Logging Summary
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| IODP Expedition 340T: |
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Atlantis Massif Oceanic
Core Complex
Expedition 340T
Scientific Party
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| Introduction |
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Figure
1. Location map of
Atlantis Massif Core Complex
Site U1309 and path of the
Atlantic transit that took place
during IODP Expedition 340T.
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IODP Expedition 340T returned to Hole
U1309D to investigate hydration of the
crust within the domal core of Atlantis
Massif, located just west of the
spreading axis of the Mid-Atlantic Ridge
at 30°N. Prior seismic imaging showed
considerable reflectivity within the
footwall of this oceanic core complex.
The results of Expedition 340T document
the geologic explanation for at least
some of the impedance contrast,
confirming that borehole velocity of
altered olivine-rich troctolite
intervals at Site U1309 is sufficiently
distinct from surrounding rock to
produce a multichannel seismic
reflection.
Science operations for Expedition 340T
were proposed in an ancillary project
letter (APL), focusing primarily on
completing the wireline logging of
existing Hole U1309D with temperature
and acoustic velocity measurements and a
zero-offset vertical seismic profile
(VSP). This work was carried out over ~5
days during a transit across the
Atlantic Ocean between two full
expeditions. During this time, the ~1415
m deep Hole U1309D was logged with the
triple combo including the Modular
Temperature Tool (MTT), a sonic tool
string, a vertical seismic imager (VSI)
tool string, and a magnetic
susceptibility sonde (MSS-B) tool
string.
Scientific results for Expedition 340T
(Atlantis Massif Oceanic Core Complex
APL), which consist primarily of results
from wireline logging, are summarized in
the Expedition 340T
Preliminary Report.
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Angela Slagle:
Expedition Project Manager/Logging Staff
Scientist, Borehole Research Group,
Lamont-Doherty Earth Observatory of
Columbia University, PO Box 1000, 61
Route 9W, Palisades, NY 10964, USA
Gilles Guerin: Logging
Staff Scientist, Borehole Research
Group, Lamont-Doherty Earth Observatory
of Columbia University, PO Box 1000, 61
Route 9W, Palisades, NY 10964, USA
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