On the rise of strongly tilted mantle plume tails

Meriaux, Catherine Anne Marie Dominique; Mansour, John; Moresi, Louis; Kerr, Ross C.; May, David A.

doi:10.1016/j.pepi.2010.10.013

Cited by 6 publications

(7 citation statements)

References 25 publications

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“…Miller et al () interpret the localized volcanism and low velocity anomalies in the sub‐lithospheric mantle to be the result of the Canary Island plume flowing sub‐horizontally beneath the Atlas. This seismologically based interpretation is supported by numerical experiments of mantle flow that incorporate the effects of the stiff, deep West African cratonic keel and nearly vertical, narrow slab beneath the Alboran (Alpert et al, ), numerical experiments of strongly tilted plumes and resulting instabilities (Mériaux et al, ), and by scaled analogue models of the Alboran slab and Canary plume interaction (Mériaux et al, ). Other hypotheses explaining the Cenozoic uplift of the Atlas and the links to recent volcanism and to upper‐mantle structure include: lithospheric delamination (Bezada et al, ; Duggen et al, ; Levander et al, ) and edge‐driven convection (Kaislaniemi & van Hunen, ; Missenard & Cadoux, ).…”

Section: The Atlas Orogenmentioning

confidence: 91%

Crustal Structure of Active Deformation Zones in Africa: Implications for Global Crustal Processes

et al. 2017

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The Cenozoic East African rift (EAR), Cameroon Volcanic Line (CVL), and Atlas Mountains formed on the slow‐moving African continent, which last experienced orogeny during the Pan‐African. We synthesize primarily geophysical data to evaluate the role of magmatism in shaping Africa's crust. In young magmatic rift zones, melt and volatiles migrate from the asthenosphere to gas‐rich magma reservoirs at the Moho, altering crustal composition and reducing strength. Within the southernmost Eastern rift, the crust comprises ~20% new magmatic material ponded in the lower crust and intruded as sills and dikes at shallower depths. In the Main Ethiopian Rift, intrusions comprise 30% of the crust below axial zones of dike‐dominated extension. In the incipient rupture zones of the Afar rift, magma intrusions fed from crustal magma chambers beneath segment centers create new columns of mafic crust, as along slow‐spreading ridges. Our comparisons suggest that transitional crust, including seaward dipping sequences, is created as progressively smaller screens of continental crust are heated and weakened by magma intrusion into 15–20 km thick crust. In the 30 Ma Recent CVL, which lacks a hot spot age progression, extensional forces are small, inhibiting the creation and rise of magma into the crust. In the Atlas orogen, localized magmatism follows the strike of the Atlas Mountains from the Canary Islands hot spot toward the Alboran Sea. CVL and Atlas magmatism has had minimal impact on crustal structure. Our syntheses show that magma and volatiles are migrating from the asthenosphere through the plates, modifying rheology, and contributing significantly to global carbon and water fluxes.

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Section: The Atlas Orogenmentioning

confidence: 91%

Crustal Structure of Active Deformation Zones in Africa: Implications for Global Crustal Processes

et al. 2017

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“…We note that using the stokes velocity of a sphere (e.g. Mériaux et al 2011) or that of a tilted conduit (Happel & Brenner 1965;Skilbeck & Whitehead 1978) are similarly appropriate for estimating rise times, however, neither of these methods accounts for both the viscosity ratio and plume tilt that our results suggest are important for instability development. Additionally, we find that the velocity calculated using the method presented here exhibits the fastest rise times and the smallest range of viscosity ratios for instability development (e.g.…”

Section: Comparisons To Previous Workmentioning

confidence: 82%

“…Galapagos and St Helena) may have a tilt above 60 • (Steinberger 2000). However, even above this critical tilt, scaling analyses based upon numerical and laboratory studies suggest that plume conduits may remain stable under mantle conditions (Kerr et al 2008;Mériaux et al 2011). Yet, previous studies examining instability growth in tilting plumes used one or multiple simplifying assumptions such as constant or only temperature-dependent rheology, a simplified plume conduit geometry and a uniform mantle structure (e.g.…”

Section: Pulsing Of Tilted Plume Conduitsmentioning

confidence: 99%

“…Although early analogue models demonstrated diapir formation from instabilities in a tilted plume conduit (Whitehead 1982), later studies suggest that such instabilities will fail to form in thermal plumes under mantle conditions (Kerr et al 2008;Mériaux et al 2011). The primary arguments against instability formation in the mantle include: (1) thermal diffusion helps stabilize low Rayleigh number plumes (Kerr et al 2008) and ( 2) the theoretical growth rate of instabilities, in most cases, is larger than the time for material to rise through the upper mantle (Mériaux et al 2011). However, these previous studies examine the rise of horizontal cylinders of buoyant, less viscous material in an initially motionless 'mantle' with either constant or temperature dependent rheology.…”

Section: Comparisons To Previous Workmentioning

confidence: 99%

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Temporal variations in plume flux: characterizing pulsations from tilted plume conduits in a rheologically complex mantle

Neuharth

Mittelstaedt

2022

Geophysical Journal International

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Summary Along age-progressive hotspot volcano chains, the emplacement rate of igneous material varies through time. Time-series analysis of changing emplacement rates at a range of hotspots finds that these rates vary regularly at periods of a few to several tens of millions of years, indicative of changing melt production within underlying mantle plumes. Many hotspots exhibit at least one period between ∼2–10 Myr, consistent with several proposed mechanisms for changing near-surface plume flux, and thus melting rate, such as small-scale convection, solitary waves, and instability formation in tilted plume conduits. Here, we focus on quantifying instability growth within plumes tilted by overlying plate motion. Previous studies using fluids with constant or temperature-dependent viscosity suggest that such instabilities should not form under mantle conditions. To test this assertion, we use a modified version of the finite element code ASPECT to simulate 400 million years of evolution of a whole-depth mantle plume rising through the transition zone and spreading beneath a moving plate. In a two-dimensional spherical shell geometry, ASPECT solves the conservation equations for a compressible mantle with a thermodynamically consistent treatment of phase changes in the mantle transition zone and subject to either a temperature-, and depth-dependent linear rheology or a temperature-, depth-, and strain-rate dependent non-linear rheology. Additionally, we examine plume evolution in a mantle subject to a range of Clapeyron slopes for the 410 km (1 to 4 MPa/K) phase transitions. Results suggest that plume conduits tilted by > 67° become unstable and develop instabilities that lead to initial pulses in the transition zone followed by repeated plume pulsing in the uppermost mantle. In these cases, pulse size and frequency depend strongly on the viscosity ratio between the plume and ambient upper mantle. Based upon our results and comparison with other studies, we find that the range of statistically significant periods of plume pulsing in our models (∼2–6 Myr), the predicted increase in melt flux due to each pulse (5–15 × 10−4 km3 km−1 yr−1), and the time estimated for a plume to tilt beyond 67° in the upper mantle (10–50 Myr) are consistent with observations at numerous hotspot tracks across the globe. We suggest that pulsing due to destabilization of tilted plume conduits may be one of several mechanisms responsible for modulating the melting rate of mantle plumes as they spread beneath the moving lithosphere.

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“…The experiment was carried out in the Geodynamic Modelling Laboratory of the School of Earth, Atmosphere and Environment at Monash University. The Following chandrasekhar Chandrasekhar (1961), the amplitude A of the growing mode k should have a solution whose dependence on time t is exponential and, as given by Mériaux et al (2011) in appendix B, its form would follow…”

Section: Acknowledgmentsmentioning

confidence: 99%

Benchmark of three-dimensional numerical models of subduction against a laboratory experiment

Meriaux

May

Mansour

et al. 2018

Physics of the Earth and Planetary Interiors

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On the rise of strongly tilted mantle plume tails

Cited by 6 publications

References 25 publications

Crustal Structure of Active Deformation Zones in Africa: Implications for Global Crustal Processes

Crustal Structure of Active Deformation Zones in Africa: Implications for Global Crustal Processes

Temporal variations in plume flux: characterizing pulsations from tilted plume conduits in a rheologically complex mantle

Benchmark of three-dimensional numerical models of subduction against a laboratory experiment

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