Foraminiferal stratigraphy of Late Cretaceous red beds in southern Tibet

A group of red beds occurs in the hemipelagic to pelagic Upper Cretaceous succession of southern Tibet. They are composed of red shale, marl and foraminiferal wackestone and packstone, and considered to be deep-marine sediments that accumulated under oxic conditions following an environmental recovery after anoxia in the worldʹs oceans. Abundant planktonic foraminifera occur in them. The Dicarinella asymetrica, Globotruncanita elevata, Globotruncana ventricosa and Globotruncanita calcarata zones are recognized in the Chuangde succession, indicating an age range of late Santonian–middle Campanian. The age of the red beds in the Gyangze and Sagya regions spans the late Santonian–Campanian. In the Gyirong-Saga region the foraminiferal fauna is characterized by the Gansserina gansseri and Abathomphalus mayaroensis zones, indicating a late Campanian–Maastrichtian age. The oceanic, oxic-bottom, depositional environment developed during the Campanian and Maastrichtian period in southern Tibet, but disappeared from east to west following the regression that is thought to have been caused by the collision between the Indian and Asian plates.