科研之友
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摘要
Brachiopods serve as important sources of marine paleoecological data in the Paleozoic. In this regard, an ecological framework for much of North America during the Devonian is well established; however, the brachiopod communities of the Western Canada Sedimentary Basin (WCSB) are understudied. Brachiopod communities of the Late Givetian and Early Frasnian Waterways Formation of northern Alberta were analyzed to identify associations between community species composition, basin topography/architecture, and environmental conditions. During the Givetian-Frasnian, this region experienced a transition in basin architecture from a ramp to a carbonate shelf setting; this transition is associated with an increase in energy and decrease in siliciclastic input. A total of 5144 brachiopod specimens from 44 samples were collected, identified to species level, and ordinated using NMDS. Recurring communities were defined based on taxonomic similarity, as indicated by groupings in the ordination. Brachiopod species can be separated into two distinct fauna along the first axis of the ordination. This faunal change co-occurs with the change in basin topography from ramp to shelf. This finding, in combination with the presence of taxa in other stratigraphically younger formations within the WCSB, suggests that faunal differences in the Waterways are a result of environmental factors, as opposed to biogeographic or evolutionary trends through time. The Ramp Fauna and Shelf Fauna can be further subdivided into five reoccurring communities. In comparison to other North American Devonian brachiopod communities, communities of the Ramp Fauna are similar to those of Iowa from the same time, which is consistent with the proximity of the two basins and the fact that both basins are carbonate-dominated. However, Shelf communities in the Waterways include a unique combination of taxa, including abundant productidines.
- 出版日期2018-10-1
