Palaeotemperature calibration of palynological assemblages and palaeovegetation through the last stage of the Late Palaeozoic Ice Age

The Late Palaeozoic Ice Age (LPIA), was one of Earth's most extensive and long-lasting glacial episodes, spanning roughly from 350 to 260 Ma. The Arabian Peninsula is long known to have experienced the LPIA at its position at the northern edge of Gondwana throughout the Late Carboniferous (Pennsylvanian) to the Early Permian (Cisuralian) and particularly the deglaciation that occurred from the latest Gzhelian, through late Sakmarian/early Artinskian to mid-Kungurian. Modelling of Mean Annual Surface Temperature (MAST; Li et al. 2022) for this period superimposed on palaeogeographic maps based on PaleoDEM and points/polyline/polygon (rotation and geometry files) of Scotese and Wright (2018) allows temperature-calibration of the succession of palynological assemblages. A number of trends and generalisations are possible related to MAST change between -0.2°C to -3.4°C  (latest Gzhelian) and 9.3°C to 11.1°C (mid-Kungurian). As a group, the plants that produced monosaccate pollen (now extinct) appear amongst the most tolerant of MAST increase, with certain genera, for example Plicatipollenites and Cannanoropollis, being common throughout. Punctatisporites probably produced by the simplest most cold-adapted plants such as mosses were the most sensitive to climate warming. Cingulicamerate spores and fern spores of Microbaculispora and Horriditriletes are similarly sensitive to warming conditions particularly as MAST reaches above 0°C. MAST above 0°C appears to have stimulated a surge of caytonialean-type, probably upland, trees or shrubs that produced Pteruchipollenites indarraensis, although continued warming seems to have been at least partly responsible for restricting their distribution because such plants are almost absent at 208 Ma where MAST is ~10°C. Kingiacolpites subcircularis, probably produced by a cycad, may, also have been stimulated by MAST reaching above 0°C. Some of these trends in palaeovegetation in response to climate warming may have relevance in studies of modern environmental change.