Provenance of Early Pleistocene sediments based on a high-resolution sedimentological dataset of borehole Petten, southern North Sea

Abstract

In 2018, a fairly complete core (Petten BH 1) reaching over 300 meters into the unconsolidated, dominantly sandy Pleistocene sequence was recovered in the northwest of the Netherlands, in the coastal dune area along the present North Sea. The good recovery of the interval below 200 m depth allows combined sedimentological and palynological study in the same core. Therefore, we conducted two parallel studies of sedimentology (this MSc thesis) and palynology (MSc thesis by Krom) in the interval 200 – 380 m of the Petten BH 1, which is believed to cover the Early Pleistocene sequence in the southern North Sea Basin. In this study, we aimed to 1) reconstruct the sedimentary environment, 2) investigate the provenance of the sediments, and 3) find out the reworking and hiatus in the sedimentary history. We have used lithological-sedimentological logging, grain size analysis, heavy mineral analysis and element concentrations measurement to conduct the research. The results reveal a shallowing upwards water depth trend, with superimposed glacial-interglacial sea-level cycles, which makes that the core can be divided into three intervals, the marine/pro-deltaic phase (330 – 380 m), littoral/deltaic front phase (270 – 330 m), and fluvial/delta plain phase (200 – 270 m). As the analysis of heavy mineral composition is still in progress, the provenance of sediments has not yet been convincingly identified. However, the good correlations between heavy mineral weight percent and Zr, Ti are supporting evidences of considerable components of easterly source (Eridanos). Erosion events occurred frequently from 330 m upwards, due to sea level change and river response to this (low stand incision, transgressive reworking, high stand avulsion; repeatedly). Some erosion events are clearly recognized as sediment contacts, while other erosion events, including major erosion events in the fluvial sediment, are in the intervals that were not recovered. These findings also held up when they were integrated with the palynological study, strengthening our sedimentary environmental conclusions.