Oxygen-related controls on predepositional ichnofacies in turbidites, Guipúzcoan Flysch (Albian-lower Eocene), northern Spain

Sedimentological, geochemical and ichnological analyses of the Albian-Lower Eocene Guipúzcoan Flysch (northern Spain) suggest that dissolved oxygen levels control the size of the preturbidite trace fossils on turbidite bed soles. Low-oxygen-tolerant trace fossils include indistinct, tiny ridges and...

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Veröffentlicht in:Palaios 1991-06, Vol.6 (3), p.271-280
1. Verfasser: Leszczynski, Stanislaw
Format: Artikel
Sprache:eng
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Zusammenfassung:Sedimentological, geochemical and ichnological analyses of the Albian-Lower Eocene Guipúzcoan Flysch (northern Spain) suggest that dissolved oxygen levels control the size of the preturbidite trace fossils on turbidite bed soles. Low-oxygen-tolerant trace fossils include indistinct, tiny ridges and knobs produced by deposit-feeding and possibly suspension-feeding animals. Simple traces, including members of the Planolites-Paleophycus and Thalassinoides ichnoguilds, display wide ranges of occurrence with respect to oxygen levels. Graphoglyptid burrows seem to have a narrower range, but they still indicate lower oxygenation levels. Among these, Paleodictyon minimum is the most tolerant. The gradual disappearance of graphoglyptids with increasing oxygenation may be related to specific food requirements or to competition with other bioturbators. The limits to which different traces tolerate low oxygen conditions correspond to their vertical tiering, i.e., deeper-tier ichnotaxa also range into less oxygenated areas than higher-tier forms. Not all traces, however, follow this rule (e.g., Paleodictyon minimum and Helminthorhaphe), probably because their producers had wider oxygen tolerances.
ISSN:0883-1351
1938-5323
DOI:10.2307/3514907