共查询到17条相似文献，搜索用时 140 毫秒
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黄土塬区地形起伏大,地表黄土切割剧烈。地形起伏导致黄土厚度巨大变化,由于黄土密度与下伏地层之间存在较大的密度差异,由此产生了具有一定幅值的高频重力异常,并给重力勘探资料的处理、解释带来了困难。在SHJZ构造带高精度重力勘探中,综合运用了地形校正和黄土校正技术,有效地克服了由于地形起伏和黄土厚度变化对重力勘探产生的不利影响,取得了精确的重力资料。并将该重力异常,结合其它物探资料进行综合解释,对圈定局部构造发挥了积极的作用。 相似文献
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目前我国所采用的重力校正中包括纬度校正、高度校正、中间层校正和布格校正四大校正,这种重力外部校正方法中存在大量的简化假设,以降低计算量,提高运算效率,这种简化假设使得重力校正中存在若干问题:1)由于大地参考椭球与重力正常椭球不一致而引起的纬度误差;2)由于垂直基准面不一致而引起的高程异常;3)地形和中间层校正中密度选择不合理使得重力异常与地质构造背景相左等.随着我国重力勘探力度逐步向西部山区转移和重力勘探精度的提高,这种以大量的简化假设为前提的重力校正方法,便成为制约重力勘探的重要因素.本文对上述问题进行了分析论述,总结了国内外学者针对这些问题所进行的研究,并提出了对未来研究方向的展望,即一种基于"正常空间重力异常"的重力校正方法,这一方法的中心思想在于通过建立大地坐标系参考椭球空间任意一点的正常重力公式,将重力异常直接计算到重力测点上,取消了传统重力校正中的四大校正,从而避免各种校正过程中存在的问题. 相似文献
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利用卫星重力测量资料研究地球、月球与火星等星体的内部构造时,需要进行重力地形校正,计算全球布格重力异常,而在球坐标中实现地形校正计算是一种有效的途径.本文提出球坐标系中的球冠域地形校正计算方法,给出了该方法涉及的球坐标系之间坐标转换方法和球冠域内地形模型重构方法,并进行理论验证．作者利用嫦娥一号激光测高数据对月球重力进行地形校正,获得了月球全球布格重力异常,并与球坐标系中Tesseroid 单元体地形校正方法对比,分析了球冠域地形校正方法的计算精度、空间分辨率及其优缺点． 相似文献
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黄土塬区地形起伏大,地表黄土切割剧烈。地形起伏导致黄土厚度巨大变化,由于黄土密度与下伏地层之间存在较大的密度差异,由此产生了具有一定幅值的高频重力异常,并给重力勘探资料的处理、解释带来了困难。在SHJZ构造带高精度重力勘探中,综合运用了地形校正和黄土校正技术,有效地克服了由于地形起伏和黄土厚度变化对重力勘探产生的不利影响,取得了精确的重力资料。并将该重力异常,结合其它物探资料进行综合解释,对圈定局部构造发挥了积极的作用。 相似文献
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本文利用解析函数的罗朗展开式对复杂磁异常进行分解,并指出,分解异常的方法亦能同时用于解决山区的地形校正问题,最后探讨了确定复杂磁异常的延深、倾角和截面积的定量计算方法,并举出某铁矿区的勘探实例来阐明上述方法在磁测资料定量解释中的实际应用。 相似文献
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在大地热流评估中，经常要对接近地表的实测值进行校正，然而在迅速抬升剥蚀的崎岖山区，在抬升剥蚀校正基础上进一步作地形校正时，没有剥蚀静态条件下的地形校正是否仍然适用是一个没有讨论过的问题．本文以新西兰的南阿尔卑斯山地区为例，通过有限单元法数值计算，探讨了迅速抬升剥蚀的山区剥蚀和地形二者对近地表不同深度地热流量影响的综合效应．结果表明，虽然迅速抬升地区大地热流密度的地形校正与不考虑剥蚀情况下的校正在较大深度处会略有差别，但总的来说差别甚微．因此，可以沿用传统的地形校正方法，根据钻孔所处地形和测温深度作地形校正． 相似文献
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地壳对不同波长地形在重力场中的响应 总被引：1，自引：3，他引：1
为有效发挥重力均衡在地质、地球物理和大地测量中的作用，本文进一步阐明重力位球函数的阶数与波长的关系．以及地形及其补偿与波长的关系．指出在研究短波长地形的重力效应时无需考虑补偿的影响，否则将会引起场效应的失真．模型的研究表明，在局部地区或测点上，利用高程资料作重力异常推估可以达到理想的结果．为检验均衡理论的适用性与局限性，文中列出高喜马拉雅一带的54块样品的岩石密度和岩性；为验证地形的重力效应，还计算出锥形山体时外部点的引力． 相似文献
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M. BLÍKOVSKÝ 《Geophysical Prospecting》1979,27(4):848-861
An economic and precise processing system for microgravity surveys is presented. Three computer processing modes covering areal ground and underground measurements, measurements in vertical shafts, and measurements of vertical gravity gradients with a 3 m high tower are dealt with. Diagrams for manual calculation of gravity effects of prismatic walls, vertical shafts, and horizontal galleries, as well as programs for calculation of accurate terrain corrections and corrections for gravity effects of bodies with complicated ground-plan are proposed. The method of processing microgravity data is two to three times quicker than any traditional way, with maximum accuracy preserved in resulting gravity micro-anomalies. Applications from the field of mining geophysics and archaeology are included. 相似文献
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Zdeněk Martinec 《Studia Geophysica et Geodaetica》1990,34(4):313-326
Summary A new method for computing the potential coefficients of the Earth's external gravity field is presented. The gravimetric
boundary-value problem with a free boundary is reduced to the problem with a fixed known telluroid. The main idea of the derivation
consists in a continuation of the quantities from the physical surface to the telluroid by means of Taylor's series expansion
in such a way that the terms whose magnitudes are comparable with the accuracy of today's gravity measurements are retained.
Thus not only linear, but also non-linear terms are taken into account. Explicitly, the terms up to the order of the third
power of the Earth's flattening are retained. The non-linear boundary-value problem on the telluroid is solved by an iteration
procedure with successive approximations. In each iteration step the solution of the non-linear problem is estimated by the
solutions of two linear problems utilizing the fact that the non-linear boundary condition may be split into two parts; the
linear spherical approximation of the gravity anomaly whose magnitude is significantly greater than the others and the non-linear
ellipsoidal corrections. Finally, in order to solve the problem in terms of spherical harmonics, the transform method composed
of the fast Fourier transform and Gauss Legendre quadrature is theoretically outlined. Immediate data processing of gravity
data measured on the physical Earth's surface without any continuation of gravity measurements to a reference level surface
belongs to the main advantage of the presented method. This implies that no preliminary data handling is needed and that the
error data propagation is, consequently, maximally suppressed. 相似文献
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本文利用澳大利亚北领地West Arnhem Land 地区实测重力异常数据并联合DEM(9")和SRTM3(3")地形高程数据,使用移去-恢复技术和Stokes积分方法计算了该地区两条剖面的重力梯度及其功率谱密度,使用FFT方法解算了整个地区的重力梯度值,结果证明了联合重力异常数据和高分辨率地形高程数据能有效地提高重力梯度的解算精度;功率谱密度的计算结果与国外成熟的重力梯度功率谱密度模型相吻合,表明高于0.3 Hz频率范围的功率谱密度可看做噪声,为重力梯度数据处理中噪声的辨别和剔除提供了借鉴,另外对重力梯度辅助导航基准图的构建以及重力梯度测量系统的标定提供了有益的探索. 相似文献
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Far-zone gravity field contributions corrected for the effect of topography by means of molodensky’s truncation coefficients 总被引：1，自引：0，他引：1
Robert Tenzer Pavel Novák Peter Vajda Artu Ellmann Ahmed Abdalla 《Studia Geophysica et Geodaetica》2011,55(1):55-71
A spectral representation of the topographic corrections to gravity field quantities is formulated in terms of spherical height
functions. When computing the far-zone contributions to the topographic corrections, various types of the truncation coefficients
are applied to a spectral representation of Newton’s integral. In this study we utilise Molodensky’s truncation coefficients
in deriving the expressions for the far-zone contributions to topographic corrections. The expressions for computing the far-zone
gravity field contributions corrected for the effect of topography are then obtained by combining the expressions for the
far-zone contributions to the gravity field quantities and to the respective topographic corrections, both expressed in terms
of Molodensky’s truncation coefficients. The numerical examples of the far-zone contributions to the topographic corrections
and to the topography-corrected gravity field quantities are given over the study area situated in the Canadian Rocky Mountains
with adjacent planes. Coefficients of the global elevation and geopotential models are used as the input data. 相似文献
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The increased popularity of airborne measurements of the gravity gradient tensor for resource studies and geological mapping has resulted in a new awareness of the importance of terrain effects. In these measurements, the terrain effect often overwhelms that of the underlying crust and it becomes important to formulate a strategy for taking it into account when presenting the data and when inverting the data into density models. Using newly acquired data from Northern Sweden, we first attempted to estimate a variable terrain density model by inverting the data using a terrain model with a laterally varying density. Using data weights related to the topography variations, we find the best estimate of the lateral variation of the terrain density. We translate this model into a full three-dimensional model such that all columns have the same vertical centre of mass as estimated from inspecting the radially averaged power spectrum of the area. This then defines a reference model for subsequent three-dimensional inversion of the gravity gradient tensor dataset. We tested this approach first on synthetic data calculated from the measured topography including two density anomalies before we applied it to the measured data. The result is a model in which the surface density variations are propagated downwards in a systematic manner now in better agreement with measured densities of rock samples in the area. 相似文献
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The prism method for terrain corrections using digital computers 总被引：1，自引：0，他引：1
Dezső Nagy 《Pure and Applied Geophysics》1966,63(1):31-39
Summary In the prism method of making terrain corrections, the topography is approximated by a model consisting of right rectangular prisms. The vertical component of the gravitational attraction of each prism is calculated and the sum of these components gives the terrain correction.The prism method as programmed has no computational limitations. It can be used on all sizes of computers; it can be applied to a large area with any fine grid interval; it can be processed in a single run and yet provides complete flexibility for both research and routine computations. This has been achieved by breaking up larger areas into regions which fit into the computer memory. The contributions of these regions are automatically summed up for each station. While processing each region, various controls may be used at each station to exclude the contribution of a distant part of the area, to use approximate expressions farther from the station, to print out details around the station. There is also provision to refine the model by using smaller prisms around each computation point. Thus full use of elevation control can be made to calculate the terrain correction, the accuracy of which depends only on the quality of the input data.The prism method has been used to calculate terrain corrections for 130 stations in the New Quebec crater area. For five of these stations terrain corrections were also calculated by usingHammer's template. The two independent sets of values differ by less than four per cent. 相似文献