Appendix1.Analytical Procedures

Appendix1.Analytical procedures

Zircon crystals were separated from a 2 kg sample using conventional crushing and heavy liquid separation at the Geology Department, University of Chile. The U-Pb isotope analyses were carried out at the ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC), Department of Earth and Planetary Sciences, Macquarie University, Australia.

Backscatter electron (BSE) images were taken of all analysed zircons to study the internal structure of the crystals prior to LA-ICPMS analysis. Mineral ablation was carried out using a LUV213 laser ablation system connected to an Agilent 4,500 high-sensitivity quadrupole ICPMS. Spot diameters ranged between 50 and 80 μm, the ablation time was about 60 s and the ablated masses of zircon were approximately 500-1,500 ng. Detection limits for heavy elements applying laser ablation sampling are typically <10 ppb for a 60 s ablation at 40-50 μm resolution. Gas blank 208Pb signals of 30-40 cps were achieved routinely. The in-house GJ-1 zircon standard (608.5±0.4 Ma) was used for optimizing ICP-MS operating conditions. Reproducibility and accuracy were controlled by zircon standards 91500 (1,065.4±0.3 Ma; Wiedenbecket al.1995) and Mud Tank (732±5 Ma; Black and Gulson 1978). Sample preparation and instrumentation are described by Jackson et al.(2004). The completel data on U-Pb ages are given in Appendix 2.

Molybdenite was separated from veins, veinlets and brecciacementThe separated molybdenitecrystals were loaded and digested by the Carius tube method (Shirey and Walker 1995). Detailed chemical procedures are described by Nagler and Frei (1997). The Re and Os were analyzed on Pt-filaments by a negative thermal ions mass spectrometer (NTIMS-VG54 mass spectrometer) at the University of Arizona (Creaser et al. 1997). Errors are expressed at 0.5 % of the sample age which includes uncertainties measured by the use of spikes, samples and the 187Re decay constant.The complete geochronologic data set is presented in Appendix 3.

Four40Ar/39Ar analyses were completed at the geochronology facility of the Pacific Isotope Center and Geochemical Research at the University of British Columbia in Canada. Samples were irradiated at the McMasters reactor inHamilton, Canada. The flux monitors used during irradiation were FCT-3 (Fish Canyon Tuff) with an accepted age of 28.02 Ma (Renne et al. 1998) and the ACs (Alder Creek sanidine) with an accepted age of 1.19 Ma (Turrin et al. 1994). Step heating analyses were undertaken by a CO2 laser connected to a VG 5400 mass spectrometer MAP250/50. One sample (SM-101; 1049.5-1050.2 m), analyzed at Oregon State University was irradiated for 6 hrs. in the 1 MW TRIGA reactor located at the same university. The flux monitor used during this irradiation was also the FCT-3. For the step heating procedure a CO2 laser connected to the MAP205/50 mass spectrometer was used.A plateau age (PA) is defined by at least three successive heating steps including more than 50 % of 39Ar released. Errors are external errors including the analytical error, flux monitor error and the error of the decay constants. Errors are quoted at the 2 sigma (2)level.The full data set is given in Appendix 4.