Mantle heterogeneity and off axis volcanism on young Pacific lithosphere

Harmon, Nicholas; Forsyth, Donald W.; Weeraratne, D. S.; Webb, Spahr C.; Yang, Yue-Tzu

doi:10.1016/j.epsl.2011.09.038

Cited by 44 publications

(42 citation statements)

References 56 publications

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“…Frictional heating due to shear and heat transfer at the base of the transition zone would create a thermal anomaly at depth which would then form the base of an upwelling limb of the convection cell. Evidence has been found for similar, but shallower, convection cells have been found beneath linear volcanic chains without age progression west of the East Pacific Rise [Harmon et al, 2011]. Harmon et al [2011] found evidence that these convection cells were associated with both partial melt and a thermal anomaly.…”

Section: 1002/2014jb011580mentioning

confidence: 52%

“…Evidence has been found for similar, but shallower, convection cells have been found beneath linear volcanic chains without age progression west of the East Pacific Rise [Harmon et al, 2011]. Harmon et al [2011] found evidence that these convection cells were associated with both partial melt and a thermal anomaly. In this study, we observe a low velocity zone that is pronounced down to 200 km depth.…”

Section: 1002/2014jb011580mentioning

confidence: 52%

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Lithospheric instability and the source of the Cameroon Volcanic Line: Evidence from Rayleigh wave phase velocity tomography

et al. 2015

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The Cameroon Volcanic Line (CVL) is a 1800 km long volcanic chain, extending SW-NE from the Gulf of Guinea into Central Africa, that lacks the typical age progression exhibited by hot spot-related volcanic tracks. This study investigates the upper mantle seismic structure beneath the CVL and surrounding regions to constrain the origin of volcanic lines that are poorly described by the classic plume model. Rayleigh wave phase velocities are measured at periods from 20 to 182 s following the two-plane wave methodology, using data from the Cameroon Seismic Experiment, which consists of 32 broadband stations deployed between 2005 and 2007. These phase velocities are then inverted to build a model of shear wave velocity structure in the upper mantle beneath the CVL. Results show that phase velocities beneath the CVL are reduced at all periods, with average velocities beneath the CVL deviating more than -2% from the regional average and +4% beneath the Congo Craton. This distinction is observed for all periods but is less pronounced for the longest periods measured. Inversion for shear wave velocity structure indicates a tabular low velocity anomaly directly beneath the CVL at depths of 50 to at least 200 km and a sharp vertical boundary with faster velocities beneath the Congo Craton. These observations demonstrate widespread infiltration or erosion of the continental lithosphere beneath the CVL, most likely caused by mantle upwelling associated with edge-flow convection driven by the Congo Craton or by lithospheric instabilities that develop due to the nearby edge of the African continent.

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Section: 1002/2014jb011580mentioning

confidence: 52%

Section: 1002/2014jb011580mentioning

confidence: 52%

Lithospheric instability and the source of the Cameroon Volcanic Line: Evidence from Rayleigh wave phase velocity tomography

et al. 2015

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“…This discrepancy is probably caused by different geometry for deformation experiments. The cylindrical piston cut at an angle (Hashin and Shtrikman, 1962); EM, effective medium theory (Landauer, 1952); and GM, geometrical mean model (Shankland and Duba, 1990). of 90 • in this study, whereas the cut angle was 45 • in most previous studies. As a result, nearly simple shear was applied for our deformed samples.…”

Section: Melt Topologymentioning

confidence: 66%

Electrical conductivity anisotropy in partially molten peridotite under shear deformation

Zhang

Yoshino

Yamazaki

et al. 2014

Earth and Planetary Science Letters

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“…Another important process at play below the Pacific lithosphere is small-scale or secondary convection which takes place at the base of the lithosphere, either in terms of Richter rolls, or viscous fingering. Some of these features have been detected at long wavelengths as low velocity or anisotropy channels (Montagner, 2002;Weeraratne et al, 2007;Harmon et al, 2011;French et al, 2013). How these underlying secondary convective processes might participate to the breakup of rigid plates is still an open question?…”

Section: Anisotropy At Different Depthsmentioning

confidence: 99%