The major uplift in Himalayas was no earlier than the Miocene: Evidence from marine sediment record in the Bay of Bengal.

The timing of tectonic uplift in the Himalayan orogen, the highest mountain range on the Earth, remains controversial due to a lack of long-term continuous records. Here, we provide a long-term marine sediment record from Ocean Drilling Program (ODP) Site 758 in the southern Bay of Bengal (BoB) since 37 Ma, as well as the stacked terrigenous flux of the BoB since the Oligocene, to constrain sediment provenance variation since the late Eocene. The provenance results indicate that the sediment supply to the study site has become dominated by the Himalayan rivers (Ganges, Brahmaputra and Irrawaddy) since the early Miocene (∼23 Ma). We also present a Nd Pb isotope mixing model combined with Monte-Carlo simulations to quantify the contributions of Himalayan rivers to ODP Site 758 sediments since 24 Ma. The simulations indicate that the Ganges, Brahmaputra and Irrawaddy rivers successively became the main sources of sediments in the southern BoB from the early to late Miocene. Our quantitative provenance analysis, combined with evidence of paleogeographic evolution of the Himalayas, suggest that the major uplift of the Himalayan orogen might have occurred no earlier than the Miocene. Furthermore, tectonic activity in the Himalayas persisted during the Miocene, with progressive west-to-east deformation, and the eventual formation of a mountain range resembling modern elevations by the late Miocene. • Himalayan rivers dominated the terrigenous input to the Southern Bay of Bengal since the early Miocene. • The Nd‒Pb isotope mixing model combined with Monte-Carlo simulations is a powerful quantitative method for measuring sediment source contributions. • The Ganges, Brahmaputra and the Irrawaddy rivers were the main sediment suppliers to ODP Site 758 in succession since the early to late Miocene. • The major and rapid uplift stage of the Himalayan orogen might have occurred during the early Miocene (∼23 Ma). • The Himalayan orogen might have undergone progressive west-to-east deformation during the Miocene. [ABSTRACT FROM AUTHOR]