PALEOCLIMATIC CONDITIONS ACROSS THE MID-CARBONIFEROUS BOUNDARY REFLECTED IN PALEOFLORA ASSEMBLAGE OF PEAT-FORMING ENVIRONMENTS (LATE VISEAN THROUGH BASHKIRIAN, LUBLIN BASIN, POLAND)

The pericratonic Lublin Coal Basin contains a condensed but relatively complete section across the Mississippian-Pennsylvanian boundary in which coal-bearing beds alternate with marine limestones. Systematic palynological investigations of the coal seams of 16 successive parasequences (designated A-P) from eight boreholes were originally made to aid in stratigraphic correlations. A reinterpretation of the palynological data using natural affinities allows the for the reconstruction of floral assemblages and an interpretation of paleoecological and paleoclimatic trends. The following ecological groups were distinguished: arborescent lycopsids, herbaceous lycopsids, arborescent sphenopsids, ferns/pteridosperms, Cordaites/conifers, and fungi. Palynological taxa of unknown affinity make up only a small percentage of 1-3% of the samples. The Visean-Serpukhovian boundary is marked by the appearance of new palynomorph taxa and an increase in diversity. Arborescent lycopsids dominate coals of parasequences A and B (47 and 52%) but otherwise the two units are different having herbaceous lycopsids (36% in A) and ferns/pteridosperms (38%) as their second most common component. Parasequence C has poor preservation of palynomorphs, but nonetheless serves as confirmation of a hiatus/paleo-weathering event comprising parts of chronozones E1 and E2. Parasequences D through G are dominated by herbaceous lycopsids (66-52%). The following parasequences H to P (latest Serpukhovian through Bashkirian) are all dominated by increasing percentages of arborescent lycopsids (45-87%) with herbaceous lycopsids and ferns/pteridosperms contributing low percentages (7-23%). These changes can be interpreted as a paleoecological signal of the degree of wetness in these tropical, peat-forming, isotaphonomic settings. The Serpukhovian (parasequences A-H) is characterized in the mires by fluctuating wetness with dry intervals and exposed peat while in the Bashkirian the dominance of arborescent lycopsids points to a rather consistently high water table.