In addition, the fact that granites contain elevated concentrations of U and Th means that they are also enriched in radiogenic lead
, especially when compared with radiogenic lead
-depleted basalt and island arc volcanic rocks.
Samples with older ages (higher radiogenic lead
and lower radioactive uranium, leading to higher Pb/U ratios) plot further to the top and right on the curve, and younger samples plot toward the bottom left.
Its strong radiogenic lead
enrichment suggests a source that is enriched in U relative to Pb (Chauvel et al.
Also, in Antapite the source of radiogenic lead
proceed of an orogenic area, with prevalence both the upper crust and the lower crust, contrary to the others zones, that only show influence of the upper crust.
Tantalo-niobates such as tantalite and columbite are ideally suited for U-Pb dating because of the potential to incorporate U (200-1000 ppm; Romer & Wright 1992; Kinny 2000) and, therefore, contain a significant radiogenic lead
More radiogenic leads
in walrus occurred in Thule and Repulse Bay, areas characterized by Proterozoic or Archean crust reworked in the Proterozoic.
2] are the production ages of the radiogenic leads
, and a calculated slope of 0.