Hibonite-spinel-corundum-hematite assemblage in plagioclase-clinopyroxene pyrometamorphic rocks, Hatrurim Basin, Israel

database, nuove specie, discrediti,
ridefinizioni, classificazioni, ecc.
Rispondi
Avatar utente
Marco E. Ciriotti
Messaggi: 24374
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Hibonite-spinel-corundum-hematite assemblage in plagioclase-clinopyroxene pyrometamorphic rocks, Hatrurim Basin, Israel

Messaggio da Marco E. Ciriotti » mer 04 lug, 2018 10:19

Prossima pubblicazione.

Referenza:
▪ Sharygin, V.V. (2018): A hibonite-spinel-corundum-hematite assemblage in plagioclase-clinopyroxene pyrometamorphic rocks, Hatrurim Basin, Israel: mineral chemistry, genesis and formation temperatures. Mineralogical Magazine, 82, (in press).

Abstract:
The intergrowths of Fe-rich corundum +Al-rich hematite + spinel + hibonite have been found as an assemblage in a plagioclase-clinopyroxene rock (paralava, former hornfels) at the Hatrurim Basin, Hatrurim combustion metamorphic Formation. Most spinels show oriented exsolution structures and vary from (Mg0.75Fe2+0.25)(Al1.80Fe3+0.20)O4 (with exsolutions) to (Mg0.77Fe2+0.23)(Al1.95Fe3+0.05)O4 (homogeneous) indicating a tendency towards magnesioferrite and magnetite and enrichment in NiO (up to 1.9 wt.%) and ZnO (up to 1.4 wt.%). Hibonite is Ti-rich (TiO2 > 8 wt.%) and close to CaAl9Fe3+(Mg,Fe2+)TiO19. Corundum essentially varies in Fe2O3 (4.2-11.8 wt.%). Hematite is also inhomogeneous and contains oriented exsolution structures of corundum. It shows variable concentrations of TiO2 (0.7-5.6 wt.%), Al2O3 (0.7-8.6 wt.%), Cr2O3 (0.2-1.5 wt.%), V2O3 (0.1-1.0 wt.%) and MgO (0.3-2.0 wt.%). Crystallization of this specific assemblage is assumed to be at 1000-1200oC using evaluations for the corundum-hematite pair with reference to experimental data by Feenstra et al. (2005). The active role of superheated oxidized volatiles is suggested during both crystallization of this corundum-bearing association and host rock transformation (melting event for hornfels → paralava).
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

Rispondi

Chi c’è in linea

Visitano il forum: Nessuno e 4 ospiti