Mayodia ophiolitic complex of Arunachal Pradesh, India: a multistage evolutionary record during the Tethyan closure

Abstract

ABSTRACT The Mayodia ophiolitic complex of Arunachal Pradesh, India is a highly dismembered body located close to the Namche Barwa syntaxis. It structurally represents a klippe and consists dominantly of serpentinite and dunite within which amphibolite and hornblendite occur. Detailed field observations indicate that amphibolites are concordant bodies within serpentinite, whereas hornblendite occurs as dykes. Geochemically, serpentinite samples indicate their abyssal/forearc origin showing refertilisation due to melt-mantle interactions. Massive dunite bodies, occurring as dykes within serpentinites, are replacive in origin and represent fossilized melt channels. The geochemistry of amphibolites is akin to gabbros formed at back-arc basin. Later, serpentinites were severely intruded by hornblendite dykes during the waning stage of back-arc spreading. Finally, the entire litho-package was obducted onto the passive margin of Indian plate as the Mayodia ophiolitic complex which subsequently got folded, deformed and metamorphosed during orogenesis. During this process, the crustal section of the complex was entirely eroded, preserving only the mantle section of this ophiolite.