COMPARISON OF QUANTITATIVE TECHNIQUES FOR VEGETATIONAL ANALYSIS IN A MIDDLE-PENNSYLVANIAN COAL (IOWA).

摘要

This investigation involved the biostatistical analysis of a Middle-Pennsylvanian coal and its associated coal balls from Monroe County, Iowa. A major goal of the study was to produce semi-quantitative estimates of the vegetable composition of the coal-forming flora. The types of fossil material examined in this study were coal-ball macrofossils, coal-ball miospores and coal miospores. Comparison of the three types of data was facilitated by the use of cluster analysis, which grouped the samples into clusters with similar vegetative composition.; Cluster analysis of coal ball macrofossils, based on the percent composition of six major taxonomic groups, yielded two main clusters and three minor ones. Coal balls in the largest cluster were floristically dominated by leaves and stems of medullosan pteridosperms and small cordaites. Coal balls in the second major cluster contained abundant roots in an extremely degraded peat. Coal balls in the minor clusters were dominated by large pieces of lycopod, sphenopsid or pteridosperm wood. Cluster analysis of the miospores yielded three large groups of samples (Densosporites, Lycospora or Florinites -dominated), which were present in both coal and coal balls, as well as various smaller clusters.; Comparison of cluster membership showed excellent correspondence between the root-dominated and Densosporites clusters, with lesser correspondence between the other macro and miospore clusters.; Comparison of the Lovilia miospore flora with the palynostratigraphic zonation of Iowa coals proposed by Ravn (1986), and that proposed for the Illinois Basin by Peppers (1985) suggests correlation with the Blackoak Member of the Kalo Formation in Iowa or approximately the Pope Creek Coal Member of the Abbott Formation of Illinois.