Subcontinental mantle plume impact and kimberlite genesis

Le résumé fourni par la source

The general concensus of recent theoretical and petrological studies is that the genesis of kimberlites and associated alkaline igneous rocks is related to the presence of anomalously high potential temperatures in the underlying convecting mantle (e.g.Le Roex, 1986;McKenzie, 1989;Haggerty, 1994; Gibson et al., 1995a).The impact of a mantle plume on the base of the lithosphere is believed to affect a region up to 2500 km in diameter but the composition and location of the associated melts may vary according to the thickness of the overlying lithosphere.Anhydrous decompression melting of the plume head and the genesis of basaltic magmas will only occur beneath lithosphere of about <120 km.In regions of thicker lithosphere the plume may be volumetrically less significant as a melt source, but may be responsible for transferring heat by conduction or advection in very small-fraction melts.This may initiate melting of readily-fusible Krich parts of the overlying lithospheric mantle.As a result, plume-related magmas emplaced in former mobile belts and cratons are often relatively small-volume and rich in K (e.g.kimberlites, lamproites, kamafugites and minettes).

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.