Title

M.M. FILIPPOV, YU.E. DEJNES (IG KarRC RAS), K.I. LOKHOV (SPbU), A.V. PERVUNINA (IG KarRC RAS), O.V. LOKHOVA (Institute of History of Material Culture RAS)

A new genetic type of shungite­bearing rocks of the Palaeoproterozoic Onega structure

Data on shungite­bearing rocks from Tetyugino locality, which display the main signs of fluid genesis such as mode of occurrence, texture, mineral and chemical composition and the isotope composition of carbon, are reported. Examples of such rocks are breccia in superdomal faults (diapir melange) and local subsheeted bodies (injections of metasapropelites). It is shown that Melnichny Dome is the most probable source of fluidolites, and abnormally high formation pressure, which develops during the katagenesis of organic matter and the generation of hydrocarbons, is a major driving force. Brief geological and geophysical information on the locality proves that Melnichny Dome is an injection fold which was formed after the sixth shungite­bearing horizon and is similar to the Maksovo deposit which has been studied in detail.
Keywords: organoclay, diapirs, injections, abnormally high formation pressure.