Comparison of Fluvial Styles Within the Late Carboniferous Succession of the Maritimes Basin, Atlantic Canada: Toward a Refined Understanding of Paleoclimate

Allen, Jonathan¹, Christopher R. Fielding¹, Michael C. Rygel², Martin R. Gibling³ (1) University of Nebraska-Lincoln, Lincoln, NE (2) SUNY Potsdam, Potsdam, NY (3) Dalhousie University, Halifax, NS

The Late Carboniferous succession of the Maritimes Basin provides an ideal study area to investigate the effects of climate change on stratal architecture at a number of different scales. Overall the basin preserves an arid-to-humid-to-arid climatic trend. Current near-field research from eastern Australia has shown that during the late Paleozoic Gondwanan Ice Age within the Late Carboniferous, Gondwana experienced 4 glacial intervals, each 1-8 my in duration. This new understanding of the nature and extent of the climatic regime on Gondwana, suggests that there is opportunity to resolve the climatic trends within the paleotropical realm.

Fluvial units within the Late Carboniferous succession preserve a wide variety of upper flow regime structures (UFRS) such as plane bedding, humpback cross-stratification, antidunes, etc. These sedimentary features record sediment accumulation under highly variable discharge regimes. Successions that preserve abundant UFRS, along with other climate-sensitive features such as in situ tree fossils within fluvial channel fills, may point to a paleoclimate where there was a pronounced variation in precipitation and runoff, which would have a significant effect on the type of fluvial style preserved. Preliminary investigation has shown that the preservation of UFRS varies through time. UFRS are preserved within the Boss Point (Namurian), South Bar (Westphalian B-D), and Inverness (Westphalian C/D-Stephanian) Formations, however, the Joggins Formation (Langsettian) does not preserve any such structures. The use of such paleoclimatically sensitive features can be used to refine the overall arid-to-humid-to-arid climatic trend previously recognized within the Maritimes Basin, and may have implications for other paleoclimatic interpretations of similar successions. Furthermore, this trend may potentially correlate with the recent records from Gondwana in order to assess the synchroneity of global climate shifts in the Late Paleozoic.