An Acetic Acid-Based Extraction Protocol for the Recovery of U, Th and Pb from Calcium Carbonates for U-(Th)-Pb Geochronology

作者：Mason Andrew J^*; Henderson Gideon M; Vaks Anton

来源：Geostandards and Geoanalytical Research, 2013, 37(3): 261-275.

DOI：10.1111/j.1751-908X.2013.00219.x

• U-Pb
• speleothem
• ion-exchange chromatography
• geochronology
• ICP-MS

A new method for the simultaneous recovery of U, Th and Pb from ca.0.5g calcium carbonate samples for the purpose of U-(Th)-Pb geochronometry is presented. The protocol employs ion-exchange chromatography. Standard anion exchange resin (AG 1-X8 100-200 mesh) was used as the static phase, and 90% acetic acid was used as the mobile phase to elute the unwanted matrix components; dilute nitric acid was used to elute the U, Th and Pb. Blanks of 1.8pg Th, 6.4pg Pb and 8.4pg U were obtained. The protocol was evaluated by determining the isotopic composition of U-Th-Pb separates obtained from an in-house reference material (prepared from a natural speleothem) by MC-ICP-MS. An independently dated speleothem was also reanalysed. Based on these tests, the extraction protocol had an acceptable blank and produced a Pb separate sufficiently free of matrix-induced instrumental biases to be appropriate for U-Th-Pb chronology.

• 出版日期2013-9