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

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

Descriptive taxonomy, biostratigraphic correlation and paleoenvironmental reconstruction of an upper carboniferous macrofloral assemblage, Bay St. George Basin, Southwestern Newfoundland

A diverse, well preserved macrofloral assemblage (herein termed the Blanche Brook Assemblage), which is characterized by large tree petrifactions of cordaitean affinity and an array of adpressed foliage that includes lycopsids, sphenopsids, ferns, pteridosperms and cordaiteans, has been recovered from coal-bearing strata of the Upper Carboniferous Barachois Group of the Bay St. George Basin, southwestern Newfoundland. The locality constitutes part of the northernmost onshore extent of the Maritimes Basin of eastern Canada, which developed on the southern margin of paleoequatorial Laurentia and is included in the Europe Paleoarea of the Euramerian Paleokingdom. Although the fossil site was initially investigated in the late 1800's, the present study comprises the first comprehensive taxonomic description and biostratigraphic correlation of the macrofloral assemblage, and provides an interpretation of the depositional environment and paleoecotogical conditions under which the flora flourished. -- Recovery of very well preserved cuticles exhibiting fine epidermal cellular details from adpressed cordaitean and pteridosperm foliage reflects the fact that fossiliferous strata have experienced very little deformation or burial metamorphism, and supports earlier claims that rocks in the northern part of the Bay St. George Basin and on Port au Port Peninsula are thermally immature. Paleoecological evidence and homotaxial biostratigraphic comparison of selected adpressed macroflora with other localities in the Europe Paleoarea (e.g., Maritimes Basin, western and central Europe, midcontinental North America) indicates that the assemblage is middle to late Bolsovian in age, which corroborates ages determined earlier from palynological studies. -- Fossiliferous and associated rocks in the stratigraphic succession are here subdivided and assigned to one of seven sublithofacies, each of which represents a distinct depositional environment characterized by its sedimentology and stratigraphy, vertical and lateral relationships with other sublithofacies, and plant fossil assemblages. The strata appear to record sediment accumulation in a coarse grained meandering stream system that occupied a narrow alluvial plain and was characterized by poorly developed levee/backlevees that were consequently overtopped or breached during frequent flood events. The distribution and relative abundances of taxa within each sublithofacies, including miospores recorded from associated coal seams, have been integrated with previously interpreted habitat preferences known for flora represented at the fossil site. This has resulted in construction of a working paleoenvironmental model for the Blanche Brook Assemblage, which indicates that there was considerable habitat partitioning and even competition for ecological niches between members of the five main plant groups in response to ecological preferences of each taxa. In particular, there is evidence for interspecific habitat partitioning within the medullosan pteridosperms occupying the floodplains and leveeftacklevees, while competition may also may existed between certain medullosan pteridosperms and sigillarian arborescent lycopsids for drier edaphic substrates in these habitats. Likewise, clastic swamps were inhabited by an array of flora, the composition of which depended on the rate of peat versus clastic sediment accumulation that resulted from frequent incursions of sediment-laden floodwaters