Table EA2.1 Percentage relative deviations of measured concentration from certified values in fluxed glass made from standard basalt BHVO-2

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1 Electronic Appendix EA2 Analytical details Whole-rock analyses XRF at the University of Stellenbosch Whole-rock major-element analyses were carried out by XRF, using glass disks made in an autofluxer, with lithium borate flux but with no heavy absorber added. Internal standards were basalt BHVO-1 and granite NIM-G. For the granite, calculated relative uncertainties (twice the standard errors for the NIM-G, in wt%) are; SiO 2 = 0.363, TiO 2 = 0.006, Al 2 O 3 = 0.516, FeO T = 0.043, MnO = 0.001, MgO = 0.005, CaO = 0.016, Na 2 O = 0.071, K 2 O = and P 2 O 5 = Results are reported normalized to 100 wt% anhydrous, with total Fe expressed as FeO T. LA-ICP-MS at Stellenbosch Trace elements were analysed by LA-ICP-MS in the same glass disks, using a standard BHVO-1 glass made with the same flux as the samples. The standard was run at the beginning and the end of the sample string and after each 5 sample measurements. Drift corrections were then applied. All measurements were in duplicate, with the average reported as the measured concentration. Further queries regarding analytical methods should be addressed to the Central Analytical Facility (CAF) at Stellenbosch University. Table EA2.1 shows the percentage relative deviation of the measured to the certified values for the standard. Table EA2.1 Percentage relative deviations of measured concentration from certified values in fluxed glass made from standard basalt BHVO-2 Element RSD % Element RSD % Element RSD % Rb 0.4 Ce 3.8 Tm 6.4 Sr 2.5 Pr 12.6 Yb 11.4 Ba 4.1 Nd 9.0 Lu 17.1 Sc 5.3 Sm 2.5 Hf 7.5 Cr 1.0 Eu 20.2 Ta 4.0 Ni 7.6 Gd 4.0 Pb 6.2 Y 4.1 Tb 2.2 Th 10.7 Zr 5.2 Dy 9.0 U 6.3 Nb 5.8 Ho 9.3 La 9.6 Er 6.4 Sr and Nd Isotopes Solution MC-ICP-MS at the University of Cape Town For each sample, approximately 50 mg of powder was weighed into a Teflon beaker and about 4 ml 4:1 concentrated 2B HF:HNO 3 was added. The beaker was then capped and left to digest on a hot plate for at least 2 days. The resulting solution was dried and re-dissolved in 6M 2B HNO 3, twice. After the second drying, the sample was taken up in 1.5 ml of 2M 2B HNO 3. After centrifuging, the supernatant was loaded onto a cleaned and pre-conditioned column of 0.2 ml Sr.Spec resin (Eichrom). The column was washed with 2M 2B HNO 3 and the Sr fraction collected in 0.02M 2B HNO 3 (after Míková and Denková, 2007; Pin and Zalduegui, 1997; and Pin et al, 1994). Following the final drying, these fractions were re- 1

2 dissolved in 2 ml of 0.2% HNO 3. Based on the XRF values for Sr concentrations of the original samples, 3 ml of 200 ppb Sr solutions were prepared for analysis using the same 0.2% HNO 3. Analyses were performed using a NuPlasma HR MC-ICP-MS (Nu Instruments, Wrexham, Wales, UK) in the Africa Earth Observatory Network, EarthLAB Facility in the Department of Geological Sciences at the University of Cape Town. The approximately 200 ppb Sr sample and standard solutions were aspirated into the plasma through a microcyclonic spraychamber. The on-peak background was measured for 120 seconds while aspirating the same 0.2% HNO 3 used to dilute the sample and standard solutions. These background measurements, including any krypton ( 84 Kr and 86 Kr) present in the argon gas, were subtracted from the measured signals. Instrumental mass fractionation was corrected using the exponential law and a fractionation factor based on the measured 86 Sr/ 88 Sr ratio and the accepted value of The 87 Rb contribution to the 87 amu signal was calculated and subtracted using this fractionation factor, the exponential law, the measured 85 Rb signal and a 85 Rb/ 87 Rb ratio of To assess instrument tuning and stability, a 200 ppb Sr solution of the NIST SRM987 international Sr isotope standard was analyzed twice, prior to any samples. The external, measured 2σ reproducibility of SRM987 was (n = 3) on an average 87 Sr/ 86 Sr ratio of All 87 Sr/ 86 Sr data were normalised to , the in-house long-term average, which agrees with published results. The average 84 Sr/ 86 Sr ratio was ± (n = 4), also in agreement with published values. Further queries regarding analytical methods should be addressed to AEON Laboratories at the University of Cape Town. Nd isotope analyses were carried out using the same multi-collector ICP-MS instrument that was used for the Sr isotope determinations, using the same primary solutions that were used for the Sr isotope work. Nd isotopes were analysed in 1.5 ml of 50 ppb Nd 2% HNO 3 solutions using a Nu Instruments DSN-100 desolvating nebuliser. JNdi-1 was used as bracketing standard, and all Nd isotope data presented are referenced to this standard, using a 144 Nd/ 143 Nd ratio of (Tanaka et al. 2000). All Nd isotope data were corrected for Sm and Ce interferences and for instrumental mass fractionation, using the exponential law and a 146 Nd/ 144 Nd value of For further details of the analytical techniques see Will et al. (2007). Further queries regarding analytical methods should be addressed to AEON Laboratories at the University of Cape Town. U-Pb Zircon Geochronology Samples (2 to 5 kg) were crushed and sieved, followed by panning and magnetic separation using a Frantz Isodynamic Separator. The non-magnetic fraction was further separated by a heavy-liquid technique, using 99% methylene iodide (diiodomethane) with a density of 3,325 kg/m 3. After drying of the heavy mineral fraction, zircon grains were hand-picked under a Wild M3Z microscope. Zircons were mounted in an epoxy block that was ground down and polished to expose the grain cores. The epoxy block was then gold coated and cathodoluminescence (CL) imaging was carried out with a Zeiss MERLIN Field Emission Scanning Electron Microscope (FE-SEM). All U-Pb age data obtained at the Central Analytical Facility, Stellenbosch University, were acquired by laser ablation single collector magnetic sectorfield inductively coupled plasma mass spectrometry (LA-SFICP-MS), employing a Thermo Finnigan Element2 mass spectrometer coupled to a NewWave UP213 laser ablation system. Data were obtained by single spot analyses with a spot diameter of 30 µm and a crater depth of approximately 15 to 20 µm. 2

3 Table EA2.1 LA-SF-ICP-MS, U-Th-Pb dating methods, ESI/New Wave Research Nd-YAG laser, CAF, Stellenbosch University Laboratory & Sample Preparation Laboratory name Central Analytical Facility, Stellenbosch University Sample type / mineral zircon Sample preparation conventional mineral separation, 2.5 cm resin mount, 1 µm polish to finish Imaging CL, LEO 1430 VP, 10 na, 15 mm working distance Laser ablation system Make, Model and type ESI/New Wave Research, UP213, Nd:YAG Ablation cell and volume custom built low-volume cell, ca. 3 cm 3 Laser wavelength 213 nm Pulse width 3 ns Fluence 2.5 J/cm -2 Repetition rate 10 Hz Spot size 30 µm Sampling mode / pattern 30 µm single spot analyses Carrier gas 100% He, Ar make-up gas combined using a T-connector close to sample cell Pre-ablation laser warm-up 40 seconds (background collection) Ablation duration 20 seconds Wash-out delay 30 seconds Cell carrier gas flow 0.3 l/min He ICP-MS Instrument Make, Model and type Thermo Finnigan Element2 single collector HR-SF-ICP-MS Sample introduction via conventional tubing RF power 1100 W Make-up gas flow 1.0 l/min Ar Detection system single-collector secondary electron multiplier Masses measured 202, 204, 206, 207, 208, 232, 233, 235, 238 Integration time per peak 4 ms Total integration time per reading 1 sec (represents the time resolution of the data) Sensitvity cps/ppm Pb Dead time 6 ns Data Processing Gas blank 40 s on-peak Calibration strategy GJ-1 zircon as primary reference material, Plešovice zircon as secondary reference material (quality control) Reference Material info Plešovice (Slama et al. 2008); GJ-1 (Jackson et al. 2004) Data processing package used / Correction for LIEF in-house spreadsheet data processing using intercept method for LIEF correction Mass discrimination Standard-sample bracketing with 207 Pb/ 206 Pb and 206 Pb/ 238 U normalized to reference material GJ-1 Common-Pb correction, composition and uncertainty 204-method, Stacey and Kramers (1975) composition at projected age of the mineral; 5% uncertainty assigned Uncertainty level and propagation ages quoted at 2σ absolute, propagation by quadratic addition; reproducibility and age uncertainty of reference material and common-pb composition uncertainty propagated Quality control / Validation Plešovice: concrodia age = 337 ± 3 (2σ, MSWD (C+E) = 0.84) Other information For detailed method description see Frei and Gerdes (2009) 3

4 The methods used for U-Pb isotope analysis, and data processing using an in-house Microsoft Excel spreadsheet program, are described in detail by Gerdes and Zeh (2006) and Frei and Gerdes (2009), but Table EA2.1 shows the instrumental operating conditions used. For quality control, the Plešovice (Sláma et al. 2008) zircon reference material was analysed, and the results were consistently in excellent agreement with the published ID-TIMS age. The calculation of concordia ages, and plotting of concordia diagrams, was performed using Isoplot/Ex 3.0 (Ludwig 2003). References Eggins SM, Woodhead JD, Kinsley LPJ, Mortimer GE, Sylvester P, McCulloch MT, Hergt JM, Handler MR (1997) A simple method for precise determination of 40 trace elements in geological samples by ICP-MS using enriched isotope internal standardisation. Chem. Geol. 134(4): Frei D, Gerdes A (2009) Precise and accurate in situ U Pb dating of zircon with high sample throughput by automated LA-SF-ICPMS. Chem. Geol. 261(3-4): , doi: /j.chemgeo Gerdes A, Zeh A (2006) Combined U Pb and Hf isotope LA-(MC)-ICP-MS analyses of detrital zircons: comparison with SHRIMP and new constraints for the provenance and age of an Armorican metasediment in Central Germany. Earth Planet. Sci. Lett. 249(1-2): 47-61, doi: /j.epsl Ludwig KR (2003) Isoplot/EX version 3.0, a geochronological toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication Maas R, Kamenetsky MB, Sobolev AV, Kamenetsky VS, Sobolev NV (2005) Sr, Nd and Pb isotope evidence for a mantle origin of alkali chlorides and carbonates in the Udachnaya Kimberlite, Siberia. Geology 33(7): Maas R, McCulloch MT (1991) The provenance of Archean clastic metasediments in the Narryer Gneiss Complex, Western Australia;trace element geochemistry, Nd isotopes, and U-Pb ages for detrital zircons. Geochim. Cosmochim. Acta 55(7): Míková J, Denková P (2007) Modified chromatographic separation scheme for Sr and Nd isotope analysis in geological silicate samples. J. Geosci. 52: , doi: /jgeosci.015 Pin C, Zalduegui JFS (1997) Sequential separation of light rare-earth elements, thorium and uranium by miniaturized extraction chromatography: application to isotopic analyses of silicate rocks. Anal. Chim. Acta 339: Pin C, Briot D, Bassin C, Poitrasson F (1994) Concominant Separation of strontium and samarium neodymium for isotopic analysis in silicate samples, based on specific extraction chromatography. Anal. Chim. Acta 298: Raczek I, Jochum KP, Hofmann AW (2003) Neodymium and strontium isotope data for USGS reference materials BCR-1, BCR-2, BHVO-1, BHVO-2, AGV-1, AGV-2, GSP- 1, GSP-2 and eight MPI-DING reference glasses. Geostandards Newsletter 27(2): Sláma J, Košler J, Condon DJ, Crowley JL, Gerdes A, Hanchar JM, Horstwood MSA, Morris GA, Nasdala L, Norberg N, Schaltegger U, Schoene B, Tubrett MN, Whitehouse MJ (2008) Plešovice zircon a new natural reference material for U Pb and Hf isotopic microanalysis. Chem. Geol. 149(1-2), doi: /j.chemgeo Tanaka T, Togashi S, Kamioka H, Amakawa H, Kagami H, Hamamoto T, Yuhara M, Orihashi Y, Yoneda S, Shimizu H, Kunimaru T, Takahashi K, Yanagi T, Nakano T, Fujimaki H, Shinjo R, Asahara Y, Tanimizu M, Dragusanu, C (2000) JNdi-1: a neodymium isotopic reference in consistency with LaJolla neodymium. Chem. Geol. 168:

5 Vance D, Thirlwall M (2002) An assessment of mass discrimination in MC-ICPMS using Nd isotopes. Chemical Geology 185(3-4): Will TM, Frimmel HE, Zeh A, Le Roux P, Schmädicke E (2007) Geochemical and isotopic constraints on the tectonic and crustal evolution of the Shackleton Range, East Antarctica, and correlation with other Gondwana crustal segments. Precambrian Res. 180: