Magnetite-rutile symplectite in ilmenite records magma hydration in layered intrusions

Abstract The textures and geochemical characteristics of the rocks in layered intrusions potentially provide insights into physicochemical processes that have taken place mafic magma chambers. Diverse exsolution Fe-Ti oxides may record variation subsolidus temperature oxygen fugacity (fO2) cooling Here we investigated ilmenitehematite solid solution (Ilmss) relationships evident preserved intergrowths magnetite-rutile ilmenite-hematite gabbro Xinjie intrusion. crystallographic orientation 3D morphology two intergrowth types constrain transformation mechanism from Ilmss. results reveal interface is more energetically favorable than symplectite when they are transformed Ilmss on cooling. QUILF equilibria suggests can be Ti-rich ilmenite with Ilm≥0.85 above 550 °C T-fO2 trend buffered by biotite-ilmenite-feldspar-ulvöspinel (KUIlB) mineral assemblages crystallized hydrated magmas. used as a unique texture indicator hydration evolution history terrestrial, martian, lunar