CHITINOZOAN ASSEMBLAGES FROM THE 3RD-ORDER TRANSGRESSIVE-REGRESSIVE CYCLES OF THE UPPER GASPE LIMESTONES (LOWER DEVONIAN) OF EASTERN CANADA

A palynological-sedimentological study, combined with a multivariate s tatistical treatment, has been carried out on the Lower Devonian Upper Gaspe Limestones (UGL) of the Gaspe Peninsula in eastern Canada. In e astern Gaspe, the UGL were deposited on a storm-influenced carbonate o uter shelf for which relative sea level fluctuations are recognized on the basis of lithofacies and sedimentological data. Four distinct chi tinozoan assemblages, corresponding approximately to four previously d efined stratigraphic units, have been recognized on the basis of the f irst occurrence or disappearance of given species. Reworked Upper Ordo vician material occurs embedded within the Pragian part of the success ion. The composition and abundance of the chitinozoan assemblages are not constant through their stratigraphic range. These variations are r elated either to (1) large-scale facies control (transition from silic iclastic prodeltaic to carbonate outer-shelf deposition), (2) third-or der transgressive-regressive cycles developed in carbonates, (3) varia tions in energy levels and consequent carbonate composition, (4) the p roximity of bioconstructions, and, in some cases, and (5) sporadic vol canic activity. Correspondence analysis has confirmed the key role pla yed by the first three variables on the composition of chitinozoan ass emblages.