Vestiges of the Kerguelen Mantle Plume in Southern Tibet: Evidence from 123-117 Ma Magmatism in the Dingri Area of the Central Tethys Himalaya

The widely distributed Early Cretaceous magmatism in the Tethys Himalaya (TH) of southern Tibet is related to the Kerguelen mantle plume. Associated magmatic activity products are distributed in the eastern TH, where the active age is earlier than the peak ages of the Kerguelen mantle plume. This study investigated magmatic activity of the Dingri area in the central TH which was coeval with the Kerguelen mantle plume. The intrusion in the Dingri area contains diabases and monzonites. The zircon age of diabase is 123 & PLUSMN; 1 Ma, and that of monzonite is 117 & PLUSMN; 1 Ma. Geochemistry and Sr-Nd isotopic analyses show that the mafic-intermediate dikes were formed in an intraplate extensional environment. The diabase is derived from the enriched lithospheric mantle and monzonite is derived from partial melting of the lower crust, with both magmatic evolutions being contaminated by crustal materials. These characteristics are similar to those of the Rajmahal-Sylhet basalt, a typical Kerguelen mantle plume product. The discovery of the Dingri mafic-intermediate dikes of the central TH suggests that the TH and Rajmahal-Sylhet Traps formed a continuous mantle plume overflow magmatic belt which was a product of the continuous eruption of the Kerguelen mantle plume. image