Site summaries (continued)

Site BSB-10

Priority: Primary.
Position: 62°46.70′N, 18°02.95′E
Water depth (m): 86
Target drilling depth (mbsf): +30
Approved maximum penetration (mbsf): +40
Seismic coverage: Primary line(s): 71021235 Crossing line(s): 71021316, chirp sonar profile.
Imagery: No photography or video available.
Sampling: Several short (maximum 15 m) sediment cores available from the area (published).
Objectives (see text for details): Two target areas were surveyed north of Härnösand in the easternmost part of Ångermanälven using an EdgeTech chirp sonar subbottom profiler with the SB-216s tow fish. A chirp frequency modulation pulse between 3 and 9 kHz was used. The surveyed area located at about 62°47′N contains a suitable area for drilling where an apparently undisturbed sediment section fills a trough and reaches a thickness of >40 ms TWT (30 m assuming a sound speed of 1500 m/s). The proposed primary Site BSB-10 is located on Profile 71021235, and Profile 71021316 ends 34 m southwest of the proposed site and thus nearly provides a crossing.
Drilling Program: Up to 3 × APC to refusal, XCB to target depth and up to 5 short cores to capture the upper 0.75 m of the sequence undisturbed.
Downhole logging program: Standard logging suite: neutron-porosity, lithodensity, gamma ray, resistivity, acoustic, and formation image.
Anticipated lithology: Varved glacial clay end silt.