Table 6 Data reporting template (information) for LA-ICP-MS U-Th–Pb data

Laboratory and sample preparation

 Laboratory name

C.N.R.–Istituto di Geoscienze e Georisorse, Unità di Pavia

 Sample type/mineral

Detrital and magmatic zircons

 Sample preparation

Conventional mineral separation, 1 inch resin mount, 1 μm polish to finish

 Imaging

Cathodoluminescence

Laser ablation system

 Make, model and type

Geolas200Q-Microlas

 Ablation cell and volume

95 cm³

 Laser wavelength (nm)

193 nm

 Pulse width (ns)

20 ns

 Fluence (J.cm⁻²)

12 J.cm⁻²

 Repetition rate (Hz)

5 Hz

 Ablation duration (secs)

Up to 60 s

 Ablation pit depth/ablation rate

Not determined

 Spot diameter (μm) nominal/actual

20 μm

 Sampling mode/pattern

Static spot ablation

 Carrier gas

100% He in the cell, Ar make-up gas combined using a Y-piece 50% along the sample transport line to the torch

 Cell carrier gas flow (l/min)

0.7 l/min

ICP-MS instrument

 Make, model and type

HR-ICP-MS ELEMENT I ThermoFinnigan

 Sample introduction

Ablation aerosol

 RF power (W)

1200 W

 Make-up gas flow (l/min)

0.7 l/min

 Detection system

Secondary electron multiplier

 Masses measured

202, 204, 206, 207, 208, 232, 238

 Integration time per peak/dwell times (ms)

1.5 ms for Hg²⁰², Pb²⁰⁴, Pb²⁰⁶, Pb²⁰⁷, Pb²⁰⁸; 3.0 ms for U²³⁸ and Th²³²

 Total integration time per output datapoint (secs)

~1.2 s

120 s

 ‘Sensitivity’ as useful yield (%, element)

6 × 10⁶ (%Th) [NIST610]

 Dead time (ns)

25 ns

Data processing

 Gas blank

60 s of gas blank acquisition prior ablation

 Calibration strategy

Zircon GJ1 used as primary external standard, zircon 91500 used as validation standard

 Reference material info

GJ1 (Jackson et al. 2004)

91500 (Wiedenbeck et al. 1995)

 Data processing package used/correction for LIEF

Iolite (Paton et al. 2010, 2011???) LIEF correction assumes reference material and samples behave identically

 Mass discrimination

²⁰⁷Pb/²⁰⁶Pb and²⁰⁶Pb/²³⁸U normalised to reference material

 Common-Pb correction, composition and uncertainty

No common-Pb correction applied to the data

 Uncertainty level and propagation

Ages are quoted at 2 s absolute; propagation is by quadratic addition. Reproducibility and age uncertainty of reference material are propagated where appropriate

 Quality control/validation

91500 (1065 Ma, Wiedenbeck et al. 1995)