ORDOVICIAN DEPOSITS OF THE GANYCHALAN TERRANE (PENZHINSKII RANGE OF THE KORYAK HIGHLAND)

Abstract

The volume of both original and published material on the fauna, composition, and facies types of the Ordovician deposits of Penzhinskii Range is summarized in this work. The deposits (the Elgeminai Group) represent a characteristic component of the Ganychalan Terrane, one of the basic structural units of the range. Five sections are considered, and three stratigraphic units are distinguished: the Khinantykul (Arenigian (?)-early Llanvirnian), Kuyulpil (Llanvirnian-early Caradocian), and Olenii (late Caradocian-Ashgillian) formations. The Khinantykul Formation, mostly comprising volcanic rocks, represents an upper part of the ophiolite association. The Kuyulpil Formation of more variable rock facies includes shallow-water clastic carbonates in northern sections and deep-water siliceous black shales in the southern sections. The Olenii Formation is flyschoid and sandy-shaly in composition with conglomerate horizons in its lower part. The underlying Ordovician deposits are found to be eroded at the base of the formation, although the main part of its clastic material is allochthonous. The Olenii Formation reflects a period of accretion or amalgamation of the Ordovician plate to the North American continent. The continent supplied much of the coarse clastic material derived from volcanites of the differentiated series and from the Cambrian organogenic limestones. This work is supplemented with complete lists of conodonts and radiolarians of the Elgeminai Group.