The reconstruction of paleocurrents is crucial for understanding ancient environments and the past climate. Such reconstructions are often based on the distribution of marine species as well as on geochemical proxies. In this talk, a new approach is proposed which uses the occurrence of glendonites as a proxy for cool bottom currents. Glendonites are pseudomorphs after the hydrous carbonate mineral ikaite that only forms in environments characterised by near-freezing temperatures. The pseudomorph has been identified in a number of Phanerozoic successions deposited in high latitudes. However, occurrences in mid-latitudinal sections have also been reported. These occurrences are of particular interest as they document the formation of glendonite in temperate areas, where the prevailing temperatures were above the threshold required for the precipitation of the precursor mineral ikaite.
This study investigates a recently discovered glendonite-bearing interval from the Buttenheim clay pit section (Bavaria, Germany), which represents the southernmost glendonite occurrence in the late Pliensbachian (Early Jurassic). Based on geochemical and sedimentological analyses, the glendonite-bearing interval is interpreted as the result of cold bottom-water masses which originated in the Arctic Sea and migrated southward into the Tethys Ocean, thereby passing the extensive shelf areas of the European epicontinental sea. The influx of cold water caused a significant temperature decrease in the deeper parts of the epeiric sea, which led to the formation of glendonites in lower latitudes. This model can help to explain unexpected mid-latitudinal glendonite occurrences and can serve as a valuable tool for the reconstruction of paleocurrent patterns.