Feat accumulation on a drowned coastal braidplain: the Mullins Coal (UpperCarboniferous), Sydney Basin, Nova Scotia

The Mullins Coal lies within the braided-fluvial South Bar Formation. The l ateral extent (15 km) and thickness (2 m) of the coal suggest that controls for peat accumulation were allogenic. Marine inundation of the distal brai dplain, as indicated by the high-sulphur content of the coal and the occurr ence of agglutinated foraminifera in associated shales, caused ponding of f reshwater near maximum marine transgression, with accumulation of thick par alic peat across a stable platform of sandy fluvial sediments. Highstand pa rasequences with thin capping coals were subsequently incised beneath a seq uence boundary as the braidplain readvanced. The Mullins Coal thins and spl its in association with muddy bayfill deposits eastward towards the Glace B ay Syncline, a long-lived palaeotopographic element related to fault-bounde d basement blocks. Although relative sea-level change controlled the strati graphic position of the precursor peats, differential tectonic subsidence a nd/or compaction modified their extent, thickness and quality. (C) 1999 Els evier Science B.V. All rights reserved.