A Shallow‐Marine Ecosystem Before Initial Tibetan Plateau Uplift

Abstract The uplift of the Tibetan Plateau profoundly influences global atmospheric circulation, sediment transport, and biodiversity, but its pre‐uplift marine paleoenvironment remains poorly understood. Here we report the first discovery of an in situ benthic fossil assemblage from the Puga area in central Tibet, which was deposited on a shallow‐marine carbonate platform during the late Cenomanian. Containing rudist bivalves and gastropods, this assemblage represents a chronologically reliable marine biota in central Tibet. Sr–O–C isotopic data from sessile fossil shells reveal shallow‐marine environmental and biotic responses to the Late Cretaceous greenhouse climate. These records capture early signals of Oceanic Anoxic Event 2 and the Plenus Cold Event, yielding high‐resolution paleotemperature variations peaking at ∼39°C and a positive carbon isotope excursion of 1.28–3.01‰. This study provides new evidence for reconstructing the shallow‐marine ecosystem prior to the initial uplift of the Tibetan Plateau during the Late Cretaceous.