Spur and groove morphology from a Late Devonian reef

Spur and groove structures form on the windward side of modern coral reefs in response to wave action. Hitherto, no examples have been confirmed in the Palaeozoic record. We confirm here ancient spur and groove morphology from the Teichert Hills, an exhumed platform atoll from the Upper Devonian (Frasnian) reef complex of the Canning Basin, Western Australia. Oriented growth of the reef-building metazoans (laminar tabulate corals and stromatoporoid sponges) proves an organic and constructional origin for the spurs. Grooves acted as sediment traps that filled with coarse bioclastic sand and winnowed brachiopods derived from the back reef and reef flat. Geometry and style of ancient spurs and grooves may provide indications of ancient synoptic hydrodynamic regimes: on the basis of the relationship between modern coral reef spur orientation and incoming wave direction, these ancient spurs are inferred to have formed normal to refracted waves. The presence of these structures offers unequivocal evidence for the active growth of mid-Palaeozoic reefs in wave-dominated hydrodynamic regimes, and demonstrates that reef-building biota can show a common morphological response to wave energy independent of taxonomic position. (C) 2000 Elsevier Science B.V. All rights reserved.