Table 4.

Apatite (U–Th)/He data

SampleGeometryU (ppm)σTh (ppm)σHe (pmol)He error (%)eUσFT (238U)FT (235U)FT (232Th)Uncorr. age (Ma)σCorr. age (Ma)σWeighted mean age (1σ; n)
NT-02 (3)Cylindrical40.2050.4329.230.10.013010.0002342.370.4330.7570.7210.71519.1440.39825.40.52727.6 Ma (1.5 Ma; 2)
NT-02 (4)Hexagon 1T21.040.2242.6550.0270.0580.0001521.660.2240.8630.8420.83925.6140.27229.70.316
KM-07 (1)Hexagon 2T69.3960.625137.53180.97880.01230.00022101.70.6660.7310.690.68410.8890.21215.20.29725.02 Ma (4.19 Ma; 3)
KM-07 (2)Hexagon 0T22.9250.32872.4410.7780.012150.0002339.940.3760.6980.6540.64822.010.46732.60.693
KM-07 (3)Hexagon 2T37.5960.38287.5460.6670.016890.0002458.170.4130.7510.7130.70820.2480.3227.60.436
KM-07 (4)Hexagon 1T19.460.42875.2680.8390.005430.0002237.140.4710.6560.6070.59924.441.0338.91.64
KM-09 (1)*Hexagon 2T1.150.326.9250.2940.000860.000217.480.30.640.5880.5825.616.31431126.8 Ma (2.4 Ma; 3)
KM-09 (2)Hexagon 1T1.820.1313.220.1170.001330.000214.920.130.7180.6760.6718.883.0927.54.5
KM-09 (3)Hexagon 0T1.660.1218.8170.1820.001040.000216.090.130.6890.6440.63714.863.122.84.76
KM-09 (4)Cylindrical4.380.217.6580.180.001760.000218.530.20.7050.6610.65519.632.4428.93.6
KM-15 (1)*Hexagon 2T33.4610.343142.0071.1180.19050.001466.830.3470.7570.7210.715132.5431.271179.61.723Single grain age: 33.0 ± 1.0 Ma
KM-15 (2)Hexagon 2T25.3720.39183.9330.7110.007130.0002245.090.3240.6720.6240.61721.3980.69533.11.07
KM-15 (3)*Hexagon 2T16.6020.40727.8060.30.001960.0002623.130.3040.6390.5860.57816.522.2426.63.61
KM-15 (4)*Hexagon 0T74.184.96373190.011850.00023161.86.7970.7440.7070.7013.530.164.90.23

The concentrations and analytical uncertainty of the U, Th and He measurements are displayed for each aliquot. Uncorrected ages are subsequently corrected for He ejection based on the geometry and specific dimensions of the analysed apatite crystal. Mean ages are calculated with IsoplotR (Vermeesch 2018).

*Incomplete degassed grains (e.g. KM-09 (1) and KM-15 (3)) and grains with anomalous ages (KM-15 (1), KM-15 (4)) were not used in this calculation.