International Polar Year 2007–2008 - WMO

278
IPY 20 07–20 08
Fig. 2.8-5. PLATES &
GATES research areas
in Antarctica and the
Southern Ocean.
(Credit: ETOPO2 database, NOAA,
National Geophysical Data Center,
www.ngdc.noaa.gov/mgg/global/
etopo2.html)
timing of shallow- and deep-water opening between
the Indian and Pacific Oceans as well as the motion
between East and West Antarctica can be better
constrained, which is critical to the determination of
the timing of the uplift of the Transantarctic Mountains
and the evolution of the West Antarctic Rift System.
This large-scale continental rift may have played a
role as an additional Pacific-Atlantic gateway at times
when the submarine-based West Antarctic ice sheet
did not exist or retreated entirely.
As global and regional bottom-water currents
are strongly affected by seafloor morphology, the
dynamics of outstanding oceanic plateaus, ridges
and fracture zones as well as the varying morphology
along continental margins and rises (e.g. development
of sedimentary drift deposits) was an additional
subject of the PLATES & GATES investigation. The
Antarctic Circumpolar Current, for instance, is
deviated by the elongated and up to three-kilometer-
high basement ridges of the Udintsev and Eltanin
Fracture Zone systems in the southern Pacific as well
as the Kerguelen Plateau in the southern Indian Ocean.
Investigating the crustal and sedimentary transition
of the deep water Princess Elizabeth Trough between
the shallower southern Kerguelen Plateau and the
Antarctic continent was the aim of a specially designed
Russian-German two-ship seismic experiment with
RV Polarstern and RV Akademic Karpinsky in early
2007. This is just one example of several experiments
in the true IPY spirit: a coordinated, multi-national,
multi-ship effort with a large science added-value
compared to individual experiments. The Russians
conducted further extensive geophysical surveys
along the continental margin of East Antarctica,
which has already resulted in compiled stratigraphic
models of the area from the Riiser-Larsen Sea to
the eastern Wilkes Land margin (e.g. Leitchenkov
et al., 2007). This mapping and interpretation effort