Quantitative Analysis of Scale of Aeromagnetic Data Raises Questions About Geologic-Map Scale     

Vesa Nykänen  Gary L. Raines 《Natural Resources Research》2006,15(4):213-222

A recently published study has shown that small-scale geologic map data can reproduce mineral assessments made with considerably larger scale data. This result contradicts conventional wisdom about the importance of scale in mineral exploration, at least for regional studies. In order to formally investigate aspects of scale, a weights-of-evidence analysis using known gold occurrences and deposits in the Central Lapland Greenstone Belt of Finland as training sites provided a test of the predictive power of the aeromagnetic data. These orogenic-mesothermal-type gold occurrences and deposits have strong lithologic and structural controls associated with long (up to several kilometers), narrow (up to hundreds of meters) hydrothermal alteration zones with associated magnetic lows. The aeromagnetic data were processed using conventional geophysical methods of successive upward continuation simulating terrane clearance or ‘flight height’ from the original 30 m to an artificial 2000 m. The analyses show, as expected, that the predictive power of aeromagnetic data, as measured by the weights-of-evidence contrast, decreases with increasing flight height. Interestingly, the Moran autocorrelation of aeromagnetic data representing differing flight height, that is spatial scales, decreases with decreasing resolution of source data. The Moran autocorrelation coefficient scems to be another measure of the quality of the aeromagnetic data for predicting exploration targets.  相似文献   

高频电磁测深在地下热水勘探中的应用     

曹辉  何兰芳  何展翔  赵晓鸣 《应用地球物理》2006,3(4):248-254

高频电磁测深法是一种利用天然高频电磁场作为场源的电磁勘探方法,具有高分辨率和相对直流电法较深的勘探深度的特点,特别适合中浅层地热和地下水勘探。本文介绍了一个应用高频电磁测深评价地下热水资源的一个成功实例。野外数据采集采用了高频电磁测深系统MT-U5A,采用远参考技术,以保证数据采集质量。高频电磁测深资料二维反演成像处理结果较好地描述了地下热水的空间分布范围,为查明该区的地下热水的来源提供了较有利的证据。  相似文献   

The application of the high-frequency electromagnetic sounding method in the exploration of underground thermal water     

Cao Hui He Lanfang He Zhanxiang Zhao Xiaoming 《应用地球物理》2006,3(4):248-254

High-frequency electromagnetic sounding is an electromagnetic exploration method using the natural high-frequency electromagnetic field as a field source. It has higher resolution and greater depth penetration than the direct current method and is especially fit for geothermal energy exploration and low- and mid-level groundwater detection. We introduce a successful application of high-frequency electromagnetic sounding for evaluating geothermal water resources. The high frequency electromagnetic system （MT-USA with a frequency range from 10 KHz to 1 Hz） is first applied to sample field data from China. A remote reference station is used to assure sampled data quality. We then perform 2D inversion image processing with the electrical method data. The results basically indicate the spatial distribution of underground geothermal water and provide favorable clues to finding the sources of the subsurface geothermal water in this area.  相似文献   

基于GIS降水空间分析的逐步插值方法   总被引：17，自引：0，他引：17  

周锁铨  薛根元  周丽峰  孙琪  康娜 《气象学报》2006,64(1):100-111

根据长江中上游697个气象观测站1971—2000年30年降水资料,利用逐步回归方法和地理信息技术(GIS),建立了平均季降水和年降水与4km分辨率的DEM、坡向、坡度等地形数据的回归方程,并通过了信度为0.05的F检验,将降水量中地形影响部分分离出来。在此基础上,发展了逐步插值方法(SIA),并与GIS技术和多元逐步回归方法结合,显著提高了年、季降水空间分布的计算精度。结果表明:SIA季节降水空间分布的相对误差为6.86%,绝对误差为13.07mm,平均变差系数为0.070,平均相关系数为0.9675;年降水量的绝对误差为72.1mm,相对误差为7.34%,平均变差系数为0.092,相关系数达到了0.9605。对SIA年平均降水量的分析表明,采用3—5步的SIA计算,就可以显著提高计算精度,绝对误差由211.0mm下降到62.4mm,相对误差由20.74%下降到5.97%,变差系数从0.2312下降到0.0761,相关系数由0.5467提高到0.9619,SIA方法50步的计算表明,SIA计算的结果一致收敛于观测值。  相似文献   

Model tank electrical resistivity characterization of LNAPL migration in a clayey-sand formation     

A. A. Adepelumi  A. A. Solanke  O. B. Sanusi  A. M. Shallangwa 《Environmental Geology》2006,50(8):1221-1233

A modeling tank time-lapse 2D electrical resistivity experiment was undertaken to model the leakage of petroleum products from underground pipelines into a clayey-sand aquifer. Numerical modeling was employed to simulate the electrode arrays that would resolve the post-leakage subsurface image most efficiently. Of the four arrays tested, the dipole–dipole array proved most effective and was adopted for the laboratory studies. Pre-injection surveys were conducted to assist in discriminating between features caused by hydrocarbon accumulation and those due to natural geologic variability. Subsequently, controlled injection of diesel–oil into the model tank was undertaken at regular intervals over a period of 3 days. Experimental evidence obtained from the studies indicates that high resistivity build up few hours after injection is directly related to hydrocarbon accumulation. Rather than biodegradation of the hydrocarbon, a more probable explanation for the observed decrease in resistivity observed a few hours after injection is simply that the hydrocarbons drained to a deeper level after pooling temporarily at a shallow level.  相似文献   

金坛石灰岩资源合理利用与供需保障分析     

倪嘉曾  宋云飞 《江苏地质》2006,30(1):77-79

金坛非金属矿产资源比较丰富,石灰岩是主要的优势矿产。石灰岩原探明的储量有2亿多吨,但因部分储量位于茅山风景名胜区禁采区内不能利用,加之20多年来的开采消耗了较多储量,资源形势日趋严峻。有限的资源,持续上升的需求,供需矛盾严峻的形势摆在面前,为促进经济社会的可持续发展,必须加强对石灰岩资源的保护,科学配置、合理利用资源,以提高石灰岩矿资源保障能力。  相似文献   

天津市武清区地热资源分布特征与开发利用     

刘现川 《中国煤田地质》2006,(Z1)

武清区分布有丰富的地下热水资源,热储层具有双层结构,成因类型为传导型,热水矿化度低,赋存深度大多在可及深度范围之内,为热水资源的多重开发和利用提供了有利条件,在供暖、医疗、饮用、养殖等方面都具有良好的开发利用前景。  相似文献   

河北省地热资源分布特征、开发利用现状、存在问题与建议   总被引：4，自引：0，他引：4  

张国斌 《中国煤田地质》2006,(Z1)

河北省境内赋存和分布有多种成因的地下热水资源,按地质构造和地貌可初步划分冀北山地区、冀西山地区、冀西北山间盆地区、河北平原区等四大地下热水区,各地已将地热直接用于地热供暖、浴疗保健、温泉洗浴、旅游、地热种植、养殖及工业利用等,但地热利用中存在着勘查评价程度差、开发利用程度低、资源浪费严重等问题。为了保护地下热水资源,做到有序、合理开发,还应加强我省地热资源开发利用管理力度。  相似文献   

论化学矿产资源开发中存在的矛盾与待解决的问题   总被引：3，自引：0，他引：3  

魏东岩 《化工矿产地质》1998,20(3):241-246

人口、资源、环境是国际社会所面临的重要问题。资源的合理配置是２１世纪可持续发展的一个关键问题。化学矿产与其它矿产资源一样,形势严峻。在开发利用过程中存在着资源短缺与资源浪费、国家和地区、当前和长远、开采与保护、开发与环境污染等５个矛盾。要实施可持续发展战略,必须正确处理这些矛盾。急待解决的主要问题有：提高国民素质和全社会节约意识、确实贯彻矿产保护法、加强矿产基地建设、提高机械化程度、适应市场化经济、稳定地质科研队伍等。  相似文献   

我国金矿的分布与开发利用     

涂怀奎 《黄金地质》1998,4(4):58-61

我国金矿床的分布很不均匀,从地理位置上看,东部优于西部;从大地构造位置上分,地台区优于褶皱区。近１０上来,我国的金矿地质勘查和黄金工业取得了重大成就,但目前的金矿资源和矿山生产经菜势都不容乐观。  相似文献