Publication Date:
2008-05-29
Description:
The Archaean to Palaeoproterozoic Khanfous area from the Archaean In Ouzzal granulite terrane (Western Hoggar, Algeria) preserves exceptional thermal-peak (1150〈T 〈 1300 {degrees}C) mineral parageneses, consisting of orthopyroxene+spinel+quartz, sapphirine+spinel+quartz and sapphirine+orthopyroxene+quartz, in quartz-rich Al-Mg granulites. Reaction textures coupled with P-T FMASH pseudosections indicate that rocks experienced complex multi-stage evolution. Our results suggest that the Khanfous area, as well as the entire northern In Ouzzal metacraton, experienced ultrahigh-temperature crustal metamorphism attributed to a 2 Ga Palaeoproterozoic event, followed by exhumation along a clockwise P-T path. The extreme temperatures attained suggest delamination of the lithosphere and ascent of the asthenosphere after crustal thickening.
Permalink