Improvement in the Analytical Capabilities of LA-ICP-MS for High Spatial Resolution U-Pb Dating of Zircon Using Mixed-Gas Plasma

Table 2

The weighted mean ²⁰⁶Pb/²⁰⁸U age of SRMs Plešovice, GJ-1, and 91500 under different experimental conditions.

Experimental conditions	Spot size 10 μm				Spot size 16 μm				Spot size 24 μm				Spot size 32 μm				Reference age
	Age	RSD (%)	RE (%)	2σ	Age	RSD (%)	RE (%)	2σ	Age	RSD (%)	RE (%)	2σ	Age	RSD (%)	RE (%)	2σ
	Ma			Ma	Ma			Ma	Ma			Ma	Ma			Ma
Plešovice																	337.1 ± 0.4^a
Dry plasma	323.7 ± 5.6	3.1	4.0	12.9	328.7 ± 5.9	2.9	2.8	6.1	346.0 ± 2.0	1.4	2.6	4.0	344.9 ± 1.7	1.1	2.8	3.2	338.0 ± 1.0^b
Ethanol plasma	343.3 ± 4.6	2.8	1.8	8.0	333.8 ± 2.4	1.5	1.0	5.1	339.0 ± 2.4	1.3	0.6	3.3	335.4 ± 2.2	1.1	0.5	2.4
GJ-1																	599.8 ± 4.5^c
Dry plasma	572.9 ± 7.7	3.2	4.5	17.3	593.8 ± 5.3	1.2	1.0	9.2	596.3 ± 2.8	0.9	0.6	5.9	600.5 ± 3.7	1.0	0.1	5.0	604.6 ± 2.9^d
Ethanol plasma	597.6 ± 7.8	2.4	0.4	14.8	598.1 ± 4.4	0.7	0.3	8.2	598.6 ± 2.8	0.6	0.2	5.6	597.2 ± 2.1	0.8	0.4	4.6	603.2 ± 2.4^e
91500																	1065.4 ± 0.6^f
Dry plasma					1057.9 ± 9.7	1.8	0.7	24.8	1060.2 ± 6.1	1.4	0.5	15.5	1058.3 ± 5.8	1.4	0.7	12.2	1061.8 ± 5.3^d
Ethanol plasma					1061.1 ± 8.0	0.8	0.4	20.3	1064.4 ± 5.7	0.1	0.1	12.8	1064.2 ± 4.3	0.1	0.1	9.7	1064.4 ± 4.8^e

The concordance was lower than 90% when dry plasma was used at the spot size of 10 μm. ^aID-TIMS ²⁰⁶Pb/²³⁸U age of Plešovice from [16]. ^bLA-ICP-MS ²⁰⁶Pb/²³⁸U age of Plešovice from [17]. ^cID-TIMS ²⁰⁶Pb/²³⁸U age (mean of the apparent ages) of GJ-1 from [18]. ^dLA-ICP-MS ²⁰⁶Pb/²³⁸U age of GJ-1 and 91500 using the U-Pb method from [19]. ^eLA-ICP-MS ²⁰⁶Pb/²³⁸U age of GJ-1 and 91500 using ablation spot size 20 μm from [20]. ^fID-TIMS ²⁰⁶Pb/²³⁸U age of 91500 from [21].