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doi:10.2204/iodp.proc.327.106.2011

Operations

Transit to Grizzly Bare outcrop

The R/V JOIDES Resolution departed Site U1362 at 1300 h on 30 August 2010 following installation of a second subseafloor borehole observatory (“CORK”) at that site. The 31 nmi transit to Grizzly Bare outcrop took 3 h at an average speed of 10.0 kt. Upon arrival, the thrusters and hydrophones were lowered and the ship was moved in dynamic positioning (DP) mode to a location midway between the three projected Grizzly Bare holes so that a positioning beacon could be deployed.

Hole U1363A

At 1730 h on 30 August the ship was offset to Hole U1363A (prospectus Site GRB-1A). The sole purpose of drilling Hole U1363A was to determine the depth of basement to avoid impact with an advanced piston corer (APC) core barrel or temperature shoe at the next hole. A two-stand APC/extended core barrel (XCB) bottom-hole assembly (BHA) was made up and tripped to the seafloor, and an XCB center bit was deployed. The seafloor was tagged at 2250 h on 30 August at 2689 meters below rig floor (mbrf). Drilling without coring continued for 2.5 h to the basement contact at 58 mbsf (Table T1). The XCB center bit was recovered, and the drill string was pulled out of the seafloor.

Hole U1363B coring and temperature measurements

The ship was offset 10 m on a bearing of 135°, and Hole U1363B was spudded at 0530 h on 31 August at 2690 m. Cores 327-U1363B-1H through 6H advanced to 42.5 mbsf by 1300 h, at which point the APC was unable to penetrate the sandy turbidite formation. APCT-3 measurements were taken with Cores 3H through 6H. Cores 7X and 8X advanced to 55.0 mbsf by 1610 h. The first SET tool measurement was taken at ~56 mbsf, and coring continued with Core 9X, which advanced through the sediment/basalt interface to 57 mbsf. Core 10X advanced to 61 mbsf and was on deck by 2100 h. The drill string was pulled clear of the seafloor at 2140 h on 31 August.

Hole U1363C coring and temperature measurements

The ship was offset in DP mode to the coordinates for Hole U1363C (prospectus Site GRB-3A), the deepest of the five-hole transect at Grizzly Bare outcrop. Hole U1363C was spudded at 2255 h on 31 August at 2689 mbrf. Hole U1363C was drilled without recovering cores to 170 mbsf. A SET temperature measurement was taken at ~171 mbsf, followed by Cores 327-U1363C-2X and 3X to a depth of 183.2 mbsf. A second SET temperature measurement was taken at ~184 mbsf, followed by Cores 4X and 5X to a depth of 202.4 mbsf. A third SET temperature measurement was taken at ~204 mbsf. At 1445 h on 1 September the SET tool became stuck inside the outer core barrel because of the sandy formation, and the drill string had to be recovered back to the ship. The SET tool was retrieved at 0145 h on 2 September, and the ship was offset 10 m on a bearing of 135°.

Hole U1363D coring

Hole U1363D was spudded at 0745 h on 2 September at 2689 mbrf. Drilling without coring continued using an XCB bit to 198 mbsf. Cores 327-U1363D-2X through 5X advanced to 231 mbsf, the sediment/basalt interface, by 0035 h on 3 September, and the drill string was pulled out of the seafloor at 0700 h, ending Hole U1363D.

Hole U1363E

Hole U1363E was positioned closer to Grizzly Bare outcrop than Holes U1363A and U1363B (within the area approved for prospectus Site GRB-1A) to recover sediments and pore fluids that were less reacted. Hole U1363E was spudded at 0840 h on 3 September and was drilled without coring to determine the depth to basement. The sediment/basalt interface was confirmed at 36 mbsf at 1000 h. The drill string was pulled out of the seafloor at 1125 h, ending Hole U1363E, and the ship was offset 10 m on a bearing of 135°.

Hole U1363F coring and temperature measurements

Hole U1363F was spudded at 1200 h on 3 September, and Cores 327-U1363F-1H through 4H advanced to 35 mbsf by 1600 h. APCT-3 temperature measurements were taken with Cores 3H and 4H. The drill string was pulled out of the seafloor at 1735 h, ending Hole U1363F.

Hole U1363G coring and temperature measurements

The ship was offset even closer to Grizzly Bare outcrop (but still within the clearance area of prospectus Site GRB-1A), and basement contact was established at 17 mbsf by washing down (no hole number was assigned). Hole U1363G was spudded at 2000 h on 3 September, and Cores 327-U1363G-1H through 3H advanced to 24.9 mbsf by 2250 h. The true advance is closer to 17 mbsf because the last core recovered mostly flow-in material. An APCT-3 temperature measurement was taken with Core 2H.

Transit to Victoria, British Columbia (Canada)

The rig floor was secured for transit, and the thrusters were raised at 0930 h on 4 September. The JOIDES Resolution was under way at full speed at 1015 h. The pilot boarded at 0752 h on 5 September, and the first line ashore at Ogden Point, Victoria (Canada), was at 0836 h.

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