The Isentobel in Central Switzerland: remnants of the Penninic ocean and a source of inspiration for Gustav Steinmann’s idea of young ophiolites

A marine pebbly mudstone from the Swiss Alps: palaeotectonic implications and some consequences for the interpretation of Precambrian diamictites

“…Thus, the resolution of this ''diamictite dichotomy'' (Le Heron et al 2017) is an exciting new field of geological research and will possibly help to better understand the severe climatic changes during the Neoproterozoic ice-house world (''Snowball Earth''). Even though it is beyond the scope of the present paper to further discuss these issues in detail, we want to stress the remarkable similarity between the megablocks in the Lower Sandstone Member of the SRZ sequence and the megaclasts reported by Le Heron et al (2014, 2017. However, whereas the latter are embedded in diamictite and were hence interpreted as passive passengers in a highdensity olistostrome, the former are embedded in undeformed shale and sandstones and hence points towards deposition independent of their surrounding matrix.…”

“…The Penninic and Austroalpine tectonic outliers Klippen of the Iberg (Yberg) area in the Helvetic Alps of Canton Schwyz east of Lake Lucerne (Fig. 2) have attracted geologist's attention ever since the days of Arnold Escher von der Linth around 1845 (Kaufmann 1877;Quereau 1893;Jeannet 1941;Tru ¨mpy 2006;Letsch 2017). Of almost equal interest has been the occurrence of big exotic blocks connected to partly heavily deformed flysch units (supposed equivalents of the Schlierenflysch and the Iberg Wildflysch or Me ´lange) in the footwall of the Mesozoic klippen (Quereau 1893;Heim 1907;Frei 1963;Bayer 1982).…”