New data on the age and paleogeodynamic setting of the Kalinovsky ophiolite complex (Sikhote-Alin): results of geochemical and U-Pb isotope LA-IСP-MS studies of zircons

Abstract

The structure of the Sikhote-Alin orogenic belt contains ophiolites, the age and paleogeodynamic setting of which remain controversial. The article presents the results of U-Pb isotope LA-IСP-MS-geochemical studies of zircons from gabbroids of the Chuguevsky and Breevsky massifs of the Kalinovka ophiolite complex. The cross-section of the complex revealed that it contains various rocks formed at different stages of a long-lived oceanic basin evolution and coexisting due to different tectonic processes. The studied Breevka and Chuguevka mafic-ultramafic massifs are fragments of ophiolites that formed during about 20 Ma in the Permian, but not in the Devonian-Carboniferous, as previously thought. The paleotectonic setting of the formation of massifs is not associated with intra-oceanic structures. We assume that they developed either in a back-arc basin in the presence of fragments of continental crust or at an active continental margin. Oceanic island basalts and Carboniferous-Permian limestones tectonically associated with mafic-ultramafic rocks probably belong to an older massif of the oceanic plateau.