SUPPLEMENTARY ONLINE MATERIAL

Polyphase exhumation in the Western Qinling Mountains, China: Rapid

Early Cretaceous cooling along a lithospheric-scale tear fault and pulsed

Cenozoic uplift

Bianca Heberer1, Thomas Anzenbacher1 ,Franz Neubauer1, Johann Genser1, Yunpeng Dong2,

István Dunkl 3

1. Microprobe Analytical Techniques and P-T Estimates

The chemical composition of rock-forming minerals from sample QL-49 has been determined by electron microprobe in order to assess the pressure and temperature conditions during solidification and granitoid intrusions. Polished thin sections were analyzed by using a fully automated JEOL 8600 electron microprobe at the University of Salzburg. Point analyses were obtained using 15 kV accelerating voltage and 40 nA beam current. The beam size was set to 5 µm. Natural and synthetic oxides and silicates were used as standards for major elements.

We used Mathematica package PET (Dachs, 2004) for mineral formula calculation (including nomenclature for amphibole according to the IMA scheme), calculation of single equilibrium geothermobarometers and plotting of mineral compositions. Structural formulas for all hornblendes were calculated according to Holland and Blundy (1994).

Pressures were calculated using the hornblende geobarometer of Schmidt (1992) in the modification of Anderson & Smith (1995). This geobarometer is based on the Al content of igneous hornblendes in equilibrium with plagioclase, biotite, K-feldspar, and sphene. For a temperature estimate, the geothermometer of Holland and Blundy (1994) was applied. In both cases we used the PET software (Dachs, 2004). For pressure estimates, we used a temperature of 775 ºC.

In general, core and rim compositions for zoned mineral grains were probed. Only analyses selected for P-T determinations are listed in Table A1. A back-scattered image of amphibole showing some chemical variation is shown in Fig. A1. Chemical compositions of the amphibole can be seen in Fig. A2. The calcic amphiboles have a lower percentage of Na and K than 0.5 and plot in the field of tschermakite, close to the boundary of ferro-tschermakite. Concerning the mineral formula of amphibole the aluminium is mostly placed on position IV in this sample.

The results of pressure calculations are shown in Fig. 3 of the main part of the text. The P-T diagram on the left side combines two different methods of temperature calculation. Both are plagioclase-amphibole thermometers of Holland and Blundy (1994) but on the assumption of different amphibole compositions. The lines from the upper left side to the lower right side represent an edenite-tremolite thermometric calculation and yield an average temperature of 790°C (for a pressure of 4 kbar). The tie lines from the lower left to upper right show the

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results of the second type of calculation based on an edenite-richterite amphibole composition. For the same pressure we got a temperature of 785 °C. Using the approach of Anderson and Smith (1995) we performed a third method of thermometrical calculation and found a temperature of 780°C for a pressure of 4 kbar. Finally, based on a histogram we estimate a pressure of 4.2 ± 0.2 kbar at a temperature of 800 °C.

References

Anderson, J.L., Smith, D., 1995. The effects of temperature and fO2 on the Al-in-hornblende barometer. American Mineralogist, 80, 549–559

Dachs, E., 2004. PET: Petrological Elementary Tools for Mathematicas: an update. Computers & Geosciences, 30, 173–182.

Holland, T.J B., Blundy, J., 1994. Non-ideal interactions in calcic amphiboles and their bearing on amphibole-plagioclase thermometer. Contributions to Mineralogy and Petrology, 116, 433–447.

Schmidt, M. W., 1992. Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al-in-hornblende barometer. Contribution to Mineralogy and Petrology, 110, 304–310.

Fig. A1. Back-scattered electron image of amphibole from sample QL-49.

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Fig. A2. Mineral composition of amphibole of sample QL-49. Mg-Si-plot shows that the

amphibole lies in the field of tschermakite. The majority of Al is placed on the position IV within the chemical formula of amphibole. On the right side the Ca-Na content of the mineral is displayed.

Table A1. Chemical composition of amphibole and plagioclase used for P-T estimation

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amph amph amph amph amph amph amph amph amph amph amph amph amph amph41 40.4 40.97 40.84 40.7 40.71 40.74 39.78 40.55 40.17 40.52 40.32 40.42 39.96

1.01 1.1 0.93 0.91 0.92 1.06 0.83 0.74 0.96 1.02 0.95 0.89 0.9510.02 10.38 10.32 10.57 10.46 10.5 10.33 10.71 10.49 10.48 10.51 10.67 10.65 11.09

n.d. n.d. 0.04 0.04 0.01 n.d. n.d. 0.01 0.01 n.d. n.d. 0.02 0.02n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.

21.11 21.33 21.43 21.32 21.64 21.85 22.06 22.08 21.8 22.11 22.28 22.19 22.08 22.682.19 2.06 2.18 2.24 2.16 2.33 2.26 2.3 2.17 2.2 2.3 2.25 2.25

7.6 7.27 7.45 7.47 7.04 7.23 7.08 6.72 7.12 6.8 6.78 6.82 6.8610.51 10.55 10.59 10.69 10.52 10.65 10.74 10.46 10.51 10.46 10.55 10.4 10.45 10.61

1.7 1.82 1.71 1.73 1.78 1.75 1.52 1.76 1.74 1.85 1.67 1.8 1.781.46 1.63 1.48 1.49 1.61 1.58 1.49 1.55 1.48 1.61 1.57 1.63 1.630.11 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.

96.71 96.54 97.1 97.3 96.84 97.66 97.05 96.11 96.83 96.7 97.13 96.99 97.096.283 6.232 6.256 6.222 6.258 6.199 6.233 6.167 6.223 6.203 6.215 6.197 6.205 6.1410.116 0.128 0.107 0.104 0.106 0.121 0.095 0.086 0.111 0.118 0.11 0.103 0.11 0.0731.81 1.887 1.857 1.898 1.896 1.884 1.863 1.957 1.897 1.907 1.9 1.933 1.927 2.009n.d. n.d. 0.005 0.005 0.001 n.d. n.d. 0.001 0.001 n.d. n.d. 0.002 0.002

1.266 1.159 1.273 1.294 1.181 1.319 1.374 1.37 1.286 1.241 1.317 1.295 1.273 1.3981.44 1.593 1.464 1.423 1.601 1.463 1.448 1.492 1.512 1.614 1.54 1.557 1.562 1.517

0.284 0.269 0.282 0.289 0.281 0.301 0.293 0.302 0.282 0.288 0.299 0.293 0.293 0.2861.736 1.672 1.696 1.697 1.614 1.641 1.615 1.553 1.629 1.565 1.55 1.563 1.57 1.5071.726 1.744 1.733 1.745 1.733 1.738 1.761 1.737 1.728 1.731 1.734 1.713 1.719 1.7470.505 0.544 0.506 0.511 0.531 0.517 0.451 0.529 0.518 0.554 0.497 0.536 0.53 0.5070.285 0.321 0.288 0.29 0.316 0.307 0.291 0.307 0.29 0.317 0.307 0.32 0.319 0.3040.007 n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.

n.d. = not determined

Mineral amph amph amph plag plag plag plag plag plag plag plagSiO2 40.21 39.64 40.79 61.72 62.74 62.47 62.47 62.54 62.54 61.78 62.45TiO2 0.92 0.98 0.85 n.d. n.d. 0.02 n.d. 0.02 n.d. n.d.Al2O3 10.33 10.56 10.21 22.4 22.4 22.67 22.63 22.57 22.59 22.62 22.67Cr2O3 0.01 n.d. 0.01 n.d. 0.02 n.d. n.d. 0.01 n.d. n.d.Fe2O3 n.d. n.d. n.d. 0.15 0.15 0.11 0.17 0.19 0.11 0.12FeO 22.25 22.32 21.52 n.d. n.d. n.d. n.d. n.d. n.d. n.d.MnO 2.35 2.37 2.17 0.01 n.d. 0.01 0.02 0.03 0.02 0.02MgO 6.93 6.61 7.3 n.d. n.d. n.d. n.d. n.d. n.d. n.d.CaO 10.65 10.48 10.37 4.34 4.16 4.27 4.42 4.43 4.38 4.25Na2O 1.62 1.7 1.76 9.2 9.24 9.21 9.24 9.25 9.16 9.25K2O 1.49 1.6 1.56 0.42 0.39 0.38 0.29 0.35 0.39 0.35BaO n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.Total 96.76 96.26 96.54 98.24 99.1 99.14 99.24 99.39 99.19 98.39 99.39Si 6.183 6.146 6.274 2.789 2.805 2.793 2.791 2.792 2.795 2.785 2.789Ti 0.106 0.114 0.098 n.d. n.d. 0.001 n.d. 0.001 n.d. n.d.Al 1.872 1.93 1.851 1.193 1.18 1.195 1.192 1.188 1.19 1.202 1.193Cr 0.001 n.d. 0.001 n.d. 0.001 n.d. n.d. n.d. n.d. n.d.Fe3 1.428 1.397 1.252 0.005 0.005 0.004 0.006 0.006 0.004 0.004 0.007Fe2 1.434 1.497 1.516 n.d. n.d. n.d. n.d. n.d. n.d. n.d.Mn 0.306 0.311 0.283 n.d. n.d. n.d. 0.001 0.001 0.001 0.001 0.001Mg 1.589 1.528 1.674 n.d. n.d. n.d. n.d. n.d. n.d. n.d.Ca 1.755 1.741 1.709 0.21 0.199 0.205 0.212 0.212 0.21 0.205 0.212Na 0.483 0.511 0.525 0.806 0.801 0.798 0.801 0.801 0.794 0.809 0.795K 0.292 0.316 0.306 0.024 0.022 0.022 0.017 0.02 0.022 0.02 0.025Ba n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.

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Mineral kf kf kf kf kf kf kf kf kf kf btSiO2 63.43 63.83 64.08 63.96 63.53 63.58 63.69 63.76 63.72 63.75 36.47TiO2 0.07 0.09 0.12 0.05 0.08 0.1 0.06 0.05 0.06 0.11Al2O3 18.36 17.81 18.21 18.25 18.44 18.12 18.14 18.1 17.81 18.23 13.27Cr2O3 n.d. n.d. 0.02 0.03 n.d. n.d. 0.02 n.d. n.d. n.d.Fe2O3 0.05 0.14 0.07 0.08 0.03 0.14 0.03 0.06 0.01 0.19FeO n.d. n.d. 0.00 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 19.84MnO n.d. n.d. 0.01 n.d. n.d. 0.01 0.02 n.d. n.d. n.d.MgO 0.01 0.01 0.01 n.d. 0.02 0.02 n.d. 0.01 n.d. 0.01CaO 0.03 0.03 0.05 0.02 0.06 0.01 0.01 0.03 0.04 0.03Na2O 1.62 1.41 1.70 1.63 1.93 1.34 1.41 1.67 1.59 1.2K2O 14.27 14.73 14.19 14.23 13.86 14.68 14.51 14.25 14.37 15BaO 0.8 0.85 0.82 0.81 0.84 n.d. n.d. n.d. n.d. n.d.Total 98.64 98.9 99.28 99.06 98.79 98 97.89 97.93 97.6 98.52 94.21Si 2.976 2.994 2.985 2.986 2.973 2.988 2.993 2.993 3.003 2.984 2.856Ti 0.002 0.003 0.004 0.002 0.003 0.004 0.002 0.002 0.002 0.004 0.162Al 1.015 0.984 1.000 1.004 1.017 1.004 1.005 1.001 0.989 1.006 1.225Cr n.d. n.d. 0.001 0.001 n.d. n.d. 0.001 n.d. n.d. n.d.Fe3 0.002 0.005 0.002 0.003 0.001 0.005 0.001 0.002 n.d. 0.007Fe2 n.d. n.d. 0.000 n.d. n.d. n.d. n.d. n.d. n.d. n.d. 1.299Mn n.d. n.d. 0.000 n.d. n.d. n.d. 0.001 n.d. n.d. n.d. 0.119Mg 0.001 0.001 0.001 n.d. 0.001 0.001 n.d. 0.001 n.d. 0.001 1.226Ca 0.002 0.002 0.002 0.001 0.003 0.001 0.001 0.002 0.002 0.002 0.003Na 0.147 0.128 0.154 0.148 0.175 0.122 0.128 0.152 0.145 0.109 0.015K 0.854 0.881 0.843 0.847 0.827 0.88 0.87 0.853 0.864 0.896 0.944Ba 0.015 0.016 0.015 0.015 0.015 n.d. n.d. n.d. n.d. n.d.

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Mineral bt bt bt bt sphen sphen sphen sphen spin spin spinSiO2 36.72 36.58 36.64 36.65 30.32 30.72 30.36 30.25 n.d. 0.02TiO2 2.39 3.14 3.19 3.19 34.54 33.79 30.96 34.6 0.16 0.14Al2O3 13.35 13.45 13.3 13.27 1.76 2.15 3.35 1.86 0.35 0.32Cr2O3 n.d. 0.03 n.d. 0.02 0.04 n.d. n.d. n.d. 0.03 n.d.Fe2O3 n.d. n.d. n.d. n.d. 2 2.1 2.47 1.97 n.d. n.d.FeO 19.83 21.77 21.2 20.86 n.d. n.d. n.d. n.d. 94.3 93.48 94.63MnO 1.28 1.32 1.41 1.41 0.26 0.42 0.61 0.31 0.56 0.39MgO 10.98 10.06 10.12 10.08 0.03 0.01 0.06 0.02 0.02 n.d.CaO n.d. 0.01 0.04 n.d. 27.02 26.78 26.36 26.85 0.01 n.d.Na2O 0.09 0.04 0.13 0.07 0.02 0.02 0.08 0.02 0.02 n.d.K2O 9.58 9.66 9.64 9.69 0.01 n.d. n.d. n.d. 0.01 n.d.BaO n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.Total 94.22 96.06 95.67 95.24 96 95.99 94.25 95.88 95.46 94.35 95.43Si 2.867 2.829 2.84 2.849 1.03 1.041 1.047 1.028 n.d. 0.001Ti 0.14 0.183 0.186 0.186 0.882 0.861 0.803 0.884 0.005 0.004 0.004Al 1.229 1.226 1.215 1.216 0.07 0.086 0.136 0.074 0.015 0.014 0.007Cr n.d. 0.002 n.d. 0.001 0.001 n.d. n.d. n.d. 0.001 n.d.Fe3 n.d. n.d. n.d. n.d. 0.051 0.054 0.064 0.05 1.977 1.976 1.985Fe2 1.295 1.408 1.374 1.356 n.d. n.d. n.d. n.d. 0.981 0.992 0.988Mn 0.085 0.086 0.093 0.093 0.007 0.012 0.018 0.009 0.018 0.013 0.016Mg 1.278 1.16 1.169 1.168 0.002 0.001 0.003 0.001 0.001 n.d.Ca n.d. 0.001 0.003 n.d. 0.983 0.973 0.974 0.978 n.d. n.d.Na 0.014 0.006 0.02 0.011 0.001 0.001 0.005 0.001 0.001 n.d.K 0.954 0.953 0.953 0.961 n.d. n.d. n.d. n.d. n.d. n.d.Ba n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d. n.d.

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2. Analytical techniques of LA-ICP-MS zircon U-Pb datingThe U-Pb analytical techniques largely follow those described in Liu et al. (2008). Zircons were dated in-situ on an excimer (193nm wave length) laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) at the State Key Laboratory of Continental Dynamics, Northwest University, Xi´an, China. The ICP-MS used is an Agilent 7500a (with shield torch). The unique shield torch increases analytical sensitivity by a factor of >10, (for example, 4500cps/ppm 238U at a spot size of 40 µm and laser frequency of 10Hz), which is important for LA-ICP-MS. The GeoLas 200M laser ablation system (MicroLas, Göttingen, Germany) was used for the laser ablation experiments. Helium was used as carrier gas. The used spot size and laser frequency were 40µm and 10Hz, respectively. The data acquisition mode was peak jumping (20ms per isotope each cycle). Raw count rates were measured for 29Si, 204Pb, 206Pb, 207Pb, 208Pb, 232Th and 238U. U, Th and Pb concentrations were calibrated by using 29Si as an internal standard and NIST SRM 610 as the reference standard. Each analysis consists of 30s gas blank and 40s signal acquisition. High-purity argon was used together with a custom helium filtration column, which resulted in 204Pb and 202Hg being less than 100 cps in the gas blank. Therefore, the contribution of 204Hg to 204Pb was negligible and no correction was made. 207Pb/206Pb, 206Pb/238U, 207Pb/235U and 208Pb/232Th ratios, calculated using GLITTER 4.0 (Macquarie University), were corrected for both instrumental mass bias and depth-dependent elemental and isotopic fractionation using Harvard zircon 91500 as external standard. The ages were calculated using ISOPLOT 3 (Ludwig, 2003). Our measurement of TEMORA 1 as an unknown yielded a weighted 206Pb/238U age of 415±4 Ma (MSWD=0.112, n=24) (Yuan et al., 2004), which is in good agreement with the recommended ID-TIMS age of 416.75 ± 0.24 Ma (Black et al., 2003). Analytical details for age and trace and rare earth element determinations of zircons are reported in Yuan et al. (2004). Common Pb corrections were made following the method of Andersen (2002). Because measured 204Pb usually accounts for <0.3 percent of the total Pb, the correction is insignificant in most cases. Catholdoluminescence pictures of dated zircons are shown in Fig. A3. Age dating results are given in Table A2.

References

Andersen, T., 2002, Correction of common lead in U-Pb analyses that do not report 204Pb: Chemical Geology, v. 192, p. 59–79, doi:10.1016/S0009-2541(02)00195-X.

Black, L. P., Kamo, S. L., Allen, C. M., Aleinikoff, J. N., Davis, D. W., Korsch, R. J., and Foudoulis, C., 2003, TEMORA 1: A new zircon standard for Phanerozoic U-Pb geochronology: Chemical Geology, v. 200, p. 155–170, doi:10.1016/S0009-2541(03)00165-7.

Liu, X., Gao, S., Diwu, C., Ling, W., 2008. Precambrian crustal growth of Yangtse Craton as revealed by detrital zircon studies. American Journal of Science, 308, 421–468, DOI 10.2475/04.2008.02.

Ludwig, K. R., 2003, ISOPLOT 3: a geochronological toolkit for Microsoft excel: Berkeley Geochronology Centre Special Publication, v. 4, 74 p.

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Yuan, H. L., Gao, S., Liu, X. M., Li, H. M., Günther, D., and Wu, F. Y., 2004, Accurate U–Pb age and trace element determinations of zircon by laser ablation-inductively coupled plasma mass spectrometry: Geostandards and Geoanalytical Research, 28, 353–370, doi:10.1111/j.1751-908X.2004.tb00755.x.

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Fig. A3a. Cathodoluminescence images of dated zircon grains for sample QL47A.

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Fig. A3b. Cathodoluminescence images of dated zircon grains for sample QL-44.

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Table A2. U-Pb analytical data of samples QL-44 and QL-47A of the Taibai granite.

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3. 40Ar/39Ar Analytical Techniques40Ar/39Ar analytical techniques largely follow descriptions given in Handler et al. (2004) and Rieser et al. (2006). Preparation of the samples before and after irradiation, 40Ar/39Ar analyses, and age calculations were carried out at the ARGONAUT Laboratory of the Department Geography and Geology at the University of Salzburg. Mineral concentrates were packed in aluminium-foil and loaded in quartz vials. For calculation of the J-values, flux-monitors were placed between each 4-5 unknown samples. The sealed quartz vials were irradiated in the MTA KFKI reactor (Budapest, Hungary) for 16 hours. Correction factors for interfering isotopes were calculated from 10 analyses of two Ca-glass samples and 22 analyses of two pure K-glass samples, and are: 36Ar/37Ar(Ca) = 0.00022500, 39Ar/37Ar(Ca) = 0.00061400, and 40Ar/39Ar(K) = 0.026600. Variation in the flux of neutrons were monitored with DRA1 sanidine standard for which originally a 40Ar/39Ar plateau age of 25.03 ± 0.05 Ma has been reported (Wijbrans et al., 1995). Here we use the revised value of 25.26 ± 0.05 Ma (Hinsbergen et al., 2008).40Ar/39Ar analyses were carried out using a UHV Ar-extraction line equipped with a combined MERCHANTEKTM UV/IR laser system, and a VG-ISOTECHTM NG3600 mass spectrometer. Stepwise heating analyses of samples were performed using a defocused (~1.5 mm diameter) 25 W CO2-IR laser operating in Tem00 mode at wavelengths between 10.57 and 10.63 µm. Gas admittance and pumping of the mass spectrometer and the Ar-extraction line are computer controlled using pneumatic valves. The NG3600 is an 18 cm radius 60° extended geometry instrument, equipped with a bright Nier-type source operated at 4.5 kV. Measurements are performed on an axial electron multiplier in static mode, peak-jumping and stability of the magnet is controlled by a Hall-probe. For each increment the intensities of 36Ar, 37Ar, 38Ar, 39Ar, and 40Ar are measured, the baseline readings on mass 34.5 are automatically subtracted. Intensities of the peaks are back-extrapolated over 16 measured intensities to the time of gas admittance either by a straight line or a curved fit, depending on intensity and type of pattern of the evolving gas. Intensities are corrected for system blanks, background, post-irradiation decay of 37Ar, and interfering isotopes. Isotopic ratios, ages and errors for individual steps are calculated following suggestions by McDougall and Harrison (1999) and Scaillet (2000) using decay factors reported by Steiger and Jäger (1977). Definition and calculation of plateau ages has been carried out using ISOPLOT/EX (Ludwig, 2001). Time-scale calibration follows Ogg et al. (2004, 2008).40Ar/39Ar dating: results

Measurements of ten mineral concentrates of amphibole, biotite and K-feldspar have been carried out for 40Ar/39Ar stepwise heating. The descriptions are on the one hand arranged according to the Ar retention temperatures in decreasing order (550 ± 25 °C for amphibole, 300 ± 25 °C for biotite and 200 ± 25 °C for K-feldspar) and on the other hand with increasing elevation. For detailed analytical results see Table A3. All plots are similarly arranged and are shown in Figure 4 of the main text.

Sample QL-47B: Measured mineral: amphibole. Grain size: 200–250 µm. Rock type: biotite-amphibolite. The first three steps are considered as excess argon. Steps 4 and 5 represent 58 % of the 39Ar and give a mean age of 119.1 ± 0.6 Ma (MSWD = 0.37). The last 5 steps yield a plateau age of 122.2 ± 0.7 Ma (MSWD = 0.28) including 42% of the 39Ar released. The

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isochrone plot shows a similar age but with a large error (121 ± 11 Ma, MSWD = 2.7). We consider the plateau age of 122.2 ± 0.7 Ma as geologically significant and to date cooling through ca. 550-500°C, the argon closure temperature of amphibole.

Sample QL-44: Measured mineral: biotite (two separate experiments). Grain size: 250–355 µm.

The first step yielded an age of 108.8 ± 1.7 Ma. Steps 2 to 11 (fusion) result in a slightly disturbed age pattern with a mean age 118.4 ± 0.7 Ma (MSWD = 1.8). We repeated the measurement with another concentrate and found a plateau age of 119.9 ± 0.7 Ma (50.1 % of 39Ar released). The mean age considering steps 4 – 11 (99.7 % of 39Ar released) is 119.4 ± 0.5 Ma, similar within error with the plateau age. We consider, therefore, the plateau of 119.9 ± 0.7 Ma as geologically significant.

Sample QL-49: Measured mineral: biotite. Grain size: 250–355 µm.

The results of the measurement of a biotite concentrate of sample QL-49 show a stable age pattern in high laser-energy steps and argon loss in the first step with an age of 71.9 ± 2.8 Ma caused by chloritization. The exact age of argon loss is insignificant because of low proportions of radiogenic 40Ar*.The remaining steps include 97.7% of the 39Ar and form a plateau age of 115.0 ± 0.4 Ma (MSWD = 1.3). An isochrone age calculation without step 2 gives a similar age of 115.2 ± 0.7 Ma (MSWD = 1.5).

Sample QL-48: Measured mineral: biotite. Grain size: 250–355 µm.

Biotite from sample QL-48 yields an integrated age (91.81 % of 39Ar released) for step 3 to 9 of 116.9 ± 1.0 Ma (MSWD = 28). The first two steps mark a maximum age of 92.2 ± 0.9 Ma due to Ar loss caused by chloritization. The exact age of argon loss is insignificant because of low proportions of radiogenic 40Ar*. An isochrone age of 118.3 ± 1.8 Ma (MSWD = 24) confirms the result of steps 3 to 9.

Sample QL-45A: Measured mineral: biotite. Grain size: 250–355 µm.

A biotite concentrate from sample QL-45A yields a staircase pattern. The first step gives an age of 66.4 ± 1.5 Ma (38.0 % of 39Ar released) with a relatively low percentage 40Ar* of 35.5 %. The age increases regularly up to step 6 with an age of 237.4 ± 4.7 Ma, which is likely too old because of possible excess Ar present in a retentative Ca-bearing mineral phase. The age of the first step is considered as the maximum age of a thermal overprint and/or hydrothermal alteration, which is relatively significant in this sample. We repeated the measurement of biotite of this sample and found a U-shaped age pattern. Excess Ar is present in the first two steps. Steps 1 to 4 yield only a low percentage of 40Ar* and we consider these steps as geologically meaningless. Step 4 yields an age of 76.5 ± 4.4 Ma (18.8 % of 39Ar released). The ages of following steps regularly increase to a maximum age of 197.3 ± 5.4 Ma. We consider this age as the minimum age of cooling through the appropriate Ar retention temperature biotite. Isochrone age calculation gives no results in both analytical experiments.

Sample QL-47A: Measured mineral: biotite. Grain size: 250–355 µm.

The age of the first two steps (70.3 ± 1.4 Ma of step 2) is considered as insignificant due to Ar loss because of low proportions of radiogenic 40Ar*. Step 4–9 yields a mean age of 120.0 ±

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0.6 Ma (MSWD = 13, including 91.6% of the 39Ar). The isochrone calculation only shows a plausible age without step 2 and 10 with an isochrone age of 120.3 ± 1.7 Ma (MSWD = 14).

Sample QL-47B: Measured mineral: biotite. Grain size: 250–355µm.

Step 1 with a very low percentage of 40Ar* (17.2 %) marks a maximum age of a thermal overprint at 40.3 ± 4.8 Ma. Steps 3–7 include 66.3 % of 39Ar and yield a mean age of 123.4 ± 0.3 Ma (MSWD = 0.99). Ages of the following steps decrease to a minimum age of 116.1 ± 0.3 Ma. If we ignore step 1 the isochrone calculation gives an age 121.0 ± 3.5 Ma.

Sample QL-44: Measured mineral: K-feldspar. Grain size: 250–355µm.

The first two steps are influenced by excess argon. The mean age considering steps 3 to 6 (67.2% of 39Ar released) is 111.1 ± 1.9 Ma. The ages of the following steps increase and form another mean age of 118.7 ± 1.2 Ma (step 7–10, MSWD = 6.0, Table A3).

Sample QL-48: Measured mineral: K-feldspar. Grain size: 250–355µm.

A K-feldspar concentrate of sample QL-48 shows a stable age pattern with excess Ar in the first step. Steps 2–9 yield a mean age of 113.0 ± 0.3 Ma (MSWD = 2.6) including 91.6% of the 39Ar. The ages of the last steps are increasing but have too low percentages of 39Ar to be geologically significant. The isochrone age calculation gives a comparable age with 115.7 ± 6.1 Ma (MSWD = 5.3).

Sample QL-47A: Measured mineral: K-feldspar. Grain size: 250–355µm.

K-feldspar of sample QL47A gives a slightly disturbed age pattern with some excess Ar in the first step. Steps 2 – 11 yield a mean age of 117.0 ± 1.4 Ma. We consider this mean age as geologically significant and to date cooling through the appropriate Ar retention temperature. The isochrone calculation yields an age of 113.9 ± 3.3 Ma.

References

Handler, R., Velichkova, S.H., Neubauer, F. &  Ivanov, Z., 2004. 40Ar/39Ar age constraints on the timing of the formation of Cu-Au deposits in the Panagyurishte region, Bulgaria. Schweizerische Mineralogische und Petrographische Mitteilungen 84, 119–132.

Harrison, T. M., Célérier, J., Aikman, A. B., Hermann, J. and Heizler, M. T., 2009. Diffusion of 40Ar in muscovite. Geochimica et Cosmochimica Acta, 73, 1039–1051.

Hinsbergen, D.J.J. van, Straathof, G.B., Kuiper, K.F., Cunningham, W.D.,Wijbrans, J, 2008. No vertical axis rotations during Neogene transpressional orogeny in the NE Gobi Altai: coinciding Mongolian and Eurasian early Cretaceous apparent polar wander paths: Geophys. J. Intern., v. 173, p. 105–126.

Ludwig, K.R., 2001, Users Manual for Isoplot/Ex – A Geochronological Toolkit for Microsoft Excel, Berkeley Geochronological Center, Special Publication No. 1a.

McDougall, I., and Harrison, M.T., 1999, Geochronology and Thermochronology by the 40Ar/39Ar Method: 2nd ed, Oxford Oxford, University Press, p. 269.

15

Ogg, J.G., Gradstein, F.M., and Smith, A.G., 2004, A Geologic Time Scale 2004, Gradstein, F.M., ed., eds.: Cambridge, UK, New York: Cambridge University Press, ISBN-13: 9780521781428.

Ogg, J.G., Ogg, G., and Gradstein, F.M., 2008, The Concise Geologic Time Scale, eds.: Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo, Delhi: Cambridge University Press, ISBN-13: 9780521898492.

Rieser, A.B., Liu, Y.J., Genser, J, Neubauer, F, Handler, R., Friedl, G., Ge, X.H., 2006. 40Ar/39Ar ages of detrital white mica constrain the Cenozoic development of the intracontinental Qaidam Basin, China. Geological Society of America Bulletin 118, 1522–1534.

Scaillet, S., 2000, Numerical error analysis in 40Ar/39Ar dating: Earth and Planetary Science Letters, v. 162, p. 269–298.

Steiger, R.H., and Jäger, E., 1977, Subcommission on geochronology: Convention on the use of decay constants in geo- and cosmochronology: Earth and Planetary Science Letters, v. 36, p. 359–362.

Wijbrans, JR., Pringle, MS., Koppers, AAP, and Schveers, R., 1995, Argon geochronology of small samples using the Vulkaan argon laserprobe: Proc. Koninklijke Academie Wetenschappen, v. 98, no. 2, p. 185–218.

16

Table A3. Analytical results of 40Ar/39Ar mineral dating of samples from the Taibai pluton.

Sample QL-47B, Amphibole (200-250µm), 15 grains, J-Value: 0.008014 ± .00002

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.745662 0.214389 12.779833.5876

9 226.541 57.675 0.003292 4.44E-04 7.077 29.989 3.1 0.0 99.5 410.3

2 0.248704 0.020970 3.646430.3556

5 96.686 4.514 0.002572 1.81E-04 23.462 5.305 24.2 0.2 310.8 64.6

3 0.023616 0.007687 9.440840.1942

3 18.528 0.228 0.001275 4.15E-04 12.221 2.289 65.7 0.8 168.6 30.2

4 0.004869 0.000170 8.786520.0319

9 9.312 0.034 0.000523 1.82E-05 8.476 0.060 90.8 30.1 118.6 0.9

5 0.004332 0.000158 8.807140.0185

1 9.199 0.020 0.000471 1.72E-05 8.524 0.051 92.4 26.9 119.2 0.8

6 0.030018 0.001682 9.289080.0672

5 16.984 0.064 0.001767 9.89E-05 8.755 0.501 51.3 2.9 122.3 6.8

7 0.018762 0.000859 9.339350.0426

6 13.707 0.068 0.001369 6.26E-05 8.808 0.261 64.0 5.5 123.1 3.5

8 0.003446 0.000172 9.087660.0249

8 9.110 0.020 0.000378 1.89E-05 8.718 0.055 95.4 14.9 121.8 0.8

9 0.006241 0.000359 8.854050.0418

6 10.089 0.061 0.000619 3.55E-05 8.855 0.121 87.5 9.3 123.7 1.7

10 0.015621 0.000489 8.942410.0765

9 12.740 0.074 0.001226 3.84E-05 8.740 0.158 68.4 9.4 122.1 2.2total 77.4 100.0 121.1 0.7

Sample QL-44, 1. Attempt, Biotite (250-355µm), 7 grains, J-Value: 0.006366 ± .00004

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.0137070.00047

5 0.000380.0207

0 13.846 0.040 0.000990 3.42E-05 9.764 0.143 70.7 2.0108.

8 1.72 0.001683 0.00012 0.00610 0.0022 11.206 0.022 0.000150 1.13E-05 10.678 0.043 95.6 5.6 118. 0.8

17

6 8 7

3 0.0008830.00009

6 0.009840.0013

6 10.853 0.048 0.000081 8.89E-06 10.561 0.055 97.6 8.9117.

4 0.9

4 0.0002270.00005

9 0.011330.0010

8 10.803 0.007 0.000021 5.48E-06 10.705 0.019 99.4 10.9118.

9 0.7

5 0.0000380.00006

2 0.018890.0008

5 10.802 0.012 0.000004 5.73E-06 10.761 0.022 99.9 11.0119.

5 0.7

6 0.0000200.00014

5 0.022440.0034

8 10.821 0.016 0.000002 1.34E-05 10.785 0.046 100.0 3.2119.

8 0.8

7 0.0000390.00002

3 0.042210.0003

4 10.671 0.013 0.000004 2.12E-06 10.631 0.014 99.9 29.8118.

1 0.7

8 0.0000210.00005

1 0.003350.0037

0 10.526 0.017 0.000002 4.87E-06 10.488 0.023 99.9 11.2116.

6 0.7

9 0.0001590.00006

3 0.004170.0043

3 10.715 0.017 0.000015 5.91E-06 10.637 0.025 99.6 9.6118.

2 0.7

10 0.0000330.00012

9 0.004980.0073

8 10.673 0.015 0.000003 1.21E-05 10.632 0.041 99.9 5.6118.

2 0.8

11 0.0005120.00018

4 0.003290.0183

2 10.932 0.029 0.000047 1.68E-05 10.749 0.062 98.6 2.2119.

4 0.9

total 98.6 100.0118.

1 0.6

Sample QL-44, 2 Attempt, Biotite (250-355µm), 6 grains, J-Value: 0.006366 ± .00004

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.0573600.00524

0 36.53378 49.83449 19.942 0.428 0.002876 2.56E-04 5.514 3.731 27.1 0.1 62.3 41.4

2 0.0405880.00359

4 22.94129 4.53810 16.091 0.224 0.002522 2.21E-04 5.672 1.115 34.8 0.2 64.0 12.4

3 0.0104880.00042

2 2.13888 0.20494 13.955 0.033 0.000752 3.02E-05 10.981 0.128 78.8 3.6121.

9 1.5

4 0.0022520.00008

5 0.19352 0.12440 11.474 0.009 0.000196 7.44E-06 10.791 0.028 94.3 10.4119.

9 0.75 0.000352 0.00015 0.58455 0.19456 10.997 0.017 0.000032 1.40E-05 10.904 0.050 99.4 7.1 121. 0.9

18

4 1

6 0.0004280.00006

7 0.05536 0.05987 10.932 0.008 0.000039 6.08E-06 10.778 0.022 98.9 16.8119.

7 0.7

7 0.0001370.00006

7 0.12071 0.10681 10.839 0.013 0.000013 6.19E-06 10.776 0.025 99.7 13.1119.

7 0.7

8 0.0001810.00004

6 0.00105 0.04907 10.789 0.010 0.000017 4.25E-06 10.704 0.017 99.5 22.7118.

9 0.7

9 0.0002600.00003

2 0.14959 0.37441 10.773 0.010 0.000024 2.97E-06 10.675 0.029 99.4 22.6118.

6 0.7

10 0.0001790.00023

2 0.82335 2.42504 10.926 0.023 0.000016 2.12E-05 10.902 0.177 100.0 3.4121.

1 2.0tota

l 97.4 100.0119.

4 0.7

Sample QL-49, Biotite (250-355µm), 7 grains, J-Value: 0.007957 ± .00002

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.088280 0.008975 1.28925 1.29294 30.398 0.548 0.0029042.92E-

04 4.374 2.626 14.4 0.1 61.7 36.4

2 0.023961 0.000674 0.16344 0.08256 12.206 0.023 0.0019635.52E-

05 5.111 0.199 42.0 2.2 71.9 2.8

3 0.006474 0.001076 0.24921 0.13295 10.573 0.038 0.0006121.02E-

04 8.651 0.320 82.0 0.9 120.1 4.3

4 0.003018 0.000161 0.08737 0.02436 9.138 0.017 0.0003301.76E-

05 8.226 0.050 90.3 5.7 114.4 0.8

5 0.000916 0.000053 0.00133 0.06231 8.557 0.008 0.0001076.21E-

06 8.260 0.018 96.8 10.7 114.8 0.4

6 0.000596 0.000090 0.02118 0.01081 8.458 0.013 0.0000701.06E-

05 8.257 0.029 97.9 10.0 114.8 0.5

7 0.000429 0.000037 0.00334 0.03064 8.427 0.010 0.0000514.34E-

06 8.274 0.015 98.5 22.2 115.0 0.4

8 0.000348 0.000027 0.00164 0.02492 8.438 0.013 0.0000413.23E-

06 8.309 0.015 98.8 27.0 115.5 0.49 0.000294 0.000050 0.00320 0.04489 8.372 0.006 0.000035 5.96E- 8.259 0.016 99.0 16.2 114.8 0.4

19

06

10 0.001063 0.000178 0.02767 0.02329 8.625 0.025 0.0001232.07E-

05 8.286 0.058 96.4 5.0 115.2 0.8total 95.5 100.0 114.1 0.4

Sample QL-48, Biotite (250-355µm), 5 grains, J-Value: 0.007984 ± .00002

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.0779350.00197

2 0.110330.5571

3 29.123 0.095 0.002676 6.72E-05 6.069 0.580 20.9 0.9 85.4 8.0

2 0.0101630.00020

7 0.013870.0700

4 9.598 0.016 0.001059 2.15E-05 6.564 0.062 68.6 7.3 92.2 0.9

3 0.0016640.00008

1 0.022320.1127

3 9.082 0.012 0.000183 8.89E-06 8.560 0.028 94.6 4.5119.

3 0.5

4 0.0019340.00008

1 0.010010.0505

3 9.193 0.009 0.000210 8.83E-06 8.591 0.026 93.8 10.1119.

7 0.5

5 0.0037300.00010

1 0.004990.0679

3 9.634 0.023 0.000387 1.04E-05 8.501 0.037 88.5 8.9118.

5 0.6

6 0.0018480.00008

1 0.004270.0580

6 8.986 0.009 0.000206 9.05E-06 8.409 0.026 93.9 10.4117.

3 0.5

7 0.0006290.00004

1 0.003050.0415

7 8.567 0.007 0.000073 4.79E-06 8.350 0.014 97.8 14.5116.

5 0.4

8 0.0004150.00002

9 0.002200.0299

1 8.562 0.009 0.000049 3.39E-06 8.408 0.012 98.6 20.1117.

2 0.4

9 0.0002540.00002

1 0.083360.0036

8 8.432 0.006 0.000030 2.44E-06 8.331 0.008 99.2 23.4116.

2 0.4

total 91.9 100.0115.

2 0.4

Sample QL-45A, 1.Attempt Biotite (200-355µm), 10 grains, J-Value: 0.006370 ± .00004

20

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.036311 0.000399 0.46532 0.00761 16.612 0.121 0.0021862.23E-

05 5.883 0.127 35.5 38.0 66.4 1.5

2 0.014515 0.000399 0.18140 0.00722 14.872 0.115 0.0009762.64E-

05 10.565 0.147 71.2 16.2 117.5 1.7

3 0.006846 0.000294 0.14991 0.00868 16.204 0.107 0.0004221.81E-

05 14.161 0.131 87.6 16.3 155.8 1.6

4 0.005928 0.000362 0.63542 0.01080 17.790 0.054 0.0003332.03E-

05 16.055 0.118 90.4 14.8 175.7 1.5

5 0.006849 0.000534 1.37447 0.13508 20.904 0.053 0.0003282.55E-

05 18.956 0.165 90.7 10.0 205.7 2.0

6 0.008129 0.001312 3.29184 0.37105 24.246 0.241 0.0003355.40E-

05 22.076 0.447 91.0 3.6 237.4 4.7

7 0.024798 0.005141 14.38268 1.21353 22.439 0.428 0.0011052.29E-

04 16.179 1.575 71.6 1.1 177.0 16.4total 66.7 100.0 127.5 1.0

Sample QL-45A, 2.Attempt Biotite (200-355µm), 10 grains, J-Value: 0.006370 ± .00004

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.395595 0.042577 0.44239 0.27657 148.389 7.255 0.0026662.56E-

04 31.497 11.322 21.2 0.4 329.9 108.4

2 0.267824 0.012914 0.01066 0.72155 87.745 2.492 0.0030521.20E-

04 8.573 3.120 9.8 0.7 95.9 34.0

3 0.052160 0.000814 0.01407 0.00586 18.345 0.091 0.0028434.36E-

05 2.901 0.238 15.8 18.7 33.0 2.7

4 0.030425 0.001365 0.02924 0.01732 10.763 0.113 0.0028271.24E-

04 1.743 0.396 16.2 5.9 19.9 4.5

5 0.032551 0.001221 0.01212 0.00542 16.443 0.286 0.0019807.33E-

05 6.794 0.398 41.4 18.8 76.4 4.4

6 0.014915 0.000774 0.00915 0.00387 15.836 0.208 0.0009424.89E-

05 11.398 0.288 72.1 17.2 126.5 3.2

7 0.011926 0.000956 0.02477 0.00796 17.850 0.100 0.0006685.35E-

05 14.296 0.295 80.2 11.9 157.2 3.2

21

8 0.014463 0.001433 0.05262 0.01384 21.455 0.141 0.0006746.67E-

05 17.154 0.438 80.1 6.2 187.1 4.6

9 0.013943 0.001176 0.02776 0.01014 20.822 0.103 0.0006705.64E-

05 16.672 0.357 80.2 10.6 182.1 3.8

10 0.014247 0.001662 0.06703 0.01318 22.370 0.199 0.0006377.41E-

05 18.134 0.516 81.2 6.7 197.2 5.4

11 0.022359 0.002740 0.11094 0.03039 24.547 0.219 0.0009111.11E-

04 17.917 0.824 73.1 3.0 195.0 8.6total 54.8 100.0 115.0 1.6

Sample QL-47A, Biotite (250-355µm), 5 grains, J-Value: 0.006371 ± .00004

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.0479580.00100

9 0.169520.0184

7 21.189 0.085 0.002263 4.69E-05 6.998 0.295 33.1 0.7 78.7 3.3

2 0.0116010.00043

0 0.070780.0033

5 9.688 0.019 0.001197 4.44E-05 6.234 0.128 64.6 2.5 70.3 1.5

3 0.0066020.00043

7 0.066390.0072

1 12.112 0.075 0.000545 3.60E-05 10.134 0.143 83.9 1.6112.

9 1.7

4 0.0010840.00007

4 0.024230.0009

5 11.010 0.017 0.000098 6.71E-06 10.660 0.028 97.1 11.6118.

6 0.7

5 0.0004300.00003

1 0.007960.0008

7 10.943 0.012 0.000039 2.83E-06 10.785 0.015 98.8 16.1119.

9 0.7

6 0.0005400.00005

0 0.019780.0009

3 11.018 0.015 0.000049 4.50E-06 10.829 0.021 98.6 11.4120.

4 0.7

7 0.0001640.00002

6 0.017430.0007

5 10.913 0.010 0.000015 2.39E-06 10.835 0.012 99.6 22.8120.

4 0.7

8 0.0000790.00002

4 0.024680.0007

3 10.815 0.008 0.000007 2.20E-06 10.762 0.011 99.8 23.9119.

7 0.6

9 0.0004600.00012

0 0.019850.0025

9 11.131 0.022 0.000041 1.08E-05 10.966 0.042 98.8 5.7121.

8 0.8

10 0.0018360.00024

3 0.031930.0041

9 14.869 0.035 0.000123 1.63E-05 14.298 0.079 96.4 3.6157.

3 1.2total 97.0 100.0 119. 0.6

22

7

Sample QL-47B, Biotite (250-355µm), 7 grains, J-Value: 0.006373 ± .00003

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.0458540.00114

5 0.009110.0396

5 16.392 0.043 0.002797 6.96E-05 2.816 0.337 17.2 2.8 40.3 4.8

2 0.1050450.00213

9 0.619640.0422

6 38.799 0.070 0.002707 5.50E-05 7.776 0.631 20.0 3.2109.

2 8.6

3 0.0673950.00137

2 0.015980.1749

9 28.890 0.045 0.002333 4.74E-05 8.950 0.405 31.0 4.8125.

2 5.5

4 0.0277550.00061

1 0.018040.1975

4 17.017 0.036 0.001631 3.58E-05 8.790 0.182 51.7 4.3123.

0 2.5

5 0.0039130.00015

4 0.001640.0748

9 10.026 0.008 0.000390 1.54E-05 8.844 0.046 88.4 11.0123.

7 0.7

6 0.0008160.00004

8 0.061860.0067

5 9.097 0.010 0.000090 5.29E-06 8.833 0.017 97.4 28.6123.

6 0.4

7 0.0006170.00006

7 0.072860.0080

6 8.985 0.009 0.000069 7.50E-06 8.782 0.022 98.0 17.5122.

9 0.5

8 0.0003410.00005

4 0.094950.0117

0 8.640 0.009 0.000039 6.27E-06 8.520 0.019 98.9 17.6119.

4 0.4

9 0.0005210.00007

9 0.102840.0161

3 8.451 0.009 0.000062 9.40E-06 8.278 0.025 98.3 10.1116.

1 0.5

total 74.3 100.0119.

3 0.6

Sample QL-44, K-feldspar (250-355µm), 7 grains, J-Value: 0.006364 ± .00004

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.094864 0.001371 0.08209 0.00860 183.199 0.513 0.0005187.35E-

06 155.149 0.592 84.7 0.61239.

1 6.1

2 0.004562 0.000091 0.08586 0.00110 13.553 0.021 0.0003376.70E-

06 12.180 0.033 90.1 5.2 134.7 0.83 0.001305 0.000040 0.11772 0.00107 10.185 0.013 0.000128 3.88E- 9.777 0.017 96.3 9.7 108.9 0.6

23

06

4 0.000785 0.000018 0.05733 0.00046 10.235 0.010 0.0000771.78E-

06 9.975 0.011 97.8 25.5 111.0 0.6

5 0.000474 0.000027 0.03794 0.00074 10.246 0.010 0.0000462.63E-

06 10.077 0.013 98.7 11.9 112.1 0.6

6 0.000858 0.000046 0.04640 0.00043 10.279 0.012 0.0000834.48E-

06 9.998 0.018 97.6 20.0 111.3 0.6

7 0.001569 0.000075 0.16235 0.00139 11.245 0.011 0.0001406.68E-

06 10.762 0.025 96.0 9.0 119.5 0.7

8 0.001815 0.000172 0.31873 0.00286 11.194 0.028 0.0001621.54E-

05 10.649 0.058 95.4 2.7 118.3 0.9

9 0.000794 0.000046 0.18098 0.00095 10.883 0.015 0.0000734.24E-

06 10.630 0.020 97.9 12.3 118.1 0.7

10 0.000981 0.000127 0.11320 0.00269 11.034 0.020 0.0000891.15E-

05 10.721 0.042 97.4 2.6 119.1 0.8

11 0.004329 0.001002 0.84633 0.02455 13.911 0.100 0.0003117.20E-

05 12.663 0.311 91.2 0.4 139.8 3.4total 95.7 100.0 124.2 0.7

Sample QL-48, K-feldspar (250-355µm), 10 grains, J-Value: 0.007971 ± .00002

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.007198 0.000125 0.48950 0.01466 14.107 0.020 0.0005108.82E-

06 11.984 0.041 85.1 6.4 164.6 0.7

2 0.000107 0.000058 0.25607 0.01122 8.126 0.011 0.0000137.10E-

06 8.081 0.020 99.8 11.2 112.6 0.4

3 0.000531 0.000263 1.46179 0.03781 8.156 0.020 0.0000653.22E-

05 8.072 0.080 99.3 2.1 112.5 1.1

4 0.000295 0.000017 0.01151 0.00501 8.270 0.012 0.0000362.00E-

06 8.152 0.012 99.0 28.6 113.6 0.4

5 0.000294 0.000030 0.00402 0.00905 8.215 0.006 0.0000363.64E-

06 8.097 0.010 98.9 16.6 112.8 0.4

6 0.000461 0.000025 0.04134 0.01247 8.246 0.018 0.0000563.05E-

06 8.081 0.020 98.4 11.3 112.6 0.4

24

7 0.000371 0.000046 0.08299 0.01319 8.252 0.016 0.0000455.59E-

06 8.117 0.021 98.7 9.3 113.1 0.4

8 0.000498 0.000047 0.00000 0.01690 8.275 0.019 0.0000605.74E-

06 8.097 0.023 98.2 8.6 112.8 0.5

9 0.000880 0.000093 0.10754 0.03451 8.369 0.029 0.0001051.11E-

05 8.085 0.040 97.0 3.8 112.7 0.6

10 0.001850 0.001080 0.08347 0.37292 9.032 0.067 0.0002051.20E-

04 8.460 0.326 94.0 0.5 117.7 4.4

11 0.000340 0.000618 0.25232 0.14301 8.950 0.054 0.0000386.90E-

05 8.836 0.190 99.1 1.2 122.8 2.6

12 0.001887 0.001450 0.00065 0.62409 10.260 0.118 0.0001841.41E-

04 9.671 0.445 94.5 0.3 134.0 6.0

13 0.041360 0.011018 0.00549 5.31534 24.798 0.856 0.0016684.41E-

04 12.545 3.282 50.7 0.0 172.0 42.9total 97.2 100.0 116.6 0.4

Sample QL-47A, K-feldspar (250-355µm), 7 grains, J-Value: 0.006373 ± .00003

step 36Ar/39Ara ± 37Ar/39Arb ± 40Ar/39Ara ± 36Ar/40Ar ± 39ArK/40Ar* ± %40Arc %39Ar age ±

1 0.0279100.00103

5 0.000000.0068

7 28.313 0.033 0.000986 3.66E-05 20.034 0.307 70.8 1.2216.

8 3.3

2 0.0020810.00008

2 0.006160.0003

8 11.350 0.012 0.000183 7.19E-06 10.704 0.027 94.6 6.5119.

0 0.7

3 0.0010420.00004

9 0.006670.0003

7 10.796 0.009 0.000097 4.51E-06 10.457 0.017 97.1 7.8116.

4 0.6

4 0.0015890.00003

7 0.003920.0002

5 10.748 0.007 0.000148 3.47E-06 10.248 0.013 95.6 14.6114.

1 0.6

5 0.0011090.00004

7 0.002820.0002

6 10.732 0.008 0.000103 4.36E-06 10.373 0.016 96.9 13.2115.

5 0.6

6 0.0015810.00004

2 0.004690.0002

0 11.046 0.007 0.000143 3.78E-06 10.548 0.014 95.8 12.8117.

4 0.6

7 0.0016850.00005

4 0.002760.0002

0 11.027 0.007 0.000153 4.91E-06 10.498 0.017 95.5 12.5116.

8 0.68 0.001030 0.00003 0.00246 0.0001 10.816 0.009 0.000095 3.37E-06 10.480 0.014 97.2 14.9 116. 0.6

25

6 8 6

9 0.0007300.00002

3 0.002020.0002

6 11.059 0.012 0.000066 2.04E-06 10.812 0.014 98.0 11.0120.

2 0.7

10 0.0004880.00025

5 0.006430.0029

0 10.952 0.014 0.000045 2.33E-05 10.777 0.077 98.7 0.8119.

8 1.0

11 0.0007580.00004

5 0.000080.0035

1 10.907 0.013 0.000069 4.13E-06 10.652 0.018 97.9 4.2118.

5 0.7

12 0.0000660.00045

0 0.001150.0047

6 11.092 0.070 0.000006 4.06E-05 11.041 0.150 99.8 0.5122.

7 1.7

total 95.7 100.0118.

2 0.6

Errors of ratios, J-values, and ages are at 1-sigma level.

a) measured

b) corrected for post-irradiation decay of 37Ar (35.1 days)

c) non atmospheric 40Ar

26

4. Apatite fission-track analytical methods

Specimens were first reduced to approximately 5 cm diameter pieces using a sledgehammer and a steel plate. The pieces were then run through a jaw-crusher multiple times. The clay and silt fractions were removed by sieving and the residual fraction 80-355 µm was treated by standard magnetic and heavy liquids (bromoform) separation techniques. Separated apatites were mounted and polished with epoxy on glass slides. They were etched at 21°C for 20 s with 5N HNO3 to reveal the spontaneous fission tracks. Mounts were then covered with a thin sheet of low-uranium muscovite as external detector and sent for irradiation at the FRM-II reactor in Garching, together with CN5 dosimeter glasses to monitor the neutron fluence. Total thermal neutron flux was 1 x 1016 n cm2. After irradiation, the white mica detectors were etched for 45 to 50 minutes in 40% HF to reveal the induced track set. Track counting and length measurements were carried out under transmitted and reflected light on an Olympus BX51 microscope with a computer-driven stage and a digitizing tablet. The external detector method and the zeta-calibration approach were applied (Hurford and Green, 1982; Naeser et al., 1989). Fission-track ages were calculated using MacTrackX. Four dpar values (mean diameters of etch figures on prismatic surfaces parallel to the crystallographix c-axis) (Burtner et al., 1994) were measured for each grain to constrain annealing kinetics. All track lengths were corrected for c-axis orientation (Donelick et al., 1999).Results of AFT analysis are given in Table 3 of the main text. Screenshots of HeFTy modelling results are given in Fig. A4.

References

Burtner, R.L., Nigrini, A., Donelick, R.A., 1994. Thermochronology of Lower Cretaceous source rocks in the Idaho-Wyoming thrust belt. AAPG Bulletin 78, 1613-1636.

Donelick, R.A., Ketcham, R.A., Carlson, W.D., 1999. Variability of apatite fission-track annealing kinetics; II, Crystallographic orientation effects. Am Mineral 84, 1224-1234.

Hurford, A.J., Green, P.F., 1982. A users' guide to fission track dating calibration. Earth and Planetary Science Letters 59, 343-354.

Naeser, N.D., Naeser, C.W., McCulloh, T.H., 1989. The application of fission-track dating to the depositional and thermal history of rocks in sedimentary basins. Springer-Verlag, New York, NY, United States (USA).

27

Fig. A4a: HeFTy modeling for sample QL50 (929 m) – arrows indicate GOF values

28

Fig. A4b: HeFTy modeling for sample QL44 (1163 m)

29

30

Fig. A4c: HeFTy modeling for sample QL49 (1750 m)

31

Fig. A4d: HeFTy modeling for sample QL8 (2196 m)

32

33

Fig. A4e: HeFTy modeling for sample QL45 (2755 m)

34

Fig. A4f: HeFTy modeling for sample QL47 (3375 m)

35

5. (U–Th–Sm)/He analytical technique

For (U–Th–Sm) ⁄He analysis, apatite crystals were hand-picked following the selection criteria of Farley (2002). Euhedral crystals were inspected for inclusions under 250x magnification and cross-polarized light. Only inclusion-free grains that exceeded 70 µm diameters were selected. To calculate the alpha ejection correction factor (Farley et al., 1996) microphotographs were taken for determining shape parameters like width, total length, and length of prismatic section. After proper documentation, each crystal was wrapped in platinum capsules and degassed in high vacuum by heating with an infrared laser in the Thermochronology Laboratory at Geoscience Center, University of Göttingen (GÖochronoly). A SAES Ti-Zr getter purified the gas extracted from the crystals and a Hiden® triple-filter quadrupol mass spectrometer measured the 4He content. For the detection of the alpha-emitting elements (uranium, thorium and samarium) the degassed crystals were spiked with calibrated 230Th and 233U solutions. The apatite crystals were dissolved in 2 % HNO3 at room temperature in an ultrasonic bath. The actinide concentrations were determined by isotope dilution method and the Sm by external calibration method, using a Perkin Elmer Elan DRC II ICP-MS equipped with an APEX micro-flow nebulizer.

Age dating results are given in Table 4 in the main text.

References

Farley, K.A., 2002. (H-Th) ⁄He dating: Techniques, calibrations, and applications. Mineral. Soc. Am. Rev. Mineral. Geochem., 47, 819–844.

Farley, K.A., Wolf, R.A. and Silver, L.T., 1996. The effects of long alpha-stopping distances on (U-Th) ⁄He ages. Geochim. Cosmochim. Acta, 60, 4223–4229.

Hourigan, J. K., Reiners, P. W., and Brandon, M. T., 2005, U-Th zonation-dependent alpha-ejection in (U-Th)/He chronometry: Geochimica Et Cosmochimica Acta, v. 69, no. 13, p. 3349-3

36