SUPPLEMENTARY MATERIAL

Transcription

1 GSA DATA REPOSITORY Earth s youngest-known ultrahigh-temperature granulites discovered on Seram, eastern Indonesia Jonathan M. Pownall 1, Robert Hall 1, Richard A. Armstrong 2, and Marnie A. Forster 2 1 SE Asia Research Group, Department of Earth Sciences, Royal Holloway University of London, Egham TW20 0EX, UK 2 Research 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-

2 consistent thermodynamic dataset (Holland and Powell, 1998), both available from Modelling was performed in the 10 component Na 2 O CaO K 2 O FeO MgO Al 2 O 3 SiO 2 H 2 O TiO 2 Fe 2 O 3 (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 H 2 O-absent and all-fe-as-fe 3+ whole-rock XRF analysis of sample KP (Table DR1) to which H 2 O has been added and Fe 2+ substituted accordingly, as inferred from the T M H2O and T M O modelling (Figs. DR2 and DR3, respectively), in which an M H2O value of 1 is defined as equivalent to adding 1 wt% (~3.7 mol%) H 2 O to the dry bulk composition. For this study, an M O value of 1 is defined as equivalent to an XFe 3+ value of ⅔, in order that XFe 3+ was varied over the range of the redox reaction 3FeO = Fe 2 O 3 + Fe. T M H2O and T M O pseudosections were necessarily constructed using an iterative procedure because the mol% H 2 O or XFe 3+ value indicated by the respective pseudosection was required for the calculation of the other pseudosection in the pair. T M H2O and T M O pseudosections were calculated at a pressure of 7.5 kbar based on preliminary P T pseudosection modelling at estimated mol% H 2 O and O content. M H2O and M O 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% H 2 O 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 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 206 Pb/ 238 U 208 Pb/ 232 Th age concordance, and was corrected

3 for Proterozoic and Archaean zircon using measured 204 Pb/ 206 Pb ratios. Ages are given at 95% confidence. 40 Ar/ 39 Ar BIOTITE GEOCHRONOLOGY Ar Ar dating of 2.7 mg biotite separated from sample KP 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 mol mv 1. Correction factors applied were as follows: 36 Ar/ 37 Ar ; 39 Ar/ 37 Ar ; 40 Ar/ 39 Ar ; ( 36 Ar) Cl /( 37 Ar) K ; ( 38 Ar) K /( 39 Ar) K ; Ca/K 1.90; λ 40 K A J- factor of was applied to sample KP K 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 using methods outlined by Forster and Lister (2004). Plots of log 10 (D 0 /r 2 ) against T -1 (Arrhenius plot; Fig. DR6) and log 10 (r/r 0 ) against % 39 Ar release (Fig. DR7), where D 0 = frequency factor of diffusion, r 0 = 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 (T C ) of 289 C and 228 C, respectively. As shown by the apparent age spectrum (Fig. DR8), the grain domains with T C = 289 C were degassed by heating steps 10 to 12 (accounting for 37% of total 39 Ar release) relating to a cooling age of ± 0.04 Ma and the grain domains with T C = 228 C were degassed by heating steps 1 and 2 (accounting for 10% of total 39 Ar release) relating to a cooling age of ± 0.29 Ma. Both domains are confirmed by the 36 Ar/ 40 Ar versus 39 Ar/ 40 Ar plot (York plot; Fig. DR9) to have housed negligible atmospheric argon. TABLES & FIGURES

4 KP KP KP residuum melanosome crd diatexite E, S E, S E, S SiO Al 2 O Fe 2 O 3 * MgO CaO Na 2 O K 2 O TiO MnO P 2 O SO Total LOI X Mg Table DR1 XRF major element bulk composition (wt.%) for Kobipoto Complex samples. *Total iron measured as Fe 2 O 3. LOI = loss on ignition (wt.%). X Mg = Mg/(Mg + Fe total ).

5 spot U (ppm) 206 Pb* (ppm) Th (ppm) 232 Th / 238 U 206 Pb c (%) Ratios 238 U / 206 Pb ±σ (%) 207 Pb / 206 Pb ±σ (%) Ages (Myr) 206 Pb/ 238 U ±σ 207 Pb/ 206 U ±σ KP11-588: Cenozoic zircon (rims) KP11-588: Mesozoic and older zircon (cores) KP11-619: Cenozoic zircon (rims) Table DR2 U-Pb zircon geochronology results for Kobipoto granulites. For Cenozoic zircons, the quoted 207 Pb/ 206 Pb and 238 U/ 206 Pb ratios relate to total Pb and U, and common Pb is corrected by assuming 206 Pb/ 238 U- 208 Pb/ 232 Th age-concordance. For older zircons, the quoted 207 Pb/ 206 Pb and 238 U/ 206 Pb ratios relate to radiogenic Pb only and common Pb was corrected using measured 204 Pb/ 206 Pb ratios. Pb c and Pb* indicate the common and radiogenic portions, respectively.

6 spot U (ppm) 206 Pb* (ppm) Th (ppm) 232 Th / 238 U 206 Pb c (%) Ratios 238 U / 206 Pb ±σ (%) 207 Pb / 206 Pb ±σ (%) Ages (Myr) 206 Pb/ 238 U ±σ 207 Pb/ 206 U ±σ KP11-619: Mesozoic and older zircon (cores) KP11-621: Cenozoic zircon (rims) KP11-621: Mesozoic and older zircon (cores) Table DR2 (continued)

7 KP ; biotite; 21 steps; λ 40 K = E-10; J = E-3 Temp 36 Ar 37 Ar 38 Ar 39 Ar 40 Ar % 40 Ar* 40 Ar*/ 39 Ar (K) Cumulative Calculated Age Ca/K Cl/K ( o C) (mol) (% err.) (mol) (% err.) (mol) (% err.) (mol) (% err.) (mol) (% err.) 39 Ar (%) (Ma ± 1σ) E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E E E E E E ± E E+01 Total 1.54E E E E E ± 1.71 Table DR3 Data from 40 Ar/ 39 Ar step-heating experiments of biotite from sample KP Biotite standard GA1550 (98.5 ± 0.8 Myr; Spell and McDougall, 2003) was used as the neutron flux monitor. 40 K 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.

8 KP Garnet Cordierite Spinel Sapphirine Ilmenite Sillimanite Plagioclase Chlorite Biotite core rim coronae symplectite inclusions in grt with spinel inclusions in grt wt.% SiO TiO Al 2 O Cr 2 O Fe 2 O 3 * FeO MnO MgO CaO Na 2 O K 2 O ZnO Totals Oxygens c.p.f.u. Si Ti Al Cr Fe Fe Mn Mg Ca Na K Sum Table DR4 Representative electron microprobe (EMP) mineral chemical analyses of KP *Fe 2 O 3 was calculated from all-fe-as-fe 2+ microprobe analyses by the programme AX (Holland, 2012).

9 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.

10 KP pseudosection H 2 O SiO 2 Al 2 O 3 CaO MgO FeO K 2 O Na 2 O TiO 2 O P-T (Fig. 3A) M H2O = 0.42; M O = T-M H2O (Fig. DR2) M H2O = 0.00; M O = M H2O = 1.00; M O = T-M O (Fig. DR3) M O = 0.00; M H2O = M O = 1.00; M H2O = Table DR6 Effective bulk compositions (mol%) in the NCKFMASHTO chemcial system, as input to THERMOCALC for calculation of pseudosections for sample KP An M H2O of 1 is equivalent to adding 1 wt.% water to the dry bulk composition and an M O value of 1 is equivalent to an XFe 3+ value of 2/3.

11 A :5:1 SAPPHIRINE KP KP11-581C ideal Sa OTHER PHASES FROM KP Sp Crd Crn Chl Al (wt% ) :9:3 2:2:1 mixing line B Si (wt% ) SAPPHIRINE KP KP11-581C ideal Sa A l :5:1 7:9: :2: Figure DR1 Sapphirine compositional plots. A: Al v. Si (wt.%) plot of sapphirine compositions (normalised to 100%) for granulites KP and KP11-581C compared to corundum, chlorite, spinel, and cordierite. Sapphirine analyses plot on a mixing line passing through the 2:2:1-7:9:3-3:5:1 sapphirine solid solution (red), demonstrating the reaction Sa + H 2 O Crn + Chl (± Sp). B: Al v. Si (cations per formula unit) plot of sapphirine compositions for granulties KP and KP11-581C compared to the 2:2:1-7:9:3-3:5:1 sapphirine solid solution (red). Si

12 KP M O = 0.50 & P = 7.5 kbar NCKFMASHTO (+ qtz + pl + ilm + sill) 1000 sa sp ksp liq sa sp liq sa crd sp liq crd sp liq T ( C) T ( C) 1050 KP ksp liq mt ksp sa grt sp grt sp ksp liq 6 sa sp osm liq sp osm liq sp crd 9 ksp osm sp crd osm sp crd grt 50liq sp ksp crd ksp osm grt ksp grt sp crd ksp bt mt 52bi 51cd grt mt crd ksp osm 14g 8 25osm 29sa 31osm 33mt 32sp 12ksp grt mt ksp liq sp crd osm liq sa sp liq 11 grt bt sp crd ksp 43cd osm liq mt liq 49liq grt sp mt crd ksp 13ksp 26ksp 24osm 27ksp 28sa 23osm 30ksp sa sp crd osm liq mt ksp liq 53liq sa grt sp liq grt sp liq 34ksp 3 7g 4sa 19mt 20sp sp crd ksp liq 47cd grt mt liq 10 8cd 35ksp 2cd sa sp crd liq 17cd 41cd 1 grt sp crd 44bi ksp liq 48ksp 12 54liq grt sp mt 55cd bt mt crd ksp liq 0 1sa 2 3g 45ksp 42ksp sp liq 7 kbar & M O = 0.50 NCKFMASHTO (+ qtz + pl + ilm + sill) 5sa mt liq 15mt 16sp sp crd liq 1) sa sp liq 2) sp mt liq 3) grt sp mt liq bt mt liq 4) sa osm grt sp ksp liq 5) sa osm grt sp liq grt sp crd liq 6) osm grt sp ksp liq 7) osm grt sp liq 46bi 8) grt sp mt ksp liq grt sp mt crd liq 9) ksp bt mt 10) bt mt ksp liq 11) grt ksp bt mt liq 12) grt bt mt grt mt crd liq 6g cd 0 grt mt crd ksp ksp 0.4 grt mt crd ksp liq liq M H 2 O (where an M H O of 1 = 1 wt% H O added to dry bulk composition) 2 2 Figure DR2 T-M H2O pseudosection of granulite KP Diagram is calculated at 7.5 kbar 850 pressure and with 0 M O = 0.50 (XFe = 0.33). The 0.4 grey line indicates 0.6 the chosen 0.8 M H2O value 1 used 0.11 in the T-MO pseudosection (Supplementary Fig. DR3) M H 2 Oand the P-T (where an M H 2 O of 1 = pseudosection 1 wt% H 2 O added to dry bulk composition) (Fig. 3A). The target field is outlined in blue (and neighbouring sa-present field is dotted). Minerals are abbreviated 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.

13 KP M H2O = 0.42 & P = 7.5 kbar NCKFMASHTO (+ qtz + pl + ilm + sill) 1000 sa sp liq sa sp mt liq sa crd mt liq 950 grt liq grt sp liq sa grt sp liq 2 grt mt liq 1 sp liq mt liq sa crd sp liq 3 sa crd sp mt liq sa mt liq crd ksp mt liq T ( C) 900 grt ksp liq grt ksp mt liq ksp mt liq 8 ksp mt crd ksp mt grt bt ksp liq grt bt liq grt bt mt liq 10 9 bt mt liq bt mt bt ksp mt 1) sa sp liq 2) grt sp mt liq 3) sp mt liq 4) sa sp mt liq 5) sa mt liq 6) sa crd ksp mt liq 7) crd bt ksp mt 8) bt ksp mt liq 9) grt bt ksp mt liq 10) bt liq XFe M 3+ = 0 XFe 3+ = ⅔ O Figure DR3 T-M O pseudosection of granulite KP Diagram is calculated at 7.5 kbar pressure and with M H2O = The grey line indicates the chosen M O value used in the T-M H2O pseudosection (Fig. DR2) and the P-T pseudosection (Fig. 3A). The target field is outlined in red (and neighbouring sa-present field 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.

14 0.6 KP Mean 206 Pb/ 238 U age: ± 0.52 Ma MSWD = 1.08 probability = Ma 194 Ma 3,416 Ma 1,836 Ma Ma 207 Pb/ 206 Pb μm Ma Lower intercept: ± 0.38 Ma MSWD = 1.00; probability = Ma U/ 206 Pb Figure DR4 Tera-Wasserburg plot of Miocene metamorphic zircon rims from migmatite sample KP Mean 206 Pb/ 238 U age is quoted at 95% confidence. Data-point error ellipses are drawn at 68.3% confidence. MSWD mean square weighted deviation. Representative cathodoluminescence images of the zircon grains are shown top-right, annotated with individual analytical spots. See Table DR2 for full dataset KP Mean 206 Pb/ 238 U age: ± 0.23 Ma MSWD = 1.20 probability = 0.30 to common Pb Ma 20 μm 404 Ma 1,764 Ma 207 Pb/ 206 Pb Ma Ma Lower intercept: ± 0.23 Ma (anchored at 207 Pb/ 206 Pb = 0.836) MSWD = 1.07; probability = U/ 206 Pb Figure DR5 Tera-Wasserburg plot of Miocene metamorphic zircon rims from migmatite sample KP Mean 206 Pb/ 238 U age is quoted at 95% confidence. Data-point error ellipses are drawn at 68.3% confidence. MSWD mean square weighted deviation. Representative cathodoluminescence images of the zircon grains are shown top-right, annotated with individual analytical spots. See Table DR2 for full dataset.

15 -2-3 log 10 D0/r (D 0 /r 2 = 2.73 x 10 4 s -1 ) T c = 366 C (D 0 /r 2 = 9.13 x 10 9 s -1 ) (D 0 /r 2 = 1.53 x 10 7 s -1 ) T c = 289 C T c = 228 C / T Kelvin Figure DR6 Arrhenius plot for Ar-Ar step-heating experiments of KP 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 (T c ) 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. D 0 = frequency factor of diffusion and r = radius of domain under consideration (Forster and Lister, 2004). Calculations performed by eargon.

16 CAN ANU#13, Foil P13; Sample KP11-619, Biotite, 21 steps 3 2 log 10 r / r Percentage Ar released Figure DR7 log 10 (r/r 0 ) vs. % 39 Ar released plot for Ar-Ar step-heating experiments of KP 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 different radii are shown by the plot, which correspond to the different closure temperatures inferred from the Arrhenius plot (Supplementary Fig. DR6). r = radius of domain under consideration and r 0 = radius of the reference domain (Forster and Lister, 2004). Calculations were performed by eargon.

17 20.0 Sample KP11-619, Biotite, 21 steps Apparent Age (Myr) Upper limit ± 0.04 Myr MSWD = 0.73 (T c = 289 C) Lower limit ± 0.29 Myr (T c = 228 C) Percentage 39 Ar released Figure DR8 Apparent age spectrum for Ar-Ar step-heating experiments of KP 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. The upper limit ± 0.04 Ma age is interpreted to relate to cooling through 289 C and the lower limit ± 0.29 Ma age is interpreted to relate to cooling through 228 C (see Arrhenius plot in Supplementary Figure DR6). Calculations were performed by eargon.

18 Sample KP11-619, Biotite, 21 steps Ar/ 40 Ar Ar /40 Ar Figure DR9 York plot for Ar-Ar step-heating experiments of KP 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 Supplementary Figures DR6, DR7, and DR8).

19 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 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 Na 2 O CaO FeO MgO Al 2 O 3 SiO 2 H 2 O O: Journal of Metamorphic Geology, v. 25, p , doi: /j 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 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 , doi: /am 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 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 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 , doi: /s z. Holland, T.J.B., AX: A programme to calculate activities of mineral endmembers from chemical analyses: (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 Spell, T.L., and McDougall, I., 2003, Characterization and calibration of 40 Ar/ 39 Ar dating standards, Chemical Geology, v. 198, p 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 Taylor-Jones, K., and Powell, R., 2010, The stability of sapphirine + quartz: calculated phase equilibria in FeO MgO Al 2 O 3 SiO 2 TiO 2 O: Journal of Metamorphic Geology, v. 28, p , doi: /j x. White, R.W., 2000, The effect of TiO 2 and Fe 2 O 3 on metapelitic assemblages at greenschist and amphibolite facies conditions: mineral equilibria calculations in the system K 2 O FeO MgO Al 2 O 3 SiO 2 H 2 O TiO 2 Fe 2 O 3 : v. 18, p 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 K 2 O FeO MgO Al 2 O 3 SiO 2 H 2 O TiO 2 Fe 2 O 3 : Journal of Metamorphic Geology, v. 20, p 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 , doi: /j x.