Radiometric dating of sedimentary rocks: the application of diagenetic xenotime geochronology

In metamorphosed sedimentary rocks, diagenetic xenotime retains its age information up to lower amphibolite facies in sandstone, and up to mid-upper greenschist facies in pelitic rocks. In many Precambrian basins (e.g., Witwatersrand Basin, South Africa), diagenetic xenotime is overgrown by chemically distinct and texturally younger xenotime related to burial diagenesis, contact metamorphism, hydrothermal alteration or regional metamorphism. With the aid of petrography, geochemical microanalysis and the use of isotopic techniques with fine spatial resolution, it may be possible to use xenotime to date early diagenesis, and potentially every major fluid and thermal event to have affected a depositional basin.