[1] Satellite gravity inversion incorporating a lithosphere thermal gravity correction has been used to map crustal thickness and lithosphere thinning factor for the NE Atlantic. Predicted oceanic crustal thicknesses in the Norwegian Basin are between 4 and 7 km on the extinct Aegir Ridge, increasing to 9 – 14 km at the margins, consistent with volcanic margin continental breakup at the end of ...

Bulk-rock major and trace element geochemistry of a range of eclogite, garnet blueschist and garnet amphibolite rocks from northern New Caledonia has been determined in order to geochemically characterise subducted oceanic crust. The rocks experienced peak metamorphic conditions of 1.9 GPa and 600 jC and represent excellent samples of oceanic crust that was subducted to depths of approximately ...

There is growing evidence that the top part of the oceanic mantle is pervasively serpentinized prior to subduction. Because the interior of a subducting slab heats up slowly, the serpentinized layer can be preserved for tens of Myr, thereby forming a weak zone that allows for mechanical decoupling between the oceanic crust and underlying lithospheric mantle. Once the crust is eclogitized, a she...

Ophiolites are the remnants of ancient oceanic crust and upper mantle that were tectonically emplaced into continental margins. They display the only evidence for magmatic, tectonic, and hydrothermal processes associated with seafl oor spreading prior to 170 Ma because no oceanic lithosphere older than this age is preserved in the modern oceans. The occurrence of sheeted dikes, side-byside tabu...

The continental crust is 41.4 km thick on average and covers 39% of the Earth’s surface. Information from the isotopic and trace element composition of >4-billion-yearold (Ga) zircon grains and the evolution of mantle isotopic reservoirs indicates that 75%, and possibly more, of the continental crust was created before 2.5 Ga (Harrison 2009; Belousova et al. 2010). Thus, the continental crust i...

Much of the Earth's mantle was melted in the Moon-forming impact. Gases that were not partially soluble in the melt, such as water and CO2, formed a thick, deep atmosphere surrounding the post-impact Earth. This atmosphere was opaque to thermal radiation, allowing heat to escape to space only at the runaway greenhouse threshold of approximately 100 W m(-2). The duration of this runaway greenhou...

Much of the Earth’s mantle was melted in the Moon-forming impact. Gases that were not partially soluble in the melt, such as water and CO2, formed a thick, deep atmosphere surrounding the postimpact Earth. This atmosphere was opaque to thermal radiation, allowing heat to escape to space only at the runaway greenhouse threshold of approximately 100 W m−2. The duration of this runaway greenhouse ...