hitinozoan assemblages from the third-order transgressive–regressive cycles of the Upper Gaspé Limestones (Lower Devonian) of eastern Canada

A palynological–sedimentological study, combined with a multivariate statistical treatment, has been carried out on the Lower Devonian Upper Gaspé Limestones (UGL) of the Gaspé Peninsula in eastern Canada. In eastern Gaspé, the UGL were deposited on a storm-influenced carbonate outer shelf for which relative sea level fluctuations are recognized on the basis of lithofacies and sedimentological data. Four distinct chitinozoan assemblages, corresponding approximately to four previously defined stratigraphic units, have been recognized on the basis of the first occurrence or disappearance of given species. Reworked Upper Ordovician material occurs embedded within the Pragian part of the succession. The composition and abundance of the chitinozoan assemblages are not constant through their stratigraphic range. These variations are related either to (1) large-scale facies control (transition from siliciclastic prodelta to carbonate outer-shelf deposition), (2) third-order transgressive–regressive cycles developed in carbonates, (3) variations in energy levels and consequent carbonate composition, (4) the proximity of bioconstructions, and, in some cases, (5) sporadic volcanic activity. Correspondence analysis has confirmed the key role played by the first three variables on the composition of chitinozoan assemblages.