Data were collected in peak-jumping mode by inductively coupled plasma mass spectrometry on a VG PlasmaQuad 2+ instrument at the Massachussetts Institute of Technology. Analyses were performed using the method of Janney and Castillo (1996), except that dissolved rock standards (BIR-1, DNC-1, W-2 and an in-house MORB glass standard) were used instead of elemental standard solutions for calibration. Data are reported relative to the USGS rock standard concentrations reported by Eggins et al. (1997, doi:10.1016/S0009-2541(96)00100-3)