Tag Archives: uranium lead isotope decay

The provenance of detrital zircon

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detrital zircon from Pleistocene dune sands, northern NZ. Note relatively sharp crystal faces

This post is part of the How To…series – using zircon geochronology to decipher provenance

Zircon is a common accessory mineral in igneous and metamorphic rocks so it’s not surprising that it is also a common constituent of sedimentary heavy mineral suites. Detrital zircon has assumed a remarkable popularity over the last 2-3 decades as a provenance indicator because:

  • crystals contain measurable amounts of uranium (U), lead (Pb) and thorium (Th) isotopes and can therefore be dated radiometrically,
  • zircon is resistant to chemical and mechanical change – crystals can survive multiple sedimentary cycles (i.e. episodes of erosion from source rocks, deposition, burial and uplift, whereupon the whole process begins anew), and
  • they commonly contain multiple stages of crystal growth that record magmatic, metamorphic and depositional episodes.

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