Dear friends:
I read somewhere (I think in Hoskin & Schaltergger, 2003 - apologies if I
give the wrong reference - I donšt remember the right one) that in general
the Th/U content of igneous zircons is something like Th/U > 0.5 and in
metamorphic zircons it is < 0.05.
I would like to ask if this is what you see in general (from your experience
with zircon dating) and how much we can rely on this compositional feature
to discriminate between what is "metamorphic" and what is "magmatic" in the
absence of clear textural evidence (such as zoning in igneous zircons).
I thank you very much in advance for your reply.
Wishing you all the best,
hassina
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