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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-ϭ ĂŶĚ WůĞƐŽǀŝēĞ njŝƌĐŽŶ͘ ĐĐƵƌĂĐLJ ĂŶĚ ƌĞƉƌŽĚƵĐŝďŝůŝƚLJ ǁĂƐ ĐŚĞĐŬĞĚ ďLJ ƌĞƉĞĂƚĞĚ ĂŶĂůLJƐĞƐ ŽĨ ƌĞĨĞƌĞnce zircon GJ-1 and
WůĞƐŽǀŝēĞ ;ĚĂƚĂ ŐŝǀĞŶ ĂƐ ŵĞĂŶ ǁŝƚŚ Ϯ ƐƚĂŶĚĂƌĚ ĚĞǀŝĂƚŝŽŶ ƵŶĐĞƌƚĂŝŶƚŝĞƐͿ͘
(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 с ůŶ;;
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
,Ĩ ĂŶĚ ɴ;zďͿ͘
(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
,Ĩ ĂŶĚ ɸ,Ĩ ĐĂůĐƵůĂƚĞĚ ƵƐŝŶŐ ƚŚĞ ĂƉƉĂƌĞŶƚ h-Pb age determined by LA-ICP-MSdating (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)
Apparent U-Pb age determined by LA-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.
323