共查询到20条相似文献，搜索用时 734 毫秒
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柬埔寨王国位于低纬度地区,地质勘查程度较低,地面高精度磁测技术能够快速获取磁异常信息,进行找矿评价。在低纬度地区磁化方向主要以水平磁化为主,磁性体产生的磁异常以负磁异常为主。本文通过对柬埔寨王国Mesam金矿磁测数据进行倒相180°、化赤和低纬度化极处理对比,认为三种处理方法得到的结果都能够完整地反映磁场分布特点,在不能忽略剩磁影响的低纬度地区对实测数据进行低纬度化极后再进行解释更加贴近真实且细节更加丰富。通过对低纬度化极后的磁异常进行水平总梯度模和小波多尺度分解计算等位场异常处理,认为磁异常水平总梯度模计算能够较好地反映深部地质体的边界范围,小波多尺度分解计算能够提取特定深度地质体的空间信息,在该区选取的磁异常处理技术是有效的,为进一步扩大该金矿区远景储量提供了新的思路。 相似文献
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低纬度地区（尤其是磁赤道附近）磁场化极是长期以来没有很好解决的问题。这里提出的方法只时常规化极稍加改进，通过时化极因子的频点偏移，避开无界点，使化极结果改善很大，甚至在赤道上也可以化极。它既有很高的精度，又因仍是在频率域内进行，故计算方便、快速，非常适合大面积的资料计算 相似文献
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基于总梯度模分析的磁源体边界信息提取及找矿意义 总被引：1，自引：0，他引：1
低纬度地区磁异常的化极处理极不稳定,甚至出现奇异现象。因此,低纬度地区磁异常的化极处理一直是位场研究的难点。磁异常总梯度模的曲线形态与磁化强度的大小及方向无关,且其极大值位置与磁源边界具有一定的对应性,模型试验表明了该方法在低纬度地区磁异常分析与解释方面的有效性。本文将基于总梯度模的磁异常分析方法应用于老挝爬立山铁矿区的磁测资料处理,由此排除了由化极不稳定导致的虚假磁异常,圈定了矿致异常的分布范围,进一步指导矿区铁矿勘探。已完成的钻孔资料证明,由该方法确定的磁异常区域与区内磁铁矿体分布位置的吻合性较好。由此表明,该方法对低纬度区磁异常分析与解释具有重要的意义。 相似文献
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磁异常的最小均方差滤波化极 总被引：8，自引：0，他引：8
本方法是波数域磁异常化极的正则化方法,能增强化极算子的稳定性,同时压制高波数干扰.对低纬度地区及干扰严重的中低纬度地区航磁异常化极,能压制磁南北方向的条带状干扰,获得稳定结果.对含有较高噪声水平的高精度地面磁测△T异常化极,不论纬度高低,都能较大程度地压低噪声水平,得到高质量的化极结果. 相似文献
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塞拉利昂位于赤道附近,属于低纬度地区。在低纬度区,以水平磁化为主的条件下,磁性体所产生的ΔT磁异常以负异常为主,正异常伴生。通过对磁资料进行倒相180°、化赤、化极处理方法的对比,认为在不考虑剩磁、磁性体退磁作用的情况下,结合当地地质情况,倒相180°的处理方法能够展现该区的磁场特征,以此作为基础资料对全区的磁异常进行解释。利用不同高度的向上延拓处理,有效地排除了浅层干扰,突出深层异常特征,再结合最大坡度法、经验切线法、欧拉奇次方程法确定其磁性体的埋深和水平大致位置,最后,采用二度半人机交互反演拟合磁性体大致的形态,通过布设钻探施工,验证结果与推断吻合较好。 相似文献
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克服低纬度化磁极困难的有效方法 总被引：8，自引：0，他引：8
低纬度地区磁场化极是长期以来没有很好解决的问题，这里提出的方法只对常规化极积加改进，通过对化极因子的频点偏移，避开无界点，使化极结果改善很大，甚至在赤道上也可以化极，它既有很高的精度，又因仍是频率域内进行，故计算方便、快速、非常适合大面积的资料计算。 相似文献
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首钢秘鲁马尔科纳铁矿位于南半球低纬度地区,地磁场对磁性体的磁化以水平磁化为主,磁性体产生的ΔT异常与中国的△T异常特征差别很大,国内常用的化极方法在此类地区的应用文献少见,使用不当很难取得良好效果,虽然化赤方法在低纬度地区能取得较好的结果,但针对化赤异常的解释技术却相对较少.通过常规化极与化赤方法对秘鲁马尔科纳胡斯塔铜... 相似文献
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蚁群算法（ACO）主要应用于组合优化问题（COPs）,很少应用于地球物理重磁资料物性反演。首先,对蚁群系统中目标函数值与信息素的映射机制进行改进。理论模拟表明,改进后的Gauss模型在收敛速度和反演精度方面比传统的ant-cycle模型要好,适用于重磁资料物性反演。然后,将蚁群算法应用于南岭地区千里山岩体和九嶷山岩体重力资料反演与解释。结果表明:蚁群算法圈定的花岗岩岩体与地面地质填图结果及大地电磁测深反演结果吻合,较好地控制了千里山岩体和九嶷山岩体的深度和形状。该结果可为研究南岭地区花岗岩侵入模式和多金属成矿规律提供参考。 相似文献
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单位圆外域到任意开挖断面隧洞外域共形映射的计算方法 总被引：1，自引：0，他引：1
将复杂开挖断面为边界的力学问题转化成单位圆为边界的力学问题,是利用复变函数理论开展地下隧洞围岩力学分析的前提。从黎曼存在定理出发,建立了以洛朗级数有限项表示的单位圆外域到任意开挖断面隧洞外域的共形映射函数。根据边界对应原理,将域到域的共形映射问题转化成单位圆周线到任意开挖断面隧洞边界线的共形映射问题。从三角插值理论出发,采用奇偶插值点反复相互迭代对映射函数的求解开展了研究。为快速地进行迭代计算,采用法线逼近法进行计算点（映射点）调整。提出了以映射边界线与实际开挖洞形边界线之间的绝对误差作为迭代计算的收敛条件,保证了共形映射精度。给出了3个开挖断面隧洞映射函数的求解算例,并将研究结果与文献中的方法进行了比较。结果表明,提出的单位圆外域到任意开挖断面隧洞外域共形映射的计算方法具有操作简单、精度高和收敛快等特点。 相似文献
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《International Geology Review》2012,54(2):191-195
The author proposes a method of telluric-magnetic mapping, profiling, and exploration. The profiling involves recording of short-period variations in the telluric current and the magnetic field (MTP) and an areal (MVR), similar to the above. The method can be used on any segment of the crust, especially with newly designed, highly sensitive short-period magnetometer. The magnetic fields of telluric currents are measured by means of a four-channel oscillograph controlled from a panel in which switches are incorporated. The magnetic fields of the telluric current are measured at two points, since the automatic switching arrangement permits a procedure identical with the measurements in the telluric current. Amplitudes and periods of almost sinusoidal waves are measures of the chords of the elliposidal electric and magnetic fields. Analysis of magnetic field mapping and its results are given. The author feels that the telluric-magnetic profiling should replace direct telluric voltage measurements in many regions because of its economics. It gives precise data on the structure of the sedimentary cover. Telluric-exploration will open up entirely new possibilities in permafrost zones and the method will be substantially more efficient than direct telluric measurements. — A.W. Bellais 相似文献
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Constraining Surface Interpolations Using Elastic Plate Bending Solutions with Applications to Geologic Folding 总被引：3，自引：2，他引：1
Geologic surface interpolations can be augmented by adding physical constraints to available data. Here a method is outlined
that allows one to constrain surface interpolations for two geologic surfaces based on the apparent thickness of the bounded
layer. The resulting interpolation scheme is posed as a quadratic programming in which the interpolation of each surface is
solved approximately and subject to linear constraints on the apparent thickness. Results can be further improved by adding
cubic polynomials to the interpolating functions to regularize the problem. In one-dimensional interpolations of geologic
folds, the method improves the results over unconstrained interpolations by eliminating interpenetrations (negative apparent
thicknesses) and regions of small apparent thicknesses. In a two-dimensional application for the monocline at Raplee Ridge,
UT, the capability of this method is illustrated by overcoming interpenetration of two surfaces, the tops of the Mendenhall
oil sand and the Unnamed limestone. The minimum curvature spline interpolation is applied to topographic data taken from an
airborne laser swath mapping (ALSM) survey and interpolated by detailed geologic mapping. This method can be extended to allow
for multiple layers. 相似文献
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根据火烧区烧变岩△T磁异常特征,选择均匀滋化多边形体反演模型,采用最优化反演方法圈定火烧区边界通过阻尼最小二乘法自动迭代反演,减少了迭代次数和多解性,提高了解释精度。经理论模型与实例试算,证明了方法的有效性。 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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Mohamed Sharif Berguig Mohamed Hamoudi Jean Louis Lemouël Yves Cohen 《Arabian Journal of Geosciences》2013,6(4):1063-1072
In this work, we report a global mapping of vector lunar magnetic field based on new method of separation of internal and external fields. The magnetic measurements collected during the lifetime of lunar prospector (LP) extended mission during 1999 were strongly disturbed by the solar wind, a period which coincided with a maximum of the 23 cycle activity. The multiscale wavelength external fields were analyzed using spherical harmonic transform. The external field determined by inversion was then removed from each magnetic field component for each half orbit. To map the vector magnetic crustal anomalies, all LP magnetometer data collected at low altitudes in the three different lunar environments: (1) geomagnetic tail, (2) solar wind, and (3) geomagnetic sheath were processed using this new approach. The results obtained using these selection criteria allow us to get a global coverage of the lunar surface by the vector magnetic field at variable spacecraft low altitudes. To validate our mapping, we have developed and applied a method based on properties of potential fields functions. This method can be used to determine both horizontal north and east components using only vertical component. The validated lunar internal magnetic measurements obtained at variable spacecraft altitudes were then continued to a common altitude of 30 km using an inverse method. This mapping confirms firstly the nature of the crustal sources of lunar magnetic field and clearly shows that the strongest concentrations of anomalies are associated with high albedo and/or located antipodal to large young basins (Orientale, Serenitatis, Imbrium, and Crisium) of age about 3.9 Ga. 相似文献