Upb dating Perteen dating
When calibrated using GBW04420 as the external standard, two samples give weighted mean U-Pb dating of uraninite can deliver more reliable formation ages of the deposit than dating coeval high-U zircon because the latter commonly suffer significant Pb loss after formation.
TY - JOURT1 - In situ LA-ICP-MS U–Pb dating of metavolcanics of Norrbotten, Sweden: records of extended geological histories in complex titanite grains AU - Storey, Craig AU - Smith, M. This study reports data chiefly from titanite, but also from rutile and apatite, obtained using the laser ablation (LA)-ICP-MS methodology on polished thick sections in order to retain as much petrologic information as possible, and allowing trace element analyses from adjacent areas to the U–Pb analyses.
Apatite has a lower closure temperature than zircon, i.e., ~400 - 500°C, and so are more easily ‘reset’ by heating than zircons.
Therefore, they provide different information about the source of sandstones than zircons such as low grade metamorphic rocks.
However, the 207Pb/206Pb ages are fairly precise (1–3% 2σ) and the calculated age is geologically reasonable, suggesting that the data may be accurate.
The titanite grains studied show complex internal structures.
Thus, the accurate U-Pb dating of uraninite by LA-ICP-MS requires matrix-matched external standards for calibration.
Titanite rims record a U–Pb age of 1870 ± 24 Ma (2σ) at Luossavaara, and 1826 ± 15 Ma (2σ) at the smaller Fe oxide–apatite body at Gruvberget.
If, however, a zircon crystal has lost Pb, one can still calculate its age by plotting the data on a ‘discordia line’ instead.
Sandstones frequently contain detrital zircon grains and if these grains are undisturbed and concordant, their ages provide some clue as to their provenance.
Here, we developed a technique for U-Pb dating of titanite using the 193 nm Ar F laser-ablation system and Agilent 7500a Q-ICP-MS.
Standards of titanite (BLR-1 and OLT-1) and zircon (91500 and GJ-1) were dated using single spot and line raster scan analytical methods.