On predicting mantle mushroom plumes

Tan, Ka Kheng; Thorpe, Rex B.; Zhao, Zhidan

doi:10.1016/j.gsf.2011.03.001

Cited by 8 publications

(7 citation statements)

References 102 publications

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“…The intruded area around the Walvis Ridge is surprisingly small in comparison to the oftencited diameters of plume heads, between 800 and 2000 km based on the regional extent of flood basalt volcanism (White and McKenzie, 1989) and theoretical calculations (Tan et al, 2011). However, the exact location of the hotspot during breakup is crucial for the interpretation of our results: a distant location could account for the relatively limited intruded area.…”

Section: Discussionmentioning

confidence: 65%

South Atlantic opening: A plume-induced breakup?

Fromm

Planert

Jokat

et al. 2015

Geology

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Upwelling hot mantle plumes are thought to disintegrate continental lithosphere and are considered to be drivers of active continental breakup. The formation of the Walvis Ridge during the opening of the South Atlantic is related to a putative plume-induced breakup. We investigated the crustal structure of the Walvis Ridge (southeast Atlantic Ocean) at its intersection with the continental margin and searched for anomalies related to the possible plume head. The overall structure we identify suggests that no broad plume head existed during opening of the South Atlantic and anomalous mantle melting occurred only locally. We therefore question the importance of a plume head as a driver of continental breakup and further speculate that the hotspot was present before the rifting, leaving a track of kimberlites in the African craton.

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Section: Discussionmentioning

confidence: 65%

South Atlantic opening: A plume-induced breakup?

Fromm

Planert

Jokat

et al. 2015

Geology

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“…Based on the distribution of surface volcanism, White et al (1987) estimated a diameter of 1000-2000 km for a plume head, while laboratory experiments and modelling of Griffiths and Campbell (1990) suggested 2000-2500 km. Theoretical analysis based on mantle heat flux and viscosity led Tan et al (2011) to calculate that the flattened plume might affect the lithosphere over a distance of 1173-1842 km centred on the plume conduit. However, such large structures have never been detected in seismic tomography of the lithosphere-asthenosphere boundary.…”

Section: Indications For a Plume Head?mentioning

confidence: 99%

The onset of Walvis Ridge: Plume influence at the continental margin

et al. 2017

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The opening of the South Atlantic is a classical example for a plume related continental breakup. Flood basalts are present on both conjugate margins as well as aseismic ridges connecting them with the current plume location at Tristan da Cunha. To determine the effect of the proposed plume head on the continental crust, we acquired wide-angle seismic data at the junction of the Walvis Ridge with the African continent and modelled the Pwave velocity structure in a forward approach. The profile extends 430 km along the ridge and continues onshore to a length of 720 km. Crustal velocities beneath the Walvis Ridge vary between 5.5 km/s and 7.0 km/s, a typical range for oceanic crust. The crustal thickness of 22 km, however, is approximately three times larger than of normal oceanic crust. The continent-ocean transition is characterized by 30 km thick crust with strong lateral velocity variations in the upper crust and a high-velocity lower crust (HVLC), where velocities reach up to 7.5 km/s. The HVLC is 100 to 130 km wider at the Walvis Ridge than it is farther south, and impinges onto the continental crust of the Kaoko fold belt. Such high seismic velocities indicate Mg-rich igneous material intruded into the continental crust during the initial rifting stage. However, the remaining continental crust seems unaffected by intrusions and the root of the 40 km-thick crust of the Kaoko belt is not thermally abraded. We conclude that the plume head did not modify the continental crust on a large scale, but caused rather local effects. Thus, it seems unlikely that a plume drove or initiated the breakup process. We further propose that the plume already existed underneath the continent prior to the breakup, and ponded melt erupted at emerging rift structures providing the magma for continental flood basalts.

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“…In the realm of Nature, astrophysical flows (on planetary and galactic scales) involve compressible variable density (VD) effects [9,10]. In geophysics, density changes due to variations in temperature and salinity are known to drive ocean flows [11]; changes in moisture (which affect the density) drive atmospheric flows [12,13]; and thermal abnormalities in the earth's crust lead to mantle plumes [14] which result in volcanic island formation [15]. Together with the shear-driven Kelvin-Helmholtz instability (KHI) [16,17] and the shock-driven Ritchmyer-Meshkov instability (RMI) [18,19], the accelerationdriven RTI [1,2] are some of the most fundamental but still open problems in fluid mechanics [20].…”

Section: Introductionmentioning

confidence: 99%

Rayleigh-Taylor Instability: A Status Review of Experimental Designs and Measurement Diagnostics

Banerjee

2020

Journal of Fluids Engineering

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The focus of experiments and the sophistication of diagnostics employed in Rayleigh Taylor Instability (RTI) induced mixing studies have evolved considerably over the past seven decades. The first theoretical analysis by Taylor and experimental results by Lewis on RTI in 1950 examined two-dimensional, single-mode RTI using conventional photographic techniques. Over the next 70 years, several experimental designs have been used to creating an RTI unstable interface between two materials of different densities. These early experiments though innovative, were arduous to diagnose and provided little information on the internal, turbulent structure and initial conditions of the RT mixing layer. Coupled with the availability of high-fidelity diagnostics, the experiments designed and developed in the last three decades allow detailed measurements of various turbulence statistics that have allowed broadly to validate and verify late-time non-linear models and mix-models for buoyancy-driven flows. Besides, they have provided valuable insights to solve several long-standing disagreements in the field. This review serves as an opportunity to discuss the understanding of the RTI problem and highlight valuable insights gained into the RTI driven mixing process through experiments. For the current review, the focus is on low to high Atwood number (> 0.1) experiments.

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On predicting mantle mushroom plumes

Cited by 8 publications

References 102 publications

South Atlantic opening: A plume-induced breakup?

South Atlantic opening: A plume-induced breakup?

The onset of Walvis Ridge: Plume influence at the continental margin

Rayleigh-Taylor Instability: A Status Review of Experimental Designs and Measurement Diagnostics

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