scholarly journals Analysis of gravity anomaly for groundwater basin in Bandar Lampung city based on 2D gravity modeling

2020 ◽  
Vol 1572 ◽  
pp. 012006
Author(s):  
A Zaenudin ◽  
R Risman ◽  
I G B Darmawan ◽  
I B S Yogi
Keyword(s):  
Gravity Anomaly ◽  
2D Gravity ◽  
Gravity Modeling ◽  
Groundwater Basin

scholarly journals Gravity modeling of the Alpine lithosphere affected by magmatism based on seismic tomography

2020 ◽  
Author(s):  
Davide Tadiello ◽  
Carla Braitenberg
Keyword(s):  
Density Distribution ◽  
Gravity Anomaly ◽  
Seismic Tomography ◽  
Gravity Modeling ◽  
Tauern Window ◽  
Density Anomaly ◽  
Alpine Regions ◽  
Alpine Zone ◽  
Magmatic Underplating ◽  
Density Values

Abstract. The Southern Alpine regions have been affected by several magmatic and volcanic events between the Paleozoic and the Tertiary. This activity has undoubtedly had an important effect on the density distribution and structural setting at lithosphere scale. Here the gravity field is used to create a 3D lithosphere density model on the base of a high-resolution seismic tomography model. The results of the gravity modelling demonstrate a highly complex density distribution in good agreement with the different geological domains of the Alpine area represented by the European plate, the Adriatic plate and the Tyrrhenian basin. The Adriatic derived terrains (Southalpine and Austrolpine) of the Alps are typically denser (2850 kg m−3), whilst the Alpine zone composed by European terrains provenance (Helvetic and Tauern window) presents lower density values (2750 kg m−3). Inside the Southalpine, south of the Dolomites, a well-known positive gravity anomaly is present and one of the aims of this work is to investigate the source of this anomaly that has not yet been explained. The modelled density suggests that the anomaly is related to two different sources, the first involves the middle-crust below the gravity anomaly and is represented by localized mushroom-shaped bodies interpreted as a magmatic intrusion, while a second wider density anomaly affects the lower crust of the Southern Alpine realm and could correspond to a mafic and ultramafic magmatic underplating (gabbros and related cumulates) developed during Paleozoic extension.

Regional gravity setting of the Sudbury Structure

Geophysics ◽  
2001 ◽  
Vol 66 (6) ◽  
pp. 1680-1690 ◽  
Author(s):  
R. B. Hearst ◽  
W. A. Morris
Keyword(s):  
Numerical Methods ◽  
Gravity Anomaly ◽  
Gravity Field ◽  
Downward Continuation ◽  
Gravity Models ◽  
Gravity Modeling ◽  
Meteorite Impact ◽  
Sudbury Structure ◽  
Regional Gravity ◽  
Impact Origin

In the vicinity of Sudbury, Ontario, Canada, the boundary between the Southern and Superior tectonic provinces is overlain by the elliptical Sudbury Structure. On the basis of gravity modeling, genesis of the Sudbury Structure has been attributed to either a magmatic origin (having a dense hidden differentiate zone) or a meteorite impact origin (there being no dense hidden mass). The difference between the two gravity models centers on the problem of regional‐residual separation. As shown by numerous previous studies, any such separation of components is nonunique. This becomes especially problematic when, as in Sudbury, a portion of the near‐surface geology has a similar orientation and dimension to more deep‐seated source. In this paper, several numerical methods (upward continuation, downward continuation, wavelength filtering, trend‐surface analysis) for determining the regional component of the gravity field associated with the Sudbury Structure have been applied and evaluated. Of the numerical methods used, the upward and downward continuation operators provided the most insight into the deep structural controls of the Sudbury Basin. Our preferred interpretation of the regional gravity field invokes a two‐component structure. Underlying the southern half of the Sudbury Structure is a laterally continuous gravity anomaly that is probably associated with a zone of uplifted Huronian volcanics. The gravity anomaly under the northern portion of the Sudbury Structure has a more restricted spatial extent. The close association between the northern limit of the gravity anomaly and the surface outcrop of the Levack Gneiss suggests the source of this anomaly is probably a slab of dense Levack Gneiss. This interpretation favors a meteorite impact origin for the Sudbury Structure.

2D vector gravity potential and line integrals for the gravity anomaly caused by a 2D mass of depth-dependent density contrast

Geophysics ◽  
2008 ◽  
Vol 73 (6) ◽  
pp. I43-I50 ◽  
Author(s):  
Xiaobing Zhou
Keyword(s):  
Gravity Anomaly ◽  
Density Function ◽  
Case Studies ◽  
Two Dimensions ◽  
Density Contrast ◽  
Gravity Potential ◽  
Gravity Modeling ◽  
Desktop Computer ◽  
Contrast Function ◽  
Dependent Density

Using line integrals (LIs) used to calculate the gravity anomaly caused by a 2D mass of complicated geometry and spatially variable density contrast is a computationally efficient algorithm, that reduces the calculation from two dimensions to one dimension. This work has developed a mechanism for defining LIs systematically for different types of density functions. Two-dimensional vector gravity potential is defined as a vector, the net circulation of which, along the closed contour bounding a 2D mass, equals the gravity anomaly caused by the 2D mass. Two representative types of LIs are defined: an LI with an arctangent kernel for any depth-dependent density-contrast function, which has been studied historically; and an LI with a simple algebraic kernel for any integrable density-contrast function. The present work offers (1) a vectorial-based derivation of formulas that do not suffer from the arbitrary sign conventions found in some historical approaches; and (2) a simple algebraic kernel in line integrals as an alternative to the historical arctangent kernel, with the possibility of extension to more general cases. The concept of 2D vector gravity potential provides a useful tool for defining LIs systematically for any mass density function, helping us understand how dimensions can be reduced in a calculating gravity anomaly, especially when the density contrast varies with space. LIs have been tested in case studies. The maximum differences in calculated gravity anomalies by different LIs for the case studies were between [Formula: see text] and [Formula: see text]. Processing time required per station per segment of the 2D polygon of a 2D mass using LIs is [Formula: see text] on a Dell Optiplex GX 620 desktop computer, almost independent of the density function. The results indicate that the two types of LIs provide very fast, efficient, and reliable algorithms in gravity modeling or inversion for various types of density-contrast functions.

scholarly journals Implementation of Two-point Quadrature Gauss-Legendre Method on 2D Gravity Anomaly Modeling in Basins with Density Distribution Varied Polynomially as a Function of Depth

2018 ◽  
Vol 16 (2) ◽  
pp. 11
Author(s):  
Wahyu Srigutomo ◽  
Sesri Santurima ◽  
Cahyo Aji Hapsoro ◽  
Hairil Anwar ◽  
I Gede Putu Fadjar Soerya Djaja
Keyword(s):  
Density Distribution ◽  
Gravity Anomaly ◽  
Surface Topography ◽  
2D Gravity ◽  
Gravity Anomalies ◽  
Density Contrast ◽  
Quadrature Method ◽  
Gravity Method ◽  
Basin Geometry ◽  
Legendre Quadrature

Study of basin geometry basin is important in geosciences and geophysical exploration. Gravity method can be used to address this issue by measuring gravity anomalies on the surface caused by density contrast between the bedrock and the sediment that fills the basin, geometry of the basin and surface topography. Numerically, gravity anomaly modeling can be conducted using two-point rule Gauss-Legendre Quadrature method, for a case where density contrast varies with depth exponentially. Within the scope of this study, gravity anomalies on the surface are significantly affected by the geometry of the curvature of the bedrock as well as the topographic elevation of the surface and the selected density contrast, and are not significantly affected by the undulation of the bedrock curvature.  

scholarly journals Gravity modeling of the Alpine lithosphere affected by magmatism based on seismic tomography

Solid Earth ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 539-561
Author(s):  
Davide Tadiello ◽  
Carla Braitenberg
Keyword(s):  
Density Distribution ◽  
Gravity Anomaly ◽  
Seismic Tomography ◽  
Gravity Modeling ◽  
Tauern Window ◽  
Density Anomaly ◽  
Alpine Regions ◽  
Alpine Zone ◽  
Magmatic Underplating ◽  
Density Values

Abstract. The southern Alpine regions were affected by several magmatic and volcanic events between the Paleozoic and the Tertiary. This activity undoubtedly had an important effect on the density distribution and structural setting at lithosphere scale. Here the gravity field has been used to create a 3D lithosphere density model on the basis of a high-resolution seismic tomography model. The results of the gravity modeling demonstrate a highly complex density distribution in good agreement with the different geological domains of the Alpine area represented by the European Plate, the Adriatic Plate and the Tyrrhenian basin. The Adriatic-derived terrains (Southalpine and Austroalpine) of the Alps are typically denser (2850 kg m−3), whilst the Alpine zone, composed of terrains of European provenance (Helvetic and Tauern Window), presents lower density values (2750 kg m−3). Inside the Southalpine, south of the Dolomites, a well-known positive gravity anomaly is present, and one of the aims of this work was to investigate the source of this anomaly that has not yet been explained. The modeled density suggests that the anomaly is related to two different sources; the first involves the middle crust below the gravity anomaly and is represented by localized mushroom-shaped bodies interpreted as magmatic intrusions, while a second wider density anomaly affects the lower crust of the southern Alpine realm and could correspond to a mafic and ultramafic magmatic underplating (gabbros and related cumulates) developed during Paleozoic extension.

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