Jun Korenaga

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Editor: T.M. Harrison Non-arc basalts of Archean and Proterozoic age have model primary magmas that exhibit mantle potential temperatures TP that increase from 1350 °C at the present to a maximum of ∼1500–1600 °C at 2.5–3.0 Ga. The overall trend of these temperatures converges smoothly to that of the present-day MORB source, supporting the interpretation(More)
Possible geodynamic regimes that may have prevailed in the Archean are investigated by back-tracking the thermal history of Earth from the present-day conditions. If the temporal evolution of plate-tectonic convection is modulated by strong depleted lithosphere created at mid-ocean ridges, more sluggish plate tectonics is predicted when the mantle was(More)
[1] The development of transient thermal stress in suboceanic mantle is investigated on the basis of two-dimensional thermoviscoelastic models incorporating composite rheology appropriate for dry oceanic lithosphere. Thermal stress is shown to be sufficiently high to deeply fracture the coldest part of lithosphere, e.g., to the depth of at least 30 km (and(More)
[1] We present a new statistical method to construct a model for the chemical composition of Earth’s primitive mantle along with its variance. Earth’s primitive mantle is located on the melting trend exhibited by the global compilation of mantle peridotites, using cosmochemical constraints on the relative abundances of refractory lithophile elements (RLE).(More)
[1] We investigate the physics of multiscale convection in Earth’s mantle, characterized by the coexistence of large-scale mantle circulation associated with plate tectonics and small-scale sublithospheric convection. In this study, conditions for the existence of smallscale convection beneath oceanic lithosphere are investigated by deriving a scaling law(More)
High-MgO (s 8.5 wt%), aphyric lavas erupted at various locations in the North Atlantic igneous province are utilized to characterize the nature of mantle melting during the formation of this province. Based on the observation that the Ni concentration in residual mantle olivine mostly falls in the range of 2000^3500 ppm, these high-MgO samples are corrected(More)
[1] Reconstructing the thermal history of the Earth, consistent with the low concentration of heat-producing elements in convecting mantle as well as with modest secular cooling required by geological records, has been a major challenge in geophysics and geochemistry. By developing the self-consistent energetics of plate-tectonic mantle convection, we show(More)
Seafloor topography has been a key observational constraint on the thermal evolution of oceanic lithosphere, which is the top boundary layer of convection in Earth's mantle. At least for the first ~70 Myr, the age progression of seafloor depth is known to follow the prediction of half-space cooling, and the subsidence rate is commonly believed to be ~350 m(More)