Supplemental files. Supplemental file 1 analytical method

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1 GSA Data Repository Item Liu, H., Wang, Y., Cawood, P.A., and Guo, X., 2016, Episodic slab-rollback and back-arc extension in the Yunnan- Burma region: Insights from Cretaceous Nb-enriched and oceanic-island basalt-like mafic rocks: GSA Bulletin, doi: /b Supplemental files Supplemental file 1 analytical method Zircon mineral separates were prepared by conventional heavy liquid and magnetic techniques. Grains were mounted in epoxy, polished and coated with gold and then photographed in transmitted and reflected light. Their internal texture was examined using cathodoluminescence (CL) imaging at the Institute of Geology and Geophysics (IGG), Chinese Academy of Sciences (CAS), Beijing. Zircon U-Pb ages and trace elements for samples HH-22C and ML-37A were analyzed using a Laser ICP-MS at the IGG CAS. The zircon standards CN92-2, and GJ were used to calibrate the U-Th-Pb ratios. The standard silicate glass NIST 610 was used to optimize the machine. The spot size for data collection was 30 μm. The errors for individual U-Pb analyses are presented with 1 error and uncertainties in grouped ages are quoted at 95 % level (2 ). The age calculations and plots were made using Isoplot (version 3.0; Ludwig, 2001). Further detailed descriptions of the instrumentation and analytical procedure for the LA-ICP-MS zircon U-Pb and trace element technique are similar to those described by Yuan et al. (2004). Measurements of U, Th and Pb for sample HH-22A were conducted using the Cameca IMS-1280 at IGG-CAS. U Th Pb ratios were determined relative to the standard zircon Ples ovice (Sla ma et al., 2008), and their absolute abundances were calibrated to the standard zircon (Wiedenbeck et al., 1995), using operating and data processing procedures similar to those described by Li et al. (2009). The weighted mean U Pb ages and Concordia plots were processed using Isoplot/Ex v.3.0 program (Ludwig, 2001). SIMS zircon U-Pb isotopic data are presented in table 3. Whole rock samples for geochemistry were crushed to 200-mesh using an agate mill for elemental and Sr-Nd isotopic analyses. The major oxides were analyzed by a wavelength X-ray fluorescence spectrometry at the State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry (GIG), Chinese Academy of Sciences (CAS). Trace element analyses were performed at the GIG CAS by a Perkin-Elmer Sciex ELAN 6000 ICP-MS. Detailed sample preparation and analytical procedure followed Li et al. (2002). Sr, Nd isotopic analyses were carried out at the GIG CAS on a Neptune Plus (Thermo Fisher Scientific, MA, USA) multi-collection mass spectrometry equipped with nine Faraday cup collectors and eight ion counters. Details analytical methods are presented by Yang et al. (2006). Normalizing factors used to correct the mass fractionation of Sr and Nd during the measurements were 86 Sr/ 88 Sr = and 146 Nd/ 144 Nd = (Yang et al., 2005, 2007). References Li, X.H., Li, Z.X., Zhou, H.W., Liu, Y., Kinny, P.D., U-Pb zircon geochronology,

2 geochemistry and Nd isotopic study of Neoproterozoic bimodal volcanic rocks in the Kangdian Rift of South China: implications for the initial rifting of Rodinia. Precambrian Research 113, Li, X. H., Liu, Y., Li, Q. L., Guo, C. H., and Chamberlain, K. R., Precise determination of Phanerozoic zircon Pb/Pb age by multicollector SIMS without external standardization. Geochemistry, Geophysics, Geosystems 10, Ludwig, K.R., Sqiud 1.02:A User Manual. Berkeley:Berkeley Geochronological Center Special publication, Sla ma, J., Kosler, J., Condon, D. J., Crowley, J. L., Gerdes, A., Hanchar, J. M., Horstwood, M. S. A., Morris,G. A., Nasdala, L., Norberg, N., Schaltegger, U., Schoene, B., Tubrett, M. N., and Whitehouse, M. J., Plesˇovice zircon-a new natural reference material for U-Pb and Hf isotopic microanalysis. Chemical Geology 249, Wiedenbeck, M., Alle, P., Corfu, F., Griffin, W. L., Meier, M., Oberli, F., Von Quadt, A., Roddick, J. C., and Speigel, W., 1995, Three Natural Zircon Standards for U-Th-Pb, Lu-Hf, Trace-Element and REE Analyses. Geostandards Newsletter 19, Yang, J.H., Wu, F.Y., Shao, J.A., Wilde, S.A., Xie, L.W., Liu, X.M., Constraints on the timing of uplift of the Yanshan Fold and Thrust Belt, North China. Earth and Planetary Science Letters 246, Yuan, H.L., Gao, S., Liu, X.M., Li, H.M., Gunther, D., Wu, F.Y., Accurate U-Pb age and trace element determinations of zircon by laser ablation-inductively coupled plasma-mass spectrometry. Geostandards and Geoanalytical Research 28, Yang, Y.H., Zhang, H.F., Wu, F.Y., Xie, L.W., Zhang, Y.B., Accurate Measurement of Strontium Isotopic Composition by Neptune Multiple Collector Inductively Coupled Plasma Mass Spectrometry. Journal of Chinese Mass Spectrometry Society 26, (in Chinese with English abstract). Yang, Y.H., Zhang, H.F., Xie, L.W., Wu, F.Y., AccurateMeasurement ofneodym ium Isotopic Composition Using Neptune Multiple Collector Inductively Coupled P lasmamass Spectrometry. Chinese Journal of Analytical Chemistry 1, ( in Chinese with English abstract).

3 Supplemental file 2 LA-ICPMS Zircon U-Pb dating results for the Mili diabase and Nb-enriched Yaoshan amphibolite Analysis 207 Pb/ 235 U 206 Pb/ 238 U 207 Pb/ 235 U 206 Pb/ 238 U Ratio 1 Ratio 1 Age (Ma) 1 Age (Ma) 1 Mili Diabase Th/U ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A ML-37A Nb-enriched Yaoshan amphibolite HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C HH-22C

4 Supplemental file 3 SIMS Zircon U-Pb dating results for the OIB-like Yaoshan amphibolite Sample/spot # 207 Pb/ 235 U 206 Pb/ 238 U 207 Pb/ 235 U 206 Pb/ 238 U 207-corr Ratio 1 Ratio 1 age (Ma) 1 age (Ma) 1 age (Ma) 1 Th/U HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@ HH-22A@

5 Supplemental file 4 Major oxides and elemental analyzed results Sample 10HH-22A 10HH-22B 10HH-22C 10HH-22D 10HH-22E 10HH-22P 10HH-22L 11ML-37A 11ML-37B 11ML-37E 11ML-37F 11ML-37K 11ML-37N 11ML-37Z Dalongkai OIB-like amphibolite Nb-enriched amphibolite Nb-enriched diabase Pl-pyroxunite SiO TiO Al 2 O Fe 2 O 3 t MnO MgO CaO Na 2 O K 2 O P 2 O L.O.I Total P K Sc Ti V Cr Co Ni Cu Zn

6 Sample 10HH-22A 10HH-22B 10HH-22C 10HH-22D 10HH-22E 10HH-22P 10HH-22L 11ML-37A 11ML-37B 11ML-37E 11ML-37F 11ML-37K 11ML-37N 11ML-37Z Dalongkai OIB-like amphibolite Nb-enriched amphibolite Nb-enriched diabase Pl-pyroxunite Ga Rb Sr Y Zr Nb Cs Ba La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta

7 Sample 10HH-22A 10HH-22B 10HH-22C 10HH-22D 10HH-22E 10HH-22P 10HH-22L 11ML-37A 11ML-37B 11ML-37E 11ML-37F 11ML-37K 11ML-37N 11ML-37Z Dalongkai OIB-like amphibolite Nb-enriched amphibolite Nb-enriched diabase Pl-pyroxunite Pb Th U Dalongkai samples are from Liu et al. (under review-a) References Liu, H. C., Wang, Y. J., Guo, X. F., Fan, W. M., and Song, J. J., under review-a. Late Triassic post-collisional slab break-off along the Ailaoshan suture: insights from OIB-like metagabbros and associated rocks. Int J Earth Sci.

8 Supplemental file 5 Sr-Nd isotopic compositions Sample 10HH-22C 10HH-22E 10HH-22G 11ML-37A 11ML-37B 11ML-37E 11ML-37Z 11ML-18A 11ML-18e 11ML-19A 11ML-19B 10HH-67A 10HH-67D 10HH-69E Ref. This study Dalongkai mafic rocks (Liu et al., under review-b) ~810 Ma amphibolites (Cai et al., 2014) Age (Ga) Rb Sr Rb/Sr Rb/ 86 Sr Sr/ 86 Sr s ( 87 Sr/ 86 Sr) i ( 87 Sr/ 86 Sr) CHUR e Sr Sm Nd Sm/ 144 Nd Nd/ 144 Nd s T CHUR (Ga) T DM (Ga) ( 143 Nd/ 144 Nd) i ( 143 Nd/ 144 Nd) CHUR Nd (t) References Liu, H. C., Wang, Y. J., and Zi, J. W., under review-b. Petrogenesis of the Dalongkai mafic-ultramafic intrusion and its tectonic implication for the Paleotethyan evolution in

9 the Ailaoshan tectonic zone (SW China). J. Asian Earth Sci. Cai, Y. F., Wang, Y. J., Cawood, P. A., Fan, W. M., Liu, H. C., Xing, X. W., and Zhang, Y. Z., Neoproterozoic subduction along the Ailaoshan zone, South China: Geochronological and geochemical evidence from amphibolite. Precambrian Res. 245,

10 Supplemental file 6 Selected major (wt. %) and trace elements (ppm) versus Zr (ppm) diagrams for checking element mobility during post-intrusive alteration. Symbols are the same as in Figure 10.

11 Supplemental file 7 Nb/La versus MgO (wt. %) diagram. Symbols are the same as in Figure 6A.

12 Supplemental file 8 Selected trace elements (Cr, Ni and Sr; ppm) versus Mg # diagrams. Symbols are the same as in Figure 10.

13 Supplemental file 9 Selected major elements (wt. %) versus Mg # diagrams. Symbols are the same as in Figure 10.

14 Supplemental file 10 Sr/Y versus Y diagram (Defant et al., 1993) and La N /Yb N versus Yb N (Martin, 1999) diagrams. Symbols are the same as in Figure 6A. References Defant, M.J., Drummond, M.S., Mount, S.T.H., Potential example of the partial melting of the subducted lithosphere in a volcanic arc. Geology, 21( ). Martin, H., Adakitic magmas: modern analogues of Archaean granitoids. Lithos, 46(3):

15 Supplemental file 11 Selected trace elements (ppm) versus Nb diagrams. Symbols are the same as in Figure 6A.

16 Supplemental file 12 Ta versus Nb, Zr versus Ta, La versus Nb, TiO 2 versus Zr diagrams. Shown for reference are model curves generated through mixing between the OIB-like (Sample HH-22A from this study) and Arc-like (Dalongkai plagioclase-pyroxenites from Liu et al. under review-b) mantle components. Symbols are the same as in Figure 10. References Liu, H. C., Wang, Y. J., and Zi, J. W., under review-b. Petrogenesis of the Dalongkai mafic-ultramafic intrusion and its tectonic implication for the Paleotethyan evolution in the Ailaoshan tectonic zone (SW China). J. Asian Earth Sci.

17 Supplemental file 13 Tectonic discrimination diagrams involving: (a) Ti/100-Zr-Y*3 (Pearce and Cann, 1973), (b) Cr versus Y (Pearce, 1982). N-MORB: normal mid-oceanic ridge basalt, E-MORB: enriched mid-oceanic ridge basalt, BABB: back-arc basin basalt, OIB: ocean island basalt, IAB: island arc basalt, WPB: within-plate basalt. Symbols are the same as in Figure 6A. References Pearce, J.A., Trace element characteristics of lavas from destructive plate boundaries. In: Thorpe R. S. (ed.). Andesites. Chichester: Wiley: Pearce, J.A., Cann, J.R., Tectonic setting of basic volcanic rocks determined using trace element analysis. Earrh and Planetary Science Letters, 12: