Notes on plant tissue preservation and mineralization in a Permian deposit of peat from Antarctica

Abstract

Three generations of primary silica can be distinguished in specimens from a deposit of permineralized peat on Mount Augusta in the central Transantarctic Mountains, Antarctica. Initial chalcedonic mineralization was responsible for preserva- tion of plant tissues. Later chalcedonic mineralization served to consolidate and lithify the rock. Prismatic quartz was deposited last in open cracks and cavities. Deposition of chalcedony is probably related to a fluctuation in the water table when the ground water was highly charged with silica. Later recrystallization of the chalcedony has produced microcrystalline prismatic quartz and destroyed the structure in some of the denser types of plant tissue. Recrystallization may have been induced by heating accompanying the intrusion of Jurassic diabase into adjacent strata. The organic sub- stance of fossils also has been reduced on some surfaces by weathering. Examples of various types of preservation are illustrated.