Geochemistry of the Permian “Kolymic” Limestones of the Omolon Massif (Northeast Asia)

Five types of carbonate rocks were distinguished among the Middle Permian (Roadian–Wordian) deposits of the Omolon massif based on the rare-earth and trace element distribution and petrographic characteristics. New geochemical data obtained on the “kolymic” limestones indicate their bacterial nature. The rocks were formed in shallow oxygen-rich environments under humid climate conditions. Possible sources of volcano-terrigenous admixture in the limestones were intermediate and basic volcanics (Okhotsk–Taigonos volcanic arc), as well as felsic igneous rocks (Devonian volcanics of the Kedon Series), which were located near the sedimentary basin.