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前言磁异常对数功率谱可用来直接求场源埋深.有些作者对使用此法的影响因素做过研究,给出了一些很有用的结论,但这些研究都仅限于某几个方面,不甚全面,也没有给出在不利条件下的处理方法.本文在对这种方法作简单概述之后,把它应用于二度磁性体的异常解释,研究其应用的可靠性和在不利条件下的改正方法.最后对这种埋深估算方法的实际应用作出评价. 相似文献
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本文是在研究Tridem航空电磁系统原有零水平改正方法的基础上、探讨了新的零水平改正方案,并给出了改正过程、叙述并分析了在确定零水平过程中的几种影响因素.利用新的零水平改正方案对实测数据作了初步处理应用,获得了较好的效果. 相似文献
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在野外数据采集过程中,时常会遇到由控制点数据错误产生测点位置错误问题。总结分析了可能出现的多种情况,归纳出了错误的类型。并且提出了采用距离交会算法对测点坐标进行改正的新方法,导出坐标数据改正的数学模型,总结出了用一种数学模型解决控制点坐标有误、无控制点坐标等多种错误类型的测点坐标改正方法及其注意事项。并用VC 编写了相应的程序工具,经实验数据验证了它的可行性和正确性。该方法的提出和应用,可提高外业测绘工作的效率,具有较高的实际应用价值。 相似文献
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航空伽马能谱测量地形影响改正实现方法 总被引：1，自引：0，他引：1
航空伽马能谱测量受地形因素影响较大,采用常规高度改正方法对复杂地形条件下的航空伽马能谱数据进行改正,会造成结果失真。笔者结合航测动态测量特点,论述了利用航测过程中获得的地形数据,对作用带内的地形进行细化,应用点状辐射体辐射场理论,采用地形校正系数对航空伽马能谱数据进行地形影响改正的具体实现方法;通过实测的航空伽马能谱数据对该方法进行检验,并与地面异常查证的结果对比,表明该地形改正方法效果较好,基本能消除地形起伏对测量结果产生的影响。 相似文献
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郭积忠 《物探化探计算技术》1980,(2)
应用网函数插值方法进行重力区域改正计算是内蒙古物探队和内蒙古大学数学系合作进行的。是应用电子计算机快速处理重力测量数据一种新方法。有关网函数插值方法的实质、原理、推导及计算重力区域场改正的理论讨论、模型试验都已在不同文章中给予介绍。本文着重介绍网函数插值法用来进行区域改正计算的具体方法和地质效果。 相似文献
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介绍了采用“方域”方案时,在一般地形条件下求取近区重力地形改正值的公式和实测方法。讨论了沟渠、堤坝、路基等特殊地形情况下的地形改正与实测方法及其优越性。提出了判断是否进行地形改正实测及改正范围的原则。 相似文献
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第四纪沉积物磁性勘查油气法的原理及应用 总被引：3，自引：0，他引：3
本文介绍了利用第四纪沉积物磁性调查油气的原理,地下油气藏会在近地表第四纪沉积物中产生磁性矿物并形成多种磁性参量异常。检验了形成磁性异常的磁性矿物的种类;发现了油田地区土壤中存在着趋磁细菌。在5个油田地区近450km2范围应用该方法调查油气分布的研究结果表明,各种磁性异常(κ、Mn、Mr、Ir、Iκ)呈综合异常的形式,它们的形成及分布特征受油气活动、通道及环境条件的控制。实际资料证实,磁性综合异常能反映油田地区油气活动的分布状态。该方法作为综合勘查方法之一,应进一步推广。 相似文献
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The Bicester magnetic anomaly is one of several high wavenumber features superimposed on the magnetic anomaly associated with the London Platform. Seismic reflection data suggest that the source of the Bicester anomaly is a body of basaltic rocks of Carboniferous age that can be traced from the Steeple Aston borehole. Three-dimensional interpretational techniques indicate that the magnetic source has a total magnetization vector dipping at 60°, azimuth 170°, with an intensity of 1.39 A m−1 and this has been used to derive a three-dimensional model of the source. The nature of the magnetic remanence contributing to this vector is discussed. A detailed two-dimensional magnetic model has been constructed using the seismic control. 相似文献
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Marcos A. E. Chaparro Juan M. Lirio Héctor Nuñez Claudia S. G. Gogorza Ana M. Sinito 《Environmental Geology》2005,49(1):30-43
Magnetic properties of lagoon and stream sediments from Chascomús area (Buenos Aires Province) and the relevance of various magnetic parameters as giving pollution status are studied in the present work. This work is focussed on magnetic parameters, such as concentration-dependent (magnetic susceptibility, saturation anhysteric and isothermal remanent magnetisation) and feature-dependent parameters (S-ratio, coercivity of remanence, anhysteric susceptibility/magnetic susceptibility-ratio), as pollution indicators. Firstly and most importantly, different magnetic parameters and chemical measurements were correlated in order to investigate their goodness, obtaining the best results for feature-dependent magnetic parameters. Coercivity of remanence correlate very well with chemical variables, showing correlations at high level of significance up to 0.9094, and the anhysteric susceptibility/magnetic susceptibility-ratio also shows very good correlations (up to 0.8376). Some results and advantages of using a new experimental method in order to discriminate hard and soft magnetic phases are also shown. This method uses alternately backfield isothermal remanent magnetisation and alternating field demagnetisation. From the experimental separation, the presence of hard magnetic phases in some samples was confirmed. 相似文献
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Muthamilselvan A 《地下水科学与工程》2021,9(3):256-268
The study aims to identify a suitable site for open and bore well in a farmhouseusing ground magnetic survey in south India. It also aims to define depth to granitoid and structural elements which traverse the selected area. Magnetic data(n=84) measured, processed and interpreted as qualitative and quantitatively. The results of total magnetic intensities indicate that the area is composed of linear magnetic lows trending NE-SW direction and circular to semi-circular causative bodies. The magnetic values ranged from -137 nT to 2 345 nT with a mean of 465 nT. Reduction to equator shows significant shifting of causative bodies in the southern and northern directions. Analytical signal map shows exact boundary of granitic bodies. Cosine directional filter has brought out structural element trending NE-SW direction.Results of individual profile brought to light structurally weak zone between 90 m and 100 m in all the profile lines. Sudden decrease of magnetic values from 2 042 nT to 126 nT noticed in profile line 6 between 20 m and 30 m indicates fault occurrence. Magnetic breaks obtained from these maps were visualized,interpreted and identified two suitable sites for open and bore well. Radially averaged power spectrum estimates depth of shallow and deep sources in 5 m and 50 m, respectively. Euler method has also been applied to estimate depth of granitoid and structural elements using structural indexes 0, 1, 2, and 3 and found depth ranges from 10 m to 90 m. Study indicates magnetic method is one of the geophysical methods suitable for groundwater exploration and site selection for open and borewells. 相似文献
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庐枞火山岩盆地及其外围重、磁场特征 总被引：9，自引：5，他引：4
为探测长江中下游成矿带庐江-枞阳白垩纪火山岩盆地的深部构造和地壳结构,2007年初在庐枞火山岩盆地进行了以深反射地震剖面探测为主的,新一轮重力、磁力和大地电磁剖面测量。作者在前人研究的基础上对庐枞火山岩盆地及其外围重、磁场特征进行了研究。作者首先分析长江中下游地区重、磁场的分布特征,然后以区域重、磁场特征为背景来认识庐枞地区重、磁场的分布特征。研究各类地质体的物性参数是开展地球物理解释的前提,文中收集并分析了前人对庐枞地区的岩石物性的较为系统研究成果。为了提取重、磁异常的特征,文中对重、磁异常进行了位场转换和图像处理。利用新的深反射地震剖面探测和大地电磁剖面研究成果,采用定性和定量解释方法对庐枞地区重、磁场的分布特征进行了研究并提出新的认识。庐枞火山岩盆地深部存在隐伏的磁性强的中碱性岩类是产生区域磁异常的主要原因。庐枞火山岩盆地下部火成岩所侵入的地层向盆地东南方向延伸,盆地的西北边界向东南方向倾斜。而在罗河断裂带以西没有火成岩存在。亦即庐枞火山岩盆地是一个沿北东向罗河断裂向东发育的非对称火山盆地。另外,在庐枞火山岩盆地西部边缘罗河深部存在切穿莫霍面的断裂带沿北东向延展数十千米。 相似文献
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The method of rectangular harmonic analysis is applied to the geomagnetic field data from central India to isolate long wavelength
magnetic anomalies associated with largescale crustal structures. The long-wavelength anomalies have accounted for approximately
20 % of the spatial variability of the residual magnetic field over the International Geomagnetic Reference Field. On the
magnetic anomaly map, reflecting the surface expression of longwavelength anomalies, the Tapi-Narmada-Son zone is characterized
by a feeble positive anomaly bounded by a strong negative anomaly. The anomaly pattern is believed to be caused by the large-scale
undulation in Moho and related variations in the thickness of the lower (basaltic) crust. The other two prominent anomalies,
the magnetic low striking northwest and the magnetic high trending east-northeast, appear to be related to the deep structural
feature of the Godavari graben and the eastern Rajasthan lineament respectively. 相似文献
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S K PAL JITENDRA VAISH SAHADEV KUMAR ABHAY KUMAR BHARTI 《Journal of Earth System Science》2016,125(1):165-178
The present study deals with the coal fire mapping of East Basuria Colliery, Jharia coalfield, India, using the magnetic method. It is based on the fact that rise in temperature would result significant changes in magnetic susceptibility and thermo-remanent magnetization (TRM) of the overlying rocks. Magnetism increases slowly with the rise of temperature until the Curie temperature. Generally, rock/ overburden loses magnetization and becomes paramagnetic due to heating to Curie temperature, which results with significant reduction in magnetic susceptibility. However, magnetism increases significantly after cooling below the Curie temperature. Several data processing methods such as diurnal correction, reduction to pole (RTP), first and second vertical derivatives have been used for analysis of magnetic data and their interpretation. It is observed that the total magnetic field intensity anomaly of the area varies approximately from 44850 to 47460 nT and the residual magnetic anomaly varies approximately from ?1323 to 1253 nT. The range of the magnetic anomaly after RTP is approximately 1050–1450 nT. About 20 low magnetic anomaly zones have been identified associated with active coal fire regions and 11 high magnetic anomaly zones have been identified associated with non-coal fire regions using vertical derivative techniques. 相似文献
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Spatial confirmation of termite mounds as Bio-geo indicator for groundwater occurrences using ground magnetic survey: A case study from Perambalur Region of Tamil Nadu,India 
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下载免费PDF全文 Termite mounds are conventionally surmised as one of the best bio-geological indicator for groundwater occurrence in places where they inhibit. Ground magnetic survey was carried out to prove the assumption about termite mounds as an important indicator for groundwater exploration. Occurrences of 18 Termite mounds were mapped using handheld GPS to identify the suitable trend for magnetic survey. After considering all the criteria such as power lines, fences and fracture system, termite mound 2, 12 and 18 were selected in the NNE-SSW trend, and the ground magnetic survey was conducted in ESE-WNW direction which is perpendicular to the trend of the termite mounds using Proton Precession Magnetometer. Totally, 99 samples were collected with 5 m sampling interval and 50 m profile interval over an area of 22 500 sq.m. The magnetic values varied from –7 363 nT to 898 nT with the mean of –331 nT. Processed map of reduction to Equator indicates the presence of NNE-SSW and WNW-ESE magnetic breaks. Analytical signal map designated the presence of magnetic low in the WNW-ESE direction which coincides spatially with the magnetic breaks. The magnetic profile lines have also brought to light the structurally weak zones. Causative body depth range was estimated using power spectrum and Euler method which are from 120 m to 40 m and <20 m to >100 m, respectively. The present study appreciably brings out the spatial relationship between the termite mounds and the hydro-fractures. This confirms the assertion with regard to termite mounds as an effective tool for groundwater exploration. 相似文献
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Tayel El-Hasan 《Environmental Geology》2008,54(1):23-29
This work is a complementary investigation to the earlier urban soil survey for a rapidly growing city of relatively high
traffic density. Therefore, it aims to apply the environmental magnetism approach to assess the roadside pollution at a known
polluted site. The used magnetic proxies are the initial magnetic susceptibility and saturation magnetization. The results
prove the applicability of this method in detecting roadside pollution. The shape and magnitude of the magnetic signals was
affected by the topography and prevailing wind direction that caused the magnetic peaks to be shifted accordingly. Particle
size was found to affect the magnetic material content, where sand size (63–150 μm) bears the highest magnetic signals relative
to smaller silt size (<63 μm). The magnetic anomalies coincided positively with heavy metal pollution in the studied site,
which might indicate that the magnetic materials serve as an effective proxy for the metallic pollution (i.e., Fe, Ni, Pb,
Cu, and Zn) originated mainly from vehicular sources. 相似文献
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Yang ChangfuDepartment of Earth Science Nanjing University Nanjing Lin ChangyouLanzhou Institute of Seismology China Seismological Bureau Lanzhou 《中国地质大学学报(英文版)》2001,12(3)
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In the Goiás Alkaline Province, in central Brazil, some mafic–ultramafic alkaline bodies crop out, such as Morro do Engenho Complex (ME), whereas other intrusive bodies are completely covered by Quaternary sediments, such as A2 body, and can only be defined by their magnetic and gravity responses. The bodies give rise to strong gravity and magnetic anomalies. We inverted the gravity and magnetic data to estimate 3D density and magnetic intensity contrasts. The gravity inversion reveals that ME and A2 intrusions, totally emplaced in the upper crust, have maximum depths of about 10 and 6 km, respectively. The estimated density contrast distribution indicates a NE–SW preferential direction for ME intrusive body. Since the remnant magnetization is very important in the area, we inverted the magnetic data, testing two hypotheses: only induced field and induced plus remnant magnetizations. The results of the inversion using only induced field could not explain the observed magnetic field, which was about 1000 nT larger than the calculated one. Induced plus remnant field inferred from wandering polar path fitted the observations. 3D magnetic inversions when remnant magnetization was included recover deeper and thinner bodies compared with gravity inversion. The inverted bodies have spherical shapes which are more consistent with the model of magmatic chambers instead of plug intrusions. 相似文献