The Pennsylvanian Springhill Mines Formation: sedimentological framework for a portion of the Joggins Fossil Cliffs UNESCO World Heritage Site

Abstract

This is the first detailed study of the coastal exposure of the Springhill Mines Formation within the Joggins Fossil Cliffs World Heritage Site. A 16.9-m-thick interval of dark laminated mudrocks and sharpbased sandstones at the base of our section is reassigned to the top of the Joggins Formation. This interval records a rapid, presumably widespread flooding event and the temporary establishment of a marginalmarine to brackish bay. The overlying 697 m of strata represent deposition in poorly drained and well-drained environments, and are assigned to the Springhill Mines Formation. Strata reflecting poorly drained environments contain green and grey mudrocks, thin coals, sheet sandstones, and channel bodies interpreted to have been deposited in coastal swamps and low-lying parts of a floodplain. Intervals reflecting well-drained conditions contain reddish brown mudrocks, sheet sandstones, and channel bodies interpreted to have been deposited on a vegetated floodplain that was periodically exposed to oxidizing conditions. Strata reflecting poorly drained conditions are thick and abundant in the lower half of the formation and well-drained intervals become thick and more abundant in the upper half. The shift in facies abundance is accompanied by an interpreted evolution in fluvial style from predominantly anastomosed channels (below 376 m) to sheet-like channel bodies (376-449 m) and ultimately to predominantly meandering-channel bodies (449-697 m). The formation-scale changes in drainage conditions and fluvial style records decreased halokinetic subsidence and aggradation of the alluvial surface as sediments shed from the Caledonia Highlands prograded into this part of the basin. rÉSUMÉ Il s'agit de la première étude détaillée sur l' exposition du littoral de la formation de Springhill Mines au sein du site du patrimoine mondial des falaises fossilifères de Joggins. Un intervalle de 16,9 m d' épaisseur de pélites feuilletées foncées et de grès à base nette situé au bas de la section a été rattaché au sommet de la formation de Joggins. Cet intervalle est le résultat d'une inondation rapide et probablement de grande envergure ainsi que de la formation temporaire d'un marginal marin dans une baie saumâtre. La couche sous jacente de 697 m de strate représente un dépôt dans des milieux mal drainés et bien drainés. Ces milieux se trouvent dans la formation de

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

“…They were buried before well differentiated horizons could form and appear broadly similar to the immature redbed paleosols described from the Joggins and Springhill Mines formations (Davies et al 2005;Rygel et al 2014). Scattered organic-rich horizons, green mottles, and rare Stigmaria within redbeds suggests that some of these mudrocks were clastic wetlands where there was sufficient water to allow partial preservation of organics and growth of lycopsids.…”

“…Although scattered throughout well-drained intervals in the lower part of the formation, sandstone-rich intervals with abundant closely-spaced sandstone interbeds become particularly abundant above 940 m, a trend that Ielpi et al (2014) interpreted as representing increased seasonality. The sandstone-rich overbank motif is similar to well-drained deposits in the overlying Joggins and Springhill Mines formations (Davies et al 2005;Rygel et al 2014).…”

“…Channel bodies of the Mabou and Cumberland groups exposed in the Joggins section overwhelmingly record sediment transport to the east and southeast, away from source areas in the Caledonia Highlands and beyond (Gibling et al 1992;Rygel and Gibling 2006;Allen et al 2013;Rygel et al 2014). Noteworthy exceptions include a number of north-flowing channel bodies in the Mabou .…”

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

“…In Nova Scotia, along the shoreline of the UNESCO World Heritage site around Joggins (Figs b and ), the lowermost unit of this succession is the grey sandstone‐dominated Boss Point Fm, which is ~1 km in vertical thickness (Logan, ; Rygel & Shipley, ). Conformable up‐section are the finer grained Little River Fm (vertical thickness of 635 m, Calder et al ., ) and coal‐seam‐bearing Joggins Fm (915 m, Davies et al ., ) followed by the sandier Springhill Mines Fm (697 m, Rygel et al ., ); and locally conglomeratic Ragged Reef Fm (680 m, Ryan et al ., ). Collectively, the units are assigned to the Cumberland Gp and interpreted to represent multiple glacio‐eustatically driven cycles of alluvial to marginal marine deposition (e.g.…”

“…A plethora of recent studies have collected palaeoflow data from both the Mabou Gp and Cumberland Gp (Gibling et al ., ; Browne & Plint, ; Ryan & Boehner, ; Hamblin, ; Calder et al ., ; Allen et al ., ; Ielpi et al ., ; Rygel et al ., ; Jutras et al ., ). There is agreement that in the Cumberland Gp, fluvial drainage is dominantly towards the southeast‐northeast quadrant.…”