163 / 352
147
respectively) and the higher
176
Lu/
177
Hf ratios
(0.00083, 0.00090, 0.00035) of domain II zircon
population. Their textures are clearly different
from the rest of domain II rims. They are very
dark in the CL images (much darker than the
rest of domain II zircon) and their oscillatory
growth patterns are faded and blurred. As their
chemical contents are different from the rest of
the Devonian population, and as other zircon
grains with Ordovician–Cambrian ages show the
same textural patterns, it is concluded that this
zircon was altered by solid-state recrystallisation.
Therefore both processes (recrystallisation and
overgrowth) are present within zircon with the
same ages (Devonian) and from the same sample.
As not all the analysed domain II rims have their
corresponding domain I core analysed, it is not
possible to assess the
176
Hf/
177
Hf
(t)
ratio of the
fluid phase from which the overgrowths grew.
7.2. LEUCOSOMES