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3D spatial domain gravity inversion with growing multiple polygonal cross-sections and exponential mass density contrast
Journal of Earth System Science ( IF 1.9 ) Pub Date : 2021-04-19 , DOI: 10.1007/s12040-021-01576-4
B Ramamma , K Mallesh , V Chakravarthi

Abstract

An automatic 3D spatial domain inversion technique is developed to estimate basement depths of sedimentary basins from observed gravity anomalies using a prescribed exponential mass density contrast. A collage of vertical polygonal cross-sections, each one with unit thickness, in which the density contrast differs exponentially with depth describes the model space. The proposed technique estimates the optimum depth ordinates of the vertices of polygonal cross-sections from a given set of gravity anomalies following predefined convergence criteria. Initial depths to basement interface at plurality of observations are calculated presuming that the density contrast within the Bouguer slab at each observation is also varying exponentially with depth. A previously reported algorithm that make use of both analytic and numeric approaches to compute the gravity response of such 3D model space with exponential mass density contrast is adopted for forward modelling. The proposed inversion is efficient even when the gravity anomalies are available at non-uniform spatial grid intervals. Recovery of basement depths with modest error from a set of gravity anomalies attributable to a synthetic model in the presence of pseudorandom noise and also the fact that the estimated depth structure of the Almazán Basin in NE Spain correlates reasonably well with the information derived from seismic data demonstrates the applicability of the proposed inversion method. The snags associated with other existing density models in the analysis of gravity anomalies are demonstrated on both synthetic and real field anomalies.

Research Highlights

  1. 1.

    It is a 3D inversion technique to analyse the gravity anomalies of sedimentary basins.

  2. 2.

    Density contrast variation is automatically ascribed by an exponential function in the algorithm.

  3. 3.

    The interpretation technique does not require initial model specification to start with.

  4. 4.

    The algorithm is fully automatic.



中文翻译:

具有增长的多个多边形横截面和指数质量密度对比的3D空间域重力反演

摘要

开发了一种自动3D空间域反演技术,可以使用规定的指数质量密度对比从观测到的重力异常估算沉积盆地的基底深度。垂直多边形横截面的拼贴,每个横截面具有单位厚度,其中密度对比随深度呈指数变化,描述了模型空间。所提出的技术根据预定义的收敛准则,根据给定的一组重力异常,估计多边形横截面的顶点的最佳深度纵坐标。假定每个观测点的布格平板内的密度对比也随深度呈指数变化,则计算出多个观测点到基底界面的初始深度。正向建模采用先前报告的算法,该算法同时使用解析方法和数值方法来计算具有指数质量密度对比的此类3D模型空间的重力响应。即使重力异常在不均匀的空间网格间隔内可用,所提出的反演也是有效的。在存在伪随机噪声的情况下,从合成模型引起的一系列重力异常中恢复具有适度误差的基底深度,并且西班牙东北部阿尔马桑盆地的估计深度结构与地震数据得出的信息具有合理的相关性证明了所提出的反演方法的适用性。

研究重点

  1. 1。

    分析沉积盆地重力异常是一种3D反演技术。

  2. 2。

    密度对比变化由算法中的指数函数自动赋予。

  3. 3。

    解释技术不需要初始模型说明即可开始。

  4. 4,

    该算法是全自动的。

更新日期:2021-04-19
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