Site M0062

Abstract

IntroductionDuring Integrated Ocean Drilling Program (IODP) Expedition 347, cores were recovered from four holes at Site M0062 (Ånger-manälven River estuary), with an average site recovery of 99%. In addition, two shallow gravity (Rumohr) cores were acquired. The water depth was 69.3 m, with no tidal range. Existing data sets, including seismic reflection profiles, were evaluated prior to each site to attempt to guide the initial drilling with an anticipated lithologic breakdown. The total time spent on station was 1.03 days. Operations Transit to Hole M0062AOperations in Hole M0061C were completed at 1220 h on 5 October 2013. The vessel then awaited the arrival of a pilot at 1600 h before transiting to Hole M0062A (proposed Site BSB-11). Hole M0062AThe vessel arrived on site at 1810 h on 5 October 2013 and commenced operations, having built the dynamic positioning (DP) model ( Table T1). The uppermost 0.5 m was not cored because of the potential presence of harmful contaminants associated with historic paper mill outputs. In accordance with the risk assessment, additional personal protective equipment (PPE) was worn for the first core runs at this site.Eleven piston cores and one hammer sample were collected at this site on 5-6 October. As at Site M0061, the end of the hole was called when drilling encountered the sand lithology underlying the varved sequence. In this hole, the operation was terminated at 35.90 meters below seafloor (mbsf), and the vessel prepared to move over to Hole M0062B.A total of 12 coring attempts were made in Hole M0062A, along with one open-hole section at the surface (to avoid coring contaminated sediments). The maximum hole depth was 35.90 mbsf with a recovery of 97.41% (inclusive of the open-hole 0.5 m) and 97.82% when the open-hole interval is removed from the calculation.

Site M0061

“…Although NGR returns to high values in the middle portion of Unit III, NCR remains low to the bottom of the hole. A similar trend in NGR data is observed at nearby Site M0062, located in Ångermanälven River estuary (see "Physical properties" in the "Site M0062" chapter [Andrén et al, 2015b]). Low NCR may indicate high water content in the cores, which is consistent with P-wave velocities in Unit IV that vary around ~1500 m/s (speed in water).…”