A correlation of accretionary complexes of southern Sikhote-Alin of Russia and the Inner Zone of Southwest Japan

Abstract

This paper briefly describes the geology of southern Sikhote-Alin of Russia and the Inner zone of Southwest Japan, and presents a new correlation model in which the Samarka terrane (sensu stricto), Udeka Formation, Sebuchar Formation and Kalinovka ophiolite in Sikhote-Alin are considered as northern extensions of the Mino-Tamba terrane, Hikami Formation, Kozuki Formation, and Yakuno ophiolite in Southwest Japan, respectively. This correlation is based on the similarities in lithology, age, faunal assemblage, and structural relationship between them. The Samarka and Mino-Tamba terranes consists of Jurassic accretionary complexes including Permian greenstone-limestone complex, Permian to Lower Jurassic radiolarian bedded chert, Jurassic clastic rocks, and Jurassic melanges. The Udeka and Hikami formations are composed mainly of greenish gray sandstone with minor shale intercalations yielding Permian radiolarians. The Sebuchar and Kozuki formations are characterized by basalts accompanied with shale, limestone and chert. The limestone includes Carboniferous fusulinaceans, while Permian radiolarians occur in the chert. The Kalinovka and Yakuno ophiolites consist of a series of ultramafic to mafic igneous rocks with an ophiolitic succession. Since the ages of these ophiolites have not been clearly established, we correlate them on the basis of their lithology and tectonic positions. These units form a stack of nappes from the lower to upper horizons in the following order: Mino-Tamba terrane, Hikami Formation, Kozuki Formation, and Yakuno ophiolite in Japan, and Samarka terrane (sensu stricto), Udeka Formation, Sebuchar Formation, and Kalinovka ophiolite in Russia. This correlation supports the reconstruction model of Japan before the opening of the Sea of Japan proposed by Yamakita and Otoh (1999).