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207
Pb
a
U
b
Pb
b
Th
b 206
Pbc
c 207
Pb
d
±2
V
206
Pb
d
±2
V
ȡ
e 207
Pb
d
±2
V
206
Pb
f
±2
V
207
Pb
f
±2
V
207
Pb
f
±2
V
Conc.
g
(cps) (ppm) (ppm)
U (%)
235
U (%)
238
U (%) (rho)
206
Pb (%)
238
U (Ma)
235
U (Ma)
206
Pb (Ma) (%)
Grain
91500
h
8676 77 14 0.44 0.3 1.8408 3.8 0.1792 3.3 0.56 0.0745 1.9 1062 32 1060 25 1055 38 101
Felix
h
8886 509 76 3.98 0.1 0.6348 6.8 0.0807 7.3 0.50 0.0571 1.2 500 35 499 27 494 26 101
Plesovice
h
2366 866 45 0.15 0.4 0.3935 2.3 0.0539 1.7 0.47 0.0529 2.3 339 6 337 7 326 52 104
GJ-1
h
7647 340 31 0.02 0.1 0.8142 1.8 0.0984 0.9 0.42 0.0600 1.6 605 5 605 8
206
Pb/
238
U error is the quadratic additions of the within run precision (2 SE) and the external reproducibility (2 SD) of the
reference zircon.
207
Pb/
206
Pb error propagation (
207
Pb signal dependent) following Gerdes & Zeh (2009).
207
Pb/
235
U error is the
quadratic addition of the
207
Pb/
206
Pb and
206
Pb/
238
U uncertainty.
a
Within run background-corrected mean
207
Pb signal in cps (counts per second).
b
U and Pb content and Th/U ratio were calculated relative to GJ-1 reference zircon.
c
Percentage of the common Pb on the
206
Pb. b.d. = below detection limit.
d
Pb/U and Pb/Pb ratios. Corrected for background, within-run Pb/U fractionation (in case of
206
Pb/
238
U) and common Pb using
Stacy and Kramers (1975) model Pb composition and subsequently normalised to GJ-1 (ID-TIMS value/measured value);
207
Pb/
235
U calculated using ((
207
Pb/
206
Pb)*(
238
U/
206
Pb)*137.88).
e
ZŚŽ ;ʌͿ ŝƐ ƚŚĞ ;
206
Pb/
238
U)/(
207
Pb/
235
U) error correlation coefficient.
f
Pb/U and Pb/Pb ages.
g
Degree of concordance = ((
206
Pb/
238
U age)/(
207
Pb/
206
Pb age)) x 100.
h
Mean of 9 (91500), 9 (Felix), 9 (Plesovice), and 18 (GJ-1) analyses, respectively.
275