Telescoping ore targets by geochemical exploration at multiple scales in Eastern Yunnan Pt geochemical province,southwestern China

Platinum has been one of the highly needed mineral resources in China. The geochemical exploration at two survey scales was applied in telescoping ore targets for the first time in Eastern Yunnan Pt geochemical province that was delineated using Pt data from flood plain sediments with extra-low sampling density. Our study was based on the delineations and assessments of both regional and local Pt anomalies using the Pt data by analyzing with C-OES the composite samples with two sampling densities. The composite samples were obtained by recomposing at two sampling densities the original stream sediment samples collected by the National Geochemical Mapping Project. Semi-variograms were used to quantitatively describe the variability of Pt anomalies and further analyze the factors controlling the variability. Pt resource potentials of both the regional Pt anomalies and the local Pt anomalies in the study area were estimated based on the geochemical block methods, respectively. It comes to the conclusions as follows. (1) From the regional to local Pt anomaly, the factors controlling their variability from the deep seated faults-basalts turn into the basalts-branch faults, which suggest that Semi-variograms could identify the geological factors controlling the variability of the Pt anomalies identified by the Pt data from the stream sediments with different sampling densities. (2) There exist two types of Pt anomalies in the study area. One is those displaying at sampling densities, and its average Pt concentration significantly increases with sampling density increasing. The other is getting weaker and/or disappears with sampling density increasing. This shows that TOTGEMS could gradually eliminate non-ore anomalies and keep ore anomalies. (3) The average Pt concentration of the local Pt anomaly blocks delineated using Pt data from stream sediments with sampling density of one composite per 16 km² is twice as much as that of the regional Pt anomaly blocks delineated using Pt data from stream sediments with sampling density of one composite per 64 km2. The Pt resource amount of the local Pt anomaly blocks is 60% of the regional anomaly blocks, but the area of the former is just 35% of the latter, which suggests that the Pt resource amount is mainly concentrated in its local anomalies, and that TOTGEMS has a good exploration function that efficiently approaches ore targets. Supported by National High-Tech Research & Development Program of China (863 Program) (Grant No. 2006AA06Z113) and National Natural Science Foundation of China (Grant No. 40772197)     

编码激励用于岩石物性超声成像的仿真

数字编码技术在雷达、医学等方面广泛成功应用使得将其引入地震探测中成为可能。本文为将数字编码技术引入地震探测中,进行了岩石物性成像仿真实验。首先讨论了编码超声成像原理,分析了编码技术的规律和特点。其次通过激励Golay码,利用FieldⅡ软件包进行了岩石物性超声成像的仿真,并比较了仿真结果的成像分辨率。结果表明,编码技术是提高超声成像质量的有效方法。结果可用于指导野外编码地震探测。     

基于独立分量分析的高光谱影像小目标提取研究

借助快速独立分量分析(FICA)将高维数据中隐藏的目标信息集中投影到低维特征影像中,然后以峰度为特征度量指标选择特征影像,最后用以偏斜为指标的直方图分割方法提取小目标。实验证明,此算法精度较高,适用于对高光谱影像中的小目标进行提取。     

准噶尔盆地四棵树凹陷石油地质特征及勘探方向

准噶尔盆地南缘西段四棵树凹陷自晚三叠世以来经历了3个发展演化阶段.凹陷内发育侏罗系煤系地层和古近系安集海河组暗色泥岩二套烃源岩层,其中侏罗系是主力烃源岩;新近系塔西河组、沙湾组、古近系安集海河组、紫泥泉子组、白垩系吐谷鲁群及侏罗系头屯河组砂岩、砂砾岩储集层为主要勘探目的层;新近系塔西河组、古近系安集海河组、白垩系吐谷鲁群、侏罗系三工河组泥岩为区域性盖层;主力烃源岩生烃门限深度(Ro=0.6%)约在5 000 m左右,生烃高峰和排烃高峰期在喜马拉雅期,与凹陷内圈闭的形成期相匹配.该凹陷艾卡构造带东部、托斯台构造群及北天山推覆体之下隐伏背斜构造带是油气勘探的主要方向.     

SAR图像多尺度积增强的目标检测算法

合成孔径雷达（SAR）成像系统的热噪声和海杂波严重影响SAR图像自动目标检测的性能,去噪和均匀背景杂波是提高SAR图像目标检测性能的重要课题。根据SAR图像噪声功率一般存在于信号小尺度,没有跨尺度特征,而目标信号的边缘具有跨尺度的特点,本文提出了一种多尺度积信号增强和去噪的SAR图像船舰目标检测算法。本算法对SAR图像进行小波变换,应用多尺度积在小波域增强SAR图像船舰信号和均匀背景杂波,再对SAR图像进行目标检测。ERS SAR图像用于验证本文算法。仿真实验结果表明,新算法同传统的双参数CFAR检测算法、基于K-分布背景杂波的检测算法以及基于小波软阈值增强的检测算法相比,在虚警数和品质因数性能指标上均优于后几种检测算法。     

通过编码检校场实现双目视觉系统的自动标定

首先对普通检校场中部分圆形回光反射标志块进行编码标识,实现了标定控制点在物方空间和像方空间的自动对应;然后根据Weng’s相机模型对视觉系统进行标定,求解系统的内、外方位元素和系统畸变系数;最后依据投影几何中空间直线经中心投影变换后仍是直线的原理,提出了对随机系统的残余误差进行测定和修正的方法。实验证明,本方法实现了双目视觉系统的全自动标定,并明显提高了系统的精度。     

基于知识约简的无线网络脆弱性评价指标体系构建

针对无线网络脆弱性评价指标体系中影响因素众多、层次结构复杂且指标间存在相关性的问题,提出了一种基于知识约简算法的脆弱性指标体系构建方法.首先,初步建立无线网络脆弱性评价的指标体系,在此基础上构造脆弱性评价决策表;其次,运用知识约简算法对决策表进行简化,其中非核指标的重要性排序采用特征向量法进行确定,该方法以保证评价结果的准确性为前提,较AHP权重判断法更具客观性;最后,将该方法和AHP权重判断法进行了分析比较,说明了其有效性.     

青海南部茶曲帕查Pb-Zn矿床的勘查历史、现状与下一步找矿方向

从找矿勘查角度,对青海南部新发现的茶曲帕查Pb-Zn矿床的勘查历史和现状进行了介绍,并对下一步找矿方向提出了建议。该矿是2002年以来在1∶20万化探扫面及1∶5万水系沉积物化探发现异常后进一步通过1∶1万地质、化探、激电等综合调查及钻孔工程确定的矿床,目前控制(332+333+334)铅锌资源量99.6万吨。矿区填图表明,北部中新世五道梁组不整合于南部的二叠系九十道班灰岩之上,后者以北倾的逆冲断层和南部那益雄组碎屑岩接触,钻孔资料显示该断层可能为深部由南向北逆冲断层的反冲断层。矿体在孔莫隆矿段主要就位于灰岩内,在茶曲帕查矿段出现在那益雄组和五道梁组中,前者矿体发育好,后者矿化主要见于地表。矿区内圈出4条激电-化探异常,均呈东西向带状分布,分别出现在北部五道梁组、中部九十道班组灰岩、南部那益雄组和五道梁组中。音频大地电磁测深显示灰岩呈相对高阻,碎屑岩、灰岩破碎带、地表水、矿化呈相对低阻。综合分析表明,"三江"北段风火山-囊谦褶皱逆冲带内、与新生代盆地相伴的老于新生代的碳酸盐岩是该类矿床的主要赋矿部位,在矿区范围内,多才玛矿段激电-化探异常带内的灰岩中、地表见矿化、深部具音频大地电磁测深显示的高阻体中相对低阻部位是值得关注的勘查目标。     

安徽省霍邱铁矿区及外围铁矿成矿规律及潜力研究

安徽省霍邱铁矿是一个远景储量大于20×108t的大型铁矿田,本文首次对该矿田磁异常进行了详细的清理工作,深入研究了矿田地球物理特征,并进行解释推断,结合地质背景、矿体赋存条件研究,建立了铁矿床找矿标志,优选了13个新的找矿靶区,上述工作对该区下一步找矿具指导意义     

Contributions of secular changes in the regional evolution of ore deposits to predictive mineral exploration: A case study of the Zhongtiao Mountain Cu metallogenic area,southern North China Craton

The Zhongtiao Mountain is located in the southern part of the North China Craton. The area experienced multi-stage tectono-magmatic events during the Precambrian, including Neoarchean-Early Paleoproterozoic (2550–2350 Ma) crustal growth, Paleoproterozoic (2350–1850 Ma) rifting–subduction–accretion–collision, and Early Mesoproterozoic (1800–1750 Ma) extension. The geological events contributed to a major copper mineral system in the region. Here we evaluate the processes of the mineral system, such as the source of metals, migration pathways, the formation of trap zones, and the deposition of metal in an attempt to establish a mineral accumulation evaluation model for regional ore prospecting. A three-step process has been proposed in this study as follows. (i) Determining the spatial and temporal distribution of the essential elements and processes of the mineral system to understand the most critical ore-controlling factors. (ii) Translating the ore-forming processes into mappable features and quantitative extraction of the information on mineralization using Geographic Information System (GIS) technology to establish a mineral accumulation evaluation model. They were treated as evidence layers for weight-of-evidence (WofE) analysis. (iii) Utilizing the weighted values of the evidence layers to create a posterior probability map. Based on the posterior probabilities, four mineral accumulation horizons were finally delineated for the Zhongtiao Mountain, which are considered to provide important guidelines for further ore exploration and study.