Cyclostratigraphy of the Middle to Upper Ordovician successions of the Armorican Massif (western France) using portable X-ray fluorescence

Abstract. To expand traditional cyclostratigraphic numerical methods beyond their common technical limitations and apply them to truly deep-time archives, we need reflect on the development of new approaches sedimentary archives that are not traditionally targeted for analysis but frequently occur in impoverished record. Siliciclastic storm-dominated shelf environments a good example such records. Our case study focuses Middle Upper Ordovician siliciclastic successions Armorican Massif (western France) well-studied examples terms sedimentology sequence stratigraphy. In addition, these sections protected geological heritage due extraordinary quality outcrops. We therefore tested performance non-destructive high-resolution (centimeter-scale) portable X-ray fluorescence natural gamma-ray analyses an outcrop obtain major trace element compositions. Despite challenging conditions tidal beach zone, our geochemical provide useful information regarding general lithology several specific features as detection paleo-placers or discrimination between different types diagenetic concretions nodules. Secondly, data used experiment with application commonly techniques this environment, non-traditional sedimentological setting analysis. parts section relatively homogeneous lithology, spectral power bandpass filtering hint towards potential astronomical imprint some cycles, needs further confirmation absence more robust independent age constraints.