Refined conodont stratigraphy at Martenberg (Rhenish Massif, Germany) as base for a formal middle/upper Frasnian substage boundary

Abstract The famous Martenberg section of the eastern Rhenish Massif, Germany, type-section classical Frasnian goniatite and conodont zonations, has been restudied in order to document microfacies development refine stratigraphy around global semichatovae Event/Transgression, proposed level define a future upper substage. More than 8.000 platform elements were identified include new taxa. Palmatolepis jamieae is subdivided into subspecies Pa . , savagei n. ssp., Pa. rosa ssp. δ. Another species, adorfensis sp., was previously partly as while descendens sp. described open nomenclature from Inner Mongolia. Morphotypes are defined Icriodus symmetricus, ljaschenkoae proversa A literature survey shows that eustatic Event can be recognised more 20 regions all continents with (sub)tropical Upper Devonian outcrops. At Martenberg, transgression preceded by thin but distinctive interval unconformities, microbial mats, sheet cracks, currents brought regionally youngest volcaniclastics. data confirm no typical (sensu holotype) occur two beds originally supposed represent Zone its reference section. We fully support conclusion Ovnatanova Kononova (2020) should abandoned. Early related taxa enter at few other globally easily recognisable 10 (= plana Zone). 11 ( feisti Zone) subzones FZ 11a Subzone) 11b nasuta Subzone). base latter coincides Transgression, Subzone shallow shelf settings, substage base. On scale, currently best bed-by-bed documented for facies changes, biostratigraphy middle/upper transition. Therefore, it prime candidate GSSP selection. pelagic successions have potential precise correlation better understanding environmental changes associated Event.