Age and Tectonic Settings of the Usugli Depression Volcanics and Dotulur Alkalic Granite (West Transbaikalia)

Abstract

The Dotulur alkalic granite and Usugli Depression volcanics (West Stanovoi Superterrane of the Central Asia Fold Belt) have been dated by the U–Pb method, and their geochemistry has been analyzed. The geochemistry of the rocks suggests their intraplate nature. The alkalic granite and volcanics have similar ages of 142 ± 1 Ma and 138 ± 3 Ma, respectively. Considering the Usugli Depression structural position as an upper fault slice of the Elikan metamorphic core, the obtained dates allow the formation of the mentioned core and, accordingly, the collapse of central part of the Mongol–Okhotsk orogeny to have occurred not prior to 140 Ma.