THE MIDDLE-LATE SILURIAN FLYSCH IN THE BAINAIMIAO AREA, NEI MONGGOL

The Middle-Late Silurian flysch was for the first time discovered in the Bainaimiao area on the northern margin of the North China continental platform. It is composed of coarse flysch in the lower part and sandy-silty flysch in the upper part. This flysch formation overlies unconformably the and esitic island- arc pyroclastic-sedimentary rocks of Ordovician-Early Silurian age, and is covered unconformably by marine molasse sediments of terminal Late Silurian age. This not only proves the presence of an early Paleozoic eugeosyncline on the southern side of the Nei Monggol Variscan geosyncline, but also confirms that the preceding Monggol Caledonian cycle ended in the period from the terminal Middle Silurian to/or initial Late Silurian. The flysch in the Bainaimiao area exhibits a rather complete rhythmical texture and a bedding structure with a great variety of flysch casts. Both the systematic granulometric statistics of tbe flysch rhythmical layers and the C-M chart （R. Passega, 1964） and parameter calculations based on Sahu （Sahu, 1964） prove that this sequence of strata is typical turbidity current sediments.