SITE 1053
(Proposed Site BN-4Alt)

Hole 1053A
After the 5-nmi transit from Site 1052, we deployed a beacon at the GPS coordinates for BN-4Alt at 2030 hr on 6 February. By midnight the driller was attempting to spud Hole 1053A with the XCB. The driller gently lowered the bit to determine the seafloor depth and observed a reduction in drill string weight at 1622 mbrf. This was very close to the corrected PDR measurement of 1622.4 mbrf, and he assumed this was the seafloor depth. The bit was rotated and advanced with the XCB for 9.6 m without any discernable weight taken by the formation (reduction in drill string weight). When we retrieved the core barrel, it was empty. We then attempted an APC core over the next 9.6 m interval, but it too came up empty. On our third attempt at a mudline core, APC Core 1053A-1H recovered a nearly full barrel (9.42 m), which implied a mudline depth of 1641.0 mbrf. This was 18.6 m deeper than the observed PDR water depth.

APC Cores 1053A-1H through 15H were taken from 0 to 139.0 mbsf. APC Cores 1053A-3H to 15H were oriented using the Tensor tool. Core 15H did not achieve a full stroke, so we switched to XCB coring. XCB Cores 16X through 20X were taken to 183.2 mbsf, where coring was terminated. The bit was pulled out of the hole and cleared the seafloor at 1820 hr on 7 February.

Hole 1053B
Without offsetting the vessel, we spudded Hole 1053B with the APC at 1900 hr on 7 February. The mudline depth calculated from the recovery of the first APC core was 1641.8 mbrf. APC Cores 1053B-1H through 14H were taken from 0 to 127.4 mbsf after which we switched to XCB coring. Adara heat flow measurements were obtained at 22.9, 51.4, and 79.9 mbsf (Cores 3H, 6H, and 9H, respectively). XCB Core 1053B-15X through 20X were taken to 182.4 mbsf. The bit was pulled out of the hole and cleared the seafloor at 1220 hr. We retrieved the drill pipe and spent an extra 3 hr for the routine end-of-leg bottom-hole assembly inspection. At 1800 hr on 8 February, the drilling equipment was secured and we began the transit back to Site 1050 to core Hole 1050C.


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