Dating Micrometre‐Thin Rims Using a LA‐ICP‐MS Depth Profiling Technique on Zircon from an Archaean Metasediment: Comparison with the SIMS Depth Profiling Method. Issue 4 (December 2014)

• Record Type: Journal Article
• Authors: Kelly, Colter J.; McFarlane, Christopher R.M.; Schneider, David A.; Jackson, Simon E.
• Is Part Of: Geostandards and geoanalytical research. Volume 38:Issue 4(2014)
• Page Start: 389
• Page End: 407
• Publication Date: 2014-12
• Subjects: Analytical geochemistry -- Periodicals; Géochimie analytique -- Périodiques; 551.9
• DOI: 10.1111/j.1751-908X.2014.00314.x
• Languages: English
• ISSNs: 1639-4488

Abstract

<abstract abstract-type="main" id="ggr12055-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) was examined as a tool for measuring isotopic variation as a function of ablation depth in unpolished zircon from an Archaean metasediment specimen. This technique was able to identify micrometre‐thin (&gt; 3 μm) isotopically distinct mineral domains characterised by <italic>ca</italic>. 100 Myr younger ²⁰⁷Pb/²⁰⁶Pb ages associated with 2<italic>s</italic> age uncertainties as low ~ 0.2%, as well as elevated U content relative to grain interiors (up to an order of magnitude). Our calculated drilling rate suggests that each laser pulse excavated depths of ~ 0.06 μm. Ages resolved through the LA‐ICP‐MS methods overlap the 2<italic>s</italic> uncertainties of ²⁰⁷Pb/²⁰⁶Pb ages measured using SIMS depth profiling on the same zircon population. The rims were further evinced by the detection of relative enrichment (&gt; 3 orders of magnitude) in REE in the outermost micrometres of the same zircon, measured using a different and independent LA‐ICP‐MS depth profiling technique. We propose a LA‐ICP‐MS U–Pb technique capable of quickly identifying and quantifying rims, which are indication of late, yet geologically significant, fluid events that are otherwise undefined.</p> </abstract>