Table 2.

Pb isotope analyses of the SRM-982 reference standard during the course of this study.

SRM-982 standard	206Pb/204Pb	2SE	207Pb/206Pb	2SE
1	36.745742	0.014573	0.467062	0.000074
2	36.721561	0.027837	0.467072	0.000145
3	36.724861	0.022760	0.467100	0.000117
4	36.752794	0.015318	0.467155	0.000074
5	36.729906	0.025568	0.467186	0.000157
6	36.727710	0.011665	0.467072	0.000054
7	36.758083	0.022255	0.467039	0.000110
8	36.752202	0.010585	0.467120	0.000054
9	36.725293	0.015354	0.467089	0.000086
10	36.748559	0.020989	0.467075	0.000115
11	36.711980	0.010121	0.467020	0.000050
12	36.726637	0.013612	0.467179	0.000065
13	36.747877	0.017168	0.467042	0.000142
14	36.720595	0.016461	0.467102	0.000084
15	36.725182	0.012111	0.467197	0.000058
16	36.732675	0.011150	0.467195	0.000055
17	36.749615	0.013241	0.467094	0.000053
18	36.758620	0.015373	0.467011	0.000100
19	36.719447	0.017488	0.467077	0.000085
20	36.730312	0.024187	0.467072	0.000127
21	36.730203	0.027625	0.467317	0.000162
22	36.723632	0.014433	0.467025	0.000086
23	36.713073	0.020829	0.467102	0.000120
24	36.771984	0.028911	0.467271	0.000137
25	36.697760	0.015288	0.467262	0.000090
26	36.723179	0.021310	0.467184	0.000090
27	36.745221	0.020319	0.467136	0.000142
28	36.741355	0.013525	0.467080	0.000082
29	36.758790	0.013946	0.467078	0.000073
30	36.706886	0.018546	0.467178	0.000090
31	36.711900	0.018373	0.467112	0.000090
32	36.777560	0.033488	0.467057	0.000151
33	36.725587	0.010635	0.467052	0.000069
34	36.758454	0.018590	0.467080	0.000111
Average	36.735154		0.467114
2SD	0.0381753		0.0001490
Reproducibility	0.104		0.032
(%)

All data acquired by sequentially peak jumping the ion beams into the central SEM-ion counting system. Mass fractionation correction using the ²⁰⁸Pb/²⁰⁶Pb value and linear law.