a new study published in the journal of asian earth sciences by dr. matthias alberti from the centre for research and education on biological evolution and environment, nanjing university, and colleagues presents the first absolute estimates of jurassic water temperatures for the central-east iranian microcontinent (ceim).
stable oxygen isotope values of calcitic marine fossils indicate a significant long-term warming throughout the middle and late jurassic, which can be explained by a concurrent major plate tectonic shift of central iran from temperate to tropical latitudes. this southward drift also caused changes in ecosystem composition and sedimentary facies (from lower-middle jurassic siliciclastics including coal beds to the development of a carbonate platform in the callovian and the presence of evaporites in the uppermost jurassic).
in combination with data from other study areas in gondwana and laurasia, the iranian results point to latitudinal temperature gradients as steep as today and absolute water temperatures slightly warmer than today at comparable latitudes. finally, the results emphasize the strong impact of plate tectonics on regional long-term climate patterns in the middle and late jurassic.
see the article
matthias alberti et al. 2022. first estimates for jurassic seawater temperatures based on oxygen isotope analyses of calcitic fossils from central iran: evidence for a major plate tectonic shift? journal of asian earth sciences 236: 105338. https://doi.org/10.1016/j.jseaes.2022.105338