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Expedition
to the Mariana forearc
Mar.
23 - May 4, 2003
Day
25, April 16th
(click
on any image for the larger version)
Day
25
| Big
Blue is the tallest of the Mariana forearc seamounts at a depth of
only 1240 meters (3968 feet). Jason can be at the summit in less than
an hour after launching. Jason flew over Big Blue throughout the night
and continued most of the day. A long bottom time is one advantage
to working with a ROV
(Remotely Operated Vehicle) as opposed to an occupied-submersible
(little submarine). Occupied-submersibles are launched and retrieved
during daylight hours limiting the dive-time to 8 or 9 hours. Jason
can stay down for days, as long as there is work to do. |
Large brittle star at Big Blue Seamount |
| Sixteen
hours of small rocks, large rocks, gravel, mud, sediment, slopes and
scarps. Not quite so thrilling as
the chimney field on the fault of Quaker Seamount. Jim
wanted to nickname our new discovery and could not resist honoring
the artist/poet/author, Dr. Seuss, whose name we all shouted upon
seeing the geologic feature for the first time. Should it be as Jim
suggests, “The Lorax Chimneys on the Whoville Fault?” |
Shrimp
at Big Blue Seamount |
Sixteen
hours of rocks, mud and sediment—that’s what the geologists saw,
but I also saw fish, sponges, shrimp, jellies, sea fans and sea
stars. It’s not so easy getting a picture of a sponge or a shrimp
on this expedition. Everyone is ready to zoom in for a close-up
of any rock, but it’s only my shy little voice from the back whispering,
“I wouldn’t mind if you zoomed in on that shrimp.” I only say it
about a tenth of the times that I want to. I take a bit of teasing
on being a biologist. “After all,” they say, “geology is the basis
for biology.”
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Jason
returned to the surface for a short break while Patty
and Chris M. prepared their
new invention for deployment. Patty envisioned a core sampling device
that would leave a section of core pipe embedded in the mud of the
sea floor. From previous studies, she knows that fluids and gasses
are escaping at Big Blue and she is hoping that the section left
behind will help concentrate the fluids and gasses for collection.
Chris M. and the other coring technicians at Oregon State University
built Patty’s BAC (Break-Away Coring device).
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Break-away
core and inventors, Patty and Chris M. |
Brittle
star that came up in the core sample |
The
BAC was deployed after dinner as a full moon created sparkling highlights
on the sea’s swells. It was a beautiful night and I thought that
moon was a good omen. The scientists agreed it was a beautiful night,
but they don’t place much value in omens. The core sampling device
returned with a plastic liner full of mud, but the break-away component
was gone—just as planned! Another good omen—the plastic liner held
a picture-perfect core sample of mud layers in a variety of shades
of blue and a thin layer of sediment. In the sediment layer I found
a small brittle star. It was already dead, unable to withstand the
changes in pressure and/or temperature as it came to the surface.
I have saved it for display in my classroom. None of the geologists
were very interested—geology and the associated chemistry are definitely
the focus of this expedition.
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Jason
was launched to go to the break-away core to collect water samples
and to place a party hat (benthic barrel) over the top. Jason wasn’t
in the water for more than a minute when the dive was cancelled
because Medea’s camera was not operating. Medea looks down upon
Jason and is critical to the operations. Back for repairs, we are
hoping for an early morning launch.
Science
Summary - Day 25, April 16th
Science
Objectives, Day 25:
The
twenty-fifth day of the cruise, Apr. 16, we will core a seamount
immediately to the north of Big Blue Seamount that appears to be
recently active. Then, weather permitting, we will dive on Big Blue
Seamount in order to explore the summit mounds. After the dive we
intend to deploy the break-away corer.
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