Site 1273 is the southernmost drilling target on our transect of sites north of the 15°20´N Fracture Zone. This site was selected based on review of videotapes from Faranaut Dive 16, which recovered samples of peridotite and gabbro.
At 1716 hr on 12 June 2003 we arrived at the coordinates for the Site 1273 camera survey. While we deployed a bottom-hole assembly (BHA) including seventeen 8.25-in drill collars (nominally a total of 159 m long) at the end of the drill string, the subsea camera was lowered along with a positioning beacon. Our camera survey track (Fig. F1) was from west to east starting on a flat, sedimented terrace, moving downslope until we arrived at the edge of a precipitous cliff. During Faranaut Dive 16, the submarine traversed upslope >100 m in <5 min until the seafloor slope sharply decreased at the same water depth as our camera survey. Outcrop was exposed along all of this part of the dive track, and a sample of serpentinized peridotite was collected (Fig. F2). Inferring that we were near the same outcrop recorded on the dive survey videotapes, we moved 50 m back up the shallow slope to deploy the beacon, and at 0515 hr on 13 June we initiated Hole 1273A ~30 m west of the cliff edge.
Only one core was recovered from Hole 1273A (Table T1) before we were forced to abandon coring because of collapse of the borehole wall. Hole 1273A ended at 0920 hr on 13 June as the bit was pulled free of the seafloor.
Hole 1273B was spudded at 1050 hr on 13 June, after offsetting the ship ~15 m east (closer to the cliff edge). Cores 2R to 3R penetrated quickly (from 11.6 to 26.2 meters below seafloor [mbsf] in <2 hr), and, as in Hole 1273A, the driller could not keep the hole cleared of debris. Hole 1273B was completed by 1900 hr on June 13 as the bit was pulled free of the seafloor.
Since our site survey bathymetry data indicated the flat terrace where we drilled Holes 1273A and 1273B continued south for at least 500 m, we began a second subsea camera survey tracking south along the top of the cliff. After moving ~100 m while crossing back and forth across the cliff edge, we located a massive outcrop that we considered an ideal target for coring. At 0100 hr on June 14 we spudded Hole 1273C a few meters west of the cliff in sediment <2 m thick. Core 1R was advanced to 18 mbsf because material collapsing into the hole prevented us from setting the pipe to extract the core barrel. Cores 2R and 3R were difficult to core, as material seemed to be falling into the hole as soon as we stopped coring to make a pipe connection. After recovering Core 3R, the drill pipe would not pass 20 mbsf, indicating 8 m of material had fallen into the bottom of the hole. Given that recovery in all three holes was limited to small fragments of basalt with only two small pieces of peridotite, we chose to end coring attempts at Site 1273.
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