Longevity of sub-continental mantle lithosphere from osmium isotope systematics in orogenic peridotite massifs

Article Abstract:

A linear relationship is seen between the concentrations of 187 Osmium/188 Osmium isotopes and Al2O3 present in the orogenic peridotite massifs, Ronda Ultramafic Complex from southern Spain and eastern Pyrenean peridotites. This linear relationship cannot explained by partitioning of similar melt/residue probably because Re concentrations can be influenced by metasomatism. Slices of the upper crust which are tectonically emplaced into the crust form these orogenic peridotite massifs. The results of this study show that the sub-continental lithosphere mantle was probably stabilized by a magnetic event or a series of events occurring in a short span of time rather than asthenosphere cooling.

Earth, Isotopes, Osmium, Mantle (Geology)

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Rapid diffusive infiltration of sodium into partially molten peridotite

Article Abstract:

It is suggested that as mantle peridotite melts, the resulting basaltic liquid forms a linked network resulting in the rapid ascent of basalt. It is shown that sodium in ascending melts quickly diffuse into felts formed in peridotites at lower pressures. This changes the way in which the peridotite melts and may account for the creation of silica-rich glass inclusions in mantle xenoliths and melting modes recorded by abyssal peridotites.

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The remelting of hydrothermally altered peridotite at mid-ocean ridges by intruding mantle diapirs

Article Abstract:

The fractional crystallization of melts with the composition od mid-ocean ridge basalt (MORB) are thought to have generated most gabbroic cumulates found at ocean spreading centres. However some cumulates have come from melts containing more silica than MORB. In a fossil mantle diapir of the Oman ophilite, a dichotomy between a suite of normal, MORB-type, cumulates and a suite of cumulates from silica enriched melts, has been observed.

Mid-ocean ridges

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