We derive estimates of temperature of the Australian
continental mantle between 80 and 350 km depth from two
published S-velocity models. Lithospheric temperatures range
over about 1000°C, with a large-scale correlation between
temperature and tectonic age. In detail however, variations
ranging from 200 and 700°C occur within each tectonic
province. At the current seismic resolution, strictly Proterozoic
and Archean blocks do not have substantially different
temperatures, nor does the Phanerozoic lithosphere east and west
of the Tasman line. Temperatures close to an average (moist)
MORB source mantle solidus characterize the eastern seaboard and
its offshore. Differences between the temperatures derived from
the two velocity models illustrate the importance of
well-constrained absolute velocities and gradients for physical
interpretation. The large range of lithospheric temperatures
cannot be explained solely with documented variability in
crustal heat production, but requires significant variations in
mantle heat flow as well.
|
