Gravity Maps of the Lithospheric Structure Beneath the Indian Ocean

Rathnayake, Samurdhika; Tenzer, Robert; Eshagh, Mehdi; Pitoňák, Martin

doi:10.1007/s10712-019-09564-6

Cited by 6 publications

(3 citation statements)

References 206 publications

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“…To study the upper mantle structure, it is essential to isolate the gravity effects due to anomalous density distribution in the upper mantle (e.g., Kaban et al., 2014, 2016; Liang et al., 2019; Rathnayake et al., 2019). The mantle gravity disturbance is calculated as

\delta {g}_{M}={g}_{ob}-\gamma -{g}_{t}-{g}_{s}-{g}_{c}-{g}_{\mathit{moho}},

where g ob is the observed gravity data, γ is the normal gravity, g t is the gravity effect due to global topographic rocks, ocean water, and ice sheets, g s is the gravity effect due to sedimentary layers, g c is the gravity effect due to crystalline layers, and g moho is the gravity effect produced by the Moho undulation.…”

Section: Application To the Tibetan Plateaumentioning

confidence: 99%

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Constrained Gravity Inversion With Adaptive Inversion Grid Refinement in Spherical Coordinates and Its Application to Mantle Structure Beneath Tibetan Plateau

et al. 2022

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We develop a novel gravity inversion algorithm in spherical coordinates based on adaptive inversion mesh refinement and multiphysical parameter constraints. The inversion mesh is discretized into tesseroids (spherical prisms) to take the curvature of the Earth into account. To reduce the number of unknowns and computational cost, the inversion mesh is adaptively refined according to the spatial variation of parameters at each iteration. Wavelet compression is used to further reduce the computational requirement. Besides, to alleviate the nonuniqueness of inversion, the algorithm is capable of incorporating a priori models from other geophysical methods via cross‐gradient coupling and/or direct parameter coupling. For cross‐gradient coupling, the vector product of spatial gradients of two model parameters is included in the objective function. For direct parameter coupling, an a priori model is converted to a density model using the relation between two physical properties, which is then used as the initial and reference model in the inversion. A synthetic example is presented to demonstrate the effectiveness of our inversion method. Finally, we invert the gravity data over the Tibetan Plateau to obtain the density variations in the upper mantle, with a global S wave tomographic model used as a constraint. The inversion model shows that the mantle lithosphere beneath the Himalayan collision zone varies from west to east. Low‐density anomalies are observed beneath the southern and the northern Tibetan Plateau, which are consistent with published low‐velocity anomalies and magmatism distributions, possibly indicating two asthenospheric upwellings.

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\delta {g}_{M}={g}_{ob}-\gamma -{g}_{t}-{g}_{s}-{g}_{c}-{g}_{\mathit{moho}},

Section: Application To the Tibetan Plateaumentioning

confidence: 99%

“…To study the upper mantle structure, it is essential to isolate the gravity effects due to anomalous density distribution in the upper mantle (e.g., Kaban et al, 2014Kaban et al, , 2016Liang et al, 2019;Rathnayake et al, 2019). The mantle gravity disturbance is calculated as…”

Section: Datamentioning

confidence: 99%

Constrained Gravity Inversion With Adaptive Inversion Grid Refinement in Spherical Coordinates and Its Application to Mantle Structure Beneath Tibetan Plateau

et al. 2022

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“…In gravimetric studies of the Earth's interior, gravitational, topographic, bathymetric, and ice thickness models together with additional geophysical and geological information are typically used to investigate the lithospheric structure (e.g., [18][19][20][21][22][23][24][25][26]). To study structures deeper in the mantle, long-wavelength geoidal undulations are more suitable for this purpose ( [27]).…”

Section: Introductionmentioning

confidence: 99%

A Comparison of Gravimetric, Isostatic, and Spectral Decomposition Methods for a Possible Enhancement of the Mantle Signature in the Long-Wavelength Geoidal Geometry

Tenzer,

Chen

2023

Remote Sensing

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A long-wavelength geoidal geometry characterizes the most pronounced features of the Indian Ocean geoid low and the West Pacific and North Atlantic geoid highs. These large geoid undulations (globally roughly within ±100 m) are mainly attributed to a deep mantle structure and large lithospheric density and geometry variations (such as the African superswell), while maximum geoid modifications by a topographic relief of Himalaya and Tibet are up to ~30 m. To enhance the mantle signature in a long-wavelength geoidal geometry, gravimetric, isostatic, and spectral decomposition methods can be applied. In this study, we demonstrate that isostatic schemes yield isostatic geoid models that closely resemble a long-wavelength geoidal geometry. The gravimetric method, on the other hand, modifies the mantle geoid significantly. Further modifications of the mantle geoid by removing gravitational contributions of lithospheric mantle density and lithospheric thickness variations should (optimally) enhance the signature of the deep mantle in the sub-lithospheric mantle geoid. Our results confirm this assumption by revealing (large-scale) positive anomalies in the Central Pacific and along the Atlantic Ocean that are coupled by two negative anomalies in the East Pacific and South Eurasia. A gravimetric method thus better enhances the mantle signature in the geoidal geometry than isostatic and spatial decomposition methods. Nonetheless, our results also indicate the presence of possibly large errors in geoid modelling results that limit their full implementation in gravimetric studies of the Earth’s mantle density structure without using tomographic images of the mantle and additional geophysical, geothermal, and geochemical constraints.

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Comparison of Different Methods for a Moho Modeling Under Oceans and Marginal Seas: A Case Study for the Indian Ocean

et al. 2021

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Gravity Maps of the Lithospheric Structure Beneath the Indian Ocean

Cited by 6 publications

References 206 publications

Constrained Gravity Inversion With Adaptive Inversion Grid Refinement in Spherical Coordinates and Its Application to Mantle Structure Beneath Tibetan Plateau

Constrained Gravity Inversion With Adaptive Inversion Grid Refinement in Spherical Coordinates and Its Application to Mantle Structure Beneath Tibetan Plateau

A Comparison of Gravimetric, Isostatic, and Spectral Decomposition Methods for a Possible Enhancement of the Mantle Signature in the Long-Wavelength Geoidal Geometry

Comparison of Different Methods for a Moho Modeling Under Oceans and Marginal Seas: A Case Study for the Indian Ocean

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