The Limagne Basin: a journey through modern and fossil microbial deposits

The Limagne Basin (Massif Central, France) originated during a major, European-scale, extensive event (European Cenozoic Rift System), which led to the formation of several rift systems in foreland Alps between Upper Eocene and Pliocene. A fluvio-lacustrine system emplaced basin resulted mixed carbonate-siliciclastic sedimentation microbial metazoan buildups occupy an important place. However, deposits are not exclusive history Basin; nowadays, basin, they still form association with thermal spring systems. fieldtrip was carried out as part Microbialites: formation, evolution diagenesis (M-Fed) meeting (October 2019). objective this excursion assess diversity modern fossil (Chattian Aquitanian) sediments structures three prime locations (the Jussat Chadrat outcrops Grand Gandaillat quarry). detailed description morphologies fabrics their associated biotic components can be used discuss spatio-temporal distribution pattern. Different margin models proposed based on changes distribution, morphology size metazoan-rich through time. outcrop offers novel perspectives unravel lacustrine/palustrine cycles over time establish long-term paleoenvironmental western Aquitanian. These composed (i) lacustrine comprising organic matter-rich marls reflecting period high accommodation, (ii) palustrine made mudstones clayey paleosoils, indicative low accommodation. It is suggested that climatic, tectonic, volcanic local parameters (physiography, substrate) control deposition each different cycles. In addition, mats Sainte-Marguerite La Poix offer opportunity constrain controlling processes at origin mineralization involved microbialites preservation record.