The chemical and mineral composition of volcanic ash in the Upper Carboniferous deposits of the Usolka section (South Ural, Russia)

Abstract

© 2020 IOP Publishing Ltd. All rights reserved. Volcanic ash from the Usolka section, which is proposed as an international standard for global correlation of the lower boundaries of the Kasimovian and Gzhelian Stages, is considered. The content of rock-forming components in ashes is given. It is shown that the ashes of the Gzhelian Stage differ from older deposits in higher contents of Al, Ca, Mn and lower contents of Si, Ti, Fe. An increase in the content of some microcomponents (Cu, Cr, Ba, S) to the lower boundary of the Kasimovian Stage was noted. For the first time, information has been obtained on the mineral composition of ashes, which allows them to be used for correlation.