基于GIS的区域地质调查数字制图--以1∶5万<里庄幅>为例

本文以 1∶5万里庄幅为例 ,阐述了运用GIS系统对区调过程中各种资料的处理与编辑方法 ,并介绍了数字制图方法及工艺流程 ,提出了GIS系统在 1∶5万区调工作中的应用前景     

Gravity and magnetic signatures of volcanic plugs related to Deccan volcanism in Saurashtra, India and their physical and geochemical properties

The Bouguer anomaly and the total intensity magnetic maps of Saurashtra have delineated six circular gravity highs and magnetic anomalies of 40-60 mGal (10⁻⁵m/s²) and 800-1000 nT, respectively. Three of them in western Saurashtra coincide with known volcanic plugs associated with Deccan Volcanic Province (DVP), while the other three in SE Saurashtra coincide with rather concealed plugs exposed partially. The DVP represents different phases of eruption during 65.5±2.5 Ma from the Reunion plume. The geochemical data of the exposed rock samples from these plugs exhibit a wide variation in source composition, which varies from ultramafic/mafic to felsic composition of volcanic plugs in western Saurashtra and an alkaline composition for those in SE Saurashtra. Detailed studies of granophyres and alkaline rocks from these volcanic plugs reveal a calc-alkaline differentiation trend and a continental tectonic setting of emplacement. The alkaline plugs of SE Saurashtra are associated with NE-SW oriented structural trends, related to the Gulf of Cambay and the Cambay rift basin along the track of the Reunion plume. This indicates a deeper source for these plugs compared to those in the western part and may represent the primary source magma. The Junagadh plug with well differentiated ring complexes in western Saurashtra shows well defined centers of magnetic anomaly while the magnetic anomalies due to other plugs are diffused though of the same amplitude. This implies that other plugs are also associated with mafic/ultramafic components, which may not be differentiated and may be present at subsurface levels. Paleomagnetic measurements on surface rock samples from DVP in Saurashtra suggest a susceptibility of 5.5×10⁻² SI units with an average Koenigsberger ratio (Q_n) of almost one and average direction of remanent magnetization of D=147.4° and I=+56.1°. The virtual geomagnetic pole (VGP) position computed from the mean direction of magnetization for the volcanic plugs and Deccan basalt of Saurashtra is 30°N and 74°W, which is close to the VGP position corresponding to the early phases of Deccan eruption. Modeling of gravity and magnetic anomalies along two representative profiles across Junagadh and Barda volcanic plugs suggest a bulk density of 2900 and 2880 kg/m³, respectively and susceptibility of 3.14×10⁻² SI units with a Q_n ratio of 0.56 which are within the range of their values obtained from laboratory measurements on exposed rock samples. The same order of gravity and magnetic anomalies observed over the volcanic plugs of Saurashtra indicates almost similar bulk physical properties for them. The inferred directions of magnetization from magnetic anomalies, however, are D=337° and 340° and I=−38° and −50° which represent the bulk direction of magnetization and also indicate a reversal of the magnetic field during the eruption of these plugs. Some of these plugs are associated with seismic activities of magnitude ≤4 at their contacts. Based on this analysis, other circular/semi-circular gravity highs of NW India can be qualitatively attributed to similar subsurface volcanic plugs.     

深埋长隧道有害气体发生的地质条件初探

有害气体的深埋长隧道的主要地质灾害现象之一。本文在现场调查及查阅国内外文献资料基础上，探讨了有害气体发生的地质条件，为有害气体地质灾害的预测提供了依据。     

西安翠华山山崩地质遗迹资源保护

文论述了西安翠华山山崩地质遗迹资源保护的目的，进行了保护分区，将其分为核心保护区、缓冲区和视域保护区三个区，重点分析了核心保护区的保护现状，并在此基础上提出了相应的保护内容和对策，以实现山崩地质遗迹资源的可持续利用和发展。     

西藏地质环境问题及保护对策

作为青藏高原主体的西藏自治区,地质环境极为复杂,地质灾害相当严重,在一些地段地质灾害严重影响了人们正常的生产生活。因此,加强地质环境保护,为人们创造尽可能好的生产和生活空间,是各级政府义不容辞的责任。本文首先对西藏自治区的地质环境特征作了系统地分析,并对西藏地质环境保护及管理现状作了客观评述,在此基础上指出了西藏地质环境保护中存在的主要问题。最后提出了西藏地质环境保护的对策及建议。     

中外饭店区域集团化特征对比研究

随着饭店业全球化进程的发展，饭店之间的竞争日趋激烈，国际饭店集团的出现使国际旅游市场和饭店业都发生了极大的变化。与中国饭店集团相比，国际饭店集团具有诸多竞争优势，本文将以世界饭店集团300强为例，与中国饭店区域集团化特征进行对比分析，从而为中国饭店业借鉴国际饭店集团成功经验，应对其挑战提供启示。     

试述福建顺昌南舟萤石矿地质特征

顺昌南舟萤石矿位于顺昌县埔上镇南舟村境内，1996年福建省区域地质调查队开展1：5万埔上幅区调时发现矿体，后开展普查工作表明该矿床规模大、交通方便，易于开采，现已投入开发利用。南舟萤石矿成矿地质特征在闽北丰富的萤石资源中具有一定代表性。     

遵义市城区及周边地带制砖页(泥)岩地质特征和开发前景

文章对遵义市城区及周边地带各地质时代的页（泥）岩已有资料进行了系统收集、归纳和适当的野外调研，认为区内制砖页（泥）岩层位可分为三类，第一、二类利用价值小或仅有部分可以利用，第三类则易于露采，大部分可利用，其层位为下奥陶统湄潭组和下三叠统夜郎组九级滩段，是区内可作制砖页（泥）岩利用最有开发前景的层位。同时对页（泥）岩的形成沉积环境作了简要分析，对其资源量进行了概略估算，经优化筛选，提出了10个供制砖厂企设置布局和矿源地选择之前需进行地质勘查的区块。