Daily Update: Sayonara, Kairei
25 deg 20.17S
Longitude: 70 deg 02.31E
Wind Direction: NE
Wind Speed: 10 Knots
Sea State 2
Swell(s) Height: 2-4 Foot
Sea Temperature: 78°F (25.6°C)
Barometric Pressure: 1014.2 MB
Visibility: 18+ Nautical Miles
piece of a black chimney collected by ROV Jason. The chimney wall is
only 0.5 cm thick (about one-fifth of an inch.
By Amy Nevala
yellow, carrot orange and cinnamon brown are the colors of
the rocks we collect at the hydrothermal vents. Turn one
of these rocks in your hand and watch for the glittering
gold crystals, a mineral called pyrite.
Brought from the seafloor and displayed in Knorrs main
lab, they transform the stained wood table into a sparkling jewelry
metallic luster makes them some of the most eye-catching rocks
found on the seafloor, said Geochemist Susan Humphris.
The minerals that make up the rocks are called sulfides,
and the sulfides official
names are tongue twisters: sphalerite, chalcopyrite and wurtzite. They owe their
sparkling existence to the hot, mineral-spurting hydrothermal vents.
Here in the Indian Ocean, when we watch the super-heated
hydrothermal fluids gush from cracks in the seafloor and mix with
the icy seawater, we are seeing the formation of this new sulfide
Studying these sulfide rocks aids us in several ways.
We learn more about the habitat of shrimp, bacteria and other vent
organisms. This helps us to better understand the environment in
which these organisms live.
We also learn from sulfides more about the origin
of ores containing copper. Many ancient copper deposits now on
land formed at the bottom of the ocean. We use copper for many
things, from coins to wires in computers and telephones.
When we look at a hydrothermal vent, we are watching a mineral deposit
forming before our eyes, said Susan. This tells us a lot more about
how they form than by studying mineral deposits on land that are millions of
collects the sulfide rocks using ROV Jason to break chunks from
the black smoker chimneys and gather old sulfides from the seafloor.
Once on board, Susan photographs, describes and catalogs
each rock. Some she cuts with a ceramic saw to share with Microbiologist
Anna-Louise Reysenbach. Anna-Louise grinds the rock and extracts
from the grounds microbial genetic material called DNA to determine
what bacteria live on the chimney.
When the expedition ends, Susan will take over 250
pounds of sulfide rocks back to her lab for analysis. With her
Woods Hole colleagues, she will examine what minerals are present
and determine the chemical composition of the rocks.
She will continue to work with other scientists as
well. For example, she will combine the information she learns
with that of Chemist Karen Von Damm, who studies the hydrothermal
vent fluids that create sulfide rock.
But today, Susan was still in the beginning stages
of her rock processing as we turned away from 25°S for the last time. After a successful night
collecting samples of water, rocks and organisms, we released our elevator
from the seafloor and retrieved Jason. Early this afternoon, we bid farewell
to the Kairei Vent Field.
Though excited about the many rocks, shrimp, crabs
and bacteria we collected here, we are looking forward to further
exploring 24°S, where two days ago
we located a large - and promising - hydrothermal plume, one sign of a still
undiscovered hydrothermal vent field.
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