Clarification of the Lopingian palaeoclimatic conditions of the northwestern coastal regions of Palaeotethys based on the Transdanubian geological record

Abstract

The Lopingian sedimentary rocks of South and South-Central Europe play an important role in reconstructing the same-age equatorial climate of the Pangea. However, geological evidence suggests a mismatch between the previously supposed equatorial monsoonal, tropical summer wet climate and the more arid Lopingian climatic conditions. To clarify the Lopingian climate of the northwest coastal region of the Palaeotethys, palynofloral assemblages and the climatic background behind the occurrence of soil, aridity, biome, and vegetation patterns of present-day arid and semi-arid territories were studied. In contrast to the similar lithological characters and the proposed Lopingian geographical proximity of the Southern Alpine and Transdanubian sequences, notable differences exist between the palynofloras of these regions. While the conifer-dominated, low-diversity Transdanubian flora belonged to the tropical, the more diverse Southern Alpine flora was part of the Permian Euramerican floral kingdom. Based on the occurrence of modern conifers, it is not plausible that Permian ones occupied arid regions. However, the current distribution of juvenile anhydrite, gypsisols and calcisols shows that the similar palaeosoils of the South Alpine and Transdanubian formations were formed in a tropical desert biome. By synthesizing the evidence exhibited above, it can be concluded that arid and semi-arid environments existed along the northwestern margin of the Palaeotethys and the humid, monsoonal regions were restricted to the Hercynian ranges. Local hydrological conditions plausibly had a notable impact on the occurrence of plant taxa in semi-arid regions which can explain the differences in the palynoflora despite the similar palaeoclimates.