SHRIMP uranium-lead dating of diagenetic xenotime in siliciclastic sedimentary rocks
Diagenetic xenotime is common in siliciclastic sedimentary rocks, where it starts to form on detrital zircon shortly after sediment deposition. It is possible to estimate the age of sedimentary rocks by in situ uranium-lead analysis of that xenotime. Two Proterozoic sandstone units from northwestern Australia, previously constrained to the age interval of 1790 to 750 million years ago, have diagenetic xenotime ages of 1704 +/- 7 and 1704 +/- 14 million years ago. This method has potential for dating sedimentary sequences of all ages but should be especially valuable for refining the Precambrian time scale.
McNaughton
NJ
Centre for Strategic Mineral Deposits, Department of Geology and Geophysics, University of Western Australia, Nedlands, WA 6907, Australia.
Rasmussen
B
Fletcher
IR