Trace element analysis of scheelite by excimer laser ablation-inductively coupled plasma-mass spectrometry (ELA-ICP-MS) using a synthetic silicate glass standard

摘要: Abstract Concentrations of W and trace elements in scheelites (CaWO 4 ) associated with Archean lode-gold deposits Western Australia were determiined by ArF (193 run) excimer laser ablation-ICP-MS external calibration against a silicate glass standard reference material, NIST 610. The beam drilled well-defined pits both scheelite glass. With internal standardization Ca alone, measurements for the fall within 5% concentrations expected from electron microprobe measurements. A matrix effect between is apparent behaviour during; ablation: progressively fractionated but not scheelite. Proper data reduction, therefore, requires use early maximum count rates rather than mean during ablation. isotopic ratios measured an in-house generated glass, ANU 252, are ∼2.5% accepted values natural reproducible to ∼1%, if first ∼11 s ablation excluded. Using same reduction techniques employed W, Sr, Y, Mo, REE Pb, present at ppm levels scheelites, precision 4% or less. Measurements on Th U, 5–10 ppb level, P, Mn, Nb Ta less precise (∼5–40%) Rb, Zr, Ba, Sn, Hf, TI Bi are, most part, below detection limits. For Sm Nd, replicate ELA-ICP-MS made 80-μm wide spots largely encompass determined ID-TIMS bulk samples. patterns vary smoothly as function atomic number. Most hump-shaped others flat except positive Eu anomalies. This suggests that hydrothermal fluids formed did have common composition source.