TY - JOUR

T1 - A hibonite-spinel-corundum-hematite assemblage in plagioclase-clinopyroxene pyrometamorphic rocks, Hatrurim Basin, Israel

T2 - Mineral chemistry, genesis and formation temperatures

AU - Sharygin, Victor V.

PY - 2019/2/1

Y1 - 2019/2/1

N2 - 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 (Mg 0.75 Fe 2+ 0.25 )(Al 1.80 Fe 3+ 0.20 )O 4 (with exsolutions) to (Mg 0.77 )(Al 1.95 Fe 3+ 0.05 )O 4 (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 (TiO 2 > 8 wt.%) and close to CaAl 9 Fe 3+ (Mg,Fe 2+ )TiO 19 . Corundum varies in Fe 2 O 3 (4.2-11.8 wt.%). Hematite is also inhomogeneous and contains oriented exsolution structures of corundum. It shows variable concentrations of TiO 2 (0.7-5.6 wt.%), Al 2 O 3 (0.7-8.6 wt.%), Cr 2 O 3 (0.2-1.5 wt.%), V 2 O 3 (0.1-1.0 wt.%) and MgO (0.3-2.0 wt.%). Crystallization of this specific assemblage is assumed to be at 1000-1200°C using evaluations for the corundum hematite pair with reference to published experimental data. The active role of superheated oxidised volatiles is suggested during both crystallisation of this corundum-bearing association and host-rock transformation (melting event for hornfels → paralava).

AB - 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 (Mg 0.75 Fe 2+ 0.25 )(Al 1.80 Fe 3+ 0.20 )O 4 (with exsolutions) to (Mg 0.77 )(Al 1.95 Fe 3+ 0.05 )O 4 (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 (TiO 2 > 8 wt.%) and close to CaAl 9 Fe 3+ (Mg,Fe 2+ )TiO 19 . Corundum varies in Fe 2 O 3 (4.2-11.8 wt.%). Hematite is also inhomogeneous and contains oriented exsolution structures of corundum. It shows variable concentrations of TiO 2 (0.7-5.6 wt.%), Al 2 O 3 (0.7-8.6 wt.%), Cr 2 O 3 (0.2-1.5 wt.%), V 2 O 3 (0.1-1.0 wt.%) and MgO (0.3-2.0 wt.%). Crystallization of this specific assemblage is assumed to be at 1000-1200°C using evaluations for the corundum hematite pair with reference to published experimental data. The active role of superheated oxidised volatiles is suggested during both crystallisation of this corundum-bearing association and host-rock transformation (melting event for hornfels → paralava).

KW - combustion metamorphism

KW - corundum

KW - corundum-hematite geothermometer

KW - Hatrurim Basin

KW - hematite

KW - hibonite

KW - hornfels

KW - Israel

KW - paralava

KW - NATURAL ANALOGS

KW - COMBUSTION METAMORPHIC ROCKS

KW - NEGEV DESERT

KW - PALESTINIAN AUTONOMY

KW - LARNITE ROCKS

KW - MOTTLED ZONE

KW - SOLID-SOLUTION

KW - PEROVSKITE

KW - DEAD-SEA

KW - JABEL HARMUN

UR - http://www.scopus.com/inward/record.url?scp=85060805807&partnerID=8YFLogxK

U2 - 10.1180/mgm.2018.138

DO - 10.1180/mgm.2018.138

M3 - Article

AN - SCOPUS:85060805807

VL - 83

SP - 123

EP - 135

JO - Mineralogical Magazine

JF - Mineralogical Magazine

SN - 0026-461X

IS - 1

ER -