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Implications for geodynamic mantle
flow models and the geochemical evolution of primary hotspots
IODP Expedition 330 co-chief scientists: Anthony Koppers (Oregon State University)
and Toshitsugu Yamazaki (Geological Survey of Japan)
Integrated
Ocean Drilling Program (IODP) Expedition 330 will drill
four boreholes into underwater seamounts along the Louisville
Seamount Chain, in the southwest Pacific Gyre. The goal of
this cruise is to determine if the Louisville hotspot is a
primary hotspot, and whether or not it moves in concert with
the Hawaiian and Easter hotspots, the other two longest-lived
hotspots in the Pacific Ocean. Results from this cruise have
important implications for modeling mantle fluid flow.
Sampling will consist of drilling and coring four seamounts
in the Louisville Seamount Chain that are 50-77 million years
old (Ma). These seamounts are analogous in age to those drilled
during ODP Leg 197 to the Hawaiian-Emperor Seamounts and therefore
will help determine the movement of the Louisville Hotspot
in relation to that at Hawaii. Each of the four sampling sites
consists of a thin layer of sediments (~10 m) overlaying a
40-100 m layer of unknown composition (possibly lithified
limestones, volcaniclastics and minor lava flows) and basaltic
basement below this. The goal at each site is to drill down
and core through ~350 m of basement.
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Bathymetric map of the Southwest Pacific showing
the prominent Louisville Seamount Trail and the location
of planned primary and alternate dredge sites. |
Leg 330 looks to collect ~1400 m of basaltic basement rock,
in addition to sediment and the unknown layer between the
two, representing an excellent opportunity to study microbial
life in the subsurface basaltic basement. While these rocks
are fairly old, suggesting that metal and sulfate reduction
may be the dominant metabolisms present, they are overlain
by sediment with potentially 100% oxygen penetration, as indicated
by site survey data for IODP Leg 329. This makes the sites
to be drilled during Leg 330 particularly interesting and
exciting because we have no idea what kind of microbial life
may be present in these basement rocks. Where possible (the
sediment coring technique to be used can introduce contaminants-
this will be monitored carefully), sediment samples for geochemistry
and microbiology will be collected and will make a good comparison
with those collected nearby during Leg 329. Overall IODP Expedition
330 promises to provide a wealth of knowledge about microbial
communities in old, basaltic basement.
Learn more about the science and outreach associated with
the Louisville Seamounts expedtion from the links below.
> About our focus
study sites
> Our expedition
schedule
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