FLORAL ASSEMBLAGE OF THE D-COAL SEAM (CRETACEOUS) - IMPLICATIONS FOR BANDING CHARACTERISTICS IN NEW-ZEALAND COAL SEAMS

Two complete vertical sections were studied from the uppermost Cretace ous ''D'' coal seam near Greymouth, New Zealand. The thickest and most concentrated vitrain bands occur in the paleomire centre and bands ar e thinner and less abundant at the paleomire margin. Botanical analysi s of the vitrain bands indicates they formed entirely from the seconda ry xylem (wood) of gymnosperms. Palynomorphs indicate that there is no consistent correlation between conifer pollen abundance and the degre e of vitrain banding. However, maximum preservation of vitrain bands c oincides with an inferred transition from a rheotrophic mire (as indic ated by Phyllocladidites mawsonii pollen) to an acidic and possibly om brotrophic system (as indicated by the abundance of Gleicheniaceae spo res). This suggests that the presence/absence of gymnosperm secondary xylem as vitrain bands is controlled at least in part by mire chemistr y.