On the discovery and study of anthraxolite in Triassic plagiorhyolite on the border of the Ural and western Siberia

Abstract

This paper describes the discovery of the first solid bitumen in the plagiorhyolites of Sinara River (Kataysky District, Kurgan Oblast), which are part of the Early Triassic Turin volcanic-sedimentary series on the border of the Ural and Western Siberia. According to data provided by complex analytical studies, they were classified as low anthraxolites. It was found that the formation of solid bitumen in acidic volcanic rocks of Sinara River occurred during the late stage of establishment of the plagiorhyolite body during the formation of chalcedonic (agate) amygdales and secretions. Solidification and sedimentation of anthraxolite from hydrothermal solutions apparently took place under a radical prevalence of the carbonate ion, i.e., in the amygdales during the crystallization of calcite, while in the edge zones of brecciation of plagiorhyolite – of another carbonate, siderite. The source of the substance for the formation of anthraxolite in plagiorhyolites of Sinara River could be both the enclosing sedimentary rocks and deep (mantle) carbohydrate fluids.