Two bioerosion ichnofacies produced by early and late burial associated with sea-level change |
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| Authors: | Richard G Bromley Ulla Asgaard |
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| Institution: | (1) Geologisk Institut, Øster Voldgade 10, 1350 Copenhagen K, Denmark |
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| Abstract: | In bioerosion, as in trace fossils as a whole, deeply emplaced structures have greater survival value than shallow structures. That is to say, tiering (the relative depth to which rasping, etching and boring organisms penetrate their substrate) is of paramount importance for the preservation potential of individual trace fossils. An Entobia ichnofacies is established for trace fossil assemblages dominated by deep tier borings and arising from long-term bioerosion, such as occurs on sediment-free submarine cliffs or hardgrounds. A Gnathichnus ichnofacies comprises assemblages containing all tiers, including superficial sculptures produced by radulation that have very little preservation potential. Such assemblages occur in short-term bioerosion situations as on shell surfaces and hardgrounds buried early by sedimentation.
Correspondence to: R. G. Bromley |
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| Keywords: | Bioerosion Ichnofacies Sea-level change Burial rates Pliocene |
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