Timing of mass redeposition of sponge spicules from the peri-Tethyan shelf into the deep Carpathian Basin and their relation to mid-Cretaceous global sea level changes

Abstract

Abstract Extensive Albian–Cenomanian sponge growth on the European peri-Tethyan shelves depended on sea level fluctuations that caused significant shoreline shifts and forced facies migration across shelves and partial redeposition of sponge spicules by gravitational currents into deep basins. Such phenomena played important roles in accumulation in the Carpathian Basins, a part of the western Tethys Ocean along the southern slopes of the European platform. Spiculitic deposits formed thick bodies in the mid-Cretaceous flysch of the Silesian nappe. This study reports new, detailed biostratigraphic and chemostratigraphic (δ13Corg) data from a reference section in the Outer Carpathians that were used to date this paleoceanographic phenomenon. A high-resolution analysis of a continuous, 46.5-m-long sedimentary deep-water succession exposed in the Silesian nappe reveals that biogenic input of numerous sponge spicules occurred from latest Albian through middle Cenomanian time, controlled by third-order sea level oscillations. Chemostratigraphic data with biostratigraphic control mark carbon isotope excursions that are characteristic of the mid-Cretaceous (Albian–Cenomanian boundary interval containing oceanic anoxic event (OAE)1d, mid-Cenomanian event (MCE) Ia, MCE Ib, and MCE II) and allow precise determination of the beginning and termination of mass sponge spicule redeposition. The onset of redeposition corresponds to the top of OAE1d, which records a global regressive event (KAl8). The mass redeposition of biogenic material ended between MCE Ib and MCE II during the KCe3 eustatic event. The stratigraphic data indicate that mass redeposition of spiculitic deposits lasted ca. 4.5 Ma, with an average sedimentation rate of ~5 mm kyr–1. Precisely determining the duration of mass redeposition of spicule-bearing material into the Silesian Basin enables their correlation with deposits in epicontinental basins.