Petrology of Megacrysts, Mafic and Ultramafic Xenoliths from the Pipe of Eglazines, Causses, France.

Lherzolite xenoliths in kimberlites and basalts: petrogenetic and crystallochemical significance of some minor and trace elements in olivine, pyroxenes, garnet and spinel

“…Figure 1 contains the following sets of data: filled hexagon (HGLK); small filled circle (CGLK); open square (SLB) without garnet; filled and empty triangles (SLK; spinelbearing ultramafic in kimberlite; mainly lherzolites; with and without a titanate); cross (Fe-rich dunite xenoliths in Bultfontein kimberlite interpreted as aggregated olivine megacrysts (Dawson et al 1981)); m (mean of small range of olivine megacrysts in Bultfontein kimberlite (Dawson et al 1981)); d (inclusion in diamond (Hervig et al 1980b;Meyer & Boyd 1972;Prinz et al 1975;Meyer & Svisero 1975); only Cr 2 O 3 plotted for some inclusions); open diamond (GLM; also five olivines in garnet and spinel lherzolites, ); filled star (GHK, garnet harzburgite xenoliths in South African kimberlites (Berger & Vannier 1984)); w (garnet dunite xenoliths in Williams kimberlite (Hearn & McGee 1984)); open hexagon and small open circle (hot (HGLM) and cold (CGLM) garnet lherzolite xenoliths, respectively, greater and less than 1423 K in The Thumb minette (Ehrenberg 1982)); open star (spinel-garnet lherzolite xenolith in Eglazines basalt (Berger & Vannier 1984) and garnet lherzolite xenoliths in Salt Lake Crater basalt (Glassley & Piper 1978)). Because only eight SLK were analysed (Table 1), data were added for two spinel-garnet peridotites from the Frank Smith kimberlite (Exley et al 1982) and four spinel-garnet ultramafites from the Colorado-Wyoming kimberlites (Kirkley et al 1984).…”

Magmatic to solid-state evolution of a shallow emplaced agpaitic tinguaite (the Suc de Sara dyke, Velay volcanic province, France): implications for peralkaline melt segregation and extraction in ascending magmas

“…The formation of the Velay migmatitic complex was established in the Upper Carboniferous, at the end of the collision episode that generated the Variscan Chain, which was built during a period from the Devonian to the Carboniferous (between 400 and 300 Ma). Beneath the Velay, the crust is strongly thinned, with a thickness of about 25 km (Mergoil and Boivin, 1993, and references therein) lying above a very heterogeneous lherzolitic mantle (Berger and Vannier, 1984). Tectonically, the Velay basement is affected by large northwest-southeast faults associated with northeast-southwest faults.…”