Site summaries (continued)

Site BSB-9

Priority: Primary
Position: 58°37.60′N, 18°15.30′E
Water depth (m): 451
Target drilling depth (mbsf): 152
Approved maximum penetration (mbsf): 158
Seismic coverage: Primary line(s): 68161201: SP 2046 Crossing line(s): 68170648: SP 1804, 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): Seismic reflection data acquired over the Landsort Deep clearly show the most suitable drilling target selected for the purpose of recovering the longest undisturbed postglacial (possible partly deglacial) sediment sequence. Air gun Profiles 68170648 and 68162141 both run along Landsort Deep. From approximately shot point (SP) 1000 in 68170648 and SP 1700 in air gun Profile 68162141, the uppermost horizontally stratified sediment layer is thickening. Assuming a sediment sound speed of 1500 m/s, the horizontally stratified sediment section is ~122 m thick at the thickest part near SP 1900 in Profile 68170648. This profile is intersected by Profile 68161201, and the intersection provides an acoustically well constrained drilling target at a location in the Landsort Deep where the sediment section appears to reach the maximum thickness in the area and where there are no signs of erosion or other disturbances.
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. One additional core for the deep biosphere theme.
Downhole logging program: Standard logging suite: neutron-porosity, lithodensity, gamma ray, resistivity, acoustic, and formation image.
Anticipated lithology: Till(?) overlaid by a horizontally stratified deglacial(?) and postglacial clay sequence.