U-Pb dating by zircon dissolution method using chemical abrasion

chemical abrasion was carried out on zircons grains of the temora ii standard for u-pb dating prior to analyses using in situ laser ablation-multicollector ion coupled plasma mass spectrometer (la-icpms) followed by the isotope dissolution thermal ionization mass spectrometer (id-tims) method. the proposed methodology was herein applied in order to reduce primarily the effects of secondary pb loss, the presence of common lead and/or silicate impurities. nine temora ii zircon grains were analyzed by the laser ablation method yielding an age of 418.3±4.3 ma. zircon grains of a same population were separated for chemical abrasion before dissolution and mass spectrometry analyses. six fractions of them were separated for isotope dissolution using 235u-205pb mixed spike after we have checked and assured the laboratory conditions of low blank values for total pb of less than 2 pg/g. the obtained u-pb zircon age by the id-tims method was 415.7±1.8 ma (error 0.43 %) based on four successful determinations. the results are consistent with the published ages for the temora diorite (temora i a€“ 416.75±1.3 ma; temora ii a€“ 416.78±0.33 ma) and established as 416±0.33 ma. the technique is thus recommended for high precision u-pb zircon analyses (error < 1 %), mainly for high resolution stratigraphic studies of phanerozoic sequences.