Megaflora and palynoflora associated with a late Pennsylvanian coal bed (Bursum Formation, Carrizo Arroyo, New Mexico, USA) and paleoenvironmental significance

The only known coal bed in the Late Pennsylvanian Bursum Formation crops out in Carrizo Arroyo, Valencia County, New Mexico. Biozonation using fossils of conodonts, insects and plants suggests a latest Pennsylvanian age. The coal was first reported by Darton in 1928, and palynofloras have been previously obtained from strata below and above it. Associated megaflora was noted but not illustrated. Here, we re-describe the coal-bearing interval in detail, describe and illustrate a palynoflora from the coal and some elements of the megaflora from above and below it. The peat body from which the coal is derived appears to have formed in an abandoned channel, possibly an oxbow lake or estuary. It is high in mineral matter and inertinite macerals. It may have formed during a widespread episode of Late Pennsylvanian tropical humid equability. This humid episode was relatively less intense in western Pangea than in central Pangea, where it led to thicker and more widespread peat formation. Long-term preservation of the peat body was likely facilitated by regional syndepositional tectonism.