The upper permian (Zechstein) tunstall reef of North East England: Palaeoecology and early diagenesis

Abstract

Detailed field studies and laboratory examination have identified the palaeocommunities of the Late Permian Tunstall Reef Complex of N.E. England, and have enabled accurate 3-dimensional diagrams to be constructed illustrating the palaeocommunity structure. The different palaeocommunities reflect the development of the reef through time, from reef-base coquine to lower reef core palaeocommunities, and then through space, in the laterally equivalent reef-flat, upper reef core, reef crest and fore-reef talus palaeocommunities, and the backreef patch reef palaeocommunity. An important factor in the formation of the Tunstall Reef was the precipitation of sea-floor cement. Aragonite particularly was an extensive and rapid precipitate in the reef-base coquina, as revealed in undolomitized limestones, and this type of cementation appears to have been widespread in other reef facies too, as judged by the rare occurrence of undolomitized limestones and by textures in the dolomites which can now be interpreted as relics of marine cements.