GEODYNAMIC CONDITIONS OF SEDIMENTATION AND SOURCES OF PALEOZOIC TERRIGENOUS ROCKS FROM THE YAMKUN SERIES OF THE ARGUN CONTINENTAL MASSIF

The paper deals with the distribution of the major oxides and trace elements in the Paleozoic terrigenous rocks of the Ildikan and Gazimursky Zavod formations from the Yamkun series of the Argun continental massif. The main purpose of the study is to reconstruct depositional settings and sources of clastic material. It is shown that the terrigenous rocks of the Ildikan and Gazimursky Zavod formations correspond to different lithotypes: graywackes, arkoses, and litharenites. According to the variations in Zr/Sc and Th/Sc ratios, the rocks of the Yamkun series are the first-cycle sediments. Whole-rock geochemical composition of studied rocks suggests that the main sources of clastic material were felsic and intermediate igneous rocks, with a subordinate amount of mafic rocks. The use of these data in combination with the U-Pb geochronological data on igneous rocks from the Argun massif implies that the initial material was mainly sourced from the Tonian, Cambrian, Ordovician and Early Silurian felsic and intermediate igneous rocks, widely abundant within the Argun continental massif. Additional sources of clastic material may involve the Paleoproterozoic orthogneisses from the Xinhuadukou complex of the Argun massif. The position of figurative points of the composition of the Paleozoic terrigenous rocks from the Yamkun series of the Argun massif on the tectonic discriminant diagrams in combination with geological data indicates a passive continental margin setting for the Lower-Middle Devonian deposits of the Ildikan formation and an active continental margin (or island-arc) setting for the Lower Carboniferous deposits of the Gazimursky Zavod formation.