213 nm Nd-YAGレーザーアブレーションICP質量分析装置を用いたジルコンのU-Pb局所年代分析 : SHRIMPデータとの整合性の検討

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

勝部 亜矢

早坂 康隆

坂口 綾

高橋 嘉夫

地質学雑誌

The Journal of the Geological Society of Japan

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 213 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 provenance analysis. Consistency of the system was assessed by measuring four well-characterized standard zircon samples (Plešovice, SL13, AS3, QGNG), with weighted mean measured 206Pb/238U and 207Pb/206Pb ages of the samples only slightly offset from the reference ages and with acceptable MSWD values, barring the 207Pb/206Pb age of the Plešovice zircon, which had a low 207Pb signal intensity. Detrital zircon grains were re-measured by LA-ICP-MS to assess consistency between the LA and SHRIMP systems, with 207Pb/206Pb ages for zircons older than 1000 Ma in excellent agreement with SHRIMP ages; typical offsets were between −3.9% and 0.3%. In addition, zircons younger than 1000 Ma had more accurate 206Pb/238U than 207Pb/206Pb 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.

LA-ICP-MS

detrital zircon age dating

Nd-YAG

SHRIMP

日本語

日本地質学会

© The Geological Society of Japan 2012

[ISSN] 0016-7630

[ISSN] 1349-9963

[NCID] AN00141768

[DOI] 10.5575/geosoc.2012.0051

[DOI] https://doi.org/10.5575/geosoc.2012.0051