Glauconitic spherules from the Triassic of the Bristol area, SW England: probable microtektite pseudomorphs

Marine Lower Carboniferous Limestone is unconformably overlain by Triassic desert sediments at Wickwar, Bristol, SW England. Deposited by fluvial activity along the unconformity are pockets of partly cross-bedded marly limestones containing abundant glauconitic spherules with distinctive internal architectures, such as spheres within spheres. They are accompanied by shocked-quartz and probably pseudomorph altered glass spheres representing former micro-tektites created by a meteorite impact with Earth. Their possible link with mass extinction events are considered.