Crustal structure and Moho topography of the southern part (18° S–25° S) of Central Indian Ridge using high-resolution EIGEN6C4 global gravity model data

2021 ◽  
Vol 41 (1) ◽  
Author(s):  
Soumyashree Debasis Sahoo ◽  
Sanjit Kumar Pal
Keyword(s):  
High Resolution ◽  
Gravity Model ◽  
Crustal Structure ◽  
Model Data ◽  
Central Indian Ridge ◽  
Global Gravity ◽  
Indian Ridge ◽  
Global Gravity Model

scholarly journals The Impact of Noise in a GRACE/GOCE Global Gravity Model on a Local Quasi‐Geoid

2019 ◽  
Vol 124 (3) ◽  
pp. 3219-3237 ◽  
Author(s):  
Cornelis Slobbe ◽  
Roland Klees ◽  
Hassan H. Farahani ◽  
Lennard Huisman ◽  
Bas Alberts ◽  
...  
Keyword(s):  
Gravity Model ◽  
Global Gravity ◽  
The Impact ◽  
Global Gravity Model

scholarly journals Generalized geoidal estimators for deterministic modifications of spherical Stokes' function

2010 ◽  
Vol 40 (1) ◽  
pp. 45-64 ◽  
Author(s):  
Michal Šprlák
Keyword(s):  
Gravity Model ◽  
Spherical Harmonic ◽  
Gravity Data ◽  
Surface Integral ◽  
Terrestrial Gravity ◽  
Global Gravity ◽  
Higher Derivatives ◽  
Stokes Integral ◽  
Global Gravity Model ◽  
Local Geoid

Generalized geoidal estimators for deterministic modifications of spherical Stokes' function Stokes' integral, representing a surface integral from the product of terrestrial gravity data and spherical Stokes' function, is the theoretical basis for the modelling of the local geoid. For the practical determination of the local geoid, due to restricted knowledge and availability of terrestrial gravity data, this has to be combined with the global gravity model. In addition, the maximum degree and order of spherical harmonic coefficients in the global gravity model is finite. Therefore, modifications of spherical Stokes' function are used to obtain faster convergence of the spherical harmonic expansion. Decomposition of Stokes' integral and modifications of Stokes' function have been studied by many geodesists. In this paper, the proposed deterministic modifications of spherical Stokes' function are generalized. Moreover, generalized geoidal estimators, when the Stokes' integral is decomposed in to spectral and frequency domains, are introduced. Higher derivatives of spherical Stokes' function and their numerical stability are discussed. Filtering and convergence properties for deterministic modifications of the spherical Stokes' function in the form of a remainder of the Taylor polynomial are studied as well.

Investigation into the influence of the Réunion plume on the Central Indian Ridge

2020 ◽  
Author(s):  
Clément Vincent ◽  
Jung-Woo Park ◽  
Sang-Mook Lee ◽  
Jonguk Kim ◽  
Sang-Joon Pak
Keyword(s):  
High Resolution ◽  
Leading Edge ◽  
Middle Part ◽  
Geochemical Data ◽  
Long Distance ◽  
Transform Faults ◽  
Central Indian Ridge ◽  
Mid Ocean Ridge ◽  
Indian Ridge ◽  
Ocean Ridge

<p>Plume-ridge interaction is an important thermal and geological process, which results in various physical and chemical anomalies along a significant length of the global mid-ocean ridge system. Despite numerous studies, some remaining questions to be solved are the origin and mechanisms of geochemical variations and their possible correlation with the morphology of mid-ocean ridges.</p><p>The Central Indian Ridge, with a slow to intermediate spreading rate, provides an ideal opportunity to explore the long-distance plume-ridge interactions. Presently, the ridge is moving away from the Réunion hotspot which is located 1000 km away from the Central Indian Ridge at Réunion Island. Paleogeographic reconstruction suggests that the hotspot crossed the middle part of the Central Indian Ridge (MCIR) between 8°S and 17°S at ~34 Ma. Previous studies argue that the plume material currently flows into the Central Indian Ridge at around 19°S, south of Marie Celeste Fracture Zone (MCFZ) and geochemical enrichments of the mid-ocean ridge basalts (MORB) from the MCIR 14°S and 19°S segments can be attributed to a fossil Réunion plume component. However, a recent geophysical study has suggested that the geochemical anomalies along the Rodrigues segment (18-21°S) can be ascribed to the asthenospheric flow from the Réunion plume, reopening the debate about the origin of the enriched anomalies along the MCIR (14-19°S).</p><p>In this study, we revisited the MCIR from 14°S to 17°S with new geochemical data obtained based on high-resolution sampling and ship-board high-resolution bathymetry data to constrain the influence of the Réunion plume on geochemistry and bathymetry of the MCIR. The results show that trace element ratios and isotopic compositions of on-axis MORB vary in association with ridge discontinuities such as transform faults and non-transform fault discontinuities. The MORB from the northern parts of segments display substantially enriched geochemical features and the enrichments correspond to a shallower axial bathymetry. We attribute the chemical and morphological anomalies along the ridge to the influence of a Réunion plume component focussed by a hotspot leading edge effect. The hotspot leading segments are offset in the direction of the plume and are more efficiently affected by the enriched plume materials. These findings suggest that lithospheric discontinuities such as transform faults and fracture zones may control the flow of mantle plume material into the ridge and the geometry of the ridge coupled to its hotspot proximity may play an important role, particularly in the long-distance plume-ridge interaction.</p>

Joint estimation of gravity anomalies using second and third order potential derivatives

2019 ◽  
Author(s):  
Mohsen Romeshkani ◽  
Mohammad A Sharifi ◽  
Dimitrios Tsoulis
Keyword(s):  
Gravity Field ◽  
Gravity Model ◽  
Variance Component ◽  
Gravity Anomalies ◽  
Variance Component Estimation ◽  
Third Order ◽  
Global Gravity ◽  
Isostatic Gravity ◽  
Component Estimation ◽  
Global Gravity Model

Abstract Satellite gradiometry data provide the framework for estimating and validating Earth's gravity field from second and third order derivatives of the Earth's gravitational potential. Such procedures are especially useful when applied locally, as they relate to local and regional characteristics of the real gravity field. In the present study a joint inversion procedure is proposed for the estimation of gravity anomalies at sea surface level from second and third order potential derivatives, based on a standard Gauss-Markov estimation model. The estimation procedure is applied for a test area stretching over Iran involving simulated grids from GOCE-only model GGM_TIM_R05 at GOCE altitude and gravity anomalies recovered at sea level. In order to validate the proposed estimation three different reductions have been considered independently, namely the removal of the long-wavelength part of the observed field through a global gravity model, the removal of the high-frequency part of the field through the incorporation of a topographic/isostatic gravity model and the application of variance component estimation. The application of a global gravity model leads to an improvement in the individual component estimation of the order of magnitude 3 per cent to 73 per cent, with a significant reduction in bias to 4 mGal. Smoother gradient components can come out according to removing the topography and taking into account for isostasy that improved up results of recovery to 25 per cent for the radial second order derivative. Finally, the implementation of variance component estimation leads to no significant improvement in results of recovered gravity anomalies.

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