The Izanami Plateau : Pre-accretionary origin of Japan's low latitude triassic pelagic carbonates

The Izanami plateau is the oceanic origin of Triassic pelagic limestones in Jurassic and Early Cretaceous accretionary complexes (AC) of Japan.
Well dated by conodonts and radiolarians, the Triassic ocean type carbonate plateau, from where blocks, in the Mino-Tamba (Ashio), Mikabu and Chichibu belts, are derived, has a characteristic history of deposition related to seamount, hot-spot and plate-motion. The Izanami plateau is characterized by the changing nature of its substrate, from Paleozoic platform carbonates in more internal areas, to pillow basalts in more external zones, and by the younging of the base of the Triassic carbonates covering that substrate. In the more internal zones, depositional hiatuses relate to post - Aegean and Early Carnian emersions. Lower - Middle Norian condensation preceded the drowning of the platform in the more external zones, where Late Norian and Rhaetian strata consist of bedded chert only.
Faunistically, the realm of the Izanami plateau has more Tethyan than Pacific conodont affinities with some specific endemism.
The low latitude Izanami plateau extended over a large area, off the Yangtse block, prior to its inclusion in Jurassic to Early Cretaceous AC.

ETH Zürich, www.e-periodica.ch