2 weeks 1 day
Be Whole! Or Hole B?
Submitted by Dena Rosenberger on Fri, 11/16/2012 - 22:45
Where are we now?
Drilling Site U1412B or CRIS-9B, about 300 meters S/SW from U1412A. Off the western coast of Costa Rica, in the Pacific Ocean. Our coordinates are approximately N 8°30 min, W 84°8 min. Partly cloudy, but no rain today. Air temperature is a bit higher at 28 °C (82 °F) and the water temperature is still 33 °C (that’s 91 °F!)
Scientists at Work
We were able to recover whole-round, section half, and discrete sample measurements throughout the day using the The Advanced Piston Corer (APC) is crucial for high-resolution climate and paleoceanographic studies. The APC is a hydraulically actuated piston corer designed to recover relatively undisturbed continuous 9.5 m long oriented core samples from very soft to firm sediments that cannot be recovered well by rotary coring.
They had to switch from the APC, which is good at recovering undisturbed soft to firm sediments, to the The Extended Core Barrel (XCB) coring system is used in sedimentological, climate, and paleoceanographic studies.The XCB is used to recover 9.5 m long core samples from soft to moderately hard formations. The XCB is typically deployed when the formation becomes too stiff to piston core (i.e., upon piston coring "refusal") or when it is not hard enough to permit efficient recovery with the Rotary Core Barrel (RCB). The XCB cutting shoe extends ahead of the main bit in soft sediments but retracts into the main bit as the weight on bit increases when firm lithologies are encountered. The XCB uses the same bottom-hole assembly (BHA) as the Advanced Piston Corer (APC).">Extended Core Barrel (XCB), which can recover moderately hard samples. The cutting part of the XCB is pushed out in front of the main drill bit in soft sediments, but then retracts when it encounters harder rock. The hole turned out to be unstable above the drill bit and kept collapsing.
The core that we were able to recover was dark greenish to greenish-gray clay, with some ash layers. Apparently, some of the sediments were deformed by gas expansion as they were brought to the surface, and there was evidence of possible gas hydrates in some. The microfossils collected put the age at somewhere in the Lower Pleistocene.
As there were still issues in drilling and core recovery, the decision was made to move our position a short distance and try drilling another hole. We moved the ship about 300 meters in the S/SW direction and started drilling a new hole. This new drill site is called U1412B.
When we heard “Core on Deck” again this evening, hopes were high, but dashed when it turned out to be liquidy greenish muck that drained out onto the Core Deck floor when they tried cutting the case.
Life on Board
Our incredible cooking staff, with Efren Adona as Assistant Chef, puts on a fabulous show every night ranging from down home roast beef and potatoes to gourmet vegetarian delights, and beautifully arranged and delightful tasting desserts.
Sharkwaters! Well, not exactly, but a group of sharks congregated off the ship this evening, attracted to the mahi mahi that were attracted to the thousands of squid that were attracted by the flying fish that were attracted by something small that they eat that were attracted by the lights of the ship. Again, not good lighting for pictures, but I was able to take a fuzzy shark picture.
From 1900 meters above sea floor, Hole B, west of Costa Rica where beautiful sunsets abound…
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