Multi-proxy detrital accessory mineral analysis reveals the age and origin of eroded basement: a case study from the western Magura Nappe, Outer Western Carpathians, Poland

Abstract

The Magura Nappe is the largest unit in the Outer Western Carpathians. However, there are limited single-grain provenance data from the Magura Nappe and so far only from Paleocene-Eocene sedimentary rocks, with no single-grain provenance information from Mesozoic rocks. Here we present the first multi-proxy U-Pb and trace-element analysis of detrital minerals (zircon, rutile and apatite) from the Upper Cretaceous ‘Biotite Sandstones’ of the Jaworzynka Formation in the Magura Nappe. The data show that in the western part of the Magura Nappe the eroded crystalline basement to the Biotite Sandstone (Jaworzynka Formation) was predominantly high-grade felsic metamorphic and igneous rocks, with subordinate detritus from mafic protholiths. Detrital rutile and apatite ages correspond with the main peak seen in detrital zircon spectra and record late Variscan (320–330 Ma) tectonomagmatic activity. The Campanian Biotite Sandstone represent an episode of rapid basement erosion, transport and sedimentation, as well as rapid burial, that led to excellent preservation of primary rock-forming minerals (biotite). We envisage a depositional setting on the slopes of the North European Platform and the Moldanubicum (Hostýn Ridge) as the sediment source. The similarity of the multi-proxy U-Pb spectra in Late Cretaceous and Eocene sediments implies that sediment routing system (with sourcing from the northwest) was relatively long lived.