Impact of Kerguelen, Marion, and Reunion plumes on the ophiolitic obduction at the northern margin of Indian plate

Abstract

Geochronological data compiled for 29 major ophiolitic occurrences from the northern margin of the Indian plate precisely coincide with the three major mantle plume interactions over Indian plate (viz., Kerguelen at 130–110 Ma, Marion at 90–84 Ma, and Reunion at 65–70 Ma). We analysed i) the geological juxtapositions of these ophiolitic belts, ii) seismic tomographic imaging of the slab breakoffs, iii) equivalent deflections in the marine magnetic anomalies (MMA), iv) stratigraphic records of the Cretaceous formations and v) the paleomagnetic inclination anomalies; and propose significant influence of plume-driven forces over the subduction and obduction processes in Himalayas. The impingement of Kerguelen plume strongly influenced the ∼ 2500 km long subduction of Neo-Tethys, leading to Indus-Tsangpo-Suture-Zone (ITSZ) ophiolites with their metamorphic soles. The impact of Marion plume further led to repeated tilting of the Indian plate reinvigorating Tethyan subduction at 90 ± 5 Ma. The Reunion event at ∼ 65 Ma, led to the mega-obduction along the Tethyan margin of the Indian subcontinent. The Kerguelen plume thus played a key role in initiating the intraoceanic subductions in equatorial Neo-Tethys, and the combined slab pull and plume induced rifting separated Greater India microcontinent from the northern margin of Indian subcontinent at ∼ 120 Ma. The impact of the Reunion plume resulted in the obduction of ITSZ ophiolites at the northern margin and the Pakistan ophiolites at the northwestern margin. The mantle plume impingements caused plate tilting and triggered the subduction/obduction that is well preserved by sharp inflexions in MMA and the spreading rates. We therefore infer that the three mantle plumes have a greater role in the subduction, obduction and tilting of the Indian plate throughout the Late Mesozoic.