DGPS方法在新构造研究中的应用探讨

DGPS方法是一种小区域范围内(≤20km)精确测量的有效手段,已在许多领域和地点得到应用。但是,由于地质科学研究的独特性,高精度的测量还缺乏有效的应用。近年来,随着新构造定量研究的逐步深入,如何定性或定量评价新构造时期弱活动区断裂的活动性、盆地内隐伏断裂的活动性、冲断带内的盲断层及其相关褶皱活动性等问题日渐明显。为了解决这些问题,一些新的方法和手段得到尝试和应用。运用DGPS方法可以获得精确的层状地质地貌面数据,通过数据分析,可以得到新构造时期不同时间尺度内构造演化过程。文中以近几年的应用实例为基础,系统介绍DGPS测线的设计、野外操作注意事项、精度分析和数据处理等过程。同时分析新构造时期三种时间尺度内的研究成果,认为DGPS方法获得的数据精度满足地质地貌调查和对比的要求,从而为在弱活动区内或盆地内部等不利条件下定量评价断裂的活动性提供有利的手段。     

Temperature dependence of the relationship of thermal diffusivity versus thermal conductivity for crystalline rocks

Thermal diffusivity governs the transient heat transport equation. Thus, a realistic characterisation of this parameter and its temperature dependence is crucial for geothermal modelling. Due to sparse information from boreholes, lack of samples, and elaborate measurement procedures, there is often insufficient data on thermal diffusivity at elevated temperatures. We make use of existing data on crystalline (metamorphic and magmatic) rock samples from the Kola Peninsula and the Eastern Alps and develop a general relationship for the temperature dependence of thermal diffusivity up to 300°C. The temperature dependence of thermal conductivity is parameterised itself, using an empirical relationship which is set up for both data sets as well. Hence, only thermal conductivity at ambient temperatures is required for determining the temperature dependence of thermal diffusivity. We obtain different coefficients for both data sets which can be explained by different geological settings, and therefore different mineral compositions and internal structures. Comparisons with other expressions for these rock physical parameters show a good agreement at ambient conditions. General relations for thermal diffusivity at elevated temperatures are rare. A comparison of our results with data from two crystalline samples from the KTB and data from the Southern Indian Granulite Province highlights the need for further data, which will help to quantify uncertainties.     

黔北煤田六龙井田红山滑坡成因初探

在分析了井田地层、构造、含水层、河流及泉水的基础上,对滑坡体的地貌特征进行了详细描述,认为形成滑坡的内在因素是地形及软弱岩层,外在因素是气候、水文、构造、地震。滑坡的形成过程包括孕破岩层、裂隙岩层、孕滑体岩体或岩层、开始滑动、大量滑动等几个不同阶段,并依次渐进。该滑坡形成于中早全新世（Q42-1）,滑坡类型属切层滑坡。     

Transitive Geostatistics for Stepwise Modeling Across Boundaries between Rock Regions

A single intrinsic stationary random field may not account for transitional heterogeneity and abrupt dissimilarity of geological properties across boundaries between rock type regions. This paper proposes the stepwise construction of transitive covariance models for modeling continuous properties correlated across boundaries of multiple disjoint physical domains such as rock type bodies. Modeling in geology is usually simplified by splitting the geological space into rock type geo-domains (e.g., strata, sedimentary facies, soil series, diagenetic regions and alteration zones). Due to the limitations of simultaneous solutions, a simplification is to model each domain independently at the cost of losing the conditioning of properties across domains. This paper proposes to organize the modeling process in a triangular array which follows events in the geological time domain; for example, the younger formations are at the top of the pyramid and the older formation at the base. The estimation may go from top to base by assuming that younger events have perturbed older formations. Geology shows the scars of events that cumulate in rock formations before they are finally eroded. In some cases, older formations may be parent material for younger formations. The continuous property within each geo-domain has a conditional covariance in the main diagonal of the array which may belong to a specific event in the geological time. This sequence leads to transitive estimation and simulations in the physical space. If a simultaneous solution is sought (i.e., the future and past are correlated both ways), the complex covariance functions can be constructed stepwise from conditional spectra.     

我国地面降水的分级回归统计降尺度预报研究

利用TIGGE资料中欧洲中期天气预报中心(ECMWF,the European Centre for Medium-Range Weather Forecasts)、日本气象厅(JMA,the Japan Meteorological Agency)、美国国家环境预报中心(NCEP,the National Centers for Environmental Prediction)以及英国气象局(UKMO,the UK Met Office)4个中心1~7 d预报的日降水量集合预报资料,并以中国降水融合产品作为"观测值",对我国地面降水量预报进行统计降尺度处理。采用空间滑动窗口增加中雨和大雨雨量样本,建立分级雨量的回归方程,并与未分级雨量的统计降尺度预报进行对比。结果表明,对于不同模式、不同预报时效以及不同降水量级,统计降尺度的预报技巧改进程度不尽相同。统计降尺度的预报技巧依赖于模式本身的预报效果。相比雨量未分级回归,雨量分级回归的统计降尺度预报与观测值的距平相关系数更高,均方根误差更小,不同量级降水的ETS评分明显提高。对雨量分级回归统计降尺度预报结果进行二次订正,可大大减少小雨的空报。     

Exploring the seismic expression of fault zones in 3D seismic volumes

Mapping and understanding distributed deformation is a major challenge for the structural interpretation of seismic data. However, volumes of seismic signal disturbance with low signal/noise ratio are systematically observed within 3D seismic datasets around fault systems. These seismic disturbance zones (SDZ) are commonly characterized by complex perturbations of the signal and occur at the sub-seismic (10 s m) to seismic scale (100 s m). They may store important information on deformation distributed around those larger scale structures that may be readily interpreted in conventional amplitude displays of seismic data. We introduce a method to detect fault-related disturbance zones and to discriminate between this and other noise sources such as those associated with the seismic acquisition (footprint noise). Two case studies from the Taranaki basin and deep-water Niger delta are presented. These resolve SDZs using tensor and semblance attributes along with conventional seismic mapping. The tensor attribute is more efficient in tracking volumes containing structural displacements while structurally-oriented semblance coherency is commonly disturbed by small waveform variations around the fault throw. We propose a workflow to map and cross-plot seismic waveform signal properties extracted from the seismic disturbance zone as a tool to investigate the seismic signature and explore seismic facies of a SDZ.     

盘龙江子流域不透水表面扩张模拟

为促进盘龙江子流域的城镇化进程及保护水环境,该文模拟预测了该地区不透水表面的时空格局:通过分析流域不透水表面扩张的影响因子,建立了智能体分类体系及行为与决策规则;构建了流域的不透水表面变化模拟模型,模拟出流域2002—2013年的土地利用变化,并且验证了其模拟精度;在此基础上模拟预测了盘龙江流域2014—2020年间的不透水表面扩张趋势。研究结果表明利用智能体建模方法较为适合模拟滇池流域盘龙江子流域不透水表面的扩张过程。     

藏南亚东地区前寒武纪亚东岩群的建立及其特征

藏南亚东地区前寒武纪结晶岩系以往统称为“聂拉木群”。本次研究发现该结晶岩系可划分为上、下两部分,二者之间原始接触关系为角度不整合。下部结晶岩系为本次新建的“亚东岩群”,其岩石组合为：下部为多种片麻岩夹少量细粒石英岩和黑云片岩;中部为多种混合岩;上部为多种片麻岩夹少量变粒岩、石英岩和片岩。不同部位的片麻岩和混合岩中含辉石岩、高压麻粒岩等“暗色”包体。研究表明,亚东岩群为角闪岩相─高角闪岩相变质作用的产物,经历了多期深部构造层次的韧性变形,与“聂拉木群”显著不同。因此,认为“聂拉木群”代表喜马拉雅地区全部“前寒武系”是值得商榷的。     

起伏地形位场快速延拓新方法

将起伏地形上的测点垂直投影至水平面上,并将地形上的位场u放在水平面的对应点上,这样就有一个平面上的假想位场u。用快速傅立叶变换（FFT）计算平面位场的垂向导数δu/δn,将这个垂向导数移至地形的对应点上,近似作为地形上的位的垂向导数δu/δn。根据Green公式,从地形上的位u和位的法向导数δu/δn,用积分的方法可计算地形上部任一点的位。在计算出地形上部一个平面上的位后,可用FFT迅速计算其它平面的位,包括与地形相交的平面上的位。在通常的位场延拓方法中,如用等效源法解一个线形代数方程组要需用很大内存量,要耗去大量计算时间。本方法的主要特点是省略了解线形代数方程组的步骤,从而大大节约计算时间。模型计算表明,本方法的计算精度是令人满意的。用本方法对航磁实际资料进行延拓,取得较好的效果。     

静压桩贯入地基的球孔扩张-滑动摩擦计算模式

针对静力压桩的特点,将沉桩过程中的侧摩阻力和端阻力分开计算,建立了一种新的计算模式,即球孔扩张-滑动摩擦模式。编制了计算程序,对桩端土按球形孔扩张计算;对桩侧土按滑动摩擦计算。算例证明,该计算模式是可行的。