Sedimentology and stratigraphy of the type section of the Pennsylvanian Boss Point Formation, Joggins Fossil Cliffs, Nova Scotia, Canada

Abstract

The 1125-m-thick type section of the Pennsylvanian Boss Point Formation is well exposed along the shore of the Bay of Fundy in Nova Scotia. We provide the first comprehensive account of the entirety of this formation, which comprises nearly one-third of the stratigraphic thickness of the Joggins Fossil Cliffs UNESCO World Heritage Site. The basal Chignecto Bay Member (0-91.5 m) is composed of redbeds, single-storey channel bodies with northerly paleoflow, and thin palustrine limestones. The middle Ward Point Member (91.5-951.7 m) contains up to 16 megacycles composed of alternations between thick packages of braided fluvial sandstone and fine-grained deposits. Although regional studies of the Boss Point Formation suggest that the fine-grained deposits are largely composed of lacustrine sediments, these intervals consist largely of poorly drained and well-drained floodplain deposits in the type section. The facies variations and southeast-directed paleoflow in the Ward Point Member record modest uplift associated with the growth of the salt-cored Minudie Anticline. The North Reef Member (951.7-1125 m) is composed of redbeds and two distinctive multistorey channel bodies. This uppermost member records a shift to more arid, oxidizing conditions, was the precursor to a major phase of salt withdrawal, and represents a transition to the overlying Little River Formation. The sedimentological framework, revised stratigraphy, and detailed measured section and map will provide a foundation for future study of this remarkable Pennsylvanian exposure.

The role of discharge variability in the formation and preservation of alluvial sediment bodies

“…6C). Further examples are given by the Pennsylvanian Boss Point (upper part) and South Bar Formations of Nova Scotia, Canada (Rust and Gibling, 1989;Browne and Plint, 1994;Gibling et al, 2010;Fielding et al, 2011;Allen et al, 2013Allen et al, , 2014Rygel et al, 2015) (Figs. 6D, 8).…”

Salt tectonics in an intracontinental transform setting: Cumberland and Sackville basins, southern New Brunswick, Canada

“…relate variation in mean flow directions in the Boss Point Fm to strike-slip movement (potentially with associated relative uplift) along the general line of the Minudie Anticline and where we draw the Shepody-Beckwith Fault. The current study, following Rygel et al (2015), indicates an additional level of complexity: the faulting was accompanied by halokinesis. data indicate that the regionally dominant NE to SE palaeoflows in Cumberland and Pictou group strata (e.g.…”

“…The current study, following Rygel et al . (), indicates an additional level of complexity: the faulting was accompanied by halokinesis. Browne & Plint's () data indicate that the regionally dominant NE to SE palaeoflows in Cumberland and Pictou group strata (e.g.…”

Exact distribution of divergence times from fossil ages and tree topologies

“…Recent work suggests that the Joggins Formation, in which the oldest undoubted amniote (Hylonomus) has been recovered (Carroll 1964;Davies et al 2006;Falcon-Lang et al 2006), is coeval with the early Langsettian in the Western European sequence, which is about mid-Bashkirian (Carpenter et al 2015), around 317-319 Ma (Utting et al 2010;Raine et al 2015). In fact, recent work suggests more precise dates of between about 318.2 and 318.5 Ma (Utting et al 2010;Rygel et al 2015), but we have been more conservative in putting broader limits for the age of this formation, given the uncertainties involved in dating fossiliferous rocks. Thus, we have set the lower bound of the origin of diversification to 330 Ma, 340 Ma, 350 Ma, 400 Ma and 1 000 Ma to assess the sensitivity of our results to the older bound or the width of the interval.…”