Earth’s youngest-known ultrahigh-temperature granulites discovered on Seram, eastern Indonesia

Jonathan M. Pownall1, Robert Hall1, Richard A. Armstrong2, and Marnie A. Forster2

1SE Asia Research Group, Department of Earth Sciences, Royal Holloway University of London, Egham TW20 0EX, UK 2Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia

SUPPLEMENTARY MATERIAL Methods

Tables DR1–DR6

Figures DR1–DR9

METHODS

GEOCHEMICAL ANALYSIS

Whole-rock X-Ray fluorescence analyses and electron microprobe mineral chemical analyses

are presented in Tables DR1 and DR4, respectively. Major element mineral chemistry was

determined by analysis of polished thin section using a JEOL JXA-8100 Superprobe paired

with an Oxford Instruments INCA energy-dispersive microanalytical system (EDS) at

Birkbeck College, University of London. Analyses were performed using an accelerating

voltage of 15 kV, a beam current of 10 nA, and a beam diametre of 1 μm. Calibration was

against standards of natural silicates, oxides, and Specpure metals, and a ZAF correction

procedure was applied. Whole-rock major element chemistry was measured on fused disks

using a PANalytical Axios sequential wavelength-dispersive (WDS) X-ray fluorescence

spectrometer (XRF) fitted with a 4 kW Rh-anode X-ray tube at Royal Holloway University of

London.

PHASE EQUILIBRIA MODELLING

Pseudosections were calculated using the thermodynamic calculation programme

THERMOCALC (version 3.33; Powell and Holland, 1988) and the ds55s internally-

GSA DATA REPOSITORY 2014105

consistent thermodynamic dataset (Holland and Powell, 1998), both available from

http://www.metamorph.geo.uni-mainz.de/thermocalc/software/. Modelling was performed in

the 10 component Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3

(NCKFMASHTO) chemical system considering the activity-composition models of phases

that are listed and referenced in Table DR5. Effective bulk compositions input to

THERMOCALC (Table DR6) are based on a H2O-absent and all-Fe-as-Fe3+ whole-rock XRF

analysis of sample KP11–588 (Table DR1) to which H2O has been ‘added’ and Fe2+

substituted accordingly, as inferred from the T–MH2O and T–MO modelling (Figs. DR2 and

DR3, respectively), in which an MH2O value of 1 is defined as equivalent to adding 1 wt%

(~3.7 mol%) H2O to the ‘dry’ bulk composition. For this study, an MO value of 1 is defined

as equivalent to an XFe3+ value of ⅔, in order that XFe3+ was varied over the range of the

redox reaction 3FeO = Fe2O3 + Fe. T–MH2O and T–MO pseudosections were necessarily

constructed using an iterative procedure because the mol% H2O or XFe3+ value indicated by

the respective pseudosection was required for the calculation of the other pseudosection in

the pair. T–MH2O and T–MO pseudosections were calculated at a pressure of 7.5 kbar based

on preliminary P–T pseudosection modelling at estimated mol% H2O and O content. MH2O

and MO values were chosen that resulted in the rock’s observed (slightly) post-peak mineral

assemblage (Grt + Crd + Sill + Sp + Qtz + Pl + Ilm + Liq) in the vicinity of Sa-bearing fields

being predicted as stable by the respective pseudosection. Once determined, these mol%

H2O and O values were used to calculate the effective bulk composition (Table DR6) input

for the calculation of the P–T pseudosection (Fig. 2a). Absolute uncertainties on the location

of THERMOCALC-calculated reaction lines are typically quoted at ± 1 kbar and ± 50°C.

U–Pb ZIRCON GEOCHRONOLOGY

Zircon crystals were separated from 63–250 μm diameter crushed rock fractions using

standard heavy-liquid, magnetic, and hand-picking separation techniques. The zircons were

then mounted in epoxy resin, ground to half-thickness, and coated with gold. Analyses were

performed by sensitive high-resolution ion microprobes SHRIMP-II and SHRIMP-RG

(reverse geometry) over several analytical sessions at the Research School of Earth Sciences

at The Australian National University. Temora-II zircon standards were used for calibration,

and the data were reduced using the SQUID-2 Excel macro (Ludwig, 2009) and plotted using

Isoplot-3 (Ludwig, 2003) – see Supplementary Table DR2. Common Pb was corrected for

Phanerozoic zircon by assuming 206Pb/238U–208Pb/232Th age concordance, and was corrected

for Proterozoic and Archaean zircon using measured 204Pb/206Pb ratios. Ages are given at

95% confidence.

40Ar/39Ar BIOTITE GEOCHRONOLOGY

Ar–Ar dating of 2.7 mg biotite separated from sample KP11-619 was performed by a furnace

step-heating method at The Australian National University argon laboratory. The sample was

irradiated by the USGS TRIGA Reactor in Denver, USA, in a cadmium-shielded canister for

12 MWh. Biotite standard GA1550 (98.5 ± 0.8 Ma; Spell and McDougall, 2003) was used as

the neutron flux monitor. The sample was incrementally step-heated 21 times in a tantalum

crucible using a double-vacuum resistance furnace and analysed using a VG1200 gas-source

mass spectrometer with a sensitivity of 7.6 × 10−17 mol mV−1. Correction factors applied

were as follows: 36Ar/37Ar – 0.000219; 39Ar/37Ar – 0.00538; 40Ar/39Ar – 0.00469;

(36Ar)Cl/(37Ar)K – 0.0270; (38Ar)K /(39Ar)K – 0.0129; Ca/K – 1.90; λ40K – 5.543 × 10−10. A J-

factor of 2.737 × 10−3 was applied to sample KP11-619. 40K abundances and decay constants

are taken from standard values recommended by the IUGS subcommission on geochronology

(Steiger and Jäger, 1977). Data were reduced with the software Noble v1.8 and analysed with

eArgon software developed by G. S. Lister (available from

http://rses.anu.edu.au/tectonics/programs/) using methods outlined by Forster and Lister

(2004). Plots of log10(D0/r2) against T-1 (Arrhenius plot; Fig. DR6) and log10(r/r0) against

%39Ar release (Fig. DR7), where D0 = frequency factor of diffusion, r0 = radius of the

reference domain, and r = radius of domain under consideration (see Forster and Lister,

2004), demonstrate that two distinct reservoirs for argon retention existed within the mineral

grains, calculated to have a closure temperatures (TC) of 289°C and 228°C, respectively. As

shown by the apparent age spectrum (Fig. DR8), the grain domains with TC = 289°C were

degassed by heating steps 10 to 12 (accounting for 37% of total 39Ar release) relating to a

cooling age of 16.34 ± 0.04 Ma and the grain domains with TC = 228°C were degassed by

heating steps 1 and 2 (accounting for 10% of total 39Ar release) relating to a cooling age of

14.83 ± 0.29 Ma. Both domains are confirmed by the 36Ar/40Ar versus 39Ar/40Ar plot (York

plot; Fig. DR9) to have housed negligible atmospheric argon.

TABLES & FIGURES

KP11-588 KP11-619 KP11-621 residuum melanosome crd diatexite

129.4786°E, 3.0019°S 129.4735°E, 3.0168°S 129.4783°E, 3.0017°S SiO2 49.48 56.08 65.47 Al2O3 28.07 19.86 17.57 Fe2O3* 13.25 10.22 6.09 MgO 3.70 4.56 1.88 CaO 1.12 3.12 1.45 Na2O 0.574 1.566 1.614 K2O 0.918 2.234 3.422 TiO2 1.735 1.122 0.728 MnO 0.563 0.275 0.219 P2O5 0.027 0.063 0.103 SO3 0.06 0.10 0.03 Total 99.49 99.20 98.56

LOI 0.99 3.59 2.97

XMg 0.218 0.309 0.236

Table DR1 | XRF major element bulk composition (wt.%) for Kobipoto Complex samples. *Total iron measured as Fe2O3. LOI = loss on ignition (wt.%). XMg = Mg/(Mg + Fetotal).

Ratios Ages (Myr)

238U

/206Pb ±σ (%)

207Pb

/206Pb ±σ (%)

206Pb/ 238U ±σ

207Pb/ 206U ±σ

KP11-588: Cenozoic zircon (rims)1.1 689 2.0 9.9 0.01 2.63 284 2.4 0.0672 6.1 22.08 0.552.1 918 3.0 10.0 0.01 1.97 261 5.2 0.0621 4.9 24.20 1.303.1 575 5.2 61.7 0.04 2.40 93 4.2 0.0664 6.3 67.17 2.824.1 1338 2.8 11.9 0.01 1.33 403 1.8 0.0569 5.3 15.76 0.295.1 301 1.0 23.4 0.08 6.36 247 4.5 0.0968 7.0 24.39 1.126.1 1035 2.2 23.7 0.02 2.84 398 2.0 0.0688 17.9 15.70 0.417.1 1134 2.3 10.9 0.01 1.76 408 1.9 0.0603 9.2 15.50 0.317.2 1197 2.5 9.7 0.01 1.55 404 2.1 0.0586 13.1 15.71 0.378.1 680 1.8 8.6 0.01 4.77 302 1.1 0.0842 5.3 20.30 0.269.1 711 4.0 12.7 0.02 1.96 148 2.3 0.0624 12.3 42.50 1.0710.1 1365 2.9 19.3 0.01 2.61 389 1.6 0.0670 8.4 16.10 0.2811.1 1270 2.7 12.0 0.01 5.03 389 3.3 0.0861 17.2 15.73 0.6113.1 890 1.9 11.7 0.01 3.20 398 2.2 0.0716 5.9 15.68 0.3613.3 1075 2.3 9.4 0.01 1.31 399 2.8 0.0567 14.2 15.92 0.4814.1 934 3.4 13.5 0.01 2.05 232 2.2 0.0628 4.6 27.19 0.6216.1 959 7.3 39.3 0.04 0.96 111 3.9 0.0547 5.0 57.04 2.2517.1 745 1.5 16.2 0.02 4.35 396 3.8 0.0808 7.4 15.55 0.60

KP11-588: Mesozoic and older zircon (cores)2.2 908 0.9 257.8 0.29 0.86 4 3.4 0.0969 3.6 1440.8 43.5 1564.7 68.25.2 248 -0.5 321.0 1.34 -0.52 16 5.3 0.0521 9.5 387.8 19.8 291.5 217.86.2 367 1.2 26.7 0.08 1.21 36 1.3 0.0531 5.0 178.2 2.3 333.2 112.56.3 951 0.3 1466.8 1.59 0.28 17 1.2 0.0548 1.5 373.2 4.5 402.7 34.210.2 151 2.7 139.2 0.95 2.69 6 2.7 0.0871 4.0 931.8 23.6 1362.3 78.010.3 490 0.5 27.2 0.06 0.48 35 1.5 0.0478 4.7 180.4 2.7 89.4 112.212.1 772 1.0 25.3 0.03 0.98 42 2.6 0.0484 5.9 152.9 3.9 117.6 139.612.2 566 0.9 677.8 1.24 0.93 17 6.7 0.0529 4.1 363.7 23.9 324.6 93.013.2 285 1.0 177.1 0.64 0.97 23 1.7 0.0501 6.0 274.4 4.5 199.8 138.214.2 211 1.0 164.1 0.80 1.03 23 1.8 0.0500 8.6 279.0 4.8 193.8 200.416.2 446 0.9 111.8 0.26 0.85 40 1.3 0.0609 7.0 160.9 2.1 634.2 150.117.2 192 0.7 155.6 0.84 0.71 24 1.5 0.0588 3.9 262.4 3.9 561.4 84.618.1 777 0.4 11.6 0.02 0.43 35 3.4 0.0520 8.1 183.3 6.2 286.2 185.720.1 255 0.0 21.6 0.09 -0.02 31 1.3 0.0527 1.6 201.7 2.6 316.9 36.521.1 373 0.0 31.7 0.09 -0.02 29 1.8 0.0519 1.5 218.7 3.9 280.2 33.423.1 396 0.2 30.1 0.08 0.20 37 1.5 0.0495 1.8 174.2 2.5 171.9 40.9

KP11-619: Cenozoic zircon (rims)8.1 101 0.2 1.0 0.01 8.43 370 1.9 0.1130 6.8 15.92 0.349.1 490 1.1 5.3 0.01 1.97 390 1.2 0.0619 8.4 16.20 0.2310.1 61 0.1 0.5 0.01 16.26 354 6.1 0.1748 7.1 15.23 0.9711.1 130 0.3 1.0 0.01 6.02 374 2.2 0.0940 7.3 16.19 0.3812.1 50 0.1 0.6 0.01 20.53 319 3.0 0.2086 8.1 16.06 0.6413.1 45 0.1 0.4 0.01 18.35 327 4.7 0.1914 8.9 16.06 0.8714.1 61 0.1 0.9 0.01 13.30 378 2.3 0.1514 8.7 14.75 0.4415.1 36 0.1 1.3 0.04 27.88 278 1.4 0.2667 8.6 16.68 0.7116.1 49 0.1 0.5 0.01 22.74 310 1.3 0.2260 7.4 16.05 0.4916.1 99 0.2 2.8 0.03 24.98 294 4.1 0.2438 11.8 16.45 1.0517.1 33 0.1 0.2 0.01 43.76 220 13.0 0.3922 22.3 16.49 3.8918.1 47 0.1 0.2 0.00 42.16 231 10.9 0.3795 13.4 16.11 2.51

Table DR2 | U-Pb zircon geochronology results for Kobipoto granulites. For Cenozoic zircons, the quoted 207Pb/206Pb and 238U/206Pb ratios relate to total Pb and U, and common Pb is corrected by assuming 206Pb/238U-208Pb/232Th age-concordance. For older zircons, the quoted 207Pb/206Pb and 238U/206Pb ratios relate to radiogenic Pb only and common Pb was corrected using measured 204Pb/206Pb ratios. Pbc and Pb* indicate the common and radiogenic portions, respectively.

206Pbc

(%)

spotU

(ppm)

206Pb* (ppm)

Th (ppm)

232Th

/238U

Ratios Ages (Myr)

238U

/206Pb ±σ (%)

207Pb

/206Pb ±σ (%)

206Pb/ 238U ±σ

207Pb/ 206U ±σ

KP11-619: Mesozoic and older zircon (cores)1.1 113 0.6 1.0 0.01 4.42 164 4.4 0.0529 25.1 39.3 1.7 322.4 569.91.2 373 91.4 238.0 0.66 1.63 3 1.6 0.1138 0.8 1642.2 23.4 1861.5 15.21.3 501 77.0 197.0 0.41 4.11 5 2.3 0.1089 0.4 1103.2 23.8 1781.9 7.22.1 159 1.3 1.3 0.01 2.22 106 2.9 0.0468 17.5 60.6 1.7 41.2 419.72.2 446 19.6 181.7 0.42 0.03 20 1.4 0.0534 1.2 321.0 4.4 346.5 26.43.4 415 9.9 60.2 0.15 0.24 36 1.4 0.0519 1.3 176.7 2.5 280.1 29.27.2 504 14.0 7.7 0.02 0.11 31 1.5 0.0526 3.0 205.6 2.9 310.9 69.28.2 525 5.7 22.1 0.04 0.42 79 1.7 0.0489 2.8 81.1 1.4 141.8 64.98.3 918 228.3 825.7 0.93 1.34 3 1.3 0.1122 0.2 1657.6 19.2 1835.6 4.19.2 520 13.6 9.6 0.02 0.20 33 2.1 0.0527 3.4 193.5 4.0 316.5 76.816.2 209 93.8 114.5 0.57 11.54 2 1.9 0.2897 0.5 2995.5 45.4 3415.8 8.218.2 206 9.0 403.4 2.03 1.18 19 2.6 0.0562 6.2 322.9 8.1 459.3 137.920.1 384 11.0 37.6 0.10 0.21 30 2.0 0.0517 1.2 212.1 4.2 270.7 27.030.1 55 1.7 1.3 0.02 11.61 24 1.8 0.1341 2.7 262.0 4.7 2152.9 46.931.1 55 2.3 0.6 0.01 11.07 19 1.5 0.1331 3.3 339.2 5.0 2139.8 57.0

KP11-621: Cenozoic zircon (rims)8.1 956 2.0 11.3 0.01 0.44 423 2.0 0.0195 45.8 15.71 0.271.3 1557 3.4 21.9 0.01 0.93 425 3.7 0.0129 126.3 16.22 0.338.2 1461 3.2 11.1 0.01 2.50 416 4.0 0.0008 3407.1 16.26 0.341.1 1311 2.8 18.1 0.01 0.99 403 1.6 0.0298 27.1 16.30 0.2016.1 625 0.0 9.8 0.02 1.00 407 2.9 0.0229 70.6 16.36 0.351.4 1388 3.1 19.8 0.01 1.22 1066 28.9 1.3031 43.1 16.49 0.378.3 2128 4.8 7.9 0.00 1.00 382 3.1 0.0409 27.6 17.02 0.4818.1 694 0.0 11.9 0.02 0.66 370 2.7 0.0053 323.8 18.27 0.3319.1 654 0.0 4.3 0.01 6.66 332 3.1 0.0281 85.3 19.78 0.544.1 1696 4.5 33.8 0.02 1.58 321 1.8 0.0601 4.2 19.82 0.363.3 959 2.6 5.9 0.01 5.71 326 4.9 0.0270 119.5 20.40 0.6311.1 575 1.9 7.2 0.01 1.26 265 4.9 0.0324 22.0 24.66 1.203.1 757 4.1 5.4 0.01 2.24 161 3.2 0.0385 22.6 40.62 1.2525.1 592 0.0 7.0 0.01 0.15 151 1.3 0.0479 3.8 42.39 0.56

KP11-621: Mesozoic and older zircon (cores)1.2 743 41.3 191.7 0.27 0.13 15 1.1 0.0542 2.1 404.4 4.3 378.2 47.52.1 974 16.3 18.3 0.02 0.01 51 2.0 0.0509 3.4 124.8 2.4 234.8 78.53.2 958 25.1 5.9 0.01 0.44 33 1.2 0.0526 2.3 194.0 2.3 312.2 52.95.1 662 18.4 5.7 0.01 0.12 31 1.1 0.0499 1.5 205.0 2.1 192.0 34.16.1 558 5.8 4.7 0.01 0.26 82 1.8 0.0502 2.5 77.9 1.4 204.6 59.07.1 812 22.5 9.8 0.01 0.02 31 1.3 0.0578 1.2 204.4 2.6 523.0 25.38.5 263 56.7 72.7 0.29 0.06 4 2.1 0.1079 2.7 1444.5 26.8 1763.7 48.59.1 1018 27.6 4.0 0.00 0.08 32 1.0 0.0500 1.2 200.4 2.1 194.3 27.010.1 966 120.4 7.1 0.01 0.00 7 4.3 0.0739 1.1 873.5 35.1 1038.1 21.412.1 1295 33.7 8.9 0.01 0.02 33 1.0 0.0500 1.0 192.1 2.0 197.1 22.313.1 284 3.3 2.3 0.01 0.33 73 1.2 0.0463 3.9 87.7 1.0 10.8 93.614.1 985 0.0 40.2 0.04 -0.11 86 3.7 0.0508 2.2 74.7 2.7 230.3 51.015.1 1098 30.1 6.5 0.01 0.06 31 1.6 0.0504 1.1 202.5 3.2 213.2 24.817.1 431 0.0 3.9 0.01 1.63 76 3.0 0.0504 4.5 84.7 2.6 213.0 104.521.1 367 0.0 4.4 0.01 0.34 88 2.1 0.0512 3.6 73.1 1.6 250.1 82.722.1 1587 0.1 10.4 0.01 -0.03 35 1.5 0.0501 1.0 182.7 2.6 200.5 23.923.1 190 0.0 105.7 0.57 6.92 37 1.6 -0.0091 29.8 170.0 2.6 - -24.1 3134 0.1 21.7 0.01 0.02 41 1.6 0.0511 0.9 155.9 2.5 245.9 20.2

Table DR2 (continued)

206Pbc

(%)

spotU

(ppm)

206Pb* (ppm)

Th (ppm)

232Th

/238U

KP11-619 ; biotite; 21 steps; λ 40 K = 5.5430E-10; J = 2.7370E-3

Temp 36Ar 37Ar 38Ar 39Ar 40Ar % 40Ar* 40Ar*/39Ar (K) Cumulative Calculated Age Ca/K Cl/K(oC) (mol) (% err.) (mol) (% err.) (mol) (% err.) (mol) (% err.) (mol) (% err.) 39Ar (%) (Ma ± 1σ)

450 2.47E-16 1.04 1.05E-14 32.90 4.24E-16 3.97 2.07E-14 0.47 1.35E-13 0.68 45.9 3.015 3.05 14.83 ± 0.29 9.67E-01 2.00E-01500 3.39E-16 3.50 5.32E-15 41.02 7.98E-16 1.78 5.36E-14 0.05 2.68E-13 0.33 61.8 3.089 10.99 15.19 ± 0.33 1.89E-01 3.03E-02533 3.11E-16 0.72 4.95E-15 71.26 6.80E-16 4.25 4.80E-14 0.27 2.44E-13 0.61 61.7 3.144 18.10 15.46 ± 0.17 1.96E-01 2.37E-03566 2.77E-16 0.92 9.42E-15 12.48 6.43E-16 6.33 4.52E-14 0.37 2.29E-13 0.45 63.5 3.224 24.79 15.85 ± 0.14 3.97E-01 7.32E-03600 2.22E-16 2.03 1.11E-15 191.03 9.62E-16 3.35 5.06E-14 0.55 2.34E-13 0.61 70.9 3.273 32.29 16.09 ± 0.19 4.17E-02 1.95E-01633 2.10E-16 1.03 4.67E-15 49.24 6.32E-16 2.86 4.55E-14 0.37 2.13E-13 0.46 69.9 3.273 39.04 16.09 ± 0.13 1.95E-01 4.07E-03666 2.11E-16 1.06 4.71E-15 47.55 5.62E-16 3.09 3.79E-14 0.12 1.90E-13 0.22 66.4 3.325 44.65 16.34 ± 0.1 2.36E-01 3.28E-02700 2.05E-16 0.71 8.35E-15 29.04 5.07E-16 3.28 3.41E-14 0.07 1.75E-13 0.40 64.6 3.311 49.71 16.28 ± 0.12 4.65E-01 3.07E-02733 2.10E-16 1.04 2.99E-17 25.52 6.18E-16 1.28 3.86E-14 0.39 1.92E-13 0.48 66.9 3.335 55.43 16.39 ± 0.14 1.47E-03 7.84E-02766 1.78E-16 1.03 3.36E-15 30.23 7.80E-16 0.45 5.54E-14 0.18 2.36E-13 0.33 76.7 3.269 63.64 16.07 ± 0.08 1.15E-01 2.12E-02800 2.26E-16 1.18 7.13E-15 33.03 1.46E-15 1.13 1.06E-13 0.76 4.11E-13 0.79 82.6 3.204 79.37 15.75 ± 0.15 1.28E-01 1.51E-02833 2.97E-16 1.06 2.55E-15 71.97 1.22E-15 0.49 8.71E-14 0.27 3.60E-13 0.42 74.6 3.085 92.29 15.17 ± 0.1 5.55E-02 1.76E-02866 3.13E-16 2.25 4.92E-15 18.00 5.25E-16 6.77 3.43E-14 0.17 1.94E-13 0.29 51.6 2.923 97.37 14.38 ± 0.31 2.73E-01 2.67E-02900 3.68E-16 1.17 2.61E-15 14.85 2.68E-16 8.21 1.51E-14 0.30 1.44E-13 0.37 24.2 2.321 99.60 11.42 ± 0.45 3.29E-01 1.01E-02950 4.59E-16 1.51 3.00E-17 68.65 2.90E-17 18.17 9.12E-16 0.40 1.12E-13 0.46 -21.3 0.001 99.73 0.005 ± 11.445 6.26E-02 -2.81E+001000 5.23E-16 1.98 6.98E-15 45.31 2.17E-16 2.79 6.13E-16 1.84 1.35E-13 1.87 -14.3 0.001 99.82 0.005 ± 32 2.31E+01 6.74E+001050 5.60E-16 1.33 7.67E-15 39.28 1.57E-16 1.15 6.84E-16 0.81 1.76E-13 0.83 6.1 16.64 99.91 80.35 ± 18.47 2.27E+01 2.34E+001100 7.32E-16 4.05 3.01E-17 6.57 1.01E-16 22.28 1.46E-16 3.56 2.12E-13 3.57 -2.1 0.001 99.94 0.005 ± 391.423 3.93E-01 -9.66E+001200 1.68E-15 5.58 3.01E-17 27.63 3.91E-16 5.66 3.12E-16 5.43 4.68E-13 5.44 -5.8 0.001 99.98 0.005 ± 594.529 1.84E-01 8.53E+001300 3.13E-15 20.08 3.75E-15 41.01 5.55E-16 20.06 1.30E-16 20.06 9.44E-13 20.06 2.0 173.165 100.00 699.89 ± 6815.95 6.45E+01 -9.94E+001450 4.70E-15 20.19 1.87E-14 20.74 8.46E-16 20.19 1.09E-16 20.18 1.46E-12 20.18 4.9 8740.714 100.00 5801.55 ± 741.34 4.35E+03 -1.31E+01Total 1.54E-14 1.07E-13 1.24E-14 6.75E-13 6.73E-12 16.27 ± 1.71

Table DR3 | Data from 40Ar/39Ar step-heating experiments of biotite from sample KP11-619. Biotite standard GA1550 (98.5 ± 0.8 Myr; Spell and McDougall, 2003) was used as the neutron flux monitor. 40K abundances and decay constants are taken from standard values recommended by the IUGS sub commission on Geochronology (Steiger and Jäger, 1977). Biotite compostion (cpfu based on 22 oxygens) is as follows: 5.06 Si; 0.46 Ti; 3.16 Al; 0.16 Cr; 0.42 Fe3+; 2.42 Fe2+; 0.02 Mn; 2.50 Mg; 0.02 Ca; 0.10 Na; 1.20 K. 

KP11-588 Garnet Cordierite Spinel Sapphirine Ilmenite Sillimanite Plagioclase Chlorite Biotitetrg ni snoisulcnilenips htiwtrg ni snoisulcnietitcelpmyseanorocmireroc

wt.% SiO2 39.07 38.59 49.31 0.12 0.37 11.95 0.16 37.87 59.30 24.00 36.41TiO2 0.11 0.02 0.00 0.26 0.28 0.29 51.53 0.05 0.03 0.00 3.33Al2O3 22.34 22.01 34.09 60.24 60.12 60.84 0.18 64.62 27.51 22.48 17.70Cr2O3 0.00 0.06 0.03 0.15 0.11 0.00 0.10 0.03 0.05 0.00 0.02Fe2O3* 1.62 1.62 2.26 2.03 3.63 0.00 2.19 0.25 0.37 0.00 2.62

FeO 29.08 30.71 8.14 34.01 27.08 16.20 43.69 0.34 0.00 27.39 13.38MnO 2.97 5.12 0.68 0.87 0.30 0.31 2.21 0.02 0.02 0.40 0.34MgO 7.45 3.94 7.41 4.35 7.73 5.82 0.32 0.31 0.08 11.75 14.17CaO 1.47 1.64 0.03 0.00 0.06 0.13 0.00 0.01 8.54 0.11 0.00Na2O 0.31 0.24 0.27 0.24 0.69 0.70 0.00 0.11 6.17 0.26 0.47K2O 0.00 0.01 0.00 0.04 0.06 0.02 0.01 0.00 0.85 0.06 7.20ZnO 0.63 1.56

Totals 104.42 103.96 102.23 102.32 100.44 96.26 100.39 103.62 102.92 86.45 95.64

Oxygens 12 12 18 4 4 20 3 30 8 14 11

c.p.f.u. Si 2.94 2.97 4.93 0.00 0.01 1.54 0.00 5.94 2.58 2.61 2.67 Ti 0.01 0.00 0.00 0.01 0.01 0.03 0.97 0.01 0.00 0.00 0.18 Al 1.98 2.00 4.01 1.95 1.93 9.24 0.01 11.95 1.41 2.88 1.53 Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Fe3+ 0.09 0.09 0.17 0.04 0.07 0.00 0.04 0.03 0.01 0.00 0.15 Fe2+ 1.83 1.98 0.68 0.78 0.62 1.75 0.92 0.05 0.00 2.49 0.82 Mn 0.19 0.33 0.06 0.02 0.01 0.03 0.05 0.00 0.00 0.04 0.02 Mg 0.84 0.45 1.10 0.18 0.31 1.12 0.01 0.07 0.01 1.90 1.55 Ca 0.12 0.14 0.00 0.00 0.00 0.02 0.00 0.00 0.40 0.01 0.00 Na 0.05 0.04 0.05 0.01 0.04 0.18 0.00 0.03 0.52 0.06 0.07 K 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.05 0.01 0.68

Sum 8 8 11 3 3 14 2 18 5 10 8

Table DR4 | Representative electron microprobe (EMP) mineral chemical analyses of KP11-588.*Fe2O3 was calculated from all-Fe-as-Fe2+ microprobe analyses by the programme AX (Holland, 2012).

a-x model Reference*Amphibole Diener et al. (2007) (Diener et al., 2007) Biotite White et al. (2007) (White et al., 2007) *Clinopyroxene Green et al. (2007) (Green et al., 2007) Cordierite Holland & Powell (1998) (Holland and Powell, 1998) *Epidote Holland & Powell (1998) (Holland and Powell, 1998) Garnet White et al. (2007) (White et al., 2007) *Hematite White (2000) (White, 2000) Ilmenite White (2000) (White, 2000) K-feldspar Holland & Powell (2003) (Holland and Powell, 2003) Magnetite White et al. (2002) (White et al., 2002) Melt White et al. (2007) (White et al., 2007) *Muscovite Coggon & Holland (2002) (Coggon and Holland, 2002) *Orthopyroxene White et al. (2002) (White et al., 2002) Osumilite Holland et al. (1996) with 2010 update by T.J.B. Holland(Holland et al., 1996)

Plagioclase Holland & Powell (2003) (Holland and Powell, 2003) Sapphirine Taylor-Jones & Powell (2010) (Taylor-Jones and Powell, 2010) Spinel White et al. (2002)(White et al., 2002)

Table DR5 | a-x models used in NCKFMASHTO modelling. a-x models preceeded by an asterisk were not utilised in the modelling, but were included in the script file.

KP11-588 pseudosection H2O SiO2 Al2O3 CaO MgO FeO K2O Na2O TiO2 O

P-T (Fig. 3A) MH2O = 0.42; MO = 0.50 1.565 55.28 18.481 1.341 6.157 12.38 0.654 0.622 1.458 2.061

T-MH2O (Fig. DR2) MH2O = 0.00; MO = 0.50 0 56.159 18.775 1.362 6.255 12.577 0.665 0.632 1.482 2.094MH2O = 1.00; MO = 0.50 3.647 54.111 18.09 1.312 6.027 12.118 0.640 0.640 1.427 2.018

T-MO (Fig. DR3) MO = 0.00; MH2O = 0.42 1.598 56.444 18.87 1.369 6.287 12.641 0.668 0.635 1.489 0MO = 1.00; MH2O = 0.42 1.533 54.164 18.108 1.314 6.033 12.13 0.641 0.609 1.429 4.039

Table DR6 | Effective bulk compositions (mol%) in the NCKFMASHTO chemcial system, as input to THERMOCALC for calculation of pseudosections for sample KP11-588. An MH2O of 1 is equivalent to adding 1 wt.% water to the dry bulk composition and an MO value of 1 is equivalent to an XFe3+ value of 2/3.

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Al

S i

KP11-588

KP11-581C

ideal Sa

3:5:1

2:2:1

7:9:3

3:5:1

2:2:1

7:9:3

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30 35 40 45 50

Al (

wt%

)

Si (wt% )

Sp

Crd

Crn

Chl

KP11-588

KP11-581C

ideal Sa

SAPPHIRINE

OTHER PHASESFROM KP11-588

A

B

mixing line

SAPPHIRINE

Figure DR1 | Sapphirine compositional plots. A: Al v. Si (wt.%) plot of sapphirine compositions (normalised to 100%)for granulites KP11-588 and KP11-581C compared to corundum, chlorite, spinel, and cordierite. Sapphirine analyses ploton a mixing line passing through the 2:2:1-7:9:3-3:5:1 sapphirine solid solution (red), demonstrating the reactionSa + H2O → Crn + Chl (± Sp). B: Al v. Si (cations per formula unit) plot of sapphirine compositions for granultiesKP11-588 and KP11-581C compared to the 2:2:1-7:9:3-3:5:1 sapphirine solid solution (red).

@ 7 kbar & MO = 0.50NCKFMASHTO (+ qtz + pl + ilm + sill)

0 0.2 0.4 0.6 0.8 1850

900

950

1000

1050KP11-588

M

T (°

C)

0.11

H2O H2O(where an M of 1 = 1 wt% H2O added to dry bulk composition)

sp crd ksp liq

grt sp crd ksp liq

grt mt crd ksp liqgrt mt crd ksp

grt sp crd ksp

sp crd kspgrt sp

crd ksposm

sp crdksp osm

sp crd ksp osm liq

sp crd osm liq

sa sposm liq

sa sp liq

sa spcrd liq

sp crd liq

grt sp crd liq

grt mt crd liq

grt spmt crd

ksp

grt sp mt crd ksp liq grt sp mt crd liq

sa sp crdosm liq

sp osm liq

sp crd osm

grt mt crdksp osm

t

27ksp

t

7g

12ksp

13ksp

14g

15m 16sp

17cdt

23osm

24osm25osm 26ksp

28sa29sa

30ksp31osm

32sp33m 34ksp

0

1sa2cd

3g

4sa

5sa

6g

8cd

9cd

19m 20sp

35ksp

41cd

43cd

44bi47cd

48ksp

49liq

50liq

51cd52bi53liq

42ksp

45ksp

46bi

54liq 55cd

56ksp

60liq

62cd

grt crdsp liq

1) sa grt crd sp liq2) grt crd sp mt liq3) grt sp mt liq4) sa osm grt sp ksp liq5) sa osm grt sp liq6) osm grt sp ksp liq7) osm grt sp liq8) grt sp mt ksp liq9) grt crd ksp bt mt10) grt crd bt mt ksp liq11) grt ksp bt mt liq12) grt bt mt

crd spliq

sa crdsp liq

sa spliq

sa spksp liq

sa grt spksp liq

sa grtsp liq

grt crdmt liq

grt crdbt mt liq

grt crdbt mt

grt btmt liq

grt kspbt mt

grt mtliq

grt mtksp liq

grt sp ksp liq grt sp liq

grt crdmt ksp liq

grt crdmt ksp

1

2

3

4 5

67

8

9

10

11

12

0 0.2 0.4 0.6 0.8 1

800

850

900

950

1000

MO = 0.50 & P = 7.5 kbarNCKFMASHTO (+ qtz + pl + ilm + sill)KP11-588

M

T (°

C)

0.42

H2O (where an M of 1 = 1 wt% H2O added to dry bulk composition)H2O

Figure DR2 | T-MH2O pseudosection of granulite KP11-588. Diagram is calculated at 7.5 kbar pressure and with MO = 0.50 (XFe3+ = 0.33). �e grey line indicates the chosen MH2O value used in the T-MO pseudosection (Supplementary Fig. DR3) and the P-T pseudosection (Fig. 3A). �e target �eld is outlined in blue (and neighbouring sa-present �eld is dotted). Minerals are abbre-viated as follows: bt–biotite; crd–cordierite; grt–garnet; ilm–ilmenite; ksp–K-feldspar; liq–liquid; mt–magnetite; osm–osumilite; pl–plagioclase; qtz–quartz; sa–sapphirine; sill–sillimanite; sp–spinel.

0 0.2 0.4 0.6 0.8 1

800

850

900

950

1000

MH2O = 0.42 & P = 7.5 kbarNCKFMASHTO (+ qtz + pl + ilm + sill)

MO

T (°

C)

KP11-588

0.50

XFe3+ = 0 XFe3+ = ⅔

grt crdksp mt liq

grt crdmt liq

grt crdsp liq

sa crdsp liq

sa spliq

sa grt sp liq

sa spmt liq

sa crd spmt liq

sa crdmt liq

sa mtliq

crd kspmt liq

crd kspmt

grt crdksp mt

grt crd bt ksp mt

grt crdbt mt

grt crdbt mt liqgrt bt

mt liq

grt btliq

grt btksp liq

grt kspliq

grt liq

grt spliq

grt mtliq

grt kspmt liq

1

23 5

46

7

8

9

10

1) sa grt crd sp liq2) grt sp mt liq3) grt crd sp mt liq4) sa grt crd sp mt liq5) sa grt crd mt liq6) sa crd ksp mt liq7) crd bt ksp mt8) grt crd bt ksp mt liq9) grt bt ksp mt liq10) grt crd bt liq

Figure DR3 | T-MO pseudosection of granulite KP11-588. Diagram is calculated at 7.5 kbar pressure and with MH2O = 0.42. �e grey line indicates the chosen MO value used in the T-MH2O pseudosection (Fig. DR2) and the P-T pseudosection (Fig. 3A). �e target �eld is outlined in red (and neighbouring sa-present �eld is dotted). Minerals are abbreviated as follows: bt–biotite; crd–cordierite; grt–garnet; ilm–ilmenite; ksp–K-feldspar; liq–liquid; mt–magnetite; pl–plagioclase; qtz–quartz; sa–sapphirine; sill–sillimanite; sp–spinel.

19 18 17 15 Ma

0.04340 360 380 400 420 440

0.05

0.06

0.07

16

Mean 206Pb/ 238U age:16.24 ± 0.23 MaMSWD = 1.20probability = 0.30

KP11-621

0.0

0.2

0.4

0.6

60 50 40 30 20 Ma

Lower intercept: 15.98 ± 0.38 MaMSWD = 1.00; probability = 0.44

Lower intercept: 16.26 ± 0.23 Ma (anchored at 207Pb/ 206Pb = 0.836)MSWD = 1.07; probability = 0.38

Mean 206Pb/ 238U age:16.00 ± 0.52 MaMSWD = 1.08probability = 0.37

to common Pb

20 μm

16.05 Ma3,416 Ma

15.92 Ma

1,836 Ma

16.20 Ma

194 Ma

KP11-619

20 μm

16.30 Ma 1,764 Ma

404 Ma

16.24 Ma

207 P

b/20

6 Pb

238U/206Pb

207 P

b/20

6 Pb

238U/206Pb

100 200 300 400

Figure DR4 | Tera-Wasserburg plot of Miocene metamorphic zircon rims from migmatite sample KP11–619. Mean 206Pb/238U age is quoted at 95% con�dence. Data-point error ellipses are drawn at 68.3% con�dence.MSWD—mean square weighted deviation. Representative cathodoluminescence images of the zircon grainsare shown top-right, annotated with individual analytical spots. See Table DR2 for full dataset.

Figure DR5 | Tera-Wasserburg plot of Miocene metamorphic zircon rims from migmatite sample KP11–621. Mean 206Pb/238U age is quoted at 95% con�dence. Data-point error ellipses are drawn at 68.3% con�dence.MSWD—mean square weighted deviation. Representative cathodoluminescence images of the zircon grainsare shown top-right, annotated with individual analytical spots. See Table DR2 for full dataset.

104/T Kelvin

log 10

D0 /

r2

6 8 10 12 14-8

-7

-6

-5

-4

-3

-2

Tc = 366°C

(D0 /r 2 = 2.73 x 10 4 s -1)

Tc = 289°C

(D0 /r 2 = 1.53 x 10 7 s -1)

Tc = 228°C

(D0 /r 2 = 9.13 x 10 9 s -1)

Figure DR6 | Arrhenius plot for Ar-Ar step-heating experiments of KP11-619 biotite. Blue dots relate to heating steps 1 and 2 and red dots are from heating steps 9 to 12 (compare with apparent age plot in Supplementary Fig. DR8). Closure temperatures (Tc) of 289°C and 228°C, respectively, can be related to these steps which are interpreted to have degassed argon from two separate reservoirs within the biotite. D0 = frequency factor of di�usion and r = radius of domain under consideration (Forster and Lister, 2004). Calculations performed by eArgon.

Percentage 39Ar released

log 10

r/ r 0

CAN ANU#13, Foil P13; Sample KP11-619, Biotite, 21 steps

0 20 40 60 80 100-1

0

1

2

3

Figure DR7 | log10 (r/r0) vs. %39Ar released plot for Ar-Ar step-heating experi-ments of KP11-619 biotite. Blue dots relate to heating steps 1 and 2 and red dots are from heating steps 9 to 12 (compare with apparent age plot in Supplementary Fig. DR8). Two distinct reservoirs with di�erent radii are shown by the plot, which correspond to the di�erent closure temperatures inferred from the Arrhenius plot (Supplementary Fig. DR6). r = radius of domain under consideration and r0 = radius of the reference domain (Forster and Lister, 2004). Calculations were performed by eArgon.

Sample KP11-619, Biotite, 21 steps

Upper limit 16.34 ± 0.04 Myr MSWD = 0.73(Tc = 289°C)

Lower limit 14.83 ± 0.29 Myr(Tc = 228°C)

App

aren

t A

ge (M

yr)

Percentage 39Ar released0 20 40 60 80 100

10.0

12.0

14.0

16.0

18.0

20.0

Figure DR8 | Apparent age spectrum for Ar-Ar step-heating experiments of KP11-619 biotite. Heating steps 1 and 2 are shaded blue and heating steps 9 to 12 are shaded red, which relate to the plots shown in Supplementary Figures DR6, DR7, and DR9. �e upper limit 16.34 ± 0.04 Ma age is interpreted to relate to cooling through 289°C and the lower limit 14.83 ± 0.29 Ma age is interpreted to relate to cooling through 228°C (see Arrhenius plot in Supplemen-tary Figure DR6). Calculations were performed by eArgon.

39Ar/40Ar

36A

r /40 A

r

Sample KP11-619, Biotite, 21 steps

0.00 0.05 0.10 0.15 0.20 0.25 0.300.000

0.001

0.002

0.003

0.004

Figure DR9 | York plot for Ar-Ar step-heating experiments of KP11-619 biotite. Atmospheric argon composition is shown by the red cross. Red and blue spots, which relate to heating steps from which ages have been interpreted, plot away from this point and are therefore shown to have not been contaminated with atmospheric argon (colours correspond to Supple-mentary Figures DR6, DR7, and DR8).

REFERENCES CITED

Coggon, R., and Holland, T.J.B., 2002, Mixing properties of phengitic micas and revised garnet-phengite

thermobarometers: Journal of Metamorphic Geology, v. 20, p. 683–696.

Diener, J.F.A., Powell, R., White, R.W., and Holland, T.J.B., 2007, A new thermodynamic model for clino- and

orthoamphiboles in the system Na2O–CaO–FeO–MgO–Al2O3–SiO2–H2O–O: Journal of Metamorphic

Geology, v. 25, p. 631–656, doi: 10.1111/j.1525-1314.2007.00720.x.

Forster, M.A., and Lister, G.S., 2004, The interpretation of 40

Ar/39

Ar apparent age spectra produced by mixing:

application of the method of asymptotes and limits: Journal of Structural Geology, v. 26, p. 287–305.

Green, E., Holland, T., and Powell, R., 2007, An order-disorder model for omphacitic pyroxenes in the system

jadeite-diopside-hedenbergite-acmite, with applications to eclogitic rocks: American Mineralogist, v.

92, p. 1181–1189, doi: 10.2138/am.2007.2401.

Holland, T.J.B., Babu, E.V.S.S.K., and Waters, D.J., 1996, Phase relations of osumilite and dehydration melting

in pelitic rocks: a simple thermodynamic model for the KFMASH system: Contributions to Mineralogy

and Petrology, v. 124, p. 383–394.

Holland, T.J.B., and Powell, R., 1998, An internally consistent thermodynamic data set for phases of

petrological interest: Journal of Metamorphic Geology, v. 16, p. 309–343.

Holland, T., and Powell, R., 2003, Activity-composition relations for phases in petrological calculations: an

asymmetric multicomponent formulation: Contributions to Mineralogy and Petrology, v. 145, p. 492–

501, doi: 10.1007/s00410-003-0464-z.

Holland, T.J.B., AX: A programme to calculate activities of mineral endmembers from chemical analyses:

http://www.esc.cam.ac.uk/research/research-groups/holland/ax (last updated July 2012).

Ludwig, K.R., 2003, Isoplot 3.00: A Geochronological Toolkit for Microsoft Excel: Berkeley Geochronology

Centre Special Publication, v. 4.

Ludwig, K.R., 2009, SQUID 2: A User’s Manual: Berkeley Geochronology Centre Special Publication, v. 5.

Powell, R., and Holland, T.J.B, 1988, An internally consistent thermodynamic dataset with uncertaintites and

correlations: 3. Applications to geobarometry, worked examples and a computer program: Journal of

Metamorphic Geology, v. 6, p. 173–204.

Spell, T.L., and McDougall, I., 2003, Characterization and calibration of 40

Ar/39

Ar dating standards, Chemical

Geology, v. 198, p. 189–211.

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.

Taylor-Jones, K., and Powell, R., 2010, The stability of sapphirine + quartz: calculated phase equilibria in FeO–

MgO–Al2O3–SiO2–TiO2–O: Journal of Metamorphic Geology, v. 28, p. 615–633, doi: 10.1111/j.1525-

1314.2010.00883.x.

White, R.W., 2000, The effect of TiO2 and Fe2O3 on metapelitic assemblages at greenschist and amphibolite

facies conditions: mineral equilibria calculations in the system K2O–FeO–MgO–Al2O3–SiO2–H2O–

TiO2–Fe2O3: v. 18, p. 497–511.

White, R.W., Powell, R., and Clarke, G.L., 2002, The interpretation of reaction textures in Fe-rich metapelitic

granulites of the Musgrave Block, central Australia: constraints from mineral equilibria calculations in

the system K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3: Journal of Metamorphic Geology, v. 20, p.

41–55.

White, R.W., Powell, R., and Holland, T.J.B., 2007, Progress relating to calculation of partial melting equilibria

for metapelites: Journal of Metamorphic Geology, v. 25, p. 511–527, doi: 10.1111/j.1525-

1314.2007.00711.x.