- Arbeitsbericht NAB 18-40Télécharger
The boreholes (Quartärbohrung, QBO) at Riniken (QBO Riniken-1 / QRIN1, QBO Riniken-2 / QRIN2) were the first drilling operations within Nagra’s Quaternary investigation program (“Quartäruntersuchungen” QAU; compare Nagra 2017) project. The drill site in Riniken was chosen to characterize the geometry and infill of the Rinikerfeld channel, which is an elevated paleo-channel detached from the modern Lower Aare valley (Fig.1 and 2; Bitterli-Dreher et al. 2007, Graf 2009). Originally, only one borehole was foreseen. Due to loss of core material in the first borehole (QRIN1) over geological key intervals (roughly between 4.5-18.0 m and 31.1-41.2 m) it was decided to carry out a second borehole (QRIN2) within a few meters nearby to close the recovery gaps. The first borehole QRIN1 was conducted from 06.-21.03.2018 using a combination of Düsterloh hammer drilling and wire-line drilling (triple-tube core-barrel, i.e. with a plastic core liner). The second borehole QRIN2 was conducted from 22.03.-11.04.2018 only using the Düsterloh hammer throughout and succeeded in coring the missing intervals. The two drillings were combined into a composite profile (ref. section 2.3.2), which is called QBO Riniken composite (QRIN).
This report covers the request for a documentation of the authorized works on-site (BFE 2017, Dispositiv 5.6) and documents also the first results of the lab analyses (BFE 2017, Dispositiv 5.7). The works on-site described in the work program (“Arbeitsprogramm”, Nagra 2018) have been carried out. This report corresponds to the data report that was announced in this work program.
In this report, we present core images, sedimentological descriptions, and geophysical measure-ments of the cores, all of which were acquired at the University of Bern. Additionally, borehole geophysical reports of BLM Gesellschaft für Bohrlochmessung mbH and technical reports of Fretus AG and Nagra are presented in appendices I and J, respectively. This report is the basis for planning further core analysis and later interpretation in the larger geological context.