2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 166-9
Presentation Time: 4:00 PM


MENDONCA, Steven E.1, WEBB, Amelinda E.1, BARCLAY, Kristina M.1, ROCCA, Alexandra N.1, MOLINARO, Darrin J.1, SCHNEIDER, Chris L.1, FORCINO, Frank L.2 and LEIGHTON, Lindsey R.1, (1)Earth & Atmospheric Sciences, University of Alberta, Edmonton, AB T6G 2E3, Canada, (2)Geosciences and Natural Resources Department, Western Carolina University, 331 Stillwell Building, Cullowhee, NC 28723, smendonc@ualberta.ca

As abundant, sessile organisms, brachiopods are particularly useful for determining environmental conditions in Paleozoic marine systems. Brachiopod community composition is especially informative as it can account for both environmental effects and biotic interactions between taxa. There have been many Devonian brachiopod community studies, however, we present the first quantitative study of near-paleoequatorial Devonian brachiopod communities.

This study analyzes changes in brachiopod communities though time in the Waterways Formation (Givetian-Frasnian, Devonian) of the Western Canada Sedimentary Basin. Over 4000 brachiopods from 46 communities were collected from the Firebag, Calumet, and Moberly members (Waterways Formation) and identified to species. The communities were ordinated using Non-metric Multidimensional Scaling (NMDS), using the Wisconsin transformation and Canberra distance.

The community ordination’s first axis is primarily correlated with species richness (Pearson's r = 0.73, p << 0.0001). The ordination’s second axis is correlated with rock matrix, i.e. Dunham classification (Pearson's r = 0.58, p << 0.0001). Taxa ordinated into four distinct biofacies that are associated with lithology and stratigraphy. The most pronounced faunal shift occurs during the lower Moberly (upper Waterways) and parallels a trend from sediment-supported to shell-supported rock matrix. These results indicate that there is a strong ecological signal through time within the Waterways formation. By identifying biofacies and community patterns, this study establishes a framework for future research in determining the causes and implications of these ecological signals.