The goal of this project is to understand the causes and modes of microbialite formation in critical periods of Earth history, typified by changing environments using the example of the Permian-Triassic-Boundary mass extinction event, the most fatal ever. In the aftermath of this mass extinction, microbialite-forming microbes became major components of the marine ecosystem, whereas >90% of marine species went extinct. Despite of considerable efforts in recent years, microbialite formation and its environmental significance remain poorly understood. Moreover, understanding processes that controlled the environment in Earth history will help solving environmental problems of today and tomorrow.Research objectives:(1) identify benthic microbial communities and unravel formation mechanisms(2) determine role of EPS-related mineralization(3) answer whether the occurrence of microbialites reflects a change in sea-water chemistry, or extinction of grazing organisms, or a combination of theseComplementary objectives:(1) widen the scientific scope of the fellow by training in cutting-edge techniques(2) increase the international reputation of the fellow and all involved scientists(3) boosting the European science communityTo achieve the project goals, a multiple proxy study will be pursued on well-preserved Early Triassic microbialites from Iran, which includes the analysis of (1) lipid biomarkers and compound-specific carbon isotopes, (2) spatial relationships of organic compounds and carbonate (ToF-SIMS), (3) sulphur isotopes of carbonate-bound sulphate and of sulphide minerals, and (4) petrographic characterization (microscopy, FIB-SEM, TEM). Having confidence in the fellow, in the expertise and experience of mentor Prof. Peckmann, and in the excellent lab facilities at the host institute, the EU will engage in this international highly competitive hot topic, in which scientists from China and the USA are currently at the forefront.