SHRIMP U-Pb dating of diagenetic xenotime from sedimentary rocks has provided age constraints for sedimentary diagenesis(Mc Naughton et al.,1999;Fletcher et al.,2000;England et al.,2001;Rasmussen et al.,2004;Vallini et al.,2007).Xenotime(YPO4)may grow during early diagenesis,typically being present as a trace constituent in siliciclastic sedimentary rocks(Rasmussen,2005),in the form of syntaxial outgrowths on detrital zircon grains.Diagenetic xenotime occurs in a SHRIMP U-Pb dating of diagenetic xenotime from sedimentary rocks has provided age constraints for sedimentary diagenesis (Mc Naughton et al., 1999; Fletcher et al., 2000; England et al., 2001; Rasmussen et al., 2004; Vallini et al., 2007). Xenotime (YPO4) may grow during early diagenesis, typically being present as a trace constituent in siliciclastic sedimentary rocks (Rasmussen, 2005), in the form of syntaxial outgrowths on detrital zircon grains. Dynatime xenotime occurs in a