265 / 352
176
Yb
a
176
Lu
a
178
Hf
180
Hf Sig
Hf
b 176
Hf
176
Hf
d
ı
c
T
DM
e
age
f
ı U-Pb
g
Lu-Hf
h
177
Hf
177
Hf
177
Hf
177
Hf
(V)
177
Hf
177
Hf
(t)
İ+I (Ga) (Ma) (Ma) conc seq
İ+I
(t)
d
Grain
ı
ı
±2ı
c
Quoted uncertainties (absolute) relate to the last quoted figure. The effect of the inter-element fractionation on Lu/Hf was estimated to
be about 6 % or less based on analyses of the GJ-1 and WůĞƐŽǀŝēĞ zircon. ĐĐƵƌĂĐLJ and reproducibility was checked by repeated analyses
of reference zircon GJ-1 and WůĞƐŽǀŝēĞ (data given as mean with 2 standard deviation uncertainties).
(a)
176
Yb/
177
Hf = (
176
Yb/
173
Yb)
true
x (
173
Yb/
177
Hf)
meas
x (M
173(Yb)
/M
177(Hf)
)
ɴ;,ĨͿ
, ɴ;,ĨͿ = ln((
179
Hf/
177
Hf
true
)/(
179
Hf/
177
Hf
measured
)) /
ln(M
179(Hf)
/M
177(Hf)
), M = mass of respective isotopes. The
176
Lu/
177
Hf was calculated in a similar way using
175
Lu/
177
Hf and ɴ;zďͿ.
(b)
Mean Hf signal in volts.
(c)
Uncertainties are quadratic additions of the within-run precision and the daily reproducibility of the 40ppb-JMC475 solution.
Uncertainties for the JMC475 quoted at 2SD (2 standard deviation).
(d)
Initial
176
Hf/
177
Hf and ɸ,Ĩ calculated using the apparent U-Pb age determined by > -ICP-MS dating (see column f), and the CHUR
parameters:
176
Lu/
177
Hf = 0.0336, and
176
Hf/
177
Hf = 0.282785 (Bouvier et al. 2008).
(e)
Two stage model age in Ga using measured
176
Lu/
177
Lu of each spot (first stage = age of zircon), a value of 0.0113 for the average
continental crust (second stage, values compiled from Rudnick and Gao (2003), and depleted mantle
176
Lu/
177
Lu = 0.0379, and
176
Hf/
177
Hf
= 0.283164.
(f)
ƉƉĂƌĞŶƚ U-Pb age determined by > -ICP-MS.
(g)
U-Pb age concordance (%).
(h)
Sequence in which Lu-Hf analyses were performed. Standard analyses for each sequence are showed on Table 12.
249