Table 2 Zircon (U-Th)/He data.

TAU, total analytical uncertainty; ESR, equivalent sphere radius in micrometers; Ft, α-ejection correction factor calculated using the equation of Farley et al. (29), assuming homogeneous distribution of U and Th and corrected for the mineral portion removed by polishing. Crystals marked with asterisk were used for isotopic mapping.

Sample
code
232Th
(ng)
±
(%)
238U
(ng)
±
(%)
147Sm
(ng)
±
(%)
4He
(ncc)
±
(%)
TAU
(%)
Th/
U
Raw age
(Ma)
±1 σ
(Ma)
ESR
(μm)
FtCorrected
age (Ma)
±1 σ
(Ma)
MS14-4*0.4361.42.9041.90.00514.021.1881.72.50.5357.71.5540.8667.17.1
MS14-21.4451.42.9331.90.00217.927.1002.02.70.4967.71.8930.9273.74.2
I2-1*0.6692.03.5832.40.00711.594.7171.62.80.33204.25.81500.95215.022.8
I2-30.4201.40.8191.90.00224.825.4752.42.90.51223.86.6850.91245.414.2
I2-60.7732.03.6842.40.00317.6138.3022.53.30.21286.29.6830.91314.718.9
I2-9*1.4071.42.2271.90.00514.455.9751.62.30.53177.24.2830.91194.720.6
R-3*0.9122.01.6712.30.0068.651.7772.23.10.54221.36.8750.90247.114.5
R-3-50.1491.50.3501.90.00912.67.9542.32.90.42167.34.8640.88189.610.9
R-3-60.8181.41.6241.90.00613.246.5142.02.60.50206.65.4910.92225.312.7