Dating emplacement and evolution of the orogenic magmatism in the internal Western Alps: 1. The Miagliano Pluton

Swiss Journal of Geosciences

Table 4 Isotope measurements of single zircons

Number^a		Concentrations				Atomic ratios								Apparent ages
	Weight (mg)	U	Pb tot. (ppm)	Pb nonrad. (pg)	Th/U^b	206/204^c	207/206^d,e	Error 2σ (%)	207/235^d,e	Error 2σ (%)	206/238^d	Error 2σ (%)	Corr.	206/238^e	207/235	207/206^e
Bi0632 (Valle del Cervo Pluton)
0632-1	0.0014	280	2.35	1.21	0.49	121	0.04904	5.263525	0.03440	5.562495	0.00509	0.38	0.80	32.71	34.34	149.62
0632-2	0.0031	2,149	10.59	1.07	0.34	1,877	0.04686	0.300978	0.03106	0.339293	0.00481	0.08	0.56	30.92	31.06	42.02
0632-3	0.0029	1,867	9.13	1.40	0.20	1,187	0.04711	0.491792	0.03149	0.532045	0.00485	0.11	0.46	31.18	31.48	54.70
0632-4	0.0022	2,443	11.83	1.29	0.22	1,259	0.04698	0.448604	0.03104	0.48726	0.00479	0.09	0.51	30.82	31.04	48.01
0632-5	0.0024	1,029	5.09	1.05	0.18	723	0.04709	0.763705	0.03106	0.814178	0.00478	0.10	0.55	30.77	31.06	53.85
0632-6	0.0030	3,724	17.62	1.53	0.23	2,197	0.04685	0.254175	0.03092	0.294442	0.00479	0.08	0.60	30.79	30.92	41.49
Bi0637 (Miagliano Pluton)
0637-2	0.0047	125	1.22	2.5	0.59	95	0.05012	5.86	0.03572	6.20	0.00517	0.38	0.91	33.23	35.63	200.56
0637-3	0.0020	469	4.29	3.4	0.62	108	0.04921	5.15	0.03492	5.44	0.00515	0.32	0.91	33.09	34.85	157.68
0637-5	0.0025	167	1.30	1.0	0.57	159	0.04829	3.85	0.03431	4.06	0.00515	0.32	0.70	33.13	34.25	113.31
0637-6	0.0040	564	3.33	1.0	0.59	712	0.04699	0.81	0.03324	0.86	0.00513	0.12	0.46	33.00	33.21	48.50

^aAll zircons annealed-leached, all single grains
^bCalculated on the basis of radiogenic Pb²⁰⁸/Pb²⁰⁶ ratios, assuming concordancy
^cCorrected for fractionation and spike
^dCorrected for fractionation, spike, blank and common lead (Stacey and Kramers 1975)
^eCorrected for initial Th Disequilibrium, using an estimated Th/U ratio of 4 for the melt