呼和浩特-包头地区平均波速比研究

内蒙古呼和浩特-包头地区地质构造复杂,历史上曾发生多次6级以上强地震。本文选取该地区做为研究对象,根据2001年1月1日～2010年4月30日ML≥1.0地震的空间分布和研究区域的台网布局,划分出2个子区域,每个子区域控制在3°×2°的空间范围内,分别计算了各个子区域的平均波速比,并对比分析其时间和空间变化。计算结果表明,各个子区域的平均波速比曲线随时间而变化的幅度相差不大,基本维持在2.5%～2.584%之间;呼和浩特地区的平均波速比为1.722,明显低于包头地区的平均波速比1.733,初步推断与呼和浩特地区的断裂构造分布及地下介质性质有关。     

Accurate estimation of acoustic impedance based on spectral inversion

Acoustic impedance is one of the best attributes for seismic interpretation and reservoir characterisation. We present an approach for estimating acoustic impedance accurately from a band‐limited and noisy seismic data. The approach is composed of two stages: inverting for reflectivity from seismic data and then estimating impedance from the reflectivity inverted in the first stage. For the first stage, we achieve a two‐step spectral inversion that locates the positions of reflection coefficients in the first step and determines the amplitudes of the reflection coefficients in the second step under the constraints of the positions located in the first step. For the second stage, we construct an iterative impedance estimation algorithm based on reflectivity. In each iteration, the iterative impedance estimation algorithm estimates the absolute acoustic impedance based on an initial acoustic impedance model that is given by summing the high‐frequency component of acoustic impedance estimated at the last iteration and a low‐frequency component determined in advance using other data. The known low‐frequency component is used to restrict the acoustic impedance variation tendency in each iteration. Examples using one‐ and two‐dimensional synthetic and field seismic data show that the approach is flexible and superior to the conventional spectral inversion and recursive inversion methods for generating more accurate acoustic impedance models.     

西秦岭原“舒家坝组”地层学解体及其李坝群浊流纵向搬运模式

西秦岭原“舒家坝组”地层可解体为３个岩石地层单位：北部秦岭群深变质岩系，中部李子园群变质火山岩系及南部李坝群碎屑沉积岩系。研究表明，李坝群为一套浊积岩系，具独特的浊流纵向搬运模式，是李坝金矿床含矿岩系，时代暂定为中—晚泥盆世     

Metallogenic model and prognosis of the Shuiyindong super-large strata-bound Carlin-type gold deposit,southwestern Guizhou Province,China

The Shuiyindong deposit is one of the largest (more than 100 tonnes of Au) and highest grade (more than 7×10-6-10×10-6), strata-bound Carlin-type gold deposits in southwestern Guizhou Province, China. The deposit is controlled by both structure and favorable lithology. It is situated near the axis of the striking Huijiabao anticline and is hosted in bioclastic limestone of the Permian Longtan Formation. Gold mineralization occurred under low temperature with Th of 220℃± and is closely associated with decarbonation, silicification, sulfidation and dolomitization. The deposit has a characteristic elemental assemblage of Au-As-Hg-Tl. Studies of geochemistry and isotope compositions indicated that the ore-bearing materials and fluids of the gold deposit mainly originated from a plutonic source, and possess a mixing feature with the strata matter during transportation from mantle to crust. Fluid inclusions in vein quartz from the gold deposit are rich in volatile flux, indicating that metallogenic fluid is an overpressured one. The activity and geothermal state of the Earth's crust in the long period of time are favorable for the formation of overpressured fluids in a large area, and extensive structures would drive the fluids into ore-forming system and make gold deposits formed. The complexity of structural movement in the upper crust of southwestern Guizhou Province resulted in complicated gold mineralization. Through metallogenic prognosis and exploration, the proven reserves of the deposit increased by tens of tonnes of Au and the deposit has become a super-large strata-bound Carlin-type gold deposit.     

基于边界约束有限内存的拟牛顿CSAMT一维反演及应用

可控源音频大地电磁法（CSAMT）正演具有计算耗时、精度低的特点;常规的反演方法边界处理简单,占用内存大,搜索方向也难以精准,严重影响反演效果。为了实现CSAMT快速高精度正演,改善边界处理方法以减少内存占用,优化搜索方向以减少迭代反演次数,提出基于边界约束有限内存的拟牛顿CSAMT一维反演方法。首先,在CSAMT正演中基于高斯积分与并行算法实现了一维介质模型条件下有限长导线源激发的水平电场快速高精度计算。其次,在反演方法中,分别构建了基于相对误差和绝对误差的两种目标函数,并引入光滑模型约束,采取自适应正则化策略更新正则化因子,并采用基于边界约束的有限内存拟牛顿算法（LBFGS_B算法）,实现了CSAMT一维准确快速反演。以含低、高阻薄层的多层地电模型的水平电场E_x振幅为反演数据进行直接反演和模型检验。结果表明,该方法能够反映出地层电阻率随深度变化的趋势,并对高、低阻薄层有较好的分辨能力,低阻薄层分辨效果更佳。实际CSAMT资料的反演剖面的分辨率优于常规的连续介质反演方法,地质效果明显,表明该方法具有良好的应用前景。     

北京地区气溶胶粒度谱分布初步研究

本文对北京地区气溶胶数浓度及其诸分布特征进行了初步研究。重点探讨了气溶胶数浓度分布与相对湿度的关系。研究结果表明，气溶胶浓度和谱分布存在明显的日变化和逐日变化，并在很大程度上受空气相对湿度和理查森数影响。     

行波输入下连续梁桥纵向墩梁相对位移碰撞效应分析

结合多跨连续梁桥的结构特点,提出了一种能模拟联间碰撞行为的连续梁桥碰撞分析模型.用非线性时程方法对行波输入下连续梁桥的地震碰撞反应进行了参数分析.结果表明:相邻联的周期比对短周期联位移的碰撞效应较大,考虑地震行波输入时伸缩缝处的碰撞效应可能会大幅度增大墩梁的相对位移,从而增大了地震作用下发生落梁的风险;墩梁相对位移随滑动支座摩阻系数的增大而减小.最后提出用一个碰撞效应增大系数来考虑连续梁桥相互碰撞对墩梁相对位移的影响,利用碰撞效应增大系数的概念为连续梁桥防止落梁的设计提供了一个新的思路.