Oligocene arc. Samples (all >25% plagioclase phyric) were leached in 3 M HCl for 2 h Rb/Sr ratios were determined on the post-leach residue by ICP-MS following a HF-HNO3 dissolution An isochron for the lavas gives an age of 30 +/- 8 Ma which is close to the estimated age of eruption of 33 Ma (Taylor and Mitchell, 1992, doi:10.2973/odp.proc.sr.126.168.1992). Nd analyses were also performed on powders leached in 3 M HCl for 2 h to eliminate the possibility of extraneous Nd introduced by the pervasive REE mobility in these lava suites (Taylor et al., 1992, doi:10.2973/odp.proc.sr.126.146.1992, Taylor et al., 1995). Pb isotopes for these ODP Holes were an analysed at Royal Holloway, University of London.