Petrology of the Udayagiri Anorthosite Complex, Eastern Ghats Belt, India

The Eastern Ghats Belt (EGB), characterised by pervasive Grenvillian granulite facies metamorphism, is the host to several 950–1000 Ma old massif-type anorthosite complexes. The present work describes one such complex near Udayagiri from the northern margin of the EGB, reported for the first time as “Udayagiri anorthosite complex” (UAC). The ‘massif type’ UAC comprises mainly of anorthosite, leuconorite-olivine leuconorite and norite in the decreasing order of areal extent. Mineralogically, these rocks dominantly consist of cumulates of moderately calcic plagioclase (∼An50–60), moderately magnesian intercumulus olivine (XMg: ∼0.6) and orthopyroxene (XMg: 0.47 to 0.70). Metamorphic garnet (Alm: ∼50 mol%) is also common in these rocks.