Titel: The European continental crust through detrital zircons from modern rivers: biasing effects in the detrital zircon record
Paula Castillo1, Heinrich Bahlburg1, Rodrigo Fernández2, Mark Fanning3, Jasper Berndt4
1Institut für Geologie und Paläontologie, University of Münster, Germany; 2Departamento de Geología, Universidad de Chile, Chile; 3The Australian National University, Australia; 4Institut für Mineralogie, University of Münster, Germany
Veranstaltung: GeoKarlsruhe 2021
We present U-Pb, Lu-Hf, and O isotopic data, as well as size-shape data for approximately 3700 detrital zircons from 15 European rivers. In combination with geomorphological information for each river basin (area, drainage length, and hypsometric curves), we evaluate the representativeness and biases affecting such datasets. The new data allow us to demonstrate that the detrital zircon record from major rivers represents all relevant geological events in Europe at the continental scale, with detrital zircon ages ranging from Cenozoic to Archean. Several age peaks can be linked to different orogenic cycles and the formation of supercontinents such as Pangea and the Variscan Orogen, the largest episode of crustal reworking in Europe. These Variscan detrital zircons occur in all rivers, but Permian post-Variscan were only found in the Po (with significant crustal contamination) and Glomma rivers (with radiogenic and mantle-like signatures). Other important age clusters are the Alpine and post-Alpine Cenozoic 25-40 Ma and juvenile 0.2-10 Ma, the Caledonian 400-490 Ma, and the Avalonian-Cadomian 540-650 Ma. Detrital zircons of 930-1170 Ma and 1400-1700 Ma are significant in Scandinavia, as well as ca. 1850 and 2500-2900 Ma in east Europe. Despite the good representation of the different geological events in Europe, this does not occur when analyzing detrital zircon at smaller scales (i.e. the basin scale). The presence, importance, and proportions of peaks are strongly dominated by factors such as fertility, zircon-size-shape, and other geomorphological aspects. Excluding fertility, these factors alone can bias the proportion of peaks by up to 10%.
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