一种常见的岩体结构——板裂结构及其力学模型

岩体结构观念的提出对岩体工程地质和岩体力学的研究具有重要意义。岩体结构类型划分方案已经提出了许多,已有的岩体结构划分原则主要是岩体破碎程度。谷德振、孙玉科等曾提出过岩体结构基本单元是:结构面和结构体。1977年底谷德振教授曾提出过,碎碎带应作为一种岩体结构单元问题,没有引起人们的重视。     

贵州镇远地区含金刚石母岩再认识

贵州镇远马坪"东方一号"岩体为中国最早发现的原生金刚石矿,受当时只有金伯利岩才含金刚石矿及后来西澳阿盖尔钾镁煌斑岩型金刚石原生矿等的影响,先后定名为金伯利岩、钾镁煌斑岩、金云火山岩等。最近专题调查分析研究表明,镇远马坪地区含金刚石母岩,其岩石学矿物学和地球化学特征均更接近澳大利亚典型金伯利岩,白坟地区岩体则类似于澳大利亚典型钾镁煌斑岩,建议将镇远马坪地区"东方一号"等岩类定名为角砾凝灰质金伯利岩,白坟地区岩类定名为钾碱镁闪石-透辉石-金云母钾镁煌斑岩,镇远地区兼有金伯利岩和钾镁煌斑岩的特征,与西澳大利亚极其类似,镇远地区乃至黔东地区具有较大的金刚石原生矿找矿勘查潜力和研究意义。     

MAPGIS软件报表定义功能的应用——以绘制探槽素描图中样品分析结果表为例

地质矢量化图件中时常存在有表格附在图幅内的情况,制图者习惯在MAPGIS"输入编辑"中绘制表格,费时费力;使用MAPGIS"报表定义"功能创建表格轻松而快捷,也便于修改。"报表定义"功能还可将EXCEL表格转换成MAPGIS文件,步骤简单、易学。总之,灵活运用该两种方法,工作效率将大大提高。     

安徽南部下、中奥陶统紫台组碳酸盐岩微相与海平面变化

下、中奥陶统紫台组形成于华南奥陶纪生物大辐射的关键时期,其中蕴藏了一些与大辐射有关的重要信息。笔者通过对安徽南部石台丁香剖面、池州洪家剖面的紫台组进行野外实测、采样、室内切片和镜下观察与分析,共识别出9个碳酸盐岩微相,即:MF-1钙质泥岩、MF-2泥质泥晶灰岩、MF-3泥晶灰岩、MF-4腹足类—介形虫生屑泥晶灰岩、MF-5海绵骨针含生屑泥晶灰岩、MF-6含生屑泥质泥晶灰岩、MF-7生屑泥质泥晶灰岩、MF-8生屑泥晶灰岩和MF-9泥晶生屑灰岩。这些微相主要形成于深潮下带及相邻环境中。研究表明:皖南紫台组沉积时期水深波动幅度不大,且自早至晚沉积水深逐渐加大;丁香剖面由于更接近台地边缘,总体沉积水深要大于洪家剖面。在2条剖面的紫台组中识别出至少5次比较显著的海平面上升事件,它们与上扬子区海侵事件具有良好的对应关系,并可以与澳大利亚、北欧、北美、华北等板块进行对比。由此推断,区域性相对海平面变化、甚至全球性海平面变化控制着下扬子区下、中奥陶统紫台组的沉积及其变化。     

戈壁覆盖区化探新方法找金初步试验研究

近年来对新疆某金矿区戈壁覆盖条件下开展了不同类型金矿床进行吸附相态汞、卤素(Cl)、热释CO_2和电化学(Ks)金的找矿试验研究,对石英脉型金矿床和破碎带蚀变岩型金矿床试验结果,初步发现矿体上部壤中Au、Ag、Cu、Zn、Pb、As、Sb一般组合异常差。而壤中的吸附想态汞、Cl、热释CO_2和电化学在矿体前缘及上盘均有较好的异常,特别在厚层洪积物覆盖区,这些新方法亦能反映出盲矿体的异常。     

杨梅山矿区地洼型推覆构造的新认识及其实际意义

笔者根据现有地质资料,结合矿井考察,提出了杨梅山煤矿现在开采的煤层,也属推覆体的新认识。煤矿井巷所揭露的构造为燕山早期所形成,其主压结构面近南北向,两组斜交剪断面为北东及南东向,並有一组张断面与之直交。印支期构造为含煤沉积提供了场所,燕山早期构造对它进行初次改造,主要表现为褶曲和断裂,燕山晚期至喜山期构造对它再次改造,主要表现为逆冲断裂,有三层推覆体形成。根据这些规律,为井下开采预测可能出现的构造、追索煤层提供依据,並预测矿区东南部可能存在有广东丰田式的煤产地。     

Experimental Research Into Influence of Discontinuity Angle on Roof Breaking

Geotechnical and Geological Engineering - This study investigates the influence of pre-existing discontinuities on the roof breaking behaviors under Longwall (LW) mining condition. Taking the...     

Extraction of amplitude-preserving angle gathers based on vector wavefield reverse-time migration

Angle-domain common-image gathers (ADCIGs) transformed from the shotdomain common-offset gathers are input to migration velocity analysis (MVA) and prestack inversion. ADCIGs are non-illusion prestack inversion gathers, and thus, accurate. We studied the extraction of elastic-wave ADCIGs based on amplitude-preserving elastic-wave reversetime migration for calculating the incidence angle of P-and S-waves at each image point and for different source locations. The P-and S-waves share the same incident angle, namely the incident angle of the source P-waves. The angle of incidence of the source P-wavefield was the difference between the source P-wave propagation angle and the reflector dips. The propagation angle of the source P-waves was obtained from the polarization vector of the decomposed P-waves. The reflectors’ normal direction angle was obtained using the complex wavenumber of the stacked reverse-time migration (RTM) images. The ADCIGs of P-and S-waves were obtained by rearranging the common-shot migration gathers based on the incident angle. We used a horizontally layered model, the graben medium model, and part of the Marmousi-II elastic model and field data to test the proposed algorithm. The results suggested that the proposed method can efficiently extract the P-and S-wave ADCIGs of the elastic-wave reverse-time migration, the P-and S-wave incident angle, and the angle-gather amplitude fidelity, and improve the MVA and prestack inversion.     

Applying a modified conduit flow process to understand conduit-matrix exchange of a karst aquifer

Due to the high heterogeneity and complexity of water flow movement for multiple karst water-bearing mediums,the evaluation,effective development,and utilization of karst water resources are significantly limited.Matrix flow is usually laminar,whereas conduit flow is usually turbulent.The driving mechanisms of water exchange that occur between the karst conduit and its adjacent matrix are not well understood.This paper investigates the hydrodynamic characteristics and the mechanism of flow exchange in dual water-bearing mediums(conduit and matrix)of karst aquifers through laboratory experimentation and numerical simulation.A karst aquifer consisting of a matrix network and a conduit was proposed,and the relationship between the water exchange flux and hydraulic head differences generated from the laboratory experiments was analyzed.Two modes of experimental tests were performed with different fixed water level boundaries in the laboratory karst aquifer.The results indicate that the water exchange capacity was proportional to the square root of hydraulic head differences.The linear exchange term in the conduit flow process(CFP)source program was modified according to experimental results.The modified CFP and the original CFP model experimental data results were compared,and it was found that the modified CFP model had better fitting effects.These results showed that the water exchange mechanism between conduit and matrix is very important for solid-liquid interface reaction,water resource evaluation,and understanding of karst hydrodynamic behavior.     

四川盆地东部垫江盐盆三叠系海相钾盐成钾有利区圈定：地球物理和地球化学方法综合应用

垫江盐盆是四川盆地三叠纪时期重要的一个成盐成钾次级盆地,在早三叠世嘉陵江组四段岩盐中发现了大量含钾矿物,具备成钾潜力,但海相钾盐成矿有利区还需要进一步研究。本文通过系统收集垫江盐盆内已有钻孔资料,对嘉陵江组四段岩盐厚度进行统计,对嘉陵江组四段钻井岩盐样品进行化学成分分析,结果表明在双龙地区和五洞地区岩盐厚度大,岩盐钾含量较高,可能是古盐湖蒸发浓缩中心;对垫江盐盆内3条地震剖面进行重新解译,并开展了7条大地电磁测深剖面测量工作,结果显示早三叠世嘉陵江期在垫江盐盆北段的五洞地区和南段的双龙地区可能存在有利于钾盐沉积的凹地,地球物理和地球化学结果较为一致。综合分析认为,早三叠世嘉陵江期,垫江盐盆北段的五洞镇一带和南段的双龙一带是海相钾盐成矿的有利区,研究结果可为进一步开展钻孔验证提供科学依据。