Palynology, phytogeography and climate of the lower carboniferous
Abstract Palynological assemblages of the Tournaisian 2—Visean 1 period from different areas show distinct compositional differences. Based on these differences, three palynophytogeographical areas have been recognized: North Euramerica, South Euramerica, and Australia. A climatic model for this period has been reconstructed using the distribution of climate-sensitive rocks. Climatic belts obtained coincide with the palynophytogeographical areas recognized. Analogously to recent phytogeography, these both palynophytogeographically and climatologically characterized areas are formally termed Regions, viz., the Vallatisporites Region, the Lophozonotriletes Region and the frustulentus Region. Various aspects relevant to the recognition of Regions and their implications for world geography are discussed. The palynoflora from Cathaysia is intermediate in composition between that from the Vallatisporites Region and that from the frustulentus Region. This implies the existence of migration routes between Euramerica and Cathaysia and between Australia and Cathaysia. Consequently, a position of the Asian continent in between Euramerica and Australia is proposed. The palynophytogeography—climatology relationship established for the Tn 2—Vis 1 period has been applied to the whole Early Carboniferous. Differences in entry of taxa between areas could be related to differences in climatic conditions. Since the latter are related to world geography, it has been possible to relate the presence of taxa with world geography and with continental drift. The following conclusions may be drawn: 1. (1) The first appearance in the Late Visean of South Euramerica of taxa which were already present in the Early Visean of North Euramerica, indicates the establishment in the Late Visean of South Euramerica of climatic conditions which were already present in the Early Visean of North Euramerica. In order to explain the changing climatological conditions, a northward drift of Euramerica is proposed. 2. (2) The proposed northward drift of the Euramerican continent provides a suitable explanation for the longer presence in Australia of taxa which disappeared earlier in South Euramerica. 3. (3) Furthermore, the proposed northward drift of the Euramerican continent provides an explanation for the increasing divergence of palynological assemblages between Gondwanaland and Euramerica since the Tournaisian—Visean transition.