Gas pipes in Eocambrian volcanic breccias

Abstract

SummaryEocambrian volcanic breccias of angular dacite and andesite clasts at Wadi Fatima, Kingdom of Saudi Arabia, contain perfectly preserved gas pipe structures. Only the latter identify them as lithic-rich, pyroclastic flow breccias of Pelean type. Without the gas pipes it would not be possible to identify them as pyroclastic and different from epiclastic breccias originating as mudflows, lahars or avalanches. The pyroclastic flow breccias constitute a minor component of the volcanic Fatima Group dominated by pumiceous water deposited sediments and subaerial welded tuffs.