Delineation of potential exploration targets based on 3D geological modeling: A case study from the Laoangou Pb-Zn-Ag polymetallic ore deposit,China

The Laoangou Pb-Zn-Ag polymetallic ore deposit (LAG) is a hydrothermal vein-type deposit in the East Qinling polymetallic metallogenic belt, which is controlled by NW-, NE- and nearly SN-trending faults and mainly hosted in the dolomite marble of Meiyaogou and Baishugou formations within the Luanchuan ore district (LOD). Although district-scale metallogenic prediction related to the Pb-Zn-Ag deposits in the LOD has been attempted, there have been no studies to formulate a detailed deposit-scale metallogenic prediction of the Pb-Zn-Ag deposit in 3D space. Here we selected the LAG to formulate a metallogenic prediction model for Pb-Zn-Ag deposit based on data from 1:10,000 scale geological map, and 66 boreholes and 39 sections of exploration lines on 1:1000 scale, to extract the salient spatial features of the deposit. We apply ordinary weights and weighted weights of evidence, followed by boosted weights of evidence, logistic regression and information entropy for integrating the features of the ore deposit for exploration targeting. The C–V fractal method is applied to classify the probabilities. Accordingly, three levels of exploration targets are delineated: the first level targets are mainly distributed in the periphery of known orebodies (M2, M3, II-3 and VI), which are also located in the ore-controlling strata and fault zones; the second level targets are located in the region of known orebodies, indirectly confirming that the prediction result is reliable; and the third level targets, which are mainly located at the contact between ore-controlling strata and metagabbro bodies, offer new targets for exploration in this ore district. Combining our results obtained in this study with those in previous studies, we provide some guidelines for exploration targets in the Pb-Zn-Ag deposits in the LOD, which might help in more effectively delineating the target zones.     

An external–internal mode coupling for a 3D hydrodynamical model for applications at regional scale (MARS)

This paper presents a 3D model in sigma coordinates. Although the principles it is based on have been established for some time, some original aspects for this type of 3D mode splitting model are presented here. The model was designed to simulate flows in various coastal areas from the regional scale down to the inshore scale of small bays or estuaries where circulation is generally driven by a mix of processes. The processes to be modeled enable simplifications of the Navier–Stokes equations on the classic Boussinesq and hydrostatic hypotheses. These equations are transformed within a sigma framework to make free surface processing easier. The main point of our demonstration focuses on the original aspect of the coupling between barotropic and baroclinic modes especially designed for ADI. It explains how full consistency of the transport calculated within the 2D and 3D equation sets was obtained. Lastly, we describe the physical processes simulated on a realistic configuration at a regional scale in the Bay of Biscay.     

频率域2.5-D井间波形层析成像及其实际应用

从频率域3-D声波波动方程出发,结合井间观测方式的特点,基于Tarantola广义反演理论,提出了一种频率域2.5-D井间波形层析成像方法.数值模型试验结果表明：该方法对薄层厚度的分辨能力能达到约主频波长的1/4,且分辨率显著高于走时层析成像,尤其垂直分辨率有实质改善.模拟资料的抗噪试验表明：在信噪比为0.8的情况下,随机噪声对波形层析成像的影响较小;而相干噪声对全波形层析成像的影响显著,特别是初至波附近的强振幅干扰影响更为严重.井间实际资料的试处理结果表明：波形层析成像能很好地刻画井间介质的分布情况与储层连通性,对于油藏开发阶段的方案实施具有指导意义.     

CaTiO3－钙钛矿的晶体结构相变、高温流变及其下地幔地球动力学意义

利用高精度的ＭＴＳ材料实验系统,在１４７３－１６７３Ｋ的温度区间和可控热力学环境条件下,对［１００］ｐｃ和［１１０］ｐｃ两个方位的ＣａＴｉＯ3－钙钛矿单晶体进行了高温蠕变试验,着重观测了晶体结构相变和高温流变的相关性．研究表明,钙钛矿的晶体结构相变对其高温流变性质有明显影响,斜方晶系钙钛矿蠕变强度大大高于四方和立方晶系钙钛矿,后两者具有很强的高温塑性各向异性．在分析相变过程晶体结构变化特征和观测到的高温流变数据基础上,认为钙钛矿晶体结构相变中发生的位错结构的变化是导致其高温流变性变化的主要物理机制．     

三维F－K域DMO方法及应用效果

在常速情况下,从三维时距方程出发,通过倾角代换,将三维倾角时差分裂为两个正交方向上的二维倾角时差,然后在这两个正交方向上分别做一次二维倾角时差校正,便可达到三维倾角时差校正的目的．应用实例表明这种三维ＤＭＯ分裂方法是切实有效的．     

急性颈椎损伤的CT诊断

本文目的是分析急性颈椎损伤（ＡＣＴ）的ＣＴ征象,评价ＣＴ在ＡＣＴ诊断中的价值及限度。方法：７８例颈椎外伤患者行平片、薄层ＣＴ检查及三维重建,并做对照分析。结果经影像学诊断６０例ＡＣＴ,ＣＴ诊断５９例,１例ＣＴ阴性而由平片确诊 １例。平片与ＣＴ的骨折检出率分别为 ５３． ３％和 ９８．３％。结论：ＣＴ比Ｘ线平片可发现更多的骨折,并能明确骨折块与椎管的关系。这对临床处理严重颈椎损伤起到指导作用。     

Disector自动测量及其三维可视化系统

本文介绍了自行开发的解决Diseetor应用问题的计算机图像处理软件系统及关键技术、算法。本系统能依照Disector原理对多层组织细胞的电镜及光镜图像中的目标进行正确的分割,各层之间图像的人工交互及自动配准。针对每个目标的上下层关系实现目标的Disector自动计数及参数计算,并对每个目标进行体数据的提取和三维重建显示,通过切片级表面重建出曲面表面,再借助OpenGL的显示功能把曲面显示出来。使用Disector分析系统对多种粒子(细胞等)进行三维分析,可以简化寻找新出现粒子的过程,克服切片采集过程中的形变,在统计分析之后,立体地观察粒子结构,能够使操作者从繁琐的手工操作中解脱出来。自动统计新出现的粒子。文中同时还给出了用该系统对小白鼠神经细胞个数的Disector分析,肾小球个数统计分析和三维重建显示实例。     

Complex site effects and building codes: Making the leap

The engineering community is aware of the importance of site effects, but it lags behind seismological studies when it comes to incorporating site effect considerations in design spectra for seismic norms. This lag is reflected in the conspicuous fact that current building codes make allowance for 1D site effects but ignore complex site effects. The purpose of this paper is to explore a way for including complex site effects in a building code environment. We take as example Eurocode 8, which is a modern code that exemplifies the current approach to site effect consideration. We examine the restrictions that we have imposed to make the problem of a feasible size and discuss the approach we have taken. We propose a strategy to incorporate a class of complex site effects in a design elastic spectrum.     

Site effects at Euroseistest—I. Determination of the valley structure and confrontation of observations with 1D analysis

This paper describes the process of construction of the 2D model of Volvi's geological structure and results of empirical and theoretical approaches to the evaluation of site response at Euroseistest. The construction of the 2D model is based on a re-interpretation of the available geophysical and geotechnical data in an effort to improve the definition of the subsoil structure at Euroseistest in terms of the most important parameters needed to model site response. The results of this re-interpretation are compared with a previous published 2D model of the same alluvial valley. Different analysis of the measurements and different criteria in the synthesis of data have led to a different model, even if both studies had access to the same field measurements. This underscores the fact that a model results of an interpretation and is not uniquely determined by the data, no matter how detailed they are. The well known subsoil structure opened the possibility to correlate the geometry and the dynamic properties of the 2D model with the results of site response determined from a detailed analysis of two events in frequency and time domains and 1D numerical modeling. The study of site response shows the important effect of the lateral variations on the ground motion and suggests that the contribution of locally generated surface waves to the resonant peak may be important. In the case of Volvi's graben, the limitations of the 1D approximation to simulate ground motion under complex soil conditions in both frequency and time domains are also shown. This paper lays the ground for a companion article dealing with 2D site effects in this basin.