Samples E1309-0 and -1 are from the pebble conglomerate developed above the unconformity defining the base of TU2; both clasts and matrix were processed. Sample F1302 and F1108 are from medium-grained sandstone beds in the middle (Saddle Peak Hills) and upper (Alexander Hills) parts of the Horse Thief Springs Formation, respectively. Two samples from the Beck Spring Dolomite (E1101-92.2, -293.7) are from pebble conglomerate beds at Saratoga Springs. The three KP1 samples are very fine to fine-grained sandstones from Alexander Hills (F1106, F1107) and Saratoga Springs (F1342). Samples from the lower part of TU3 include a sandy limestone from the Virgin Spring Limestone (VSL3-6.8) in the Saddle Peak Hills, a light green and pink, poorly sorted pebble conglomerate from KP2 (E1201) in the Saddle Peak Hills, a coarse sandstone from the top of KP2 (F1343) at Saratoga Springs. F1102 is a sample of KP3 from Sperry Wash (not shown in Fig. 5). F1345-188 and E1351-191 are samples from pebble conglomerate beds in the Silurian Hills.

Analysis was performed in 19 experiments in 5 sessions. Zircons were ablated with laser spots of 25 µm or 30 µm (wide using fluence and pulse rates of 5 J/cm2 and 10 Hz, respectively, during a 45 second analysis (15 sec gas blank, 30 sec ablation) that excavated a pit ~25 µm deep. Ablated material was carried by a 1.2 L/min He gas stream to the nebulizer flow of the plasma. For experiments 1 and 2, dwell times were 5 microseconds for Si and Zr, 200 microseconds for 49Ti and 207Pb, 40 microseconds for 202Hg, 204Pb, 206Pb, 208Pb, 238U, 232Th and 10 microseconds for all other HFSE and REE. For all other experiments, dwell times were the same except for 80 microseconds for 206Pb and 238U. 
Background count rates for each analyte were obtained prior to each spot analysis and subtracted from the raw count rate for each analyte. Ablation pits that appear to have intersected glass or mineral inclusions were identified by time-resolved data that show large fluctuations in Ti or P. U-Pb dates from these analyses are considered valid if the time-resolved U-Pb ratios appear to have been unaffected by the inclusions. Analyses that appear contaminated by common Pb were rejected based on an intensity of mass 204 above baseline. For concentration calculations, background-subtracted count rates for each analyte were internally normalized to 29Si and calibrated with respect to NIST SRM-610 and -612 glasses as the primary standards. Temperature was calculated from the Ti-in-zircon thermometer (Watson et al., 2006). Because there are no constraints on the activity of TiO2 in the source rocks, an average value in crustal rocks of 0.8 was used.
For U-Pb and 207Pb-206Pb dates, instrumental fractionation of the background-subtracted ratios was corrected and dates were calibrated with respect to interspersed measurements of the Plešovice zircon standard (Sláma et al., 2008). Two analyses of Plešovice were done for every 10 analyses of unknown zircon; a polynomial fit to the standard analyses yields each sample-specific fractionation factor. Signals at mass 204 were indistinguishable from zero following subtraction of mercury backgrounds measured during the gas blank (<1000 cps 202Hg), and thus dates are reported without common Pb correction. Radiogenic isotope ratio and age error propagation for all analyses includes uncertainty contributions from counting statistics and background subtraction. For spot analyses that are individually interpreted (e.g., detrital zircon analyses), the uncertainty from the standard calibration is propagated into the error on each date. This uncertainty is the standard deviation of the time-varying U-Pb fractionation factor and the standard error of the mean of the time-invariant, smaller 207Pb-206Pb fractionation factor. Standard calibration uncertainties for 207Pb-206Pb dates ranged from 0.4% to 1.6% (2σ). Standard calibration uncertainties for 206Pb-238U dates ranged from 2.0% to 9.3% (2σ). Age interpretations are based on 207Pb-206Pb dates. Analyses with >20% discordance are not considered. Errors on the dates from individual analyses are given at 2σ. Detrital zircon age histograms were generated with Isoplot (Ludwig, 2008). To better highlight stratigraphic provenance changes within TU2 in and to avoid smoothing of data, each sample was normalized individually.
Two zircon secondary reference materials were treated as unknowns to assess accuracy, interspersed as groups of two analyses for every 20 unknown analyses. Weighted mean dates are calculated using Isoplot 3.0 (Ludwig, 2003) from errors on individual dates that do not include the standard calibration uncertainties. However, errors on weighted mean dates include the standard calibration uncertainties within each experiment. FC-1 zircon (1098 Ma from unpublished CA-TIMS data, Boise State University) and Seiland zircon (530 Ma from unpublished CA-TIMS data, Boise State University) yielded accurate dates.