The importance of parameter selection in studies of detrital zircon provenance: An example from Mesozoic deposits of the Bohemian Massif foreland (Poland)

Abstract

Detrital zircons are commonly used to identify sediment provenance, but usually only their ages are employed for interpretation. We here test the combination of four data types: crystallization ages, Th/U values, cathodoluminescence-induced internal textures, and grain shapes. Six samples of zircons from Triassic and Cretaceous deposits from the northeastern foreland of the Bohemian Massif (Poland) were used to identify as accurately as possible source rocks and their paleolocations, changes in erosional levels of source areas, and transport directions. The samples contain ten age populations, among which Carboniferous and Neoproterozoic zircons dominate, but the use of four parameters allowed subtle differences between the samples to be recognized; this makes interpretation more accurate and more reliable. A comparative analysis based on over 20,000 data points collected from ~200 contributions allowed us to identify the equivalents of crystalline source rocks, which were high-grade and medium-grade metamorphic rocks of the Bohemian Massif (mostly granulites) in the case of complex-textured zircons, and Bohemian magmatic rocks along with pyroclastics in the case of oscillatory-zoned grains. The source rocks were located in the northeastern and eastern parts of the massif, where the proportions of the specific rocks exposed to erosion have changed significantly from the Mesozoic to the present. We found distinct changes in the erosional levels of source areas caused by removal of sedimentary cover and the erosion of crystalline rocks, combined with tectonic movements, particularly in the Olenekian and Coniacian. The transport of debris from the southwest and west during the Induan–Anisian, as well as from the south and north during the Norian, were largely controlled by paleogeography. The Cretaceous transgression resulted in the supply of grains mainly from the nearest units during the Cenomanian and Coniacian. We strongly recommend using a combination of at least these four parameters in provenance studies.