U. Ryb, C. Ponton, C. France‐Lanord, K. Yoshida, J. M. Eiler
Geophysical Research Letters, 51, e2024GL109643
Voir en ligne : https://doi.org/10.1029/2024GL109643
Abstract :
The Himalaya orogen evolved since the Eocene as the Tethyan‐, Greater‐, Lesser‐ and Sub‐
Himalaya thrust sheets were uplifted and exhumed in sequence. Reconstructing the provenance of sediment in
Himalayan River systems can inform on stages in the tectonic history of the orogen. Here, we analyze the
oxygen, carbon and “clumped” isotope compositions of carbonate minerals from Himalayan bedrock, Ganga
River sediments and Bengal Fan turbidite deposits. We demonstrate that river sediments consist of a mixture of
Himalayan‐derived and authigenic calcite precipitated in the river system. The relative abundance and clumped
isotope apparent temperatures of detrital calcite in turbidite deposits decreased between the Late Miocene and
Pliocene, while chemical weathering intensity did not increase during this interval. Considered together, these
results reflect the establishment of the Lesser Himalaya as an important carbonate sediment source for
Himalayan rivers, driven by the uplift and exhumation of this thrust sheet.