提高海洋可控源电磁法信噪比的方法研究

海洋可控源电磁法(MCSEM)资料解释技术在过去几年时间里飞速发展,但是海底噪声的存在严重影响了海洋可控源电磁资料的解释精度.本文根据国内外文献总结了压制MCSEM噪声的两种方法:时域滤波方法和噪声估计方法.通过对模拟数据的处理,验证了这两种方法在压制噪声中的应用效果.结果表明:时域滤波和噪声估计方法能够较好的压制背景噪声,提高处理结果的信噪比.     

探测一阶模态三重分裂的MSE技术和SHS方法的比较研究

完全剥离一阶模态_nS₁的三重分裂信号将有助于识别出其全部分裂谱线,进而更好地约束地球内部结构.理想情况下,球谐叠加法(SHS)与多台站实验技术(MSE)均可剥离一阶模态_nS₁的三重分裂信号,但部分学者持不同观点.本文基于对二者的理论分析进一步确认,在自耦合前提下,MSE方法可成功剥离_nS₁的三重分裂信号;而SHS方法在实际应用中无法成功剥离_nS₁的三重分裂信号,但可相对增强目标信号的振幅强度.此外,本文解释了MSE可剥离单线态信号的真实原因,并指出由于MSE未考虑全频段耦合影响,故仅适用于1 mHz以下的低频模态.鉴于超导重力(SG)数据在1 mHz以下比宽频地震数据具有更高的信噪比,因此,为验证本文结论并弄清MSE和SHS的实质,基于模拟数据及SG台站实测数据,本文利用MSE和SHS分别对一阶模态的合成信号及模态₃S₁进行了探测分析.实验结果表明,MSE可成功剥离一阶模态三重分裂信号,SHS则无法完全剥离,验证了我们的理论结论,表明前人部分结果需重新审视与评价.此外,本文基于三种不同方法并利用13个SG 台站数据给出的₃S₁的分裂宽度比分别为1.008, 1.000和1.001,远小于异常分裂判别临界值1.5, 因此,₃S₁应是正常分裂模态.     

祁连山中部地壳各向异性研究:来自远震接收函数的证据

青藏高原的隆升由印度-欧亚板块的碰撞而驱动,其生长演化,特别是从内到外的扩展机制仍尚存争议。祁连山地处青藏高原向东北扩展的前缘位置,其地壳结构与各向异性对于理解青藏高原向北扩展的生长机制具有重要意义。祁连山中部是青藏高原东北缘地壳遭受挤压强烈变形的区域,已有的研究已经揭示出地壳内部非耦合不均匀变形的几何行为,揭露其对应机制是亟待探索的前沿科学问题。此前该区域的各向异性研究大多基于面状台网数据,台站间距大,无法反映横跨祁连山地壳各向异性的精细变化。为此,本研究选用一条密集线性地震台阵,使用H-κ-c叠加方法,得到了横过祁连山中部的地壳厚度,泊松比以及地壳各向异性的横向变化。结果显示,在中祁连以及南祁连北部地壳厚度最大,平均泊松比最低,反映了地壳加厚过程中铁镁质下地壳的丢失以及长英质中上地壳的水平缩短。此外,偏长英质成分的泊松比值也不支持地壳流在该区域存在。在祁连山内部,地壳各向异性快波的偏振方向与地壳向外扩展方向一致,而与地幔各向异性快波方向近垂直,揭示了壳幔变形可能是解耦的。而在地壳较薄的南祁连和北祁连南部区域,快波方向与古缝合线的走向一致,说明早古生代的构造格局仍对现今的祁连山缩短隆升产生影响。     

沉积旋回叠置形式的波形分析及旋回层序划分方法

在陆源碎屑岩地层的沉积记录中,测井曲线上一个砂泥岩旋回可以采用正弦波进行描述,测井曲线幅度的高低反映旋回粒度大小的变化,旋回波长则是度量旋回厚度的标尺。本研究表明,测井曲线变化幅度与其平均值之差计算的累积残差曲线,是识别沉积体系、判别旋回层序界面的一个有效图解方法。根据数值模拟实验,证实对于任意一个级次的旋回复合波系,累积残差曲线的正半波和负半波曲线分别对应低频旋回的向上变细和向上变粗的沉积序列,正半波和负半波曲线的转换点位置对应旋回层序界面的深度。同时,引进测井曲线的频谱分析和滤波方法,可以划分沉积旋回的级别,进而研究沉积旋回变化形式的驱动机制。文中以柴达木盆地东部地区仙3井为例,根据测井数据计算的累积残差曲线,说明了划分低频和高频旋回层序的方法和流程,讨论了旋回幅度、波长变化与沉积环境和沉积速率的关系。     

基于伪多道匹配法的地震波形一致性校正方法

由于在激发、接收和传播过程中受到众多干扰因素的影响,地震反射波形发生畸变,严重影响到叠加剖面的质量,因此,在叠前需要进行波形一致性校正.笔者针对单道匹配法的不足,引入伪多道匹配法,对地震波形的振幅、相位和时间进行高精度一致性校正,并能保持波形保真,提高叠加效果.模型测试和实际数据处理结果证明了本方法的有效性和适应性,在低信噪比资料处理中也可以获得比较好的效果.     

The (Na–Ca)amphibole–albite–chlorite–epidote–quartz geothermobarometer in the system S–A–F–M–C–N–H2O. 2. Applications to metabasic rocks in different metamorphic settings

In order to illustrate different applications of the amphibole-albite-chlorite-epidote-quartz geothermobarometer, pressure-temperature-time ( P–T–t ) ± space ( P–T–t–s ) ± deformation ( P–T–t–d ) paths have been established from literature data. They are discussed as a function of the chemical, equilibrium and microstructural data available in each case, and compared with the conclusions already established by other methods. It is clear that it is necessary to know the relative chronology of the events (directions of zoning of minerals in successive microstructural positions) to establish precise P–T paths; this enables reconstruction of complex geodynamic histories. From this point of view, it is necessary to analyse the maximum possible number of minerals in a few well-chosen metabasic rocks showing different generations of blastesis. The rocks should belong to different tectonic units to obtain the best overall picture of a metamorphic complex.     

海相三角洲高分辨率层序地层学特征--以R国K气田PF组地层为例

利用高分辨率层序地层学理论和技术方法，综合测井和岩芯资料对R国K气田PF组地层海相三角洲沉积体系进行高分辨率层序地层学分析，从中识别出短期、中期、长期3个级别的基准面旋回层序．进一步分析短期旋回层序结构，划分出向上“变深”非对称型、向上“变浅”非对称型、对称型3种基本结构类型，还细分出低可容纳空间向上“变深”非对称型、高可容纳空间向上“变深”非对称型、以上升半旋回为主的不完全对称型、近完全一完全对称型和以下降半旋回为主的不完全对称型5种亚类型。并总结出海相三角洲短期旋回层序的沉积序列、叠加样式和分布模式．为PF组进一步的精细地质研究提供了依据。     

Drivers of water pollutant discharge in urban agglomerations and their scale effects: Empirical analysis of 305 counties in the Yangtze River Delta

Revealing the drivers and scale effects of water pollutant discharges is an important issue in the study of the environmental consequences during urban agglomeration evolution. It is also a prerequisite for realizing collaborative water pollutant reduction and environmental governance in urban agglomerations. This paper takes 305 counties in the Yangtze River Delta (YRD) as an example and selects chemical oxygen demand (COD) and ammonia nitrogen (NH₃-N) as two distinctive pollutant indicators, using the Spatial Lag Model (SLM) and Spatial Error Model (SEM) to estimate the drivers of water pollutant discharges in 2011 and 2016. Then the Multiscale Geographically Weighted Regression (MGWR) model is constructed to diagnose the scale effect and spatial heterogeneity of the drivers. The findings show that the size of population, the level of urbanization, and the economic development level show global-level increase impacts on water pollutant discharges, while the level of industrialization, social fixed assets investment, foreign direct investment, and local fiscal decentralization are local-level impacts. The spatial heterogeneity of local drivers presents the following characteristics: Social fixed assets investment has a strong promoting effect on both COD and NH₃-N discharges in the Hangzhou-Jiaxing-Huzhou region and the coastal area of the YRD; industrialization has a promoting effect on COD discharges in the Taihu Lake basin and Zhejiang province; foreign direct investment has a local inhibitory effect on NH₃-N discharge, and the pollution halo effect is more prominent in the marginal areas of the YRD such as northern Jiangsu, northern Anhui, and southern Zhejiang; local fiscal decentralization has a noticeable inhibitory effect on COD discharge in the central areas of the YRD, reflecting the positive impacts on improved local environmental awareness and stronger constraints of multilevel environmental regulations in the urban agglomeration. Therefore, it is recommended to guide greener development to reduce the water pollutant discharge; to embed an environmental push-back mechanism in the fields of industrial production, capital investment, and financial income and expenditure; and to establish a high-quality development pattern of urban agglomerations systematically compatible with the carrying capacity of the water environment.     

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渭河流域水土流失治理效率的时空格局演化与影响因素

运用Bootstrap-DEA模型计算2000~2015年渭河流域陕西段39个县区水土流失治理效率;结合探索性空间分析方法（ESDA）和地理加权回归模型(GWR)分析各县水土流失治理效率的时空演化特征及其影响因素。研究结果表明：① 2000~2015年,研究区水土流失治理效率从0.263增至0.336,整体治理效率仍处较低水平;前期生态治理效率的增加缘于纯技术效率的提高,后期规模效率对治理效率的增加起到了主导作用。② 县域的治理效率在空间上呈现集聚状态;热点分析结果进一步显示,2005年治理效率表现出2个热点集聚区,即以宝鸡市千阳县为热点区、乾县和武功县为核心辐射至永寿县和礼泉县的热点集聚区,冷点区域则以临潼为中心,辐射到西安市辖区、高陵、富平和三原县;2010~2015年治理效率的热点区域与冷点区域较2005年有所收缩且保持相对稳定。③ 渭河流域水土流失治理效率的时空变化是降水、坡度、灌草面积覆盖度、人口经济和农业生产共同作用的结果,且各影响因素在不同时期对各县的治理效率的贡献呈动态变化,这意味着政策制定者需要从全局角度权衡不同因素的影响效果。