Calculation of the ages from LA-ICP-MS using zeta calibration
Arguments
- x
data.framecontaining counts of spontaneous tracks, U concentrations, and the uncertainties of U concentrations- spotsize
the laser ablation spot size (diameter in micrometer)
- zeta
two-element vector with the zeta-factor and its standard error.
- ...
additional arguments
Value
list with the single grain ages and their analytical uncertainties,
the pooled age, and the chisq statistics
Details
The fission track age using the zeta calibration approach (Hasebe et al. 2009) is given by $$t = \frac{1}{\lambda} \ln \left(1+\frac{1}{2} \lambda \zeta_{icp} \frac{N)s}{A_s [ ^{238}U/^xX]} \right)$$ where \(\lambda\) is the 238U decay constant, \(\zeta_{icp}\) is the zeta calibration factor, \(N_s\) is the count of spontaneous fission tracks, \(A_s\) is the size of the ablated area, and \([ ^{238}U/^xX]\) either stands for the \(^{238}\)U-concentration (in ppm) or for the U/Ca (for apatite) or U/Si (for zircon) ratio measurement.
References
Hasebe, N., Carter, A., Hurford, A.J., Arai, S., 2009. The effect of chemical etching on LA-ICP-MS analysis in determining uranium concentration for fission-track chronometry. Geol. Soc. Lond. Spec. Publ. 324 (1), 37--46. doi:10.1144/SP324.3
Vermeesch, Pieter, 2017. Statistics for LA-ICP-MS based fission track dating. Chem. Geol. 456, 19--27. doi:10.1016/j.chemgeo.2017.03.002
Examples
data("sample")
age_ICP(sample, spotsize = 40, zeta = c(0.1188, 0.0119))
#> $data
#> # A tibble: 57 × 5
#> Grain Ns U sU comments
#> <chr> <dbl> <dbl> <dbl> <chr>
#> 1 FCT-1 7 0.000905 0.000016 NA
#> 2 FCT-2 1 0.000828 0.000017 broken grain
#> 3 FCT-3 2 0.000774 0.000015 NA
#> 4 FCT-4 1 0.000416 0.000022 NA
#> 5 FCT-5 2 0.000724 0.000019 edge
#> 6 FCT-6 1 0.000122 0.000013 NA
#> 7 FCT-7 3 0.000929 0.000032 small area, fracture
#> 8 FCT-8 2 0.000521 0.000023 NA
#> 9 FCT-9 4 0.000907 0.000025 edge, inclusion
#> 10 FCT-10 NA 0.0005 0.00019 NA
#> # ℹ 47 more rows
#>
#> $ages
#> t st st.perc t.max t.min rhos zeta.error
#> 1 36.458380 14.270250 39.14121 50.728630 22.18812986 557042.30 0.06467491
#> 2 5.706292 5.736045 100.52140 11.442337 -0.02975275 79577.47 0.16846480
#> 3 12.202660 8.717938 71.44293 20.920598 3.48472167 159154.94 0.11943890
#> 4 11.352742 11.425341 100.63948 22.778083 -0.07259845 79577.47 0.16866367
#> 5 13.044533 9.322255 71.46484 22.366788 3.72227776 159154.94 0.11947590
#> 6 38.629126 39.040043 101.06375 77.669169 -0.41091764 79577.47 0.16937825
#> 7 15.246440 8.949459 58.69868 24.195899 6.29698051 238732.41 0.09789822
#> 8 18.120006 12.965400 71.55296 31.085406 5.15460603 159154.94 0.11962466
#> 9 20.812681 10.628607 51.06794 31.441288 10.18407364 318309.89 0.08496926
#> 10 NA NA NA NA NA NA NA
#> 11 16.140126 11.576849 71.72713 27.716975 4.56327653 159154.94 0.11991873
#> 12 NA NA NA NA NA NA NA
#> 13 40.274797 15.778634 39.17744 56.053431 24.49616252 557042.30 0.06473681
#> 14 24.988063 11.472550 45.91212 36.460613 13.51551356 397887.36 0.07621285
#> 15 33.484630 15.369680 45.90070 48.854310 18.11495049 397887.36 0.07619343
#> 16 15.667566 9.190224 58.65764 24.857791 6.47734172 238732.41 0.09782875
#> 17 NA NA NA NA NA NA NA
#> 18 24.668566 12.597579 51.06733 37.266146 12.07098736 318309.89 0.08496823
#> 19 6.241234 6.274423 100.53177 12.515656 -0.03318896 79577.47 0.16848226
#> 20 18.318973 10.759575 58.73460 29.078548 7.55939750 238732.41 0.09795901
#> 21 29.076753 13.338053 45.87188 42.414806 15.73870050 397887.36 0.07614442
#> 22 4.377302 3.130758 71.52255 7.508059 1.24654411 159154.94 0.11957332
#> 23 5.135890 5.163053 100.52888 10.298943 -0.02716260 79577.47 0.16847739
#> 24 18.108437 10.619280 58.64272 28.727716 7.48915693 238732.41 0.09780350
#> 25 39.990850 16.848473 42.13082 56.839323 23.14237639 477464.83 0.06977592
#> 26 19.108904 11.225847 58.74668 30.334751 7.88305765 238732.41 0.09797945
#> 27 16.920076 9.929758 58.68625 26.849834 6.99031746 238732.41 0.09787718
#> 28 33.163565 13.954423 42.07757 47.117988 19.20914212 477464.83 0.06968516
#> 29 18.879933 11.073508 58.65226 29.953441 7.80642479 238732.41 0.09781966
#> 30 31.859667 16.343140 51.29727 48.202807 15.51652707 318309.89 0.08535830
#> 31 8.102799 5.790755 71.46611 13.893554 2.31204336 159154.94 0.11947804
#> 32 33.705488 12.423181 36.85804 46.128669 21.28230693 636619.77 0.06077050
#> 33 21.130562 12.398043 58.67351 33.528605 8.73251938 238732.41 0.09785562
#> 34 13.414731 9.583553 71.44051 22.998283 3.83117834 159154.94 0.11943482
#> 35 20.744178 14.845701 71.56563 35.589878 5.89847719 159154.94 0.11964605
#> 36 24.778483 11.360878 45.84977 36.139361 13.41760453 397887.36 0.07610683
#> 37 25.500318 14.958441 58.65982 40.458759 10.54187631 238732.41 0.09783245
#> 38 22.772961 10.452356 45.89810 33.225316 12.32060506 397887.36 0.07618900
#> 39 18.534462 10.867671 58.63494 29.402133 7.66679156 238732.41 0.09779034
#> 40 24.340414 10.242028 42.07828 34.582442 14.09838509 477464.83 0.06968637
#> 41 15.710962 11.229039 71.47264 26.940001 4.48192286 159154.94 0.11948906
#> 42 6.080660 6.112713 100.52713 12.193373 -0.03205291 79577.47 0.16847444
#> 43 10.146472 7.249547 71.44895 17.396020 2.89692475 159154.94 0.11944905
#> 44 23.445025 12.009274 51.22312 35.454300 11.43575127 318309.89 0.08523252
#> 45 49.115177 18.507773 37.68239 67.622950 30.60740352 636619.77 0.06218120
#> 46 19.638164 11.527608 58.70003 31.165772 8.11055652 238732.41 0.09790049
#> 47 16.279089 11.636951 71.48404 27.916041 4.64213815 159154.94 0.11950831
#> 48 27.265390 19.518054 71.58546 46.783444 7.74733647 159154.94 0.11967953
#> 49 6.525566 6.560458 100.53469 13.086023 -0.03489158 79577.47 0.16848718
#> 50 8.075114 8.133361 100.72131 16.208475 -0.05824626 79577.47 0.16880149
#> 51 46.007853 16.943765 36.82798 62.951618 29.06408885 636619.77 0.06071905
#> 52 24.928761 12.727437 51.05523 37.656198 12.20132458 318309.89 0.08494770
#> 53 34.876399 14.676691 42.08201 49.553090 20.19970797 477464.83 0.06969273
#> 54 31.816777 14.642076 46.01998 46.458853 17.17470143 397887.36 0.07639626
#> 55 20.111642 11.790776 58.62662 31.902418 8.32086689 238732.41 0.09777625
#> 56 28.388229 11.113137 39.14699 39.501366 17.27509193 557042.30 0.06468479
#> 57 24.403244 14.319739 58.67965 38.722983 10.08350499 238732.41 0.09786601
#>
#> $age.pooled
#> age std
#> 15.275397 3.402745
#>
#> $stats
#> chisq probability
#> 42.2639893 0.8547253
#>