Место издания: Владивосток , Год издания: 2023

Reconstruction of proportions between juvenile and recycled crust remains challengeable because a big part of juvenile source magmatic rocks formed at intraoceanic arcs, can be destroyed by surface and tectonic erosion leaving, at best, greywacke sandstones [1]. Such sandstones are typically hosted by accretionary complexes, which study, therefore, is of crucial importance. In this paper we review available geological and micropaleontological data and present first U-Pb detrital zircon ages, geochemical data and isotope (Sm-Nd, Lu-Hf) data from sandstones of the late Cambrian-early Ordovician Zasur'ya accretionary complex (AС) of NW Altai. No island-arc units have ever been reported there. The Zasur'ya AC includes ocean plate stratigraphy (OPS) magmatic and sedimentary rocks of three formations, Listvenny (L. Cambrian), Talitsa (Tremadocian) and Marcheta (Floian), which age was constrained by microfossils [2]. The OPS assemblage includes basalt, pelagic chert and hemipelagic siliceous mudstone and siltstone, and sandstone. The sandstones under study are associated with oceanic basalts and deep-sea sediments, pelagic (ribbon chert) and hemipelagic (siliceous mudstone, siltstone, shale). In places, they occur as rhythmic packages of sediments resembling turbidities. The bedding of most sedimentary packages is almost vertical, that is typical of accretionary prisms worldwide [3].