LA-ICP-MS U–Pb dating and trace element analyses of detrital rutile from the Elbtal Group (Saxony, Germany): provenance constraints of the Saxonian Cretaceous Basin

Abstract

The steep sandstone cliffs of the Upper Cretaceous Elbtal Group exposed in the Eastern Erzgebirge and the Zittau Sandstone Mountains are impressive remnants of the Saxo-Bohemian Cretaceous Basin. Despite the excellent exposure, little is known about the provenance. Herein, we present LA-ICP-MS U–Pb and trace element data of detrital rutile grains separated from five different formations of the Elbtal Group to characterise and differentiate potential source regions. The Cenomanian samples of the Eastern Erzgebirge (Niederschöna and Oberhäslich formations, lower Elbtal Group) yield an U–Pb rutile age cluster at 320–330 Ma. The source rock lithology is predominantly of metapelitic origin. The Zr-in-rutile temperatures indicate amphibolite- to lower granulite-facies metamorphic conditions. Thus, the Variscan basement exposed in the Erzgebirge is assumed as proto source. The Middle Turonian to Early Coniacian samples from the Zittau Sandstone Mountains (Oybin, Lückendorf and Waltersdorf formations; upper Elbtal Group) yield similar U–Pb rutile ages with a cluster at 320–330 Ma. The source rock lithology is likewise predominantly classified as metapelitic and the Zr-in-rutile temperatures cluster in upper amphibolite- to granulite-facies metamorphic conditions. Exposures with high-grade metamorphic Variscan basement are assumed as likely proto sources for these sedimentary rocks. Sedimentary structures indicate a northerly source and thus contrast with direct input from the Variscan basement located to the south and east. Thus, the most likely sedimentary model is reworking of sediments that were eroded from the Variscan basement prior to the Turonian and deposited within a basin at the northern margin of the Bohemian Massif. Graphical abstract