International Polar Year 2007–2008 - WMO

Plate tectonics and polar gateways in
the Earth System
The thermohaline ocean circulation is an important
component in the global climate system. The ocean
currents transport heat and matter around the globe
and are thus likely to cause global environmental
changes. At large geological timescales, the global
circulation is affected by geodynamic processes
which control the motions of the lithospheric plates
as well as crustal uplift and subsidence. Plate tectonic
motions have constantly altered the shapes and
geometries of the ocean basins and the distribution of
land masses. In particular, the geometries of so-called
oceanic gateways act as continental bottlenecks in the
exchange of water masses between ocean basins and
are, therefore, key parameters in simulating palaeo-
ocean current systems and palaeoclimate scenarios.
The reconstruction of the geometries of ocean
gateways, basins and their continental margins feeds
into numerical models studying the tectonic effect
on climate changes. The IPY lead project PLATES &
GATES (no. 77) focuses on tectonic reconstructions
and sedimentary processes in Mesozoic and Cenozoic
times and, in particular, on the transition from climatic
greenhouse to icehouse conditions.
For the reconstruction of the oceanographic
conditions at times of climate changes, tectonicmagmatic,
geodynamic, sedimentary and
biostratigraphic processes have been studied in
the polar and sub-polar regions. Scientists of 16
nations have been involved in geophysical surveying
techniques, tectonic measurements and sedimentary
Fig. 2.8-2. Methods
in the exploration
of the subglacial
Gamburtsev
Mountains.
(Image: British Antarctic
Survey)
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