The Paleogeographic Distribution of Devonian Acritarchs and Biofacies Belts

When the composition of presently commonly known, approximately Lower to Upper Devonian acritarch assemblages in North-South American and West European and North African continental blocks bordering the Atlantic, as shown in a palinspastic map of Bullard et al, (1965) is plotted, four microplankton (acritarch) biofacies belts are conspicuous: I, the Cymatiosphaera/Multiplicisphaeridium biofacies belt; II, the Polyedryxium biofacies belt; III, the Veliferites/Pterospermopsis biofacies belt; and IV, the Maranhites/Navifusa biofacies belt. The four biofacies belts are not directly influenced or controlled by sedimentary facies (lithofacies) differences and not owing to nonsimultaneity of the microplankton assemblages compared and discussed. They are essentially paleolatitudinally influenced and it is proposed that they reflect differences in paleoclimate. The Cymatiosphaera/Multiplicisphaeridium biofacies belt is related to warmer climate, the Polyedryxium biofacies belt belongs to warmer to intermediate climate, whereas the Veliferites/Pterospermopsis biofacies belt and Maranhites/Navifusa biofacies belt being characteristic of the cooler climate.