On the deep-mantle origin of the Deccan Traps

Glišović, P.; Forte, A. M.

doi:10.1126/science.aah4390

Cited by 47 publications

(49 citation statements)

References 29 publications

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“…Earlier, a model of shallow mantle melting in which the preexisting rift zones were reactivated and magma simply poured out of the fissures was proposed (Chandrasekharam & Parthasarathy, ). However, the possibility of the center of the plume head residing at the junction of Cambay and Narmada rifts could be explained based on the hypothesis that heat is also conducted into the adjacent mantle (Cambay and Saurashtra) as the plume rises (Campbell, ), supported by the results from time reversed convection modelling (Glišović & Forte, ). The present study thus supports the theory proposed by White and McKenzie () and Campbell and Griffiths () that a mantle plume was mainly responsible for the widespread volcanic activity in northwestern India and the trace of the plume passed through the Cambay Basin to the gulf of Cambay (near the junction of Cambay and Narmada rifts).…”

Section: Discussionmentioning

confidence: 98%

“…:43°E at 67.5 Ma) northeast of the Reunion plume, which would have acted as a secondary source to the widespread Deccan flood basalt eruption. Globally, mantle plumes including the Reunion are seismically imaged in the form of low‐velocity conduits in the upper mantle (e.g., Glišović & Forte, ; Zhao, ). Consistent with the plume theory, we are able to recognize a prominent zone of low Vs in the upper mantle beneath the Cambay, Saurashtra, KSZ and along Western Ghats, down to a depth of 220 km (maximum depth of present investigation; Figures and ).…”

Section: Discussionmentioning

confidence: 99%

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Seismic Imprints of Plume‐Lithosphere Interaction Beneath the Northwestern Deccan Volcanic Province

et al. 2018

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The interaction of the Indian continental lithosphere with the Reunion plume resulted in massive outpouring of basalts manifested in the Deccan Volcanic Province. Although it is postulated that preexisting weak rift zones facilitated the eruption, deeper signatures of the plume remain contentious. In this study, we investigate the shear wave velocity (Vs) structure of the crust and upper mantle by inverting regionalized group velocity dispersion data in the period range of 6 to 100 s, down to 220 km depth, using the genetic algorithm technique. We used 1,286 dispersion curves derived from waveforms of 77 regional earthquakes recorded at 38 broadband stations. Our results reveal distinct intracrustal layers, Moho, mantle lid, and asthenospheric low‐velocity layer. Signatures of magmatic underplating are recognized in terms of high Vs and a thick crust beneath the Kutch seismic zone and Western Ghats. The lithospheric thickness varies from 80 to 124 km, being thinnest at the junction of Cambay and Narmada rifts, which could be the source zone of volcanic eruption. A thin lithosphere has also been observed beneath the Kutch seismic zone. A low‐velocity zone at depths ~80 km can be related with upwarping of the asthenosphere and/or presence of partial melts. A predominant low‐velocity zone beneath the Cambay, Saurashtra, and adjoining regions may be due to the effect of a residual thermal anomaly. A thin lithosphere beneath northwestern Deccan Volcanic Province could be the result of weakening due to plume‐lithosphere interaction, which facilitated volcanism through preexisting rift zones.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Seismic Imprints of Plume‐Lithosphere Interaction Beneath the Northwestern Deccan Volcanic Province

et al. 2018

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“…It has recently been proposed by Glišović and Forte []—who reconstruct large‐scale plume and mantle structures in the past based on present‐day seismic tomography in contrast to the forward modeling approach and much higher resolved plume in this study (due to a considerably smaller model domain and the adaptive mesh refinement)—that the northern part of the Deccan Traps was generated by an additional unrecognized plume underneath the Comoros. Since this study is not designed to handle melting in continental environments, a second plume beneath India around 65 Ma would likely result in additional flow toward thinner oceanic lithosphere (regardless of a correct plume timing and position as discussed above).…”

Section: Discussionmentioning

confidence: 99%

How plume‐ridge interaction shapes the crustal thickness pattern of the Réunion hotspot track

Bredow

Steinberger

Gassmöller

et al. 2017

Geochem Geophys Geosyst

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The Réunion mantle plume has shaped a large area of the Earth's surface over the past 65 million years: from the Deccan Traps in India along the hotspot track comprising the island chains of the Laccadives, Maldives, and Chagos Bank on the Indian plate and the Mascarene Plateau on the African plate up to the currently active volcanism at La Réunion Island. This study addresses the question how the Réunion plume, especially in interaction with the Central Indian Ridge, created the complex crustal thickness pattern of the hotspot track. For this purpose, the mantle convection code ASPECT was used to design three‐dimensional numerical models, which consider the specific location of the plume underneath moving plates and surrounded by large‐scale mantle flow. The results show the crustal thickness pattern produced by the plume, which altogether agrees well with topographic maps. Especially two features are consistently reproduced by the models: the distinctive gap in the hotspot track between the Maldives and Chagos is created by the combination of the ridge geometry and plume‐ridge interaction; and the Rodrigues Ridge, a narrow crustal structure which connects the hotspot track and the Central Indian Ridge, appears as the surface expression of a long‐distance sublithospheric flow channel. This study therefore provides further insight how small‐scale surface features are generated by the complex interplay between mantle and lithospheric processes.

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“…A best fit between observational and model fields is then sought by minimising the regularisation parameter. Glišović & Forte (2014) and Glišović & Forte (2017) utilise this technique in global models to investigate regional evolution dynamics over the previous 70 Myr. In Glišović & Forte (2014), the QRV method is tested on a known data source, with the accuracy of the QRV predictions observed to begin falling away beyond 45 Myr.…”

Section: Discussionmentioning

confidence: 99%

“…The error levels up to 70 Ma are determined to be acceptable however, allowing the authors to investigate the evolution of Earth over the entire Cenozoic. In Glišović & Forte (2017) the QRV method is applied to observational data to investigate the evolution of upwellings in the Indian ocean. With the time intervals over which these QRV studies can reliably be calculated over falling broadly in line with the results shown here, choosing either the adjoint or QRV method can be argued from both sides.…”

Section: Discussionmentioning

confidence: 99%

Profiling the robustness, efficiency and limits of the forward-adjoint method for 3-D mantle convection modelling

Price¹,

Davies²

2017

Geophysical Journal International

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SUMMARYKnowledge of Earth's past mantle structure is inherently unknown. This lack of knowledge presents problems in many areas of Earth science, including in mantle circulation modelling (MCM). As a mathematical model of mantle convection, MCM's require boundary and initial conditions. While boundary conditions are readily available from sources such as plate reconstructions for the upper surface, and as free slip at the core-mantle boundary (CMB), the initial condition is not known. MCM's have historically 'created' an initial condition using long 'spin up' processes using the oldest available plate reconstruction period available. Whilst these do yield good results when models are run to present day, it is difficult to infer with confidence results from early in a model's history. Techniques to overcome this problem are now being studied in geodynamics, such as by assimilating the known internal structure (e.g. from seismic tomography) of Earth at present day backwards in time. One such method is to use an iterative process known as the forward-adjoint method, which, while an efficient means of solving this inverse problem still strains all but the most cutting edge computational systems. In this study we endeavour to profile the effectiveness of this method using synthetic test cases as our known data source. We conclude that savings in terms of computational expense for forwardadjoint models can be achieved by streamlining the time-stepping of the calculation, as well as determining the most efficient method of updating initial conditions in the iterative scheme. Furthermore we observe that in the models presented, there exists an upper limit on the time interval over which solutions will practically converge, although this limit is likely to be linked to Rayleigh number.

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On the deep-mantle origin of the Deccan Traps

Cited by 47 publications

References 29 publications

Seismic Imprints of Plume‐Lithosphere Interaction Beneath the Northwestern Deccan Volcanic Province

Seismic Imprints of Plume‐Lithosphere Interaction Beneath the Northwestern Deccan Volcanic Province

How plume‐ridge interaction shapes the crustal thickness pattern of the Réunion hotspot track

Profiling the robustness, efficiency and limits of the forward-adjoint method for 3-D mantle convection modelling

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