黑水县巴阿泽锰矿床地质特征及成矿规律

巴阿泽锰矿位于瓦钵梁子—四美沟复背斜东部倾没端。通过对黑水县巴阿泽锰矿床的综合研究,该矿床的含矿层位为菠茨沟组中段(PTb2)。矿区共圈定2条矿体。同时对该区的矿床地质特征及成矿规律进行了分析,认为该矿床属于沉积-受变质型矿床,并归纳总结出三条找矿标志。     

Geostatistics as a groundwater exploration planning tool: case of a brackish-saline aquifer

This paper discusses a geostatistical approach to model a groundwater aquifer in 3-D. The study aims at utilizing geostatistics as a tool for characterizing zones of better-water quality in a brackish-saline aquifer. In particular, the geostatistical model was constructed to characterize the aquifer’s salinity, represented by total dissolved solids (TDS), using logs of porosity and resistivity. Quality-checked estimated TDS vertical profiles were employed to construct and model horizontal and vertical semivariograms. Parameters of semivariogram models were used to develop both the kriging plan and the generated model. Results of this modeling process are shown in the form of horizontal salinity distribution maps. The aquifer was sliced into 20 layers, each 20 m thick, to represent its overall thickness. Salinity layers maps reflect vertical stratification of TDS concentrations in the aquifer and show that water quality deteriorates with depth and toward the northern part of the aquifer. Relatively better-quality water (TDS ≤10,000 mg/l) can be found at depths between 100 and 250 m below the aquifer’s top in both eastern and southeastern parts. Water in the same interval to the western and southwestern parts reflects the presence of higher TDS concentration. From a planning point of view, it is more feasible to target the eastern part of the aquifer for pumping and desalination purposes. In addition, the generated model could be utilized as an initial condition for flow simulation.     

Occurrence of diagenetic alunites within karst cavity infill of the Dammam Formation,Ahmadi, Kuwait: an indicator of hydrocarbon gas seeps

Alunite minerals occur as white powdery lumps and laminated coloured deposits within cavity and solution channel infill of the palaeokarst zone of the Upper Eocene Dammam Formation. This formation is exposed in a quarry located on the Al Ahmadi ridge within the Greater Burgan oil field in southern Kuwait. Field occurrences and sedimentary structures of the alunite deposits were described. Collected samples were petrographically described, and their mineralogy and geochemistry were determined using X-ray diffraction and X-ray fluorescence, respectively. Microfabrics were investigated using SEM, revealing that they are primarily composed of fibrous alunogen (hydrous aluminium sulphate) and pseudo-cubical K-alunite (hydrous potassium aluminium sulphate). Their mode of occurrence suggests a hypogenetic origin, where sulphide gases associated with hydrocarbon gases reacted with an Al-rich solution leached from clay minerals and feldspars of the cavity-fill muddy sand sediments. The hydrocarbon gases may have seeped from sub-surface petroliferous formations within the Greater Burgan oil field along vertical fractures. This study suggests that these acidic seeps may have played a role in the development of the palaeokarst zone of the Dammam Formation.     

Contribution of atmospheric processes to the degradation of air quality: case study (Sohar Industrial Area,Oman)

The impact of the air pollution generated by any industrial activities may be further aggravated if the location of the industrial area is exposed to certain atmospheric characteristics. Under such conditions, the likelihood of accumulation of local air pollution is high. This paper uses two approaches (statistical and numerical simulation) to investigate the contribution of atmospheric processes towards degradation of air quality. A case study of the two approaches was conducted over Sohar Industrial Area in the Sultanate of Oman. Measured wind data were used to account for specific atmospheric characteristics such as stagnation, ventilation, and recirculation using the statistical approach. In the second approach, numerical weather prediction model was used to simulate mesoscale circulation phenomena such as sea breeze and its contribution to the processes affecting the air quality. The study demonstrates that the atmospheric processes appear to contribute substantially to the degradation of air quality in the Sohar Industrial Area. The statistical analysis shows that the atmospheric dilution potential of Sohar Industrial Area is prone to stagnation and recirculation, rather than ventilation. Moreover, model simulation shows that there is a seasonal variation in the contribution of atmospheric processes to the degradation of the air quality at Sohar Industrial Area.     

Ground penetrating radar-based experimental simulation and signal interpretation on roadway roof separation detection

Roof separation is one of the major indications for coal mine roadway roof accidents. Therefore, it is important that efforts be made to detect roadway roof separation. Currently, the instrument used for detecting roadway roof separation is the roof-off-the-strata indicator, but its installation and use is complicated and the need is greater than can be managed. This thesis takes ground penetrating radar (GPR) as a means for roof separation detection and analyzes its feasibility for use in detecting roof separation both theoretically and experimentally. First, numerical simulation experiments on roof separation detection are carried out using GprMax2D software. The results show that it is feasible to detect roof separation by using GPR electromagnetic waves. Next, physical simulation experiment on roof separation detection is carried out using MALA GPR (RAMAC/GPR). Lastly,  the traditional image segmentation algorithm of 2D maximum between a cluster variance is improved to interpret the GPR signal. Good results were achieved using the improved algorithm to interpret detection signals of roof separation by GPR in a physical simulation experiment.     

Effect of azimuthal coverage of an earthquake on moment tensor solutions estimated by waveform inversion

The purposes of this seismological investigation are to understand and describe the effect of decrease in the azimuthal coverage of an earthquake on moment tensor solution estimated by waveform inversion. It will be very useful and worthwhile as mostly seismological networks are sparse and in case when only one or two station data are available. In this work, we have used two moderate earthquakes, 21 September 2009 (near Uttarakashi) and 3 May 2010 (near Ghansali). The waveform inversion has been carried using ISOLA software. The moment tensor is first estimated by using all station data and then by removing the stations so that the azimuthal coverage changes. The results show that strike of both nodal planes is varying with the change in azimuthal coverage. However, the slip and dip of both nodal planes remain quite stable against the variation in azimuthal coverage for these two earthquakes analyzed. The effect of decrease in the azimuthal coverage showed increase in double-couple percentage (DC %) and decrease in compensated linear vector decomposition (CLVD %). The other focal parameters such as T-axis azimuth, P-axis azimuth, T-axis plunge, and P-axis plunge have been found stable against the variation in azimuth coverage. The study also demonstrates that the moment tensor solutions obtained from waveform inversion using single station are almost similar to those estimated using maximum azimuthal coverage data and by polarity inversion.     

基于激光点云的隧道断面连续提取与形变分析方法

地铁施工、运营阶段的监控量测,可有效保障隧道结构的稳定与周围环境的安全。现有的收敛计、全站仪等变形监测手段,虽然可以得到高精度的观测数据,但获取的监测点位过于稀疏,难以全面反映隧道整体的形变特征。本文将三维激光扫描技术用于地铁隧道形变监测,提出了基于激光点云的隧道断面连续提取与形变分析方法,并对提取的两期断面进行了形变分析,试验结果表明该方法能够更直观地表现隧道整体变形,研究成果可为隧道形变动态监测提供借鉴。     

三维激光扫描在建设工程竣工规划核实中的应用研究

本文介绍了建设工程竣工规划核实的主要方式,阐述了测量在竣工规划核实中的重要性,及目前核实方式中存在的问题.然后,针对三维激光扫描的技术原理,分析了三维激光扫描技术在竣工规划核实中应用的可行性,并通过对控制点布设、点云配准、建筑物特征点提取等技术方法的研究,实现了三维激光扫描在竣工规划核实中的应用,具有一定理论意义和实用价值.     

Recommendations for a system to photograph core segments and create stitched images of complete cores

High-resolution digital imagery of sediment cores increases researchers’ ability to examine, review, and disseminate complex and meaningful core data. The high cost of commercial core scanning systems currently limits the number of cores that are imaged. Here, we present a simple, inexpensive system that can be built in almost any laboratory environment and used to create complete core images. This system uses a stationary light source and a moving core tray (sledge) which provides for consistent lighting across multiple images. Polarized lens filters and diffuse light are used to minimize glare on the core surface. Our system also repurposes professionally engineered exercise equipment which, provides for precise core and camera movement. Once images are taken, stitching software is used to create the final core image. While there are many stitching programs on the market, none are explicitly aimed at stitching together many images in a single, straight line. We evaluated seven of the most common stitching programs and identified Hugin as the most useful for creating completed core images.