Some observations regarding the potential effects of doming of tropical peat deposits on the composition of coal beds

Several important concepts relative to the origin of coal beds can be gleaned from studies of modern domed and planar peat deposits in tropical-subtropical settings. These are: (1) laterally, some portions of a single continuous peat deposit may be domed and some portions may be planar; (2) domed deposits are most often found to have begun as planar deposits; (3) domed-formed peat facies may be overridden by planar-formed peat facies, due to such factors as sea level rise and/or increased rate of local and basinal subsidence; (4) domed peat facies tend to have less mineral matter and contain fewer inorganic splits than planar facies; (5) sulfur intrusion from marine waters can be retarded by doming, allowing low-sulfur peats to form relatively near to the coastline; (6) marine transgression can cause high-sulfur, marine-influenced, planar, peat facies to override freshwater domed or planar facies, resulting in enrichment of the upper parts of these underlying facies in sulfur and ash; (7) dome-formed peat facies tend to be thicker and more uniform in composition than planar-formed facies, with dome-formed peat facies having the potential to produce the more uniform bright coal types (clarains and vitrains) and planar-formed peat facies often producing duller coal types and/or alternating, durainic (inertinite-rich) and vitrainic (wood-derived) bands; (8) actively developing peat domes in wet settings often exhibit no appreciable increase in inertinitic material toward their tops; although the tops of either domed or planar peat deposits can be enriched in inertinitic material if the water table is lowered by either local or regional changes in hydrology or climate.