28 SWISSSED Stratigraphy, rocks and fossils of the Gemmi-Lämmerenalp area(VS), a poster for teaching and outreach

The Gemmi-Lämmerenalp area gives easy access to excellent outcrops of a mildly deformed Upper Jurassic-Lower Cretaceous and Paleogene sedimentary sequence of the North-Helvetic Doldenhorn nappe. Traditionally, field camps are organized by the ETH and the University of Lausanne to train students in geological mapping, stratigraphical and structural observation. Also, numerous hikers frequent the area, potentially interested in knowing more about the geology. However, to our knowledge, no recent account on the stratigraphy, sedimentology and fossils of the area has been published, that would be easily accessible to students and and interested public. Here, we present a first working version of a poster that includes a revised stratigraphic column with a chronostratigraphic correlation of the Mesozoic part to the northern Helvetic realm in the space -time diagram by Föllmi (2007, fig. 2). A set of commented panoramas and outcrop images is provided for each formation, showing formational boundaries and typical facies and fossils. Typical fossil groups of each formation are illustrated for teaching purposes, with images from the area, but also with illustrations of well-preserved micro- and macrofossils from elsewhere, including the literature. While Föllmi’s chronology is calibrated by many published fossil occurrences (ammonites, calpionelids etc.) in central and eastern Switzerland, these ages are at present poorly confirmed by fossils in the Gemmi area. A general, lithostratigraphic correlation of the Lämmeren section with Helvetic sections in central and eastern Switzerland seems feasible at the level of formations. In particular, the main disconformities in the Berriasian-Barremian interval can be correlated well. However, the corelation of members is problematic and calls for a refined sedimentological and sequence-stratigraphic analysis of the Gemmi area, as well as the definition of new members. SNF project No. 200021_185067, PI: Claudia Baumgartner-Mora