfate-reducing bacteria community in surface sediments from the adjacent area of Changjiang Estuary     

Yu Zhang  Yu Zhen  Tiezhu Mi  Hui He  Zhigang Yu 《中国海洋大学学报(英文版)》2016,15(1):107-116

Sulfate-reducing bacteria (SRB), which obtain energy from dissimilatory sulfate reduction, play a vital role in the carbon and sulfur cycles. The dissimilatory sulfite reductase (Dsr), catalyzing the last step in the sulfate reduction pathway, has been found in all known SRB that have been tested so far. In this study, the diversity of SRB was investigated in the surface sediments from the adjacent area of Changjiang Estuary by PCR amplification, cloning and sequencing of the dissimilatory sulfite reductase beta subunit gene (dsrB). Based on dsrB clone libraries constructed in this study, diversified SRB were found, represented by 173 unique OTUs. Certain cloned sequences were associated with Desulfobacteraceae, Desulfobulbaceae, and a large fraction (60%) of novel sequences that have deeply branched groups in the dsrB tree, indicating that novel SRB inhabit the surface sediments. In addition, correlations of the SRB assemblages with environmental factors were analyzed by the linear model-based redundancy analysis (RDA). The result revealed that temperature, salinity and the content of TOC were most closely correlated with the SRB communities. More information on SRB community was obtained by applying the utility of UniFrac to published dsrB gene sequences from this study and other 9 different kinds of marine environments. The results demonstrated that there were highly similar SRB genotypes in the marine and estuarine sediments, and that geographic positions and environmental factors influenced the SRB community distribution.  相似文献   

Delimiting the species <Emphasis Type="Italic">Neosiphonia yendoi</Emphasis> (Rhodomelaceae,Rhodophyta) based on COI and <Emphasis Type="Italic">rbc</Emphasis>L genetic variation in Korea and Japan     

Byeongseok Kim  Mi Yeon Yang  Myung Sook Kim 《Ocean Science Journal》2016,51(3):507-516

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Phylogenetic diversity of culturable bacteria in surface seawater from the Drake Passage,Antarctica     

李昭  邢孟欣  王伟  王丹  朱建成  孙谧 《中国海洋湖沼学报》2016,34(5):952-963

The Drake Passage is located between the Antarctic Peninsula and Tierra del Fuego in the south of South America. Surface seawater samples were collected at seven sites in the Drake Passage during the austral summer of 2012. The 16S rRNA sequences were analyzed from 187 isolated bacterial strains. Three phyla, 29 genera and 56 species were identified. The three phyla were Actinobacteria, Firmicutes and Proteobacteria; the Proteobacteria included α-Proteobacteria, β-Proteobacteria and γ-Proteobacteria. γ-Proteobacteria, Actinobacteria and Firmicutes were the dominant class or phyla in terms of quantity and species. Gram-positive bacteria (Actinobacteria and Firmicutes) accounted for 57.8% of all types identified. There were nine dominant genera, including Curtobacterium, Staphylococcus, and Halomonas, and 14 dominant species including Curtobacterium flaccumfaciens, Curtobacterium pusillum, and Staphylococcus sciuri. Of the strains identified, 87.2% were catalase positive or weakly positive.  相似文献   

The Study of Stream Sediment Geochemical Data Processing by Using <Emphasis Type="Italic">k</Emphasis>-Means Algorithm and Centered Logratio Transformation—an Example of a District in Hunan,China     

Mi Tian  Libo Hao  Xinyun Zhao  Jilong Lu  Yuyan Zhao 《Geochemistry International》2018,56(12):1233-1244

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