Quaternary Borehole QBO Kleinandelfingen-Laubhau - Data Report

pdf NAB 20-03 Quaternary Borehole QBO Kleinandelfingen-Laubhau - Data Report(484.74 MB)

In the context of the sectoral plan "Sachplan geologische Tiefenlager" (SGT) Nagra is currently investigating three siting regions (Jura Ost, Nördlich Lägern, Zürich Nordost) in northern Switzerland to potentially host repositories for radioactive waste. The field exploration project "Quartäruntersuchungen" (QAU) is dedicated to the characterisation of Quaternary deposits within and around these siting regions to further constrain scenarios of their geological long-term evolution. The investigations support the reconstruction of Quaternary landscape evolution.

The borehole (Quartärbohrung, QBO) at Kleinandelfingen-Laubhau (QBO Kleinandelfingen- Laubhau / QKLA, Tab. 1) is part of Nagra's Quaternary investigation programme (QAU; Nagra 2018a). The drill site was chosen to constrain the bedrock geometry and the valley fill of the Marthalen Trough (Fig. 1 and 2). The borehole QKLA was positioned near the crossing of 2D reflection seismic lines 16-QAU-03 and -04 and near the centre of the Marthalen Trough as constrained by 2D reflection seismic data (Nagra 2018b). It was conducted in the period from 1.10.2019 – 10.12.2019 using a combination of Düsterloh Hammer, Prakla coring and wire-line drilling with a triple-tube core-barrel, i.e. with a plastic core liner.

This report covers the request for a documentation of the authorised works on-site (UVEK 2019, Dispositiv 3.36) and documents also the core description and first lab analyses (UVEK 2019, Dispositiv 3.37). The work has been carried out according to the work programme (Arbeitsprogramm, Nagra 2019) and this report corresponds to the data report announced therein.

In this report, we present core images, sedimentological descriptions and geophysical measurements of the cores, all of which were acquired at the University of Bern. Additionally, a report on geophysical borehole logging by terratec Geophysical Services GmbH & CO KG and L. Keller (roXplore gmbh; responsible for quality control) and a technical drilling report by Blétry AG and ABT Wasser- und Umwelttechnik GmbH edited by P. Hinterholzer-Reisegger (Nagra) are presented in Appendices H and I, respectively. This report is the basis for planning further core analysis and later interpretation in the larger geological context.