共查询到18条相似文献,搜索用时 453 毫秒
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莫霍面是地壳与上地幔的分界面,莫霍面的研究有助于认识地球深部构造及演化。在以往的研究中,由于重力反演方法、使用资料不同,中国东海海域莫霍面深度反演结果有较大不确定性。通过收集中国东海海域高精度地形和自由空气重力异常数据,计算了布格重力异常并分析了其构造特征。提取了中国福建省大田至中国台湾省花莲剖面和中国东海陆架盆地至菲律宾海盆剖面的重力异常数据,采用人机交互正演、反演拟合技术得到了这两条剖面的地壳密度与莫霍面深度。通过向上延拓的方法提取了莫霍面所引起的重力异常,在两条剖面反演结果和地震探测结果的约束下进行Parker-Oldenburg界面反演,得到了该地区的莫霍面深度。反演结果显示,中国东海海域莫霍面深度的变化范围为-34.4~-8.8 km,其结构呈两凹两凸的特征。 相似文献
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蒋福珍 《武汉大学学报(信息科学版)》2002,27(2):122-126,164
利用重力,地震层析成像等多种资料,并利用场分离,正反演以及阻尼最小二乘法,约束最小二乘法等数学方法,对重力异常进行分离,用地震层析成像的结果作为约束进行反演,得到地壳上地幔不同深度的密度分布和莫霍面深度等结果。 相似文献
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三江地区重力场特征和岩石圈构造 总被引:2,自引:0,他引:2
蒋福珍 《武汉大学学报(信息科学版)》2002,27(2):122-126
利用重力、地震层析成像等多种资料 ,并利用场分离、正反演以及阻尼最小二乘法、约束最小二乘法等数学方法 ,对重力异常进行分离 ,用地震层析成像的结果作为约束进行反演 ,得到地壳上地幔不同深度的密度分布和莫霍面深度等结果。 相似文献
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四维重力反演方法初探 总被引:1,自引:0,他引:1
为利用重复水准、重力资料来解释一些地球动力学过程,本文在分析了国内外三维重力反演的基础上,提出了四维重力反演的概念,并推导了界面随时间变化时的四维重力反演公式。对于无穷大水平薄板,我们得到的公式与无穷大水平薄板的重力效应对时间求导的结果是一致的。尽管本文推导的只是密度差不变时的四维重力反演公式,但用本文的思路与类似的方法,不难导出其它情况下的四维重力反演公式。 相似文献
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全球地幔密度异常及其构造意义 总被引:4,自引:0,他引:4
利用扣除地形、莫霍面和核幔边界起伏影响的中长波大地水准面异常和全球地震层析成像资料,采用阻尼最小二乘方法反演计算了全球地幔6个不同层面上的密度异常分布。分析了全球密度异常与板块构造的关系,探讨了全球密度异常分布对板块运动的作用。全球地幔密度异常结果表明存在两个主要的密度异常中心:一个位于东经80°,北纬0°;另一个位于东经240°,北纬10°附近。 相似文献
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详细回顾了基于重力方法反演Moho面的地壳均衡理论(包括普拉特-海福特模型、艾黎-海斯卡涅模型、维宁曼尼斯区域模型3种经典模型)、Vening Meinesz-Moritz (VMM)反演理论、Parker-Oldenburg(P-O)反演理论、Parker-Oldenburg扩展反演理论、直接法反演理论等算法的研究现状,并阐述了各种算法之间的区别和联系。同时,详细论述了地壳均衡理论与Moho面反演之间的区别和联系。重点剖析了重力反演Moho面算法的优点和局限性,为高精度、高分辨率反演Moho面深度提供了理论指导。最后对重力反演Moho面方法进行了展望,并提出了新的解决方案。 相似文献
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小波分析在重力界面反演中的应用 总被引:1,自引:0,他引:1
基于Parker-Oldenburg反演方法,分析了低通滤波器B(K)的不同阈值对位场分离的影响。分别采用小波变换和低通滤波对青藏高原地区布格重力异常进行了位场分解和莫霍面反演,并将反演结果与地震资料作比较。结果表明,在重力位场分解中小波多尺度分解可以代替低通滤波器B(K),避免了闻值的选取。 相似文献
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H. Abd-Elmotaal 《Journal of Geodesy》2000,74(5):390-398
Inverse problems in isostasy will consist in making the isostatic anomalies to be zero under a certain isostatic hypothesis.
In the case of the Vening Meinesz isostatic hypothesis, the density contrast is constant, while the Moho depth (depth of the
Mohorovičić discontinuity) is variable. Hence, the Vening Meinesz inverse isostatic problem aims to determine a suitable variable
Moho depth for a prescribed constant density contrast. The main idea is easy but the theoretical analysis is somewhat difficult.
Moreover, the practical determination of the variable Moho depths based on the Vening Meinesz inverse problem is a laborious
and time-consuming task. The formulas used for computing the inverse Vening Meinesz Moho depths are derived. The computational
tricks essentially needed for computing the inverse Vening Meinesz Moho depths from a set of local and global Bouguer anomalies
are described. The Moho depths for a test area are computed based on the inverse Vening Meinesz isostatic problem. These Moho
depths fit the Moho depths derived from seismic observations with a good accuracy, in which the parameters used for the fitting
agree well with those determined geophysically.
Received: 4 February 1999 / Accepted: 4 October 1999 相似文献
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Geoid determination using adapted reference field, seismic Moho depths and variable density contrast 总被引:4,自引:0,他引:4
The traditional remove-restore technique for geoid computation suffers from two main drawbacks. The first is the assumption
of an isostatic hypothesis to compute the compensation masses. The second is the double consideration of the effect of the
topographic–isostatic masses within the data window through removing the reference field and the terrain reduction process.
To overcome the first disadvantage, the seismic Moho depths, representing, more or less, the actual compensating masses, have
been used with variable density anomalies computed by employing the topographic–isostatic mass balance principle. In order
to avoid the double consideration of the effect of the topographic–isostatic masses within the data window, the effect of
these masses for the used fixed data window, in terms of potential coefficients, has been subtracted from the reference field,
yielding an adapted reference field. This adapted reference field has been used for the remove–restore technique. The necessary
harmonic analysis of the topographic–isostatic potential using seismic Moho depths with variable density anomalies is given.
A wide comparison among geoids computed by the adapted reference field with both the Airy–Heiskanen isostatic model and seismic
Moho depths with variable density anomaly and a geoid computed by the traditional remove–restore technique is made. The results
show that using seismic Moho depths with variable density anomaly along with the adapted reference field gives the best relative
geoid accuracy compared to the GPS/levelling geoid.
Received: 3 October 2001 / Accepted: 20 September 2002
Correspondence to: H.A. Abd-Elmotaal 相似文献
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The crustal structure of Xiachayu-Gonghe geophysical profile in eastern Tibetan plateau is simulated with Bouguer anomaly corrected for sediments and lithosphere. The forward simulation shows that the thickness of upper crust in eastern Tibetan plateau is about 20 km, and the density is 2.78×103kg/m3. The bottom interface of middle crust changes from 30 km to 40 km, the density of middle crust is 2.89×103kg/m3. The materials with low density of 2.78 ×103kg/m3 exist in middle crust, and those with high density of 3.33 ×103kg/m3 exist at the bottom of middle crust between Wenquan and Tanggemu. The density is 3.10 ×103kg/m3 in lower crust. The shallowest depth of Moho interface is about 56 km, and the deepest one is about 74 km, the undulation of interface is large, the deep Moho is located in Xiachayu, Chayu, Nujiang, and Wenquan. The crustal density of eastern Tibetan plateau is larger than that of central section; the low velocity layers are located in middle crust and bottom in eastern Tibetan plateau and at the bottom of the upper crust in the central plateau. 相似文献
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The crustal structure of Xiachayu-Gonghe geophysical profile in eastern Tibetan plateau is simulated with Bouguer anomaly corrected for sediments and lithosphere.The forward simulation shows that the thickness of upper crust in eastern Tibetan plateau is about 20 km,and the density is 2.78 3 3 × 10 kg/m.The bottom interface of middle crust changes from 30 km to 40 km,the density of middle crust is 2.89 3 3 × 10 kg/m.The materials with low density of 2.78 3 3 × 10 kg/mexist in middle crust,and those with hig... 相似文献
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在重力聚焦反演基础上提出多尺度源网聚焦反演算法.首先,对源网进行粗网格剖分,用共轭梯度法求解粗网格源网模型的聚焦解,直到拟合差下降至设定的数值;然后,将粗网格得到的密度映射到细网格;最后,以细网格模型为初始模型,进一步迭代直到拟合差下降至符合反演要求.模型试验结果显示,相比于固定源网反演,多尺度源网聚焦反演迭代的总耗时... 相似文献
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地幔对流诱发的莫霍面起伏与下地壳塑性流动 总被引:3,自引:0,他引:3
本文用定量模型研究了在地幔对流作用下下地壳物质流动过程和莫霍面起伏的变化。数值结果表明莫霍面起伏与岩石层弹性厚度(hel)和载荷波长(λ)相关。对于相同的λ,hel越大,莫霍面起伏越小,反之亦然。而对于相同的hel,λ越大,莫霍面起伏调整到最终状态所需时间越长,其达到的幅值也越大。本文结果暗示,地幔对流形态与地表地形起伏可能并非直接相关。同时,本文结果为解释地球上存在与Airy均衡相偏离地区提供了一种可能的动力学机制。 相似文献
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联合反演是解释地球动力问题的有力手段,本文利用近年来发展的新优化算法-粒子群算法结合位错理论模型,比较了模拟数值的联合反演与单一数据反演的结果.并采用青藏高原东北缘2001-2004年间的GPS数据,及2003 -2004年间的重力数据,对皇城-塔尔庄断层的三维滑动速率进行了附有相对权比的联合反演计算.结果表明,多种数... 相似文献