Campaign-style titanite U-Pb dating by ICP - Earth Science ...

602603604605606607608609610611612613614615616617618619620621622623624625acetone. Dissolution occurred in 29M HF-trace HNO3 over 3 days at 220ºC in Savillexmicrocapsules. Prior to dissolution, samples were spiked with the ET535 tracer solutionand U and Pb separated by anion exchange chemistry. The U elution involved a twostageprocess. The sample was loaded onto the column in 3 N HCl after the columns hadbeen washed in the same solution. U was eluted using 1 N HBr and dried in Savillexbeakers overnight. Pb was collected in 6 N HCl, a drop of 0.33 N H3PO4 was added andthen dried in Savillex beakers. The U was reloaded into the column in 6 N HCl. Thecolumn was washed with 8 N HNO3 before U was eluted using distilled water or 1 NHCl. This second U procedure was repeated to make sure that the U was concentratedand purified. Finally, a drop of 8 N H3PO4 was added and the sample dried.The U and Pb separates were loaded separately onto degassed rhenium filaments insilica gel and run on a Thermo-Electron Triton TIMS instrument. Data were gatheredstatically using Faraday cups, except 204Pb which was measured on the SEM. Thenecessary Faraday/SEM gain corrections were applied using 205Pb to correct to.Procedural blanks were