Compact gravity inversion

Geophysics ◽  
1983 ◽  
Vol 48 (6) ◽  
pp. 713-721 ◽  
Author(s):  
B. J. Last ◽  
K. Kubik
Keyword(s):  
Density Distribution ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Complete Separation ◽  
Gravity Inversion ◽  
Dimensional Model ◽  
Regular Array ◽  
Anomalous Density ◽  
Inversion Procedure ◽  
New Criterion

We present a new criterion for the inversion of gravity data. The principle employed is to minimize the volume of the causative body, which is equivalent to maximizing its compactness. The anomalous density distribution is obtained using an iterative technique which is numerically stable and rapidly convergent. The principle can also be adapted to include modeling of gravity anomalies by single‐density sources. The advantage of this approach is that desirable geologic characteristics are automatically incorporated into the model with a minimum of subjective judgments on the part of the interpreter. The treatment of noise in the data fits naturally into the formulation of the inversion procedure. The method is illustrated by the inversion of noise‐free and noisy data generated from a two‐dimensional model consisting of a regular array of identical rectangular blocks whose densities can be individually specified. In every case the algorithm successfully recovers the correct density distribution from the data. In the case of noise‐contaminated data, a complete separation of the noise from the signal is achieved. The practical effectiveness of the method is demonstrated by the inversion of published gravity data. The results obtained are compared with existing models and with available drilling information.

A method for inversion of 1D vertical soundings of gravity anomalies

Geophysics ◽  
2018 ◽  
Vol 83 (2) ◽  
pp. G15-G23
Author(s):  
Andrea Vitale ◽  
Domenico Di Massa ◽  
Maurizio Fedi ◽  
Giovanni Florio
Keyword(s):  
Potential Field ◽  
Field Data ◽  
Gravity Data ◽  
Finite Size ◽  
Gravity Anomalies ◽  
Real Data ◽  
Gravity Inversion ◽  
Chain Process ◽  
Potential Field Data ◽  
Gamma Density

We have developed a method to interpret potential fields, which obtains 1D models by inverting vertical soundings of potential field data. The vertical soundings are built through upward continuation of potential field data, measured on either a profile or a surface. The method assumes a forward problem consisting of a volume partitioned in layers, each of them homogeneous and horizontally finite, but with the density changing versus depth. The continuation errors, increasing with the altitude, are automatically handled by determining the coefficients of a third-order polynomial function of the altitude. Due to the finite size of the source volume, we need a priori information about the total horizontal extent of the volume, which is estimated by boundary analysis and optimized by a Markov chain process. For each sounding, a 1D inverse problem is independently solved by a nonnegative least-squares algorithm. Merging of the several inverted models finally yields approximate 2D or 3D models that are, however, shown to generate a good fit to the measured data. The method is applied to synthetic models, producing good results for either perfect or continued data. Even for real data, i.e., the gravity data of a sedimentary basin in Nevada, the results are interesting, and they are consistent with previous interpretation, based on 3D gravity inversion constrained by two gamma-gamma density logs.

Topography of the crust–mantle interface under the Western Superior craton from gravity data

2003 ◽  
Vol 40 (10) ◽  
pp. 1307-1320 ◽  
Author(s):  
B Nitescu ◽  
A R Cruden ◽  
R C Bailey
Keyword(s):  
Gravity Data ◽  
Three Dimensional ◽  
Gravity Anomalies ◽  
Gravity Inversion ◽  
Constant Density ◽  
Inversion Algorithm ◽  
Data Set ◽  
Mantle Boundary ◽  
Refraction Seismic ◽  
Superior Craton

The Moho undulations beneath the western part of the Archean Superior Province have been investigated with a three-dimensional gravity inversion algorithm for a single interface of constant density contrast. Inversion of the complete gravity data set produces unreal effects in the solution due to the ambiguity in the possible sources of some crustal gravity anomalies. To avoid these effects a censored gravity data set was used instead. The inversion results are consistent with reflection and refraction seismic data from the region and, therefore, provide a basis for the lateral correlation of the Moho topography between parallel seismic lines. The results indicate the existence of a major linear east–west-trending rise of the Moho below the metasedimentary English River subprovince, which is paralleled by crustal roots below the granite–greenstone Uchi and Wabigoon subprovinces. This correlation between the subprovincial structure at the surface and deep Moho undulations suggests that the topography of the crust–mantle boundary is related to the tectonic evolution of the Western Superior belts. Although certain features of the crust–mantle boundary are likely inherited from the accretionary and collisional stages of the Western Superior craton, gravity-driven processes triggered by subsequent magmatism and crustal softening may have played a role in both the preservation of those features, as well as in the development of new ones.

scholarly journals 3D Gravity Inversion with Correlation Image in Space Domain and Application to the Northern Sinai Peninsula

2019 ◽  
Vol 1 (2) ◽  
Author(s):  
Xu Zhang ◽  
Peng Yu ◽  
Jian Wang
Keyword(s):  
Density Distribution ◽  
Gravity Data ◽  
Descent Method ◽  
Steepest Descent Method ◽  
Gravity Inversion ◽  
Inversion Method ◽  
Sinai Peninsula ◽  
Space Domain ◽  
Correlation Image ◽  
Starting Model

We present a 3D inversion method to recover density distribution from gravity data in space domain. Our method firstly employs 3D correlation image of the vertical gradient of gravity data as a starting model to generate a higher resolution image for inversion. The 3D density distribution is then obtained by inverting the correlation image of gravity data to fit the observed data based on classical inversion method of the steepest descent method. We also perform the effective equivalent storage and subdomain techniques in the starting model calculation, the forward modeling and the inversion procedures, which allow fast computation in space domain with reducing memory consumption but maintaining accuracy. The efficiency and stability of our method is demonstrated on two sets of synthetic data and one set of the Northern Sinai Peninsula gravity data. The inverted 3D density distributions show that high density bodies beneath Risan Aniza and low density bodies exist to the southeast of Risan Aniza at depths between 1~10 and 20 km, which may be originated from hot anomalies in the lower crust. The results show that our inversion method is useful for 3D quantitative interpretation.

scholarly journals A NOVEL REGIONAL-RESIDUAL SEPARATION APPROACH FOR GRAVITY DATA THROUGH CRUSTAL MODELING

2018 ◽  
Vol 36 (4) ◽  
pp. 1
Author(s):  
Nelson Ribeiro Filho ◽  
Cristiano Mendel Martins ◽  
Renata de Sena Santos
Keyword(s):  
Gravity Data ◽  
Gravity Anomalies ◽  
Forward Modeling ◽  
Gravity Modeling ◽  
Gravity Inversion ◽  
Separation Procedure ◽  
New Approach ◽  
Crustal Model ◽  
Main Target ◽  
Complex Geology

ABSTRACT. Gravity anomalies normally contain information of all sources beneath Earth’s surface. Once residual anomalies exhibit information about the main target, the knowledge of this specific residual signal is extremely important to interpretation. To find this signal, it’s necessary to perform regional-residual separation. We present here a new approach of separation by using gravity crustal modeling. We divide the surface in prisms, with density given by GEMMA. We calculate the regional signal, assuming Earth’s crust can be the source of observed anomaly. This methodology was applied on Barreirinhas basin-Brazil. Its formation is related to geologic events in South America-Africa break. Besides, the complex geology is the main obstacle on finding the residual anomaly. We compare our methodology with robust-polynomial fitting and spectral-analysis. They were not able to identify the residual anomaly. Main trouble relies on absence of crust information. Those kind of environment usually requires forward modeling and/or gravity inversion. On the other hand, our approach considers all crust’s parameters. Then the difficulty on choosing the residual no longer exists. The residual anomaly follows a geologic pattern. The crustal depocenter was mapped between structural faults. Therefore, our results satisfies the main expectation and are extremely linked to Barreirinhas basin’s geological background. We recommend this separation procedure, once Earth’s crustal model and gravity data are available for all planet.Keywords: Gravity modeling; GEMMA model; Barreirinhas basin; residual anomaly. RESUMO. Anomalias gravimétricas contêm informações de todas as fontes na superfície terrestre. Uma vez que anomalias residuais exibem informações sobre alvos principais, o conhecimento desse específico sinal residual é extremamente importante para interpretação. Para encontrá-lo, é necessário realizar separação regional-residual. Apresentamos aqui uma nova abordagem de separação utilizando a modelagem gravimétrica crustal. Discretizamos a superfície em prismas, com densidade fornecida pelo modelo GEMMA. Calculamos o sinal regional, assumindo que a crosta terrestre é a fonte da anomalia observada. Aplicamos esta metodologia na bacia de Barreirinhas - Brasil, que tem sua formação relacionada aos eventos geológicos de separação da América do Sul e África. Além disso, a complexidade geológica é considerada o principal obstáculo para encontrar esta anomalia residual. Comparamos nossa metodologia com Ajuste Polinomial Robusto e Análise Espectral. Essas técnicas não foram capazes de identificar a anomalia residual. O principal problema se dá pela ausência de informações acerca da crosta. Para esse ambiente, geralmente requer modelagem direta e/ou inversão geofísica. Por outro lado, nossa abordagem considera todos os parâmetros crustais e a dificuldade em escolher o residual deixa de existir. A anomalia residual apresenta um padrão geológico. O depocentro crustal foi mapeado entre falhas estruturais. Nossos resultados satisfazem a expectativa principal e estão extremamente ligados ao cenário geológico da bacia. Recomendamos este procedimento de separação, uma vez que os modelos crustais e dados gravimétricos estão disponíveis para todo o planeta.Palavras-chave: Modelagem gravimétrica; modelo GEMMA; bacia de Barreirinhas; anomalia residual

scholarly journals NEW ALGORITHM FOR INVERSION OF GRAVITATIONAL DATA

2018 ◽  
pp. 51-56
Author(s):  
P. Gryshchuk
Keyword(s):  
Gravity Data ◽  
Gravity Anomalies ◽  
Practical Significance ◽  
Gravity Inversion ◽  
Section Data ◽  
Number Of Layers ◽  
Coal Deposits ◽  
Mass Displacement ◽  
Definition Of ◽  
Gravity Acceleration

The article is devoted to the description of the new algorithm for inversion of gravitational anomalies.The principle of the geological objects mass displacement is used for definition of its geometry. In the grid model, the movement of blocks is performed in four directions for a two-dimensional model. The motion and changing of density is determined in a random style. This algorithm defined the geometry of three rectangular bodies of model. The conditions for determining the exact form of gravity sources by the proposed approach were clarified. An analysis of the inversion of gravity acceleration anomalies from three bodies for sections, which consisted of three, four and five layers, was performed. The bodies of identical density were determined exactly for three and four layers, and with errors for the five layers. The model with two densities had some errors in determining the geometry of the bodies. Scientific novelty is related to the development of new algorithm, which is based on the principle of movingfor density between blocks. The new approach fulfils gravity inversion much faster than the genetic algorithm. The practical significance is determination of the number of layers needed for a proper inversion of gravity anomalies. The main factors influencing the accuracy of geometry are the data of body density and the number of layers. The method was used for the interpretation of gravity data over the coal deposits of the Donbas. The model consisted of five layers and a range of minimum to their maximum densities for the geological section. Data of the inversion was determined by the depth to the surface of the limestone, which is confirmed by the data of the drilling. The developed approach determines the geometry of section from density, which is important for geological, search and environmental tasks.

scholarly journals 3D Mafic Topography of the Transition Zone between the North-Western Boundary of the Congo Craton and the Kribi-Campo Sedimentary Basin from Gravity Inversion

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Sévérin Nguiya ◽  
Willy Lemotio ◽  
Philippe Njandjock Nouck ◽  
Marcelin M. Pemi ◽  
Alain-Pierre K. Tokam ◽  
...  
Keyword(s):  
Transition Zone ◽  
Sedimentary Basin ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Gravity Inversion ◽  
Western Boundary ◽  
Northern Margin ◽  
Velocity Models ◽  
The North ◽  
North Western

The structure of the transition zone between the north-western boundary of the Congo Craton and the Kribi-Campo sedimentary basin is still a matter of scientific debate. In this study, the existing gravity data are interpreted in order to better understand the geodynamics of the area. Qualitatively, results show that the major gravity highs are associated with long-wavelength shallow sources of the coastal sedimentary basin, while large negative anomalies trending E-W correlate to low dense intrusive bodies found along the northern limit of the Congo Craton. For the delineation of the causative sources, the gravity anomalies have been inverted based on the Parker-Oldenburg iterative process. As inputs, we used a reference depth of 20 km obtained by spectral analysis and successively, the density contrasts 0.19 g/cm3 and 0.24 g/cm3, deduced from available 1D shear wave velocity models. The results reveal an irregular topography of the mafic interface characterized by a sequence of horst and graben structures with mafic depths varying between 15.6 km and 23.4 km. The shallower depths (15.6-17 km) are associated with the uprising of the mafic interface towards the upper crust. This intrusion may have been initiated during the extension of the Archean Ntem crust resulting in a thinning of the continental crust beneath the coastal sedimentary basin. The subsidence of the mafic interface beneath the craton is materialized by 2 similar graben structures located beneath both Matomb and Ebolowa at a maximum depth of 23.4 km. The intermediate depths (18-22 km) are correlated to the suture zone along the Pouma-Bipindi area. The location of some landslides across the area matches within the northern margin of the Congo Craton and suggests that this margin may also impact on their occurrence. This work provides new insights into the geodynamics, regional tectonics, and basin geometry.

PENCIRIAN SESAR-SESAR MAJOR DI SEKITAR SEMENANJUNG MALAYSIA BERDASARKAN TEKNIK SATELIT GRAVITI

2018 ◽  
Vol 80 (2) ◽  
Author(s):  
Nurul Fairuz Diyana Bahrudin ◽  
Umar Hamzah
Keyword(s):  
Gravity Data ◽  
Gravity Anomalies ◽  
Peninsular Malaysia ◽  
Gravity Inversion ◽  
Kuala Lumpur ◽  
Euler Deconvolution ◽  
Satellite Gravity ◽  
3D Euler Deconvolution ◽  
Major Fault ◽  
Fault Structures

Major fault structures of Peninsular Malaysia were interpreted by satellite gravity data obtained from EGM2008. Filtering including THD, TVD, TDR, TDX and Euler Deconvolution inversion techniuques were applied to the data and successfully delineated the major faults especially located in the area separating the granite and sedimentary rock such as Bok Bak, Kuala Lumpur, Bukit Tinggi and Lebir faults. The main finding of this research is the boundary separating the western and eastern belt of Peninsular Malaysia namely the Bentong-Raub Suture by the abrupt changes of gravity anomalies between the two belts. The average depths and dips of Kuala Lumpur, Bukit Tinggi and Seremban faults were estimated by gravity inversion 3D Euler Deconvolution. 

scholarly journals Lp-Norm Inversion of Gravity Data Using Adaptive Differential Evolution

2021 ◽  
Vol 11 (14) ◽  
pp. 6485
Author(s):  
Tao Song ◽  
Xing Hu ◽  
Wei Du ◽  
Lianzheng Cheng ◽  
Tiaojie Xiao ◽  
...  
Keyword(s):  
Differential Evolution ◽  
Density Distribution ◽  
Gravity Data ◽  
Physical Property ◽  
Gravity Anomalies ◽  
Property Distribution ◽  
Regularization Term ◽  
Lp Norm ◽  
De Algorithm ◽  
Mutation Strategy

As a popular population based heuristic evolutionary algorithm, differential evolution (DE) has been widely applied in various science and engineering problems. Similar to other global nonlinear algorithms, such as genetic algorithm, simulated annealing, particle swarm optimization, etc., the DE algorithm is mostly applied to resolve the parametric inverse problem, but has few applications in physical property inversion. According to our knowledge, this is the first time DE has been applied in obtaining the physical property distribution of gravity data due to causative sources embedded in the subsurface. In this work, the search direction of DE is guided by better vectors, enhancing the exploration efficiency of the mutation strategy. Besides, to reduce the over-stochastic of the DE algorithm, the perturbation directions in mutation operations are smoothed by using a weighted moving average smoothing technique, and the Lp-norm regularization term is implemented to sharpen the boundary of density distribution. Meanwhile, in the search process of DE, the effect of Lp-norm regularization term is controlled in an adaptive manner, which can always have an impact on the data misfit function. In the synthetic anomaly case, both noise-free and noisy data sets are considered. For the field case, gravity anomalies originating from the Shihe iron ore deposit in China were inverted and interpreted. The reconstructed density distribution is in good agreement with the one obtained by drill-hole information. Based on the tests in the present study, one can conclude that the Lp-norm inversion using DE is a useful tool for physical property distribution using gravity anomalies.

scholarly journals Characterization of geological boundaries using 1‐D wavelet transform on gravity data: Theory and application to the Himalayas

Geophysics ◽  
2001 ◽  
Vol 66 (4) ◽  
pp. 1116-1129 ◽  
Author(s):  
G. Martelet ◽  
P. Sailhac ◽  
F. Moreau ◽  
M. Diament
Keyword(s):  
Wavelet Transform ◽  
Gravity Data ◽  
Real Data ◽  
Source Analysis ◽  
Gravity Inversion ◽  
Analysis Tool ◽  
Geometric Constructions ◽  
Complex Wavelets ◽  
Inversion Procedure ◽  
Geological Boundaries

We investigate the use of the continuous wavelet transform for gravity inversion. The wavelet transform operator has recently been introduced in the domain of potential fields both as a filtering and a source‐analysis tool. Here we develop an inverse scheme in the wavelet domain, designed to recover the geometric characteristics of density heterogeneities described by simple‐shaped sources. The 1‐D analyzing wavelet we use associates the upward continuation operator and linear combinations of derivatives of any order. In the gravity case, we first demonstrate how to localize causative sources using simple geometric constructions. Both the upper part of the source and the whole source can be studied when considering low or high altitudes, respectively. The homogeneity degree of the source is deduced without prior information and allows us to infer its shape. Introducing complex wavelets, we derive analytically the scaling behavior of the wavelet coefficients for the dyke and the step sources. The modulus term is used in an inversion procedure to recover the thickness of the source. The phase term provides its dip. This analysis is performed on gravity data we measured along a profile across the Himalayas in Nepal. Good agreement of our results with well‐documented thrusting structures demonstrates the applicability of the method to real data. Also, deeper, less constrained structures are characterized.

scholarly journals Inversion of gravity data with isostatic constraints

Geophysics ◽  
2014 ◽  
Vol 79 (6) ◽  
pp. A45-A50 ◽  
Author(s):  
Ahmed Salem ◽  
Chris Green ◽  
Matthew Stewart ◽  
Davide De Lerma
Keyword(s):  
Sedimentary Basin ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Gravity Inversion ◽  
Rift Basin ◽  
Rift Basins ◽  
Isostatic Equilibrium ◽  
Crustal Thinning ◽  
Model Surfaces ◽  
Gravity Profile

We have developed a simple iterative gravity-inversion approach to map the basement and Moho surfaces of a rift basin simultaneously. Gravity anomalies in rift basins commonly consist of interfering broad, positive crustal-thinning anomalies and narrow, negative sedimentary-basin anomalies. In our model, we assumed that the Moho and basement surfaces are in Airy isostatic equilibrium. An initial plane-layered model was iterated to fit the gravity data. We applied the process to a model in which the inverted basement and Moho surfaces matched the model surfaces well and to a gravity profile across the Kosti Basin in Sudan.

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