Geochemical and petrological study of the Manamedu Ophiolite Complex, Cauvery suture zone, southern India

The Manamedu Ophiolite Complex (MOC) within the Palghat-Cauvery Suture Zone (PCSZ) in southern India comprises metamorphosed equivalents of mafic–ultramafic group of rocks including pyroxenite and dunite with locally cumulate textures; gabbroic rock types including gabbro, gabbronorite, and anorthosite; sheeted mafic dykes of amphibolite to meta-andesite and plagiogranite; a thin layer of ferruginous cherts. The tectonic discrimination of these rocks based on various geochemical plots shows that they were related to island arc tholeiite (IAT) group with tholeiitic to calcalkaline signatures. Most of the samples (hornblendite, anorthosite, and amphibolite) have similar chondrite-normalized rare earth element patterns characterized by light REE enrichment, slightly Eu anomaly, and flat heavy REE profiles, except plagiogranite has a significant Eu anomaly. In the primitive mantle-normalized spidergram, all samples show depletion in HFSE (P, Zr, Sm, Ti, and Y) and enrichment of LILE (Rb, Ba, Th, Sr) with negative Nb anomalies. The petrological and geochemical characteristics of the lithological association of MOC represent the remnants of an oceanic crust, which may be formed in a suprasubduction zone geodynamic environment.