A hiatus of 8 My duration in the Middle Jurassic with ammonite succession in Tethyan Himalaya (South Tibet)

Middle Jurassic ammonites collected in situ from the Lanongla sections, Lan ongla, South Tibet allow the precise dating of the ferruginous Oolite beds and the underlying limestone beds in this area. A large hiatus of 8 million -year duration in South Tibet is well documented by the ammonite succession . Revision of sea-level changes curve in Tibet during the Middle Jurassic i s proposed; the high sea-level stands below and above the disconformity are dated as Humphriesianum Zone (late Early Bajocian) and Orbis Zone (early L ate Bathonian), respectively.