Small-volume U-Pb zircon geochronology by laser ablation-multicollector-ICP-MS

Scott Johnston, George E Gehrels, Victor Valencia, Joaquin Ruiz

Research output: Contribution to journalArticle

69 Citations (Scopus)

Abstract

U-Pb zircon geochronology is hampered by problems acquiring meaningful geologic ages on zoned grains that retain isotope signatures from multiple growth or thermal events. We present a new method using laser ablation-multicollector-inductively coupled plasma-mass spectrometry to overcome complications associated with intricately zoned zircon crystals through in situ sampling of zircon volumes as small as 12-14 μm in diameter by 4-5 μm in depth (< 3 ng of zircon). Using Channeltron multipliers to monitor Pb intensities in conjunction with a total ion counting method and errors calculated as function of the number of counts, the small-volume technique reproduced published ages on eight Mesoproterozoic-Cretaceous secondary zircon standards precise and accurate within 2%, and an age ∼ 1 Ma too young on a Oligocene-aged grain. Two initial applications of the small-volume technique - the detrital zircon provenance of fine-grained mudstones and shales and the creation of zircon U-Pb age maps to investigate the detrital and metamorphic history of a granulite-facies paragneiss - demonstrate the utility of this technique to a variety of geologic problems and confirm the viability of laser ablation-multicollector-inductively coupled plasma-mass spectrometry as a tool for high spatial resolution U-Pb geochronology.

Original languageEnglish (US)
Pages (from-to)218-229
Number of pages12
JournalChemical Geology
Volume259
Issue number3-4
DOIs
StatePublished - Feb 25 2009

Fingerprint

Geochronology
Laser ablation
ablation
geochronology
zircon
laser
Inductively coupled plasma mass spectrometry
mass spectrometry
laser method
plasma
granulite facies
Isotopes
mudstone
provenance
Oligocene
viability
spatial resolution
isotope
Ions
crystal

Keywords

  • LA-ICP-MS
  • U-Pb geochronology
  • Zircon

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geology

Cite this

Small-volume U-Pb zircon geochronology by laser ablation-multicollector-ICP-MS. / Johnston, Scott; Gehrels, George E; Valencia, Victor; Ruiz, Joaquin.

In: Chemical Geology, Vol. 259, No. 3-4, 25.02.2009, p. 218-229.

Research output: Contribution to journalArticle

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