Fe-Ti-enriched mafic rocks from South Andaman ophiolite suite: implication of late stage liquid immiscibility

Abstract

Andaman ophiolite suite (AOS) is amongst one of the ophiolite complexes of the world, which comprises complete dismembered ophiolitic sequence. It consists of ultra-mafic and mafic cumulates, sheeted dykes, pillow lavas, felsic rocks (mainly plagiogranites), and sedimentaries, including ribbon chert. In the present communication, a mafic rock that is highly enriched in FeO-TiO₂ and encountered in the ophiolites of south Andaman is presented. Fe- Ti-enriched mafic rock is not yet reported from the south AOS. Genetically this rock may be associated with leucocratic rocks of AOS because it is experimentally proved that Fe-enriched basaltic melt and plagiogranite melt can be generated by late stage liquid immiscibility. Similar to most of the other plagiogranite occurrences of the world, Andaman plagiogranites are also supposed to be end­ products of magmatic differentiation of a mafic magma. But the discovery of Fe-Ti-enriched mafic rocks sup­ ports liquid immiscibility process.