扬子克拉通北缘新元古代岛弧花岗岩类成分极性及成因的地球化学探讨

对扬子克拉通北缘新元古代岛弧花岗岩类成分极性的地球化学研究表明,在SiO_2含量相近的条件下,由北向南岩石中K_2O、K_2O+Na_2O、K_2O/Na_2O逐渐增加,而CaO逐渐降低;从北向南,微量元素Rb、Ba、Th、Zr、Nb、Ta、 ∑REE及Rb/Th、Rb/Nb、∑LREE/∑HREE、(La/Yb)_N 逐渐增加或具增加趋势,而 Sr、Co、Ni和Sr/Ba具逐渐降低或具降低趋势;同位素组成由北向南δ~18O、εs_r(t)系统增高,而ε_(Nd)(t)逐渐降低。这些组分的空间变化规律与环太平洋带位于俯冲带上盘向陆一侧的岛弧或大陆边缘岩浆中出现的成分极性规律相一致.分析认为,大陆壳物质以不同比例的加入是影响俯冲带岛弧花岗质岩浆成分极性的一个重要因素,向陆一侧岩浆中陆壳物质所占的比例逐渐增高,而幔源物质所占比例逐渐降低。     

基于深部位移的蠕滑型滑坡预警指标及预警预报研究

基于边坡监测数据建立数学模型,是边坡变形和稳定性分析的重要方法。但是单一预测模型的形式和应用范围具有一定的确定性,不同模型对数据的利用程度也有所差别,往往不能充分运用已知信息,导致模型精度不高,适用性不强。针对单一预测模型存在的问题,提出一种基于熵权法的PSO-SVR-NGM优化组合模型。该模型结合高精度变权缓冲NGM(1,1,k,c)模型和PSO-SVR模型,能够减小单一预测模型的误差,大幅度提高预测精度。首先通过引入变权缓冲算子λ和背景值权重系数η、κ改进无偏NGM(1,1,k,c)模型,构建新的3参数变权缓冲NGM(1,1,k,c)模型。结合最大灰色关联度和最小平均相对拟合误差重新构造粒子群算法的适应度函数,利用改进的粒子群算法对提出的变权缓冲模型进行搜索寻优,确定最佳的参数组合。然后通过熵权法对改进的变权缓冲NGM(1,1,k,c)模型和PSO-SVR模型进行赋权建立优化组合模型。最后,将该组合模型应用于3个不同变形特征的边坡工程中,并与其他单一模型进行对比分析。结果表明,相对于单一模型,本文所提出的组合模型的拟合和预测误差较小,与原始位移数据的相关性较好,能够更真实地反映边坡变形规律,具有较强的工程适应性。同时组合模型的提出与发展也促进了单一模型的优化改进,为解决实际工程问题提供了良好的思路。     

Genetic algorithm for fitting a mixed Bingham distribution to 3D orientations: a tool for the statistical and paleostress analyses of fracture orientations

The clustering of fracture orientations is important for tectonic studies and for geotechnical engineering. In this study, a real‐coded genetic algorithm was adopted to fitting a mixed Bingham distribution to orientation data by maximizing the log‐likelihood function of the distribution. The maximization is a difficult problem, because the function has multimodality and singularity. It was found that the algorithm was effective for this problem. Given the orientations of dilational fractures, the present method determines not only the stress axes and stress ratio of each of the fracture groups but also the maximum non‐dimensionalized fluid pressure at the time of their formation. In addition, the software calculates the 95 % error ellipses of the concentration axes. The present method found that the orientations of ore veins of the Akenobe Mine, SW Japan, should be partitioned into three clusters. It is shown that two of the groups had distinctive Zn and Sn contents, and that the ore fluids had overpressures only slightly greater than the minimum principal stress at the time of the deposition of Zn‐ and Sn‐rich veins.     

吸附–解吸状态下煤层气运移机制

带吸附作用的煤层气运移规律一直是煤层气地质学界关注的焦点问题之一。为研究吸附-解吸状态下的煤层气运移机制,推导了气体吸附-解吸方程并分析了多孔介质扩散-渗流理论,开展了煤层气运移实验并对实验结果进行了分析。研究结果发现：煤体孔隙结构对煤层气运移具有\     

Graphical methods of river profile analysis to unravel drainage area change,uplift and erodibility contrasts in the Central Range of Taiwan

To reveal river channel steepness patterns and variance in settings with significant variation in rock uplift rate, rock erodibility and moving water divides, we present a series of graphical methods to interpret channel profiles. To complement Cartesian χ plots, longitudinal profiles and mapping methods, we introduce a new method based on a radial coordinate system. We map each basin onto polar coordinates in which the radial dimension is χ and the azimuthal coordinate, ?, is calculated with an increment (Δ?) scaled to the distance to neighboring channel heads. The elevation is contoured on this mapping. Average channel steepness is estimated by fitting a conical surface to the elevation. The graph simplifies the comparison of χ and elevation between channels that share a divide, and helps identify spatial changes in drainage area and patterns of erodibility. We apply this approach to derive the uplift pattern in the eastern and southern Central Range of Taiwan, where the high tectonic convergence and uplift rates combined with sub‐tropical climate and frequent typhoons results in high exhumation rate, and well‐developed, detachment‐limited river networks. Additionally, the tectonic activity leads to drainage basin reorganization. We identify examples of divide migration, discrete river capture as well as anomalous steepness that we attribute to local variability in rock erodibility. Estimated basin‐average steepness values show the highest and a near constant value from Hsinwulu basin to Liwu basin in the center of the Island. To the north and south of this region, the values gradually decrease. These estimates show good correlation with the topography of the Central Range and erosion rates derived from in situ ¹⁰Be concentrations in river‐borne quartz. We conclude that the basin steepness reflects systematic differences in rock uplift rate and erosion rate. Copyright © 2016 John Wiley & Sons, Ltd.     

海洋地震资料相位控制处理——东海研究实例

为了满足定量解释的需要,地震资料处理必须是高分辨率、振幅保持和相位控制的.面向海洋地震资料的相位控制处理技术包括利用远场信号进行确定性零相位化、Q补偿、预测反褶积及剩余相位校正等.利用模拟远场信号求取确定性去气泡及零相位化算子.此文基于相位控制处理,讨论了海洋地震资料的相位和极性判别方法,探讨了大于24 ms算子长度的预测反褶积对于保持信号形状的必要性,介绍了东海三维地震资料相位控制流程.     

Genetic difference of Chinese horseshoe crab (Tachypleus tridentatus) in southeast coast of China based on mitochondrial COI gene analysis

Population genetic structure and historical demography of Chinese horseshoe crab (T. tridentatus) along southeast coast of China were inferred from the sequence data of mitochondrial cytochrome c oxidase subunit I (COI) fragment. The sequence analysis for 964 bp COI fragment was conducted in 28 individuals collected from five localities: Ninghai in Zhejiang Province, Meizhou and Zhangpu in Fujian Province, Beihai of Guangxi Zhuang Autonomous Region and Danzhou of Hainan Province. Sequence variation was relatively low with a total of seven transitions observed. In all localities, Haplotype H3 was the dominant type observed among eight haplotypes defined previously, and was at the center of radiation in Median-Joining network. The prolonged star-like network suggests a signature of population expansions. The level of diversity was low in total, with haplotype diversity (H_d) being equal to 0.765 and nucleotide diversity (π) being equal to 0.001 18, respectively. The genetic structure analysis revealed the significant genetic difference between Ninghai and Danzhou populations. Both mismatch distribution analysis and Fu's F_s test provided consistent inference of historic population expansion. The low genetic diversity of horseshoe crab observed along China coast indicated that urgent measures should be taken to protect this rare marine animal.     

New magnetic field measurements of β Cephei stars and slowly pulsating B stars

We present the results of the continuation of our magnetic survey with FORS 1 at the VLT of a sample of B‐type stars consisting of confirmed or candidate β Cephei stars and Slowly Pulsating B (hereafter SPB) stars, along with a small number of normal B‐type stars. A weak mean longitudinal magnetic field of the order of a few hundred Gauss was detected in three β Cephei stars and two stars suspected to be β Cephei stars, in five SPB stars and eight stars suspected to be SPB stars. Additionally, a longitudinal magnetic field at a level larger than 3σ has been diagnosed in two normal B‐type stars, the nitrogen‐rich early B‐type star HD 52089 and in the B5 IV star HD 153716. Roughly one third of β Cephei stars have detected magnetic fields: Out of 13 β Cephei stars studied to date with FORS 1, four stars possess weak magnetic fields, and out of the sample of six suspected β Cephei stars two show a weak magnetic field. The fraction of magnetic SPBs and candidate SPBs is found to be higher: Roughly half of the 34 SPB stars have been found to be magnetic and among the 16 candidate SPBs eight stars possess magnetic fields. In an attempt to understand why only a fraction of pulsating stars exhibit magnetic fields, we studied the position of magnetic and non‐magnetic pulsating stars in the H‐R diagram. We find that their domains in the H‐R diagram largely overlap, and no clear picture emerges as to the possible evolution of the magnetic field across the main sequence. It is possible that stronger fields tend to be found in stars with lower pulsating frequencies and smaller pulsating amplitudes. A somewhat similar trend is found if we consider a correlation between the field strength and the v sin i ‐values, i.e. stronger magnetic fields tend to be found in more slowly rotating stars (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

EFFECT OF PERPENDICULAR A.C. ELECTRIC FIELD ON THE OBLIQUE WHISTLER MODE INSTABILITY IN THE EARTH’S MAGNETOSPHERE

The elements of dielectric tensor and dispersion relation for obliquely propagating whistler waves with finite in an infinite magnetoplasma are obtained for a kappa distribution in the presence of perpendicular a.c. electric field. Integrals and modified plasma dispersion functions are reduced in power series form. Numerical calculations have been performed to obtain temporal growth rate and real frequencies of the plasma waves for magnetospheric plasma, using linear theory of dispersion relation. The effect and modification introduced by the perpendicular a.c. electric field on the temporal growth rates, real frequencies and resonance condition are discussed for kappa and Maxwellian distributions. Our results and their interpretation are compared with known whistler observations obtained by ground-based techniques and satellite observations.