U-Pb zircon dating using Nd-YAG (213 nm) Laser ablation-ICP-MS, and evaluating the consistency with SHRIMP dating

Abstract

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is a powerful tool for rapid and precise U-Pb zircon age dating. Here, we report U-Pb ages for detrital zircons determined using nm Nd-YAG LA-ICP-MS analysis, and compare these results with those determined using a sensitive high-resolution ion microprobe (SHRIMP) to evaluate approaches for detrital zircon age dating during prove-nance analysis. Consistency of the system was assessed by measuring four well-characterized standard zircon samples (Plešovice, SL, AS, QGNG), with weighted mean measured Pb/ U and Pb/ Pb ages of the samples only slightly offset from the reference ages and with acceptable MSWD values, barring the Pb/ Pb age of the Plešovice zircon, which had a low Pb signal intensity. Detrital zircon grains were re-measured by LA-ICP-MS to assess consistency between the LA and SHRIMP systems, with Pb/ Pb ages for zircons older than Ma in excellent agreement with SHRIMP ages; typical offsets were between-.% and .%. In addition, zircons younger than Ma had more accurate Pb/ U than Pb/ Pb ages. Both LA-ICP-MS and SHRIMP techniques produce results that are in excellent agreement, barring a few analyses that were affected by zircon heterogeneity or zoning. ノート