Oxygen-controlled early ordovician trilobite assemblages: The Thysanopyge fauna from Northwestern Argentina.

WAISFELD, B.G.; VACCARI, N.E.

Toledo, España

Conferencia; Fourth International Trilobite Conference Trilo 08; 2008

Servicio Geológico y Minero de España

Thysanopyge was among the dominant inhabitants of a broad shallow, nutrient rich, subtidal marine setting. Although association with other asaphids and olenids are common within dark fine-grained facies, this taxon appears to cope with the widest range of environmental conditions and bottom-water oxygen levels. Thysanopyge assemblages flourished in a relatively restricted, prodelta setting with high sedimentation rate and active subsidence, responsible of the scattered and diluted nature of some of these assemblages. They varied from monospecific or paucispecific to high diversity assemblages. Among them, variations in trilobite composition, presence of other benthic groups, and diversity are interpreted to account for variable paleo-oxygen levels, from dysoxic, to fully oxic conditions.