The results of geochemical studies of terrigenous rocks of the Lower-Middle Devonian Ildikan and Lower Carboniferous Gazimursky Zavod formations of the Yamkun series of the Argun massif (Central Asian fold belt), as well as the results of U–Th–Pb dating of detrital zircon from these formations, are presented. The geochemical features of the studied rocks suggest that sediments of the first cycle were in the provenance area. Variations in contents of major and trace elements in the terrigenous rocks of the Ildikan and Gazimursky Zavod formations made it possible to establish that the main sources were felsic and intermediate igneous rocks. The Early Paleozoic and Neoproterozoic detrital zircon grains dominate in the rocks of the studied formations. The Middle Paleozoic and Late Paleozoic zircon grains occur in the siltstone and sandstone of the Gazimursky Zavod Formation. The morphological characteristics and geochemical composition of zircon crystals from the terrigenous rocks of the Ildikan and Gazimursky Zavod formations allow us to suggest that igneous and metamorphic rocks were present in the source area. The Paleozoic and Neoproterozoic granitoids and granite gneisses of the Argun continental massif should be considered as the main sources of clastic material. The absence of zircon grains of Middle Paleozoic age in the terrigenous rocks of the Ildikan Formation is related to the setting of tectonic and volcanic quiescence that existed within the Argun massif before the Eifelian. At the same time, the presence of a significant group of zircon grains of the Early Carboniferous age in the deposits of the Gazimursky Zavod Formation indicates their accumulation against the active magmatic activity.
Smirnova et al. (Thu,) studied this question.