hr title: Short China 430074, author: Wuhan *Corresponding Geosciences, of University China Sciences, Earth of School Tectonics, 5 Australia 6845, 4 USA 80401, Colorado 3 Kingdom United 9AL, KY16 2 1 Feisel Yves Scotland northwest Complex, Lewisian pro- the melt in and duction metamorphism granulite-facies on constraints New nttt fGocecs oansGtnegUiest fMiz 52 an,Germany Mainz, 55128 Mainz, of University Johannes-Gutenberg Geosciences, of Institute colo at n niomna cecs h nvriyo tAdes tAndrews, St Andrews, St of University The Sciences, Environmental and Earth of School colo at n lntr cecs utnUiest,GOBxU97 et,WA Perth, U1987, Box GPO University, Curtin Sciences, Planetary and Earth of School This article isThis article by protected copyright. All rightsreserved. 10.1111/jmg.12311doi: thisarticle as differences to lead between the of thisversion cite and Version Record.Please copyediting, paginationbeen throughthe andproofreadingtypesetting, process,may which This article acceptedhas been forpublication andundergone full peer review but hasnot eateto elg n elgclEgneig ooaoSho fMns Golden, Mines, of School Colorado Engineering, Geological and Geology of Department Accepted Global for Center and Resources Mineral and Processes Geological for Lab Key State Article 1 ihr .White W. Richard , ata etn nteLwsa Complex Lewisian the in melting Partial [email protected] 1 , 2 ihr .Palin M. Richard , 3 i .Johnson E. Tim , 4 , 5 fptooia neetadatvt-opsto oesfrsldslto hss(..Holland (e.g. phases solution solid for models activity-composition and interest petrological of derive to used been increasingly have diagrams PT phase quantitative years, 15 c. past the During 1 Complex. Lewisian Keywords: region central the from sheets felsic of compositions potas- at more melts produce (granitic) to predicted sic is granulite melt-reintegrated the environ- 610 closed-system Although between a trondhjemitic. compositions in both conditions for peak calculated at melts form Partial to ment. predicted melt fully at partial For 45% occur to rst peak. up to with metamorphic predicted Badcallian is melting the prograde for protoliths, inferred hydrated conditions or the with at hornblende-granulites, orthopyroxene-bearing garnet, fer- without produce melt to potential and expected relations both phase with similar tility, Lewisian exhibit the lithologies of region subsolidus southern Both the those in Complex. with Gairloch well from amphibolite match subsolidus precursors Melt- a undepleted for determined modelled block. compositions. these crustal protolith for probable single calculated estimate equilibria a to Phase representing order in as employed Complex was Lewisian modelling reintegration the of region central the for evidence eld of with conditions consistent metamorphic sam- peak all similar that at indicate phase equilibrated results ples rocks, Our compositions. intermediate whole-rock and using Na system mac (NCKFMASHTO) the of in to samples constructed some For were by blocks considered diagrams Gruinard terranes. are and which crustal Assynt Scotland, discrete the northwest represent Complex, of Lewisian history Archaean metamorphic the the of investigate we study this In ABSTRACT This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article INTRODUCTION siae sn nenlycnitn hroyai aaescnann end-members containing datasets thermodynamic consistent internally using estimates rhen acpaeeulbi;prilmlig pseudosection; melting; partial equilibria; phase mac Archaean; ∼ 700900 ◦ ,temdle et r ossetwt h measured the with consistent are melts modelled the C, in - situ 2 OCaOK ata etn n h lsi nepeainof interpretation classic the and melting partial 2 OFeOMgOAl ∼ 0ka and kbar 810 ◦ n 1050 and C 2 ∼ O 620 3 SiO ◦ and C 2 H ∼ thermocalc ◦ 9001000 2 r mostly are C OTiO ∼ . kbar, 9.5 2 O ◦ C, 2 mtis 07 ai,Wie re,21b ht ta. 2017). al., et White 2016b; Green, & & Kirkland, White, Gardiner, Palin, Brown, long- Johnson, 2017; and (e.g. formation Smithies, crust the continental and Archaean inves- Earth, of quantitative early evolution in-depth, the for term in allow now metamorphism relations granulite-facies These of tigation 2016). been recently al., only has et rocks, (Green intermediate calibrated a and 2001), basic high-grade of Holland, characteristic & amphibole, Powell, (White, now years 15 of over set Furthermore, for 2007). bulk-rock possible siliciclastic been Powell, silica-saturated has & in Holland, compositions anatexis Green, of investigation 2012; petrological Powell, eective & while Diener Elmer, White, 2005; Powell, Dale, Holland, (e.g. & conditions subsolidus under suitable equilibria only were phase amphibole, calculating and for clinopyroxene as such rocks, metabasic within found monly valuable representing rocks deriving intermediate poor for typically to targets is mac crust metamorphosed 2012; high-grade with earliest sediments, Earth's clastic Rollinson, the in & of of much amounts Brown, Furthermore, signicant White, 1991). produced Fischer, have Sawyer, (Johnson, to known metamorphism are during which melt 2011), partial White, Harley, & & (e.g. Johnson terranes Zandt granulite-facies (e.g. exhumed 1988; of measurements examination ev- geophysical direct the as 1987), and material, 1995), basic Taylor, Ammon, of & component (Rudnick signicant xenoliths a by under comprises idenced rock crust the lower in Earth's phases The constituent study. for descriptions thermodynamic appropriate of ability Powell, White, 2013; Kelsey, Bhattacharya, & 2004; 2002). Clark, Brown, Brown, Clarke, Korhonen, & & Johnson 2003; 2016; Powell, & Caddick, & White, textures Guevara reaction (e.g. or section zoning, thin chemical in inclusions, observed mineral from path retrograde Whole- and 2003). prograde Clarke, & estimate Powell, to White, opportunity PT the 2011; provide only diagramspseudosectionsnot White, phase & specic Johnson rock 2011; 1998, Powell, & This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved.

Accepted ( activitycomposition recently, Until Article avail- the by limited is approach pseudosection the of application advances, these Despite odtoso ekmtmrhs,btmyas eue odrv osrit nthe on constraints derive to used be also may but metamorphism, peak of conditions ax eain o ral oaii et uii lnprxn,adT-adK-bearing and Ti- and clinopyroxene, augitic melt, tonalitic broadly for relations PT odtos(..Wie ai,&Gen 2017). Green, & Palin, White, (e.g. conditions ax eain o e ermgeinmnrl com- minerals ferromagnesian key for relations ) on hut(iue1,adrcso h on Supergroup. Moine trending the SSWNNE the of by rocks east and the 1), to (Figure bound Thrust Torridon tectonically Moine Neoproterozoic is sequence the entire of this rocks and between sedimentary group, Lewisian by the mainland of overlain Scottish rocks unconformably northwest Metamorphic are the 1). Complex (Figure of south further coast Torridon to the Loch up and along Wrath rocks Cape north of exposed the are tract oldest units in the a These Hebrides of foreland, 2012). some Outer northern al., are the et which Johnson of 2010), part 2001; Kemp, as Kinny, & & Friend Whitehouse (e.g. Europe 3.12.7 2010; in of rocks ages al., protolith et with Wheeler rocks (e.g. contains Ga Scotland north-west of Complex Lewisian The 2 repre- region central the involve that block. those coherent with singlequie consistent a most senting is and formation mod- tectonothermal the competing of for els implications has consistency This identical metamorphism. near facies experienced Complex Lewisian mainland production melt and evolution reconstruct metamorphism. prograde to during the out investigate carried and was compositions modelling protolith reintegration possible Melt 1). (Figure localities eight from the use we work, calculated the this using model operating In to regimes (2016) history. tectonic al. Earth the et in into time insight enigmatic limits this and at event this lithospheric for the In responsible of reconstruction therein). processes eective references hinders al., and event "Badcallian" et 2010, granulite-facies metamorphic Johnson Ga Beach, 2.7 peak & the Rollinson, 2013; concerning Park, uncertainty Wheeler, White, tectonothermal particular, & 2005; its Fischer, of Park, Johnson, aspects key (e.g. 2012; Earth, debate on under terranes remain high-grade evolution studied widely most the This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved.

Accepted the of region central the throughout rocks that shows modelling equilibrium phase Our Article of one is Scotland northwest of Complex Lewisian ArchaeanProterozoic the Although EINLGEOLOGY REGIONAL PT and TX PT suoetosfr1 acadutaacrcscollected rocks ultramac and mac 16 for pseudosections vlto ftecnrlrgo fteLwsa Complex, Lewisian the of region central the of evolution PT ∼ P 0k ieta usfo the from runs that wide km 20  T odtosdrn granulite- during conditions odtosfrtec 2.8 c. the for conditions ax eain fGreen of relations e hmclsse Crwih anca,18,18) hs qiiru modelling equilibrium Phase 1987). 1986, 11 > Barnicoat, of & conditions (Cartwright system metamorphic chemical peak ed yielded suite t'Sidhean 9001000 an and kbar Cnoc the of rocks tary) and The kbar and 2012). the kbar from 79 al., rocks from employed. et range were ultramac Zirkler estimates thermobarometers and conventional dierent O'Hara mac 1987; various which metamorphosed for 1969; Rollinson, on area & Scourie focused Muecke, Sills studies these 2011; 1981; of White, majority Rollinson, & Johnson 1978; 1987; Yarwood, & Barnicoat, & Barnicoat, (e.g. Cartwright authors numerous by 1983; proposed been have metamorphism Badcallian peak for al., et Zirkler 1965; and Evans, 1997) Ga; Gibb, 2.482.42 & Belshaw, (c. 2012). O'Nions, episode Zhu, Inverian amphibolite-facies 1994; later a Rogers, & (c. event Heaman, Badcallian Corfu, granulite-facies Ga; earlier 2.82.7 Scourian an into 1951). divided further Watson, episodes are & deformation episodes (Sutton metamorphic and (Laxfordian) metamorphic post-dyke dykes or classify (Scourian) Scourie to pre-dyke the marker Historically, as time either 2014). relative composi- a ultramac Heaman, as & to used (Davies been mac Ga have of 2.4 dykes c. central Scourie at All intruded trending length. which NWSE in tion, by kilometres many These cut for are extend 2012). gneisses and may thick region & cumulates, Zack, metres O'Hara pyroxene-rich & hundred several and White, to metagabbro 1977; Johnson, up include 1961, Zirkler, be which bodies, O'Hara, 1987; ultramac Tarney, and 2016; & mac Park al., et 1978; Johnson rocks supracrustal Yarwood, 1987; mica-rich rare of Barnicoat, relatively sheets & abundant and (Cartwright with units, intercalated ultramac are to and mac Ar- region, metamorphosed of central levels the deep dominate relatively represent gneisses tonalitetrondjhemitegranodiorite to (TTG) Layered considered 1987). 1951) Tarney, & (Park Watson, crust & continental chaean Sutton (Peach amphibolite- rocks mainly granulite-facies 1907; of recording comprised al., units primarily et is expose region regions central southern the assemblages, and facies northern the While 1). This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. h ope a endvddit h oten eta,adsuhr ein (Figure regions southern and central, northern, the into divided been has complex The Accepted estimated of range wide a 1960s, the Since Article ∼ 1150 ◦ OHr awo,17) aeauios(oetal metasedimen- (potentially aluminous Rare 1978). Yarwood, & (O'Hara C ◦ ,bsdo hroaoer n ergntcmdligi simpli- a in modelling petrogenetic and thermobarometry on based C, ∼ 700820 ◦ PT Mek,16;Rlisn 91 o15 to 1981) Rollinson, 1969; (Muecke, C odtos(5ka n 7001150 and kbar (715 conditions P ◦ ±  C) T 3 og ta. 00 in,Fin,&Lv,20;Pr,20) lhuhteie htthe that idea the Although 2005). Park, 2005; Love, or & Friend, blocks Kinny, (Goode- discrete Palaeoproterozoic 2010; several the during in al., amalgamated et subdivided have nough be to can considered Complex are which Lewisian geochronological terranes, used the (2001) that Kinny argue and Friend to 1951), data Watson, & 1981). Sutton (e.g. Tarney, block & Weaver crustal 2005; workers Tarney, other & 2012) Rollinson 1980; Rollinson, Windley, 1969; & responsible being Rollinson rocks (e.g. Gale, source the 1991; & of Welke, metasomatism O'Hara, and Moorbath, dehydration & pre-metamorphic Windley, favour O'Nions, 2012; & Cohen, Rollinson melting al., 1983; partial et 2012; the Johnson (Barnicoat, of metamorphism result Rollinson, during the was loss 1961; depletion melt this and that O'Hara, suggest studies several 2012; While 1980). al., et (Johnson Cs) Rb, H Si, in depleted are gneisses metabasic 1976). (Beach, Front region Laxford central the the of along of part 1982) northern emplacement is the the (Sills, retrogression in places, especially Laxfordian-aged in composition, widespread granitic and, addition, of zones dykes In pegmatitic shear trending 2012). NWSE pervasive al., with et associated Zirkler 2010; 520550 and al., kbar 56.5 of granulite- conditions assem- at Badcallian hornblende-dominated blages of amphibolite-facies overprinting to local assemblages and pyroxene-dominated facies shear-zones trending NWSE 900 steep of excess within in temperatures and kbar 1315 of ◦ conditions polymeta- equilib- peak proposed phase Badcallian and employed with systems (2012) morphism chemical suite al. MnNCKFMASHTO t'Sidhean et and an Cnoc Zirkler NCKFMASHTO the the from 2012). in gneisses) ('brown' gneisses al., garnet-biotite (Cartwright et of modelling Johnson melted rium partially 1987; region central Barnicoat, the & throughout pressures rocks metamorphic metagabbroic 875975 peak most of suggested that temperatures results and Com- These kbar Lewisian 8.511.5 (2011). the of of White region and central Johnson mainland by the plex from granulites (ultra-)mac to applied Na the in .Sbeun neinmtmrhs a hrceie yteixo H of inux the by characterised was metamorphism Inverian Subsequent C. This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. ncmaio otoei h otenadsuhr ein,tecnrlrgo T and TTG central-region the regions, southern and northern the in those to comparison In Accepted single a representing as Complex Lewisian the of interpretation classic the Opposing Article 2 OCaOFeOMgOAl 2 O 3 SiO 2 ,U hadsm ag o ihpieeeet (K, elements lithophile ion large some and Th U, O, 2 H 2 OTiO ◦ ◦ ,cnitn ihl vdneindicating evidence eld with consistent C, .(odnuhe l,21;Welret Wheeler 2010; al., et (Goodenough C. 2 O(CMST)sse a rst was system (NCFMASHTO) O 2 -ihuids O-rich amtclyrn.Teflain nbt h T nissadmtgbri ok typically rocks (Figure metagabbroic and length gneisses TTG relict in the preserve metres both commonly in of and foliations The metagabbro hundreds layering. coarse-grained and magmatic to width medium- in mostly are metres These of 2a). tens to up are investigation proposed the within lies area, studied terrane, the Assynt in proposed terrane. the south Gruinard within furthest lie found 1) locality, (Figure Achiltibuie herein the considered sites sample the Gruinard eight the by the and separated north south, the the in in terrane terrane Assynt that the separate two namely proposed of fragments, and consists Complex crustal concept Lewisian allochthonous this mainland the rened subse- of further region were central (2005) that granulite-facies al. the (terranes) et fragments Kinny Complex crustal Lewisian discrete amalgamated. the quently into that subdivided propose tectonically to be geochronology U-Pb can used (2001) Kinny and Friend 3.1 size spot a and nA, 12 electron of JXA-8200 current beam JEOL a a kV, 2 on 15 of of conducted voltage were acceleration an location using each microprobe and from tube sample X-ray one rhenium analyses of a XRF analyses with spectrometer compositions. MagiXPRO and mineral Philips chemistry a individual utilised bulk-rock for for (EPMA) Geoscience, (XRF) microanalysis of uorescence probe Institute X-ray electron the via at Germany, analysed Mainz, were of area (Figure University each region central from the lithologies in Representative localities dierent eight 1). from collected were samples 72 of total A 3 2010). al., et (Wheeler uncertain still zones are suture amalgamation any of of location timing increas- the corresponding becoming 2010), the is and al., crust et Archaean (Goodenough of community the block by single accepted ingly a represent not does Complex Lewisian This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. h acbde icse eenta aebe sdfrdtie thermobarometric detailed for used been have that herein discussed bodies mac The

Acceptedµ Article IL EAIN N PETROGRAPHY AND RELATIONS FIELD m. eea edobservations eld General ∼ WS rnigSrta ie hl ee of seven While Line. Strathan trending NWSE in - situ mineral odtos(..agre-ern apeadagre-betsml) oesmlsshow samples Some sample). garnet-absent a metamorphic and equivalent sample under garnet-bearing selected formed a were that (e.g. possible, assemblages conditions where mineral and dierent outcrop, having same on the based from pairs collected sample The were locality information. pseudo- supplementary each calculated as from The presented are set. samples entire other the only the of is for representative sections modelling are our which of samples, results re- six detailed brevity, central for for presented the However, of Complex. the area Lewisian of spatial the assessment wide of an gion a permits comprising across set metamorphism modelling, sample of and large conditions analysis comparatively thermobarometric This petrological detailed total. in for samples used sixteen were 1 Figure 2010). on Powell, shown & White 2012; 2013, al., & et White, Johnson Diener, (e.g. mac 2014; 2d) pronounced (Figure by Hudson, melt rock injected host representing the them from with separated consistent be selvedges may compo- leucosomes tonalitic of large veins places and In sheets larger sition. with continuous derived petrographically are been and having into as bot- feed 2b interpreted (Figure are foliation leucosomes the Larger to elongated (sub-)parallel be oriented tom). and also length may in aggregates centimetres several grain to pyroxene up leucosomes, (Figure clinopyroxene stromatic euhedral larger-scale of In accumulations or 2c). grains large Small-scale contain commonly 2012). local and 2013, host by formed have al., to et interpreted (Johnson leucosomes, melting partial indicating (leucosomes), gations & (Johnson decompression high-temperature with 2011). consistent is White, coronae origin and plagioclase-bearing whose biotite prominent to 2b), exhibit altered (Figure commonly be may porphyroblasts but Garnet localities, to most meso- chlorite. at to occurs of up Orthopyroxene are range garnet diameter. of wide in porphyroblasts which cm a in to outcrops present, within leading where layers distinct metagabbro, locality, forms Garnet-rich usually given rocks. any metabasic leucocratic in rare absent and melanocratic, be quartz, may and which garnet, orthopyroxene, of hornblende, each and plagioclase, clinopyroxene, by of dominated proportions generally varying are contain layers Metagabbroic angles. moderate at dip This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. ayo h eaaboclyr oti eccai urz n lgols-ihsegre- plagioclase-rich and quartz- leucocratic contain layers metagabbroic the of Many Accepted localities central-region eight the of each from rocks metagabbroic two study, this In Article in - situ etn,ocri h melanocratic the in occur melting, in - source lhuhothers although , ∼ 10 n a o eoddi n fteaaye opyolss risaegnrlyFe-rich generally are Grains porphyroblasts. analysed the of any zon- in compositional recorded While internal not samples, was 16BA04). between ing inclusion-rich varied (e.g. forms garnet garnet corona of samples, plagioclase-rich compositions some representative clear minerals In any other without 3b). overgrowing porphyroblasts Figure vermicules 16ST02; anhedral garnet by (e.g. manifested corona is the mar- within cases cuspate some irregular have in commonly adjacent which also orthopyroxene porphyroblasts gins, of These layer 3a). discontinuous (Figure matrix outer hornblende the an to or and orthopyroxene porphyroblast minor the without outcrops. to or an the with adjacent comprise in rims plagioclase, reaction occur granoblastic These cm of diameter coronae. layer 10 or in inner to symplectites up mm by surrounded grains 6 be larger to also much may a.p.f.u.). up though Garnet (0.020.29 porphyroblasts studied, Al large sections and thin as the occurs a.p.f.u.) in 1), (0.020.12 (Table Na present of where amounts low Garnet, with with granoblas- diopside/augite, 1), coarse (Table are forms Fe)] samples and + size, all in in mm Grains 1.5 aggregates. to tic up grains individual with Ca-rich equigranular, relatively and is 1) (Table 16SC07 and 16AC01 ( samples up in ( subhedral, garnet around Ca-poor is coronae relatively samples in and that most size, in in plagioclase mm Matrix 1 exception to the plagioclase. with coronal variation, versus compositional matrix intragranular of or inter- signicant any lack ples sulphide accessory and magnetite rare ilmenite, occur. Minor also phases and 1). orthopyroxene (Table contain garnet study contain this two in but emphasised all samples six the many of in all abundant common However, hornblende by samples. and characterised orthopyroxene are garnet, with assemblages plagioclase, mineral tex- and granoblastic granulite-facies clinopyroxene with localities, coarse-grained, all to In medium- are tures. sampled rocks metabasic the of Most 3.2 millimetre-scale. to centimetre- a on layering compositional X This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. An Accepted sam- studied Article all in minerals major all almost that indicate analyses composition Mineral ..) aegencioyoeei l tde ape ssberlt euhedral to subhedral is samples studied all in clinopyroxene green Pale 0.70.9). = erlg n iea hmsr falsuidsamples studied all of chemistry mineral and Petrology X An .. =C/C a+K],whereas K)]), + Na + Ca/(Ca [= 0.30.6 = X Mg .. =Mg/(Mg [= 0.60.8 = re mhbl,adpaicaebigsrnl eiiie.Rtorsino clinopyroxene planes. of cleavage Retrogression along prominent sericitised. particularly strongly is being blueish- by plagioclase replaced and completely amphibole, or partly green more being show pyroxenes 16AS04) both 16TA07, with (e.g. retrogression, samples extensive Some material. opaque mantle ne-grained phyllosilicate this contains places, also some In clinopyroxene. nar- and a orthopyroxene forming around fringe biotite row or chlorite ne-grained by characterised typically alteration, retrograde 2012). al., et 2011), (Johnson terrane Sawyer, Assynt & the in Cesare, studies Holness, other microstruc- (e.g. from observations These occurred with melting consistent apparent partial 3d). small that very (Figure imply with feldspar features quartz plagioclase tural interstitial smaller surrounding or between length, angles in dihedral mm 5 to up grains quartz of intergrowths symplectic rare 3c). containing (Figure garnet, ilmenite of and fringe grains garnet prominent individual Large a by magnetite. of rimmed grains be rare ilmenite may or typically hematite are of Grains lamellae exsolution garnet. rare around with clinopyrox- layers of corona junctions orthopyroxene-rich triple within on or individually ene occur commonly oxides FeTi 2012). of al., grains et Larger Hawthorne samples (cf. magnesiohornblende retrogressed contain 16TA08) more to and while (16TA07 little Tarbet amphibole, exhibiting from pargasitic Samples by characterised opaque. are almost ne-grained retrogression grains abundant no some contain making may oxides, and FeTi colour, of in inclusions brown to dark-green matrices. generally plagioclaseclinopyroxene are throughout Grains disseminated samples in most in variation present consistent ( is samples bole No between or within matrix. observed clinopyroxeneplagioclase was the composition within aggregates as or ( Ca and Mg/(Fe+Mg+Ca)]) ( X This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Alm oesmls(..1S0)ehbtdpoietluooe ihete ag elongated large either with leucosomes prominent exhibited 16SC03) (e.g. samples Some grains, anhedral to subhedral individual as occurs present, where orthopyroxene, Matrix Accepted minor only show and apatite of amounts small contains samples studied of majority The Article .206 =F/F+gC)) ihlse muto g( Mg of amount lesser with Fe/(Fe+Mg+Ca)]), [= 0.420.63 = X Grs .402 =Ca/(Fe+Mg+Ca)]). [= 0.040.26 = X Mg .306) uhda amphi- Subhedral 0.530.68). = X Pyr .803 [= 0.080.37 = eo,wihaerpeettv falsmlsivsiae nti td.Teecomprise These study. this discussed in and investigated 4 samples Figure all in of presented representative are are region which central the below, this from in 2010; examples studied six samples al., only sixteen et brevity, the Wheeler between similarities calculated 2011; in Petrological resulted work White, 2012). & Johnson al., (e.g et equilibrated Zirkler Com- have Lewisian to the thought which at is conditions plex tectonothermal 7501050 lower-crustal of to mid- conditions the for encompass constructed were diagrams phase All 4.1 2. Table in given are modelling equilibrium phase for methods, used titration compositions standard bulk The by determined samples. was all H sample measured in each the phase in and P-bearing iron ferric sole to the ferrous be of to ratio observed was which these apatite, of P of contents measured presence CaO the to The according adjusted analysis. were (XRF) compositions (q), uorescence bulk quartz X-ray included by phases obtained Pure were culations 2000). (H Worley, uid & ilmenitehematite aqueous Holland, and 2002); Powell, (Holland (White, Powell, (ksp) & hem) K-feldspar (White (ilm, and sp) (ol) (mt, (pl) olivine magnetitespinel plagioclase 2003); 2014); 2011); Powell, & Powell, Green, biotite & & (opx), (Holland Johnson, orthopyroxene (ep) Holland, (g), epidote Powell, garnet and (White, 2016); (mu) muscovite al., and et (bi), (Green (hb) hornblende and (aug), following The rocks. intermediate to (Na system SiO NCKFMASHTO Calcula- the 6/2/2012. in updated undertaken (2011), were Powell tions and Holland of ds62 dataset consistent internally using performed were calculations All METAMORPHISM OF 4 This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. 2

Accepted ArticleH HS QIIRU OSRIT NTECONDITIONS THE ON CONSTRAINTS EQUILIBRIUM PHASE PT 2 OTiO pseudosections 2 O 2 ) pee(p) n uie(u.Bl-okcmoiin sdfrcal- for used compositions Bulk-rock (ru). rutile and (sph), sphene O), 2 2 ,wihoestems elsi netgto fpaeeulbi nmac in equilibria phase of investigation realistic most the oers which ), otnswr ae nls ninto LI.Tenraie molar normalised The (LOI). ignition on loss on based were contents O P  T suoetosta hwmn omnfaue.Tu,for Thus, features. common many show that pseudosections thermocalc ax eain eeue:mtbst et() augite (L), melt metabasite used: were relations 34i(oel&Hlad 98 n the and 1988) Holland, & (Powell v3.45i 2 OCaOK 2 O 5 otnst con o the for account to contents ◦ n 6ka,which kbar, 416 and C 2 OFeOMgOAl 2 O 3  sebae,wt lsl pcdcnor Fgr acd ugsigta 01 o. may mol.% 1015 that within suggesting produced 4a,c,d) be (Figure contours hornblendeorthopyroxene-bearing spaced closely quartz-present, with in d assemblages, positive greatest generally generally a more is with is steep, production relatively transition Melt are melt this Calculated of although proportions transition. samples, modal garnetorthopyroxene for the studied contours than the state of oxidation any bulk-rock to in equilibration, sensitive observed of was pressures metamorphic oc- rutile constrains typically no also and which as pressure-dependent 4), is (Figure kbar transition 1014 ilmeniterutile at The curs 2016). compositions bulk mac al., on et performed (Palin calculations previous particularly with temperature, consistent increasing pressures, with low consumed at fully be in to conditions either predicted subsolidus is being at but stable lithologies, them be all to to calculated owing is Quartz selected 1). were (Table equilibra- bearing/garnet-absent samples of orthopyroxene- of pressures or orthopyroxene-bearing, pairs the and many garnet- on garnet-bearing/orthopyroxene-absent, as constraint locality, tight each variable a in provides of tion feature eld assemblage topological garnet-plus-orthopyroxene This a width. denes so and elds, assemblage at occurs thopyroxene high relatively to persisting (>1000 samples hornblende some with in conditions, temperatures subsolidus at hornblende and ene high- at except ◦ d cases, has positive most typically weak stability in garnet a of of ubiquitous limit range low-pressure is The entire plagioclase conditions. the and pressurelow-temperature throughout diagram, stable each is in Augite garnet-bearing, considered of respectively. limits lines, The green brown, red, and by coloured melt. are elds of assemblage hornblende-bearing and proportions orthopyroxene-bearing, modal calculated represent contours are samples remaining the material. for supplementary pseudosections and as 16ST02 Calculated given and Bay, 2). Badcall (Table from Strathan 12BA04 from and 16ST03 16BA02 Scourie, from 16SC07 and 16SC03 .Gre-betasmlgsaecmol oiae yagt,paicae orthopyrox- plagioclase, augite, by dominated commonly are assemblages Garnet-absent C. This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved.

Accepted or- of limit stability high-pressure calculated the 16SC03, sample of exception the With Article dashed thin, and line black thick a by indicated is solidus the pseudosection, each On P /d ∼ 50 T ∼ n agsfo o75ka t750 at kbar 7.5 to 5 from ranges and ◦ . braoetelwrpesr onayo garnet-bearing of boundary lower-pressure the above kbar 0.54 bv h solidus. the above C ◦ ;eg 6T2 iue4e). Figure 16ST02, e.g. C; ◦ o8t 1ka t1050 at kbar 11 to 8 to C PT P space /d T . oes(..Pln elr aes yk 2016c). and composition and Dyck, rock & proportions bulk Waters, small Weller, in Palin, uncertainties very (e.g. to in models sensitive present of be when may determination identify stability for to modelled dicult considered their be not can were they magnetite as or conditions, quartz, rutile, as absolute such the used phases on be same constraints can the each tighter experienced for give having determined to elds as together assemblage interpreted peak be the thus can and they history, another, tectonothermal one collected was to locality proximity each close from samples in of pair each As metamorphism. granulite-facies peak of tions 5c). (Figure of kbar conditions peak 9.210.5 metamorphic combined their yield The pseudosections at solidus. both limit the of by temperature elds dened assemblage upper is the boundary dening temperature garnet lower also of The hornblende, stability intersection. low-pressure of the boundary by upper given the are and constraints of Pressure proportions small 1). containing (Tab. additionally hornblende 16ST02 dominated with assemblages plagioclase, granulite-facies and clinopyroxene garnet-bearing by comprise both 16ST03 and at 16ST02 16BA04 sample for calculated pseudosection the 990 range of pressure boundary narrow temperature very a giving from pseudosection, derived each of be in can boundaries estimates stability Pressure except garnet 1). assemblage, the (Tab. granulite-facies garnet same contains the additionally 16BA04 comprise that 16BA04, and 16BA02 samples Bay Interpreted respectively. allowing equilibration, former of the limits in peak pressure quartz lower of and presence upper and the garnet of of demarcation absence the with ilmenite, and clase, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. ∼ h nepee ekmtmrhcasmlgsi l i ape vra at overlap samples six all in assemblages metamorphic peak interpreted The plagio- orthopyroxene, clinopyroxene, contain both 16SC07 and 16SC03 samples Scourie

Accepted Article upper an denes diagrams both from lines garnet-in the of intersection The kbar. 89.2 P  ∼ T 0ka and kbar 810 odtosfrti oaiyae91 brad9701010 and kbar 910 are locality this for conditions ∼ 9001000 ◦ hl h oe eprtr ii sgvnb h oiu in solidus the by given is limit temperature lower the while C ◦ Fgr d,wihcnb nepee srepresenting as interpreted be can which 5d), (Figure C ∼ PT 875 odtoso qiirto.Minor equilibration. of conditions ◦ Fgr b.Srta samples Strathan 5b). (Figure C ◦ Fgr a.Badcall 5a). (Figure C ∼ 9201020 P  T ◦ condi- and C PT ax h ape eentflyhdae hnasmwa oe oa etpouto ol be would production melt total lower somewhat of a any result- then if the hydrated However, and fully fertility. solidus not melt were the maximum samples at the of saturated conditions uid represent was thus modelled pseudosections rocks ing above outlined the process of sample The each two. the that the with between assumes dierences compared illustrate are to compositions 3 Table `protolith' in compositions model resulting The achieved solidus mol.%. the 2739 until repeated was mol.%) (18 intersec- H melt the of at amounts reintegrated small of was the reintegration melt and solidus-position and recalculated resulting phase was the solidus new of the tion the of including position the assemblage case the this using In solidus. the of instead temperatures low- resulting the the and solidus new low- the the of again, intersection the at low- melt the of across batch another resulted integrate assemblage new The until solidus. temperature the down than increased al., was melt et of (White proportion low- method the the the point in starting not involved each should uncertainty At and the 2004). in- sample given elds each results assemblage of the the assemblage aect within peak signicantly lies granulite-facies reintegration chosen the melt were represent of to pressures point terpreted dierent starting The the that 3). ensure (Table to modelling equilibrium phase from inferred along samples three for out carried isobaric was simplied reintegration Melt meta- (2004). prograde Halpin of and during rbi-script Powell, lost White, the been using achieved have was samples to and studied assumed morphism, the melt for re-integrating compositions by protolith protolith determined a Possible were evolution, prograde required. the understand therefore are to is rocks order In composition preserved 2002). the of that Powell, preservation & implies (White the Complex residual Lewisian with the combined in production assemblages melt granulite-facies for evidence petrological Widespread 4.2 This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. 2 Accepted ( O-saturation Article oeln fml production melt of Modelling T onayo h epciel a ie ytesaiiyln famnrlrather mineral a of line stability the by given was eld respective the of boundary T onayivle h oso iea ahrte et ti osbethat possible is It melt. then rather mineral a of loss the involved boundary ∼ T PT o. H mol.% 1 onayi ie yteocrec fanwpaesaiiiga lower at stabilising phase new a of occurrence the by given is boundary ah t95ka r88ka,adsatn rmpa temperatures peak from starting and kbar, 8.8 or kbar 9.5 at paths 2 ) hc eutdi oa enertdml rprin of proportions melt reintegrated total in resulted which O), P  T ah olwn hspoeue step-wise procedure, this Following path. thermocalc T onaywste sdto used then was boundary olwn h ehdof method the following P  T ah until path, nraigpesr n h perneo ant rhprxn evsteasmlg,form- assemblage, the leaves within orthopyroxene absent garnet, of quartz appearance becomes the and assemblage orthopyroxene- pressure the increasing the temperature, crossing up After going trend. line isobaric in nearly a where follows composition line original orthopyroxene-in the the of pseudosection the in stability orthopy- orthopyroxene with of contrasts occurrence amphibolite rst of prograde the temperatures by The dened above is this. roxene pressures below medium stable at biotite transition and facies being kbar granulite K-feldspar 8 with above conditions facies pressures amphibolite at upper stable to stable are K-feldspar and and otite kbar d 13 positive around constant at relatively solidus a the intersecting until temperatures pressure lower 720 towards up particular, trends In line garnet-in pressures. higher the to restricted is stability atures al., et Palin (e.g. assemblages 2003). metabasic Pattison, amphibolite-facies common 2016; with well agree and hornblende clinopyroxene, quartz by and dominated are assemblages subsolidus Predicted higher kbar. to 15 trending above initially uid-absent shape, is irregular solidus more calculated a the has kbar, and 9.5 H Above is pressure. solidus decreasing the with kbar, temperatures 9.5 about 250 below (Figure around pressures At by composition down-temperature shape. melt-depleted shifted the is to solidus The compared H 4e). topology bulk dierent increased distinctively the to a largely has Due 6a). diagram. (Figure the protolith of 600 plausible range to the down a extended of was relations range phase temperature The predicted the illustrate to (16ST02*) A granulite Melt-reintegrated 2016). 4.2.1 al., et Palin (e.g. temperature solidus higher a with along expected This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. PT anti tbedw opesrso . bra 860 at kbar 8.5 of pressures to down stable is Garnet

Accepted◦ Article .Ti rn svr ieetfo h rgnlpedscinweegre follows garnet where pseudosection original the from dierent very is trend This C. suoeto a acltdfroeo h eutn etritgae compositions reintegrated melt resulting the of one for calculated was pseudosection ± H 2 ,paicae ant itt,msoie pdt,shn,adK-feldspar, and sphene, epidote, muscovite, biotite, garnet, plagioclase, O, ∼ P 820 /d T ◦ nteLoxagpbqasmlg ed This eld. assemblage Lopxaugplhbq the in C vrtewoetmeauerne(iue4) Bi- 4e). (Figure range temperature whole the over ◦ oesr httesldsle within lies solidus the that ensure to C ◦ ,btfrlwradhge temper- higher and lower for but C, 2 T -auae n rnst higher to trends and O-saturated eoetedn akt lower to back trending before ◦ 2 n ssrnl oie in modied strongly is and C otn,tepseudosection the content, O ∼ 50 ◦ .With C. T togyicesdadhrbed ssal pt eprtrsi xeso 1000 of excess in are temperatures temperatures to up high stable at is plagioclase hornblende and of increased proportions strongly relative closed-system the the Additionally, to compared orthopyroxene equivalent. and successively augite assumed becomes especially bulk-rock is rock phases, total residual mac 6% The the in of enriched equilibria. of event phase fractionation the loss subsequent changing melt a thus and, to a composition leading melt 2015), partial of Brown, % & (Yakymchuk 7 fractions of melt accumulation at after occurs conditions, transition this that suggested (2005) of Handy the and from drained Rosenberg be forming to by rock. melt rock partial host for the pathways of provide strength which melt-networks the overcome interconnected to melt sucient of accumulation the after ilmenite. and orthopyroxene with together quartz melt of and consumption augite the involving high- closed-system temperatures The higher hornblende. to and produced is melt partial below more produced is melt Little hornblende of K-feldspar. proportion of ◦ the appearance and the consumed with are coinciding epidote increases, and the With biotite melting, augite. and partial biotite of epidote, onset of amounts hornblende, smaller by with together dominated quartz For are and assemblages percent. plagioclase volume predicted to the approximation conditions close amphibolite a providing subsolidus cation, one by on percent based molar normalised as (lower) are output open-system are and proportions (upper) Phase closed-system 6b). assuming (Figure kbar, conditions 9.5 at section isobaric an for ( consumed granulite- fully pressure is intermediate hornblende to which path at prograde conditions the facies following generated be hornblende to later to predicted and up is conditions, biotite closed-system rst Assuming as consumed. temperature progressively increasing are with production have melt generally in isopleths crease proportion mode d Melt positive steep 2003). a Rotzler, & high-pressure (O'Brien the facies of granulite typical rocks bearing clinopyroxeneplagioclasegarnethornblende ing u ihteapaac fgre ( garnet of appearance the with but C This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. φ h eaiepootoso tbepae r lutae na on illustrated are phases stable of proportions relative The Accepted occur to expected is loss melt conditions open-system realistic more geologically Under Article ≈ .7adtre t'etcnetvt rniin MT.Teeoe o open-system for Therefore, (MCT). transition' connectivity 'melt it termed and 0.07 P /d T hc a engtv ngre ern ed n niaea in- an indicate and elds bearing garnet in negative be can which , ∼ T 840 rnlt sebaei oiae yplagioclase, by dominated is assemblage granulite ◦ )adotoyoee( orthopyroxene and C) ∼ 990 ◦ T C). md iga,calculated diagram, mode ∼ ∼ 890 5 fprilmelt partial of 45% thermocalc ◦ )signicantly C) ◦ C. ∼ but 800 brudrcoe-ytm(pe)adoe-ytm(oe)cniin r hw nFigure in shown are conditions (lower) open-system and (upper) closed-system under kbar to up path prograde amphibolite the ( the on hornblende generated of 16ST02*, consumption being for full melt predicted the partial As of 4045% isopleths. yields also increase close composition strong by a represented by mode, characterised melt is transition in amphibolitegranulite or positive the steep marking very eld a the with 16ST02*, in those thin d as by negative indicated topology melt same partial the distinctive have of major isopleths proportions one dashed Modal representing 16ST02*. diagram, the sample of from corners dierent right feature and left upper hornblende are the and and in orthopyroxene absent garnet lack assemblages clinopyroxene, the by kbar, dominated 10 mostly above pressures At absent. quartz are Laugopxhbplq narrow the ( by eld facies represented ilm amphibolitegranulite is prograde assemblages The garnet-absent temperature. in lower transition and higher to 16ST02* in in as As ( sample. temperatures lower that to in restricted predicted is K-feldspar epidote minor and biotite the of lack stability but the 16ST02* 16ST02* in assemblages as facies same Predicted-amphibolite the stability and hornblende. are solidus, and the orthopyroxene, of positions garnet, and for shapes the elds of terms in specically 16ST02*; for that H The 2010). H Connelly, al., & Tarney, et experience Park, Wheeler not 1987; did 2001; and al., et Complex (Johnson Lewisian anatexis the or Gairloch metamorphism of to granulite-facies region close collected southern was amphibolite-facies rock the The in 6c). 3; (Figure melt-reintegration a (Table. by calculate (1987) obtained to results Winchester used and was Park, "A4") Johnson, sample from composition amphibolite mac A amphibolite Lewisian 4.2.2 This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. 2 -auae < o. ud t7kbar. 7 at uid) mol.% (<1 O-saturated anti tbet lgtylwrpesrso . bra 860 at kbar 7.5 of pressures lower slightly to stable is Garnet resembles strongly A4 sample for calculated pseudosection the of topology general The oa rprin fpae rdce osaiiedrn sbrcmtmrhs t9.5 at Accepted metamorphism isobaric during stabilise to predicted phases of proportions Modal Article ∼ P 800870 /d T n nices nml rdcint ihrtmeaue.I particular, In temperatures. higher to production melt in increase an and ◦ ,<. br.A ihrtmeaue bv hsl,assemblages eld, this above temperatures higher At kbar). <7.5 C, ∼ 2 980 otn a dutds httesldswsjust was solidus the that so adjusted was content O PT ◦ ) suigcoe-ytmconditions. closed-system assuming C), suoeto nodrt opr tt the to it compare to order in pseudosection ± ◦ n olw h aetrend same the follows and C lgols.Paicaeis Plagioclase plagioclase. T <700 ◦ C). Tbe4.O nahdosbssteeiiilml opstoscnanvr iteFeO little very contain compositions SiO melt with initial wt.%) these (<0.03 basis MgO anhydrous and an H On in rich are 4). compositions (Table melt initial The 7a). (Figure ( diagram TAS the of eld granite at temperature the generated. indicate was loss Arrows composition melt melt. melt partial involving respective 7% the calculations of which open-system accumulation the for after those 6% (Figure are of events diagram plotted ternary from compositions anorthitealbiteorthoclase modied The normative basis; 7b). a normalised and anhydrous 1994) oxide, wt.% Middlemost, 7a; (Figure diagram (TAS) silica in produced calculated were melt A4 20 and partial of 16ST02* samples of steps by compositions produced compositions changing Melt modelling predicted anatexis. during equilibrium the phase of modal investigation assemblages, in change the metamorphic the allows in of involved examination phases the of and diagrams proportions phase of construction the metamorphism Alongside prograde during generated compositions Melt 4.2.3 1000 drainage of melt of temperature events a six to experiencing up after in enriched plagioclase relatively and is environment garnet, open-system orthopyroxene, an augite, in produced rock residual The around reached garnet. rstly of is environment, accumulation melt open-system of an threshold In 7% ilmenite. the and mi- orthopyroxene with plagioclase, melt of and closed- proportions garnet The clinopyroxene, nor by increases. dominated progressively is conditions assemblage granulite-facies closed-system while system at decrease, melt quickly partial proportions assemblage. of hornblende the amount and in the quartz appears garnet, plagioclase of epidote and stabilisation and solidus, the Biotite the With 16ST02*. crossing sample after similar melt-reintegrated shortly generally the consumed are for are and 6b Figure conditions, in subsolidus mi- shown at and those quartz sphene to of and amounts epidote, small biotite, with augite, hornblende by nor dominated are assemblages These 6d. ∼ This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. 5w.)btH but wt.%) 15 Accepted the in plot and similar very are samples both by produced compositions melt initial The Article ◦ ln nisobaric an along C 2 otnsdces ptmeaueadaecoet t%b 1000 by wt.% 3 to close are and temperature up decrease contents O ◦ C. PT 2 otnsaon 3w. Fgr a.Wt increasing With 7a). (Figure wt.% 73 around contents aha . bradpotdo oie oa alkali- total modied a on plotted and kbar 9.5 at path ∼ 795 ◦ ihteoccurrence the with C 2 ◦ O C hog h rndoieadtnlt ed n liaeyetrtetodjmt edat eld trondhjemite the enter ultimately and elds 940 tonalite and granodiorite 820 around the consumed through completely is pressures) lower at during biotite ◦ eld (or granite K-feldspar the until into heating strongly trend melts 16ST02*-derived until compositions. compositions normative anorthitic more towards trend A4 ∼ amphibolite the from in K-feldspar derived of Melts stability the two. in dierences strongly the diverge reecting but afterwards, step directions temperature dierent rst in the they for which assemblages from by Or-rich elds generated granite more melts and towards trondhjemite develop initial the The between boundary 1936). the on by lie (Niggli, form samples norms both would Niggli that using phases melt solid the of of proportions crystallisation to recalculated been have compositions melt calculated SiO temperatures wt.% highest the At ( 7a). (Figure it below and (1050 just boundary or the on dioritemonzonite above amphibolite the lying straddles the 16ST02* that with eld boundary granodiorite gabbroic-dioritemonzodiorite the and from path a follows samples the produced. or consumed of temperatures above Na successively increases generated The being melts to are akin 16ST02*. K-feldspar exhausted, sample they or by after decreases biotite and while temperature up increases going A4 consumed K sample The by assemblage. the produced from lost melt is hornblende where especially MgO, temperatures and high FeO in at enriched becomes melt the temperature, increasing 1050 with decreases at wt.% 5053 to down temperature increasing decreases samples both of silica-content to and anhydrous, more become melts the temperature, ∼ .Atrti on,mlsbcm esK less become melts point, this After C. This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. 800 3w. SiO wt.% 53 ∼ o h lutaino h aai nAbO enr iga Fgr b,temodelled the 7b), (Figure diagram ternary AnAbOr an in data the of illustration the For from derived melt of composition the temperature, increasing with diagram, TAS the On ◦

Accepted Article 900 around wt.% 69 .Tecmoiin ftemlsdrvdfo ohsmlsa 1050 at samples both from derived melts the of compositions The C. ◦ ◦ rmweete rgestruhtetodjmt edtwrsna Or-absent near towards eld trondhjemite the through progress they where from C )teml opstosi 6T2 r lgtymr iii n ihri alkalis in richer and silicic more slightly are 16ST02* in compositions melt the C) 2 . t%K wt.% 4.7 , 2 . t%K wt.% 5.7 , 2 Na + O ◦ .Atrti on,teSiO the point, this After C. 2 2 Na + O otn ftemlsiiilydcessbtsubsequently but decreases initially melts the of content O 2 O). ∼ 800 2 ◦ )ta hs eeae yteapioie( amphibolite the by generated those than O) ihn la orlto osldpae being phases solid to correlation clear no with C 2 -ihwt nraigtmeaueadprogress and temperature increasing with O-rich ◦ .WieteSiO the While C. 2 otn erae oesrnl with strongly more decreases content 2 otn consistently content ◦ r eysimilar very are C 2 otn fthe of content O ∼ 50 eta ein ie hs ti ieyta h ektmeaue nec oaiywr similar, were locality each in temperatures peak the that likely is it the this, within Given trends temperature region. signicant central apparent no are However, there estimates, pair. pressure sample the locality's with each as are from by orthopyroxene limits or and hornblende garnet temperature peak of with stabilities Upper rocks relative in the hornblende of melting. stability upper partial the by for constrained typically evidence showed all modelled samples ◦ lower-pressure kbar. and 810 upper- range on the constraints in lie tight which place metamorphism, to of sample concert limits each in from used rocks been metagabbroic Lewisian have garnet-bearing the location of and region garnet-absent central of the Pairs estab- throughout Complex. rocks here for undertaken conditions modelling metamorphic equilibrium peak lishes phase The metamorphism. order granulite-facies in modelled were the ilmenite constrain and to quartz, hornblende, orthopyroxene, garnet, of amounts supporting is and of assemblages Complex observations facies Lewisian eld granulite the uid-poor of of region preservation central the the by provided for from clearly rocks Evidence metabasic melting. in partial loss melt including and conditions anatexis metamorphic on placed their be for of to source Examination constraints potential 2011). formulated a newly considered Moyen, using are evolution rocks 2014; petrological such VanTongeren, where (e.g. & levels 2017), age Kaus, Brown, crustal Archaean al., (Johnson, deep of TTG et these those White worldwide, especially the 1994; orogens rocks, in basic of Martin, form of roots that proportions exposed rocks signicant the contain metamorphic in often grade seen high As of crust. feature deep inherent an is melting Partial 5 diagram. the in paths dierent along developed they though even .Telwrtmeauecntansaepoie ytepsto ftesldsa the as solidus the of position the by provided are constraints temperature lower The C. This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. o hssuy acrcsdmntdb lnprxn n lgols ihvarying with plagioclase and clinopyroxene by dominated rocks mac study, this For Accepted 850 about from ranging broader, somewhat are constraints Temperature Article ICSINADCONCLUSIONS AND DISCUSSION P  T in odtoso omto n h rdcino etdrn Archaean during melt of production the and formation of conditions - situ ecsms(iue ;Jhsne l,2012). al., et Johnson 23; (Figures leucosomes ax oesb re ta.(06 losfor allows (2016) al. et Green by models ◦ ooe 1050 over to C 01 odnuhe l,21;Lv,Kny red 04 ak 05.This 2005). Park, 2004; Friend, representing region & central Kinny, the Love, with consistent is Kinny, conditions 2010; & metamorphic (Friend in similarity terranes al., close distinct et two Goodenough of composed being 2001; the region discount not central does the but terranes, of Assynt possibility and central Gruinard the proposed throughout the from both investigated including were region, samples though even localities, dierent from Sills, 2012). 1986; al., et Barnicoat, Inverian Zirkler consistent & for (Cartwright is 1983; conditions kbar 1982, it estimated 5 as timing, to events, close the both are of metamorphism during Irrespective amphibolite-facies depth at event. remaining metamorphic Inverian rocks discrete Ga the a 2.5 the with represents during c. or occurred the event, garnet during Badcallian of overprint growth granulite-facies later the this of whether stages breakdown unclear its later to is subsequent it garnet However, of growth the 8). with (Figure consistent also is path a Such cooling. d shallow relatively a with path T Neoarchaean. the in lithosphere protocontinental with of coevally blocks developed dispersed that of systems amalgamation metamorphic the paired widespread of part the as with interpreted consistent are conditions peak calculated d The high 1978). high- Scourie some Yarwood, the or & from 2012) O'Hara granulites (e.g. ultramac al., area and et mac Zirkler of thermobarometry 1989; from derived 1987, estimates 1986, earlier Barnicoat, many & by (Cartwright proposed rocks high- range tary the the reach within not lie do They but studies (2011). White and Johnson of ndings better are 1000 8). temperatures to (Figure up peak temperatures the maximum 4c), where Figure samples 16BA02, In (e.g. 2008). constrained thermobarometric available currently Holland, by & achieved Powell be (e.g. can methods that precision the within to least at This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. eopeso olwn ekcniin Jhsn&Wie 01 ln clockwise a along 2011) White, & (Johnson conditions peak following decompression ecintxue novn h osmto fgre r ossetwt ereo high- of degree a with consistent are garnet of consumption the involving textures Reaction peak modelled The Accepted samples between variation systematic no show conditions metamorphic peak Badcallian Article T /d P (>77.5 ◦ /br yeo eaopim(rw ono,21) hc is which 2018), Johnson, & (Brown metamorphism of type C/kbar) P  T odtoso aclinmtmrhs r ossetwt the with consistent are metamorphism Badcallian of conditions P /d P T odtosbsdo hroaoer fmetasedimen- of thermobarometry on based conditions ihtercsrmiiga i-rsa et during depth mid-crustal at remaining rocks the with , ◦ ol einferred be could C P  T T ) oehtlwrqatte faot3 o. etrltv otesatn composition starting the to relative melt mol.% 30 about of quantities lower Somewhat d). each & by peak estimated produced the be at could conditions melt closed-system hy- mol.% under fully 45 composition For to up hydrous. of been partial quantities having signicant for protoliths evidence compositions, the However, drated with consistent 2016). is outcrops al., most et in Palin melting (cf. fertility melt White, their & limiting (Johnson thus fully hydration 2011), complete been mac- escaped layered had potentially of have region be bodies may larger metagabbro central cannot some ultramac it the particular, However, In of metamorphism. lithologies 2009). prograde mac during Kerkhof, hydrated the der all van that & established Holtta, terrains Foley, conclusively Archaean Nehring, other from 1997; reported gneiss (Garde, amphibolite-facies amphibolite-facies the and of rocks conditions uid-saturated region apparent southern the H on minimally based were solidus, wet protoliths the the the at from that amphibolite assumed an procedure other This the and region. region, southern central the from granulite one re-integrated undertaken: melt was a compositions protolith approximate two of modelling 1980). petrological asites, Windley, & Rollinson 2012; ion region Rollinson, large southern the 2012; some in and rocks al., Th amphibolite-facies et to U, (Johnson compared Si, Cs) in Rb, (K, depletion & elements melting consistent White lithophile for a 2018; evidence showing eld Diener, widespread evidence & by Stuck geochemical supported 2016; and further 2016b, is conclusion al., This et Palin 2002). (e.g. melt 2012; Powell, partial al., of et quantities Johnson signicant of 1973; loss Fyfe, and production the with consistent is region region. central entire the among shared being evolution Badcallian terranes, proposed post both the from with samples consistent in involving observed textures are garnet reaction of Additionally, regrowth and fortuitous. consumption terranes the Gruinard highly and is Assynt region conditions the central metamorphic If peak the 2012). in throughout similarity close al., the et then Zirkler blocks allochthonous 2010; truly 2.7 represent c. al., of et metamorphism Wheeler Badcallian (e.g. Ga of 2.492.40 2.8 ages metamorphic c. common at Park the occurred terranes post-dates event. Gruinard which and metamorphic Ga, Assynt Badcallian the the of accretion to that subsequent suggested and (2005) during block coherent single a This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved.

Accepted metab- the from produced melt of composition and amount likely the constrain to order In Article central the of much through assemblages mineral granulite-facies of preservation The P  T odtos(iue6b (Figure conditions 2 O-saturated o nov rcse uha oeta otmnto hog ecino h etwt the with melt the crystallisation. of fractional do reaction or and through rocks contamination compositions host potential liquid as modelled such are it processes However, here involve discussed gneisses. not compositions felsic melt to the intermediate that also noted likely melt is most partial and locally-derived mac preserving surrounding region the the central from with the consistent throughout are more results preserved the modelling sheets to and felsic contributor geochemical important eld, gneiss the an TTG Overall, be of sheets. may melting tonalitic from metagabbro produced from indeed it derived was eld melts material the partial granitic in while of observed bulk bodies high the mac the that subordinate Considering likely the is conditions. to similar compared gneiss at et TTG gneiss White of TTG by proportion predicted felsic those to match the intermediate closely in for compositions gneisses (2017) these TTG al. as felsic 2013) to intermediate- it al., the et units, of (Johnson melting metabasic area from the formed from been have melt also lower-temperature could derived earlier-formed, been have of conceivably batches could composition. sheets small these protolith 2012; from in amphibolite material the granitic al., more for et the especially of (Johnson much 7b, region While Figure the on in shown sheets 1994) felsic measured to Rollinson, match the close of shows spread trend compositional This the up-grade. compositions remains tonalitic composition and re-integrated granodioritic through melt from the compositions 900 in melt about melt until of contrast, granitic progression By a by trondhjemite. accompanied to granite is melt protolith the of amphibolite content the silica a decreasing On for in 1994). trend up-temperature Rollinson, this plot, 2012; AnAbOr normative al., et (Johnson region the in observed leucosomes intermediate 9001000 of conditions ( in accumulating than rather migration, millimetre and rocks. from source segregation the sizes melt various allow in would case. which leucosomes the preserve metres, likely commonly to is region which central conditions, the open-system in under Rocks produced been have to calculated is es lato sensu This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. naTSpo,tecmoiino etpoue ntemdl agsfo granitic from ranges models the in produced melt of composition the plot, TAS a On oeln fml rdcinsosta ul yrtdm ok xoe ttecurrent the at exposed rocks mac hydrated Accepted fully that shows production melt of Modelling Article ttewtsldst ogl irtcmnoii tteitrrtdpeak interpreted the at dioritic/monzonitic roughly to solidus wet the at ) ◦ Fgr a.Ti scnitn ihtecmoiino escto felsic of composition the with consistent is This 7a). (Figure C ◦ hr tte hne ncmoiinsgicnl si evolves it as signicantly composition in changes then it where C P  T n aoaoyaaye.T cnwegsspotfo pnFn PR174from GPMR210704 Fund Open from support of acknowledges Institute TJ the at Thesis analyses. eldwork Master laboratory for YF's funding and the of provided which part Mainz, was University, Gutenberg study Johannes this Geoscience, for out carried research The 2016b; al., et 6 Palin 2017; al., et 2015). Johnson 2003; Clift, 2010; & Jacob, of Parman, & topic Kranendonk, Buhre, al., Foley, Van a et Roberts,  2018; Hawkesworth remain Johnson, 2003; and & Brown  Hamilton, been 2006; the long for Bédard, have (e.g. responsible nuclei debate processes heated continental during geodynamic rst crust and Earth's the environments of constrain of stabilization tectonic and dierentiation The investigate and directly formation Archaean. to controlled the opportunity that an processes region central oer geological the thus the in & Complex of exposed (White proportions Lewisian gneisses assemblages large mac the high-temperature migmatitic protoliths, of the well-preserved hydrated preserve The fully to For 2002). lost 2016). Powell, and produced al., be White, et must Johnson, Palin melt melt 2012; to 2008; Brodie, expected & are Powell, Droop types (cf. & rock undersaturated Most uid if event. even Badcallian conditions, such Ga at 2.7 c. Archaean the the during of achieved region 900 were central exceeding the temperatures in where preserved Complex, (Bickle, well Gneiss nuclei are Lewisian cratonic processes these of for stabilization Evidence long-term 1986). the and evolution crustal understanding formed together which levels. and crustal 2012), derived higher melt at al., intrusions of et for proportion (Johnson source larger gneiss the mac a TTG of to intermediate anatexis contributed to likely by felsic depth generated from km were 20 that than Melts greater depths. at greater units at generated being ( melt km of 30 around at occurred is have region would central rocks a the Considering of melt. exposure of of volume level signicant 30 a of lost gradient and geothermal typical produced have to appear level crustal This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved.

Accepted Article to critical processes are extraction melt and melting, metamorphism, High-temperature ACKNOWLEDGEMENTS ∼ 0k et Fgr )wt usqetyhge proportions higher subsequently with 6) (Figure depth km 20 ◦ e ioee eg rw,20)adta h current the that and 2007) Brown, (e.g. kilometer per C ∼ 0ka) nta etn fthese of melting initial kbar), 10 ◦ tpesrscoet kbar 9 to close pressures at C atrgt . anca,A .(99.Eouino h cuincmlx nDl,J. Daly, In complex. Scourian the of Evolution (1989). C. A. Barnicoat, & I., Cartwright, and rocks supracrustal Scourian of Petrology (1987). C. A. Barnicoat, & I., Cartwright, and melts quartz-normative of generation The of (1986). onset C. the A. and Barnicoat, metamorphism & in I., change Cartwright, Secular (2018). E. change. T. secular Johnson, of & record M., a Brown, belts: orogenic in conditions Metamorphic (2007). loss M. heat Brown, and lithosphere the of stabilisation for melting of Implications (1986). J. M. Bickle, archaean of genesis coupled for model delamination-driven catalytic A (2006). H. J. Bédard, heat and geochemistry deformation, transport, uid of interrelations The (1976). Scotland. A. NW Beach, Complex, Scourian the of Metamorphism (1983). C. A. Barnicoat, References perceptive their for Harley S. handling. of editorial and University his Clarke for China G. Brown Resources, M. Bartoli, and Mineral O. reviews, and thank We Processes Geological Wuhan. for Geosciences, Lab Key State the This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article fLno,SeilPublication. Special London, of (Ed.), terrains grade J. Tarney, high Precambrian & comparable G. the R. of Park, evolution In geological complex. the for Lewisian implications Scotland: NW Stoer, from orthogneisses an on 3 Scotland. based North-West modelling of Lewisian petrogenetic the from anatexis: example crustal by restites corundum-bearing tectonics. plate global Review Geology International Archaean. the in 11881214. mantle. lithospheric sub-continental and crust London of Society Royal the complex. lewisian of the in zones shear proterozoic early in ow Geology Metamorphic of 7999. , at n lntr cec Letters Science Planetary and Earth mrcnMineralogist American , 1 163182. , , 49 , 280 193134. , 19) 569604. (1298), Vl 7 p 317.Gooia Society Geological 93107). pp. 27, (Vol. , eciiae omciiaActa Cosmochimica et Geochimica 103 181196. , ora fMtmrhcGeology Metamorphic of Journal , h vlto h eiinand Lewisian the evolution The 80 314324. , hlspia Transactions Philosophical Journal , 70 , , ye .S 17) h rnlt ais ata etn n h rhencrust. Archaean the and melting partial facies, granulite The (1973). S. W. Fyfe, geochrono- Complex: Gneiss Lewisian the of delami- reappraisal A by (2001). crust D. Archaean P. Kinny, the & of C., Friend, Evolution (2003). E. D. Jacob, & S., Buhre, F., Sutherland. S. Foley, Lochinver, near Basement Lewisian the of Geochronology (1965). aureole R. thermal C. the Evans, in volumes melt Anatectic (2012). H. K. Brodie, & R., T. G. Droop, redistribution production, Melt (2014). M. J. T. Hudson, & W., R. White, A., F. J. clinopyrox- Diener, for relations activitycomposition Revised (2012). R. Powell, for & ages A., zircon F. J. and Diener, baddeleyite upb New (2014). M. L. Heaman, & L., F. H. thermody- J. A Davies, (2005). B. J. T. Holland, & L., F. Elmer, W., R. White, R., Powell, J., Dale, Lewisian the of evolution Polymetamorphic (1994). G. Rogers, of & mechanism M., L. and Heaman, Chronology F., Corfu, (1991). J. M. O'Hara, & K., R. O'Nions, S., A. Cohen, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article oia vdnefristcoi sebyfo iprt ernsi h Proterozoic. the in terranes Petrology disparate and Mineralogy from to assembly Contributions tectonic its for evidence logical subduction. shallow and nation Nature melting. uid-absent and uid-present of Geology roles Metamorphic the of Journal Scotland: Complex, Etive the of melt crustal-scale for implications with transfer. rocks, source mid-crustal in accumulation and amphibole. and ene the for implications with scotland. province nw igneous of large evolution long-lived paleaproterozoic A swarm: dyke scourie the calulations. petrological for Na O in clinoamphiboles CaNa for model namic titanite zircon, of compositions isotopic U-Pb rutile. by and recorded as Scotland, NW complex, 153. granulites. Lewisian in depletion Publication. Special London, (Ed.), of Society D. Geological W. 297301). B. pp. Yardley, & A. R. Cli, S., , 207 Lithos otiuin oMnrlg n Petrology and Mineralogy to Contributions 5456. , , 201 ora fMtmrhcGeology Metamorphic of Journal 212225. , ora fMtmrhcGeology Metamorphic of Journal Nature , otiuin oMnrlg n Petrology and Mineralogy to Contributions 30 843864. , , 421 , rcmra Research Precambrian 142 249252. , vlto fMtmrhcBelts Metamorphic of Evolution 2 OCaOFeOMgOAl 198218. , , , 30 117 131142. , 215228. , , 23 , 249 771791. , 2 180198. , O 3 Philosophical SiO , 106 Vl 43, (Vol. 2 H 142 , 2 O oln,T .B,&Pwl,R 20) ciiycmoiinrltosfrpae npetro- in phases for relations Activitycomposition (2003). R. Powell, & B., J. for dataset T. thermodynamic Holland, consistent internally An (1998). R. Powell, & B., J. T. Holland, Schumacher, F., R. Martin, V., W. Maresch, E., G. Harlow, R., Oberti, C., F. Hawthorne, Storey, & S., I. A. Kemp, A., P. Cawood, B., A. Pietranik, B., Dhuime, I. J., Antarctica. C. Hawkesworth, East Group, Rauer the from granulites Proterozoic (1988). L. S. Earth. alternative Harley, An (2003). equilibria B. phase W. Hamilton, target: moving a at Shooting (2016). J. M. Caddick, & E., V. Guevara, M. R. Palin, & B., J. T. Holland, R., Powell, A., F. for J. Diener, model W., R. orderdisorder White, An R., C. E. (2007). Green, R. Powell, & B., J. T. Holland, R., C. E. Loughlin, Green, J., Wheeler, S., J. Myers, M., Krabbendam, G., R. Park, gneiss M., grey K. high-grade Goodenough, Archaean an of evolution and Accretion (1997). A. A. Garde, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article oia acltos naymti utcmoetformulation. multicomponent asymmetric an calculations: logical interest. petrological of phases supergroup. amphibole the of Nomenclature (2012). Mineralogist D. M. Welch, & C., J. crust. continental the of evolution London and of Society generation Geological The (2010). D. C. gneisses. felsic Petrology and of mac Journal from deducted paths pressure-temperature Decompressional 209235. metamorphism. high-temperature of modelling equilibria melting partial rocks. of metabasic calculation in the for relations Activitycomposition (2016). rocks. eclogitic appli- to with cations jadeitediopsidehedenbergiteacmite, system the terrane in pyroxenes end-Archean omphacitic an Zone: Shear Laxford The (2010). H. R. boundary? Graham, . . . C., S. Bulletin Survey Greenland. land West southern area, Fiskefjord the complex: amphibolite London of Society Royal the of Transactions elgclSceySeilPbiain London Publication, Special Society Geological , 97 20312048. , ora fMtmrhcGeology Metamorphic of Journal , , 29 177 10591095. , 115. , mrcnMineralogist American , 167 ora fMtmrhcGeology Metamorphic of Journal 229248. , S Today GSA , A273 ora fMtmrhcGeology Metamorphic of Journal , 92 457461. , , 11811189. , , 34 13 845869. , , 412. , 335 0 120. - 103 , , 16 309343. , elg fGreen- of Geology otiuin to Contributions ora fthe of Journal American , 34 , ono,Y . ak .G,&Wnhse,J .(97.Gohmsr,ptoeei and petrogenesis Geochemistry, (1987). A. J. Winchester, & a G., metagreywacke: R. of Park, melting A., Partial Y. (2008). Johnson, R. Powell, & W., R. White, E., T. Johnson, Archean (2012). R. H. Rollinson, & M., Brown, W., R. evidence White, S., petrographic Fischer, and E., Field T. Johnson, (2013). W. R. White, & S., Fischer, E., T. Johnson, and Delamination (2014). A. J. VanTongeren, & P., J. B. Kaus, M., Brown, E., W. T. R. Johnson, White, & D., P. Kinny, C., Clark, M., K. Goodenough, M., Brown, rst Earth's E., T. (2017). Johnson, R. Smithies, & C., Kirkland, N., Gardiner, M., Brown, E., T. the Johnson, in metamorphism on constraints Quantitative (2004). M. Brown, & E., T. Johnson, granulite- of conditions on microscope: constraints equilibrium the Phase (2011). under W. rocks R. White, Melted & T., (2011). Johnson, W. E. Sawyer, & B., Cesare, B., consistent M. internally Holness, extended and improved An (2011). R. Powell, & B., J. T. Holland, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article acltdmnrleulbi study. equilibria mineral calculated Scotland. NW Complex, Lewisian the Petrology of Region Central the geochemical from and Field Evidence - Metagabbro of Melting Partial from Dierentiation Intracrustal Lewisian mainland the of region central the Scotland. from NW complex, gneisses TTG of melting partial for instabilities. 4752. gravitational by caused crust archaean of recycling scotland. nw ultramac- of crust of archean origin the the in constraining bodies in mac ambiguity sagduction? of Subduction (2016). subduction. by form not did continents stable approach. pseudosection Petrology complementary a  brittany southern of variscides Scotland. NW London Scourie, at metamorphism facies interpretation. their and microstructures of equation new a solids. involving for interest, state petrological of phases for dataset thermodynamic Petrology and Mineralogy , 168 , , 53 45 147158. , 12371259. , 1) 21152138. (10), ora fMtmrhcGeology Metamorphic of Journal ora fteGooia oit,London Society, Geological the of Journal , 145 492501. , ora fMtmrhcGeology Metamorphic of Journal Elements Nature , rcmra Research Precambrian 29 , ora fteGooia Society, Geological the of Journal 7 333383. , , 247252. , 543 239242. , aueGeoscience Nature , 179 , 26 , 319326. , 283 837853. , ora of Journal ora of Journal 89105. , , 7 , ern,F,Fly .F,Hlt,P . a e eko,A .(09.Itra dieren- Internal (2009). M. A. Kerkhof, der van & S., P. Holtta, F., S. Foley, F., Nehring, (1969). and K. signicance, G. petrological Muecke, gneisses: grey Archaean composite in The studies (2011). isotope F. lead J. Moyen, of Signicance (1969). H. N. Gale, & H., Welke, S., system. Moorbath, rock magma/igneous the in materials Naming (1994). In K. A. E. crust. Middlemost, continental of genesis the and gneisses grey Archaean The (1994). H. Martin, metamor- and magmatism of Timing (2004). L. R. C. Friend, & D., P. Kinny, J., G. Love, interac- Osumilitemelt (2013). S. Bhattacharya, & C., Clark, M., Brown, J., nomen- F. terrane-based Korhonen, a for Proposal (2005). J. G. Love, & L., R. C. Friend, D., P. Kinny, as- Orthopyroxenesillimanitequartz (2003). R. Powell, & W., R. White, E., D. Kelsey, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article scotland. growth. crustal Archaean for setting non-unique a for evidence Scotland. Northwest rocks Lewisian of by exemplied as complexes, basement metamorphic high-grade ancient, Reviews Science York. New Elsevier, 205258). (pp. (Ed.), Condie C. K. the with comparisons complex: Petrology accretion. terrane gneiss for lewisian implications the and of terrane assynt area bay gruinard the in phism Geology implications and modelling equilibria the for phase granulites: temperature ultrahigh in tions Scotland. NW of 162 Complex Gneiss Lewisian the for clature paths. PT and Geology Metamorphic constraints of PTX Journal quantitative petrology, distribution, semblages: the of amphibolites 33 Group Scotland. Maree NW Loch Complex, Proterozoic Lewisian early the of signicance tectonic 255269. , 175186. , PTt , 31 , Upb.D-hss nvriyo Oxford) of University D.-thesis, (Unpubl. 146 881907. , vlto fteEsenGasPoic,India. Province, Ghats Eastern the of evolution 620636. , , 37 ergnsso rnlt aisrcsfo h eiino north-west of lewisian the from rocks facies granulite of Petrogenesis 215224. , rhencutleouin eeomnsi rcmra geology Precambrian in Developments evolution. crustal Archaean at n lntr cec Letters Science Planetary and Earth , 21 elgclScey odn pca Publications Special London, Society, Geological 439453. , otiuin oMnrlg and Mineralogy to Contributions elgclScey London Society, Geological , 6 ora fMetamorphic of Journal 245256. , Lithos , 123 2136. , Earth- , , ak .G,Tre,J,&Cnel,N 20) h ohMreGop Paleoproterozoic Group: Maree Loch The (2001). N. Connelly, & J., Tarney, G., high-grade Precambrian R. typical Park, a complex: Lewisian The (1987). J. Tarney, & G., R. Park, review. a model: terrane Lewisian The (2005). G. R. Park, B. J. T. Holland, & R., Powell, A., F. J. Diener, R., C. E. Green, W., R. White, M., metabasic R. of Palin, melting Partial (2016b). R. C. E. Green, & W., R. White, geological M., Quantifying R. Palin, (2016c). B. Dyck, & J., D. Waters, M., O. Weller, M., R. Palin, archaean an on point pressuretemperature High (1978). G. Yarwood, of & base J., the from M. gneisses O'Hara, archaean of excavation of history Thermal meta- (1977). lewisian early J. the M. in O'Hara, masses gneiss basic and ultrabasic peak Zoned of (1961). recovery J. formation, M. O'Hara, granulites: High-pressure (2003). J. Rotzler, & P., O'Brien, gesteinsberechnung. zur molekularnormen über (1936). P. Niggli, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article udcinaceincmlxi h eiino WScotland. NW of Lewisian the in complex subductionaccretion terrain? 105118. rocks. Geology intermediate Metamorphic and of basic Journal of melting partial and metamorphism High-grade (2016). modelling. equilibria 7390. the phase in from crust constraints (TTG) tonalitictrondhjemiticgranodioritic Archean: of generation the and rocks and interpretations. assessment tectonic Carlo for Monte implications a modelling; equilibria phase metamorphic in uncertainty garnet London for of consequences and barometry. anatexis, and crustal thermometry pyroxene by genesis magma implied geotherm, crust. continental the sutherland. scourie, at complex morphic tectonics. for implications and conditions Mitteilungen Petrographische und gische granulites of Finland. central melting in partial associations uid-controlled TTG-amphibolite and crust: continental Archean the of tiation elgclScey London Society, Geological , 288 441456. , ora fteGooia oit,London Society, Geological the of Journal , 34 , 871892. , 27 hlspia rnatoso h oa Society Royal the of Transactions Philosophical 1325. , , ora fPetrology of Journal esineFrontiers Geoscience 16 ora fMtmrhcGeology Metamorphic of Journal 295317. , ctihJunlo Geology of Journal Scottish ora fPetrology of Journal rcmra Research Precambrian cwieiceMineralo- Schweizerische , , 2 rcmra ResearchPrecambrian 7 , 248276. , 591607. , 134 185200. , , , 21 50 320. , 335. , , , 287 41 , , , oebr,C . ad,M .(05.Eprmna eomto fprilymle gran- melted partially of deformation Experimental (2005). R. M. Handy, & L., in C. depletion Rosenberg, LILE understanding to key Adaktiesthe (2005). J. Tarney, & R., gran- H. scourie Rollinson, the in barometry and thermometry Garnet-pyroxene (1981). R. H. Rollinson, of metamorphism during depletion elemental Selective (1980). F. B. Windley, & H., Rollinson, conti- lower Archaean of composition the on from constraints Geochemical evidence new (2012). granulites: H. Scourian Rollinson, the in sheets felsic of Origin (1994). H. Rollinson, Continent (2015). D. P. Clift, & S., Parman, J., M. Kranendonk, Van W., thermobarometry. M. On N. Roberts, (2008). B. J. T. Holland, & R., dataset Powell, thermodynamic consistent internally An (1988). B. J. T. Holland, & R., Powell, (1907). H. J. J. Teall, & W., L. Hinxman, T., C. Clough, W., Gunn, J., Horne, N., B. Peach, clinopy- + garnet orthopyroxene-free of signicance Petrogenetic (2003). M. R. D. Pattison, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article t eiie:ipiain o h otnna crust. continental the for implications revisited: ite granulites. scotland. nw ulites, 72 Scotland. NW Scourie, granulites, Archaean granulites. Lewisian the Letters in melting Partial crust: nental elements. earth rare Publications. Parman, Special S. London, Kranendonk, of (Eds.), Van Society Geological J. Clift 116). M. D. Roberts, P. W. & M. Shirey, N. S. In time. through formation Geology a and examples worked methods, program. Application, computer 3. correlations: and uncertainties with Scotland. of Highlands West U.K. North Survey Geological the of Structure Geological The facies. granulite plagioclase + roxene 105 257263. , 205226. , , , 351 26 Lithos 155179. , 112. , ora fMtmrhcGeology Metamorphic of Journal , 79 ora fMtmrhcGeology Metamorphic of Journal Lithos ± ctihJunlo Geology of Journal Scottish 6181. , . urzbaigmtbstswt epc oteapioieand amphibolite the to respect with metabasites quartz-bearing , 14 225238. , otnn omto hog Time Through Formation Continent otiuin oMnrlg n Petrology and Mineralogy to Contributions , , 30 21 121129. , ora fMtmrhcGeology Metamorphic of Journal , 2134. , 6 173204. , at n lntr Science Planetary and Earth ora fMetamorphic of Journal eor fthe of Memoirs Vl 8,pp. 389, (Vol. , , ht,R . oel .(00.Rtord etrsdeitrcinadteformation the and interaction meltresidue Retrograde (2010). R. Powell, & W., mineral R. facies granulite White, of preservation the and loss Melt (2002). and R. Powell, metamorphism & W., High-grade R. White, (2017). R. C. E. Green, & M., R. Palin, W., Complex: R. Lewisian The White, (2010). A. Beach, & R., H. crustal Rollinson, Archean G., and R. geochemistry Park, gneiss J., Lewisian Wheeler, (1981). J. Tarney, & L., B. Weaver, Loch the of history metamorphic pre-Torridonian The (1951). V. J. Watson, melting & open-system J., on Sutton, constraints equilibria Mineral (2018). Lewisian A. mainland F. the J. of Diener, & evolution T., Metamorphic Stuck, (1987). R. H. Rollinson, Archaean & of D., retrogression J. the Sills, during occurring NW changes of Mineralogical Scourian the (1983). from D. granulites J. ultramac Sills, of retrogression The (1982). D. J. Sills, dur- separation meltresiduum of rate the and melting Disequilibrium (1991). crust: W. lower E. the Sawyer, of petrogenesis and composition The (1987). R. S. Taylor, & L., R. Rudnick, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article 579597. migmatites. in leucosomes near-anhydrous of assemblages. complexes. gneiss Geology grey composite Archean in melting partial 335 evolution. crustal deep into insights models. development chronological the on bearing its and Lewisian. the Highlands of NW classication the in areas Scourie and Torridon compositions. metamac in complex. Scotland. NW of complex Lewisian the from gneisses Scotland. quebec. front, grenville 32 the from rocks mac of migmatization ing study. xenolith A 23 701738. , 1928. , 5179. , , 35 elgclScey odn pca Publications Special London, Society, Geological ieaoia Magazine Mineralogical 181195. , ora fMtmrhcGeology Metamorphic of Journal ora fGohsclResearch Geophysical of Journal at n lntr cec Letters Science Planetary and Earth ora fMtmrhcGeology Metamorphic of Journal ora fteGooia oit,London Society, Geological the of Journal , 46 5561. , elgclSceySeilPbiain London Publication, Special Society Geological , ora fMtmrhcGeology Metamorphic of Journal 20 621632. , , 92 Lithos 1398114005. , , , 27 55 , , 16 8192. , ora fMetamorphic of Journal 171180. , npress in 113124. , ora fPetrology of Journal . , 106 241308. , , 28 , , , h,Z . 'in,R . esa,N . ib .J 19) eiincutlhistory crustal Lewisian (1997). J. A. Gibb, & S., N. Belshaw, K., R. O'Nions, K., measure- Z. by Zhu, constrained composition crust Continental (1995). J. C. tectonics. Ammon, in & melting G., Zandt, open-system of Consequences (2015). M. Brown, & C., Yakymchuk, resi- crustal assigning of diculty the On (2010). S. I. A. Kemp, & J., M. Whitehouse, TiO of eect The (2000). A. B. Worley, & B., J. T. Holland, R., Powell, W., R. New White, (2014). R. C. E. Green, & E., T. Johnson, B., J. T. Holland, R., Powell, W., R. White, equilibria melting partial of Calculation (2001). B. J. T. Holland, & R., in Powell, W., formation R. melt White, Spatially-focussed (2004). A. J. Halpin, & R., Powell, assemblage W., metamorphic R. Prograde White, (2003). L. G. Clarke, & R., Powell, W., R. White, textures reaction of interpretation The (2002). L. G. Clarke, & R., Powell, W., R. White, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article rmi iuSM iea hooer n eae eaopi textures. metamorphic related and chronometry mineral SIMS situ in from ratio. Poisson's crustal of ments London Society, Geological the of Journal isotopes. Lu-Hf and Publications constraints U-Pb granulites: situ Lewisian in to combined ages from metamorphic and protolith magmatic dence, Fe K system the in calculations equilibria mineral Fe and metapelitic in calculations systems. thermodynamic for relations activity-composition mineral Geology Metamorphic of Na system the in 22 Australia. Hill, Broken from metapelites aluminous Australia. central migmatites Staord, pressures: Mt low from at rocks metasedimentary of melting partial during evolution K system TiO the constraints in Australia: calculations central equilibria Block, mineral Musgrave from the of granulites metapelitic Fe-rich in 2 825845. , O 2 Fe 3 . 2 O ora fMtmrhcGeology Metamorphic of Journal 2 3 ora fMtmrhcGeology Metamorphic of Journal O nmtpltcasmlgsa reshs n mhblt aisconditions: facies amphibolite and greenschist at assemblages metapelitic on 3 . , 335 ora fMtmrhcGeology Metamorphic of Journal 2 81101. , OCaOK , 19 2 139153. , OFeOMgOAl Nature ora fPetrology of Journal , , 374 , 18 , 171 32 497511. , 152154. , 2 261286. , 2 , O 2140. , OFeOMgOAl 20 3 SiO 4155. , elgclScey odn Special London, Society, Geological 2 ora fMtmrhcGeology Metamorphic of Journal OFeOMgOAl 2 H , 2 44 (NCKFMASH). O 19371960. , 2 O 3 SiO 2 O 2 3 H SiO 2 Chemical OTiO 2 Journal H 2 O 2  2 , iue S1S7 compositions. Figures rock bulk and numbers gure pseudosection S1 Table tab Supinfo.pdf information supporting the in article. online this found for be may Information Supporting Additional 7 in Polymetmamorphism (2012). T. Zack, & W., R. White, E., T. Johnson, A., Zirkler, This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article UPRIGINFORMATION SUPPORTING osrit rmteCo ntSdensuite. t'Sidhean 865885. an geochronological and Cnoc equilibria the phase from - constraints Scotland NW complex, Lewisian mainland the Geology ito h tde ape ihterrsetv apelctos oktypes, rock locations, sample respective their with samples studied the of List , 136 suoetoscluae o ahsml arfo ahlocation. each from pair sample each for calculated Pseudosections 205218. , ora fMtmrhcGeology Metamorphic of Journal , 30 , al 1: Table captions table and Tables This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article hs brvain r fe oln n oel(98,aogie`eT x o irontitanium for ox' `FeTi alongside (1998), Powell oxides. and study. Holland this after in discussed are samples abbreviations sixteen Phase the for information assemblage metamorphic and Locality 6S4Lc sytg p,p,q eT ox FeTi q, pl, opx, g, ox FeTi opx, ox pl, FeTi cpx, q, g, pl, Assynt opx, Loch cpx, 16AS04 Assynt Loch pl opx, cpx, Strathan g, 16AS02 ox FeTi Strathan pl, opx, 16ST03 cpx, g, ox ox FeTi FeTi pl, pl, ox opx, FeTi opx, 16ST02 cpx, q, cpx, Bay pl, g, Badcall opx, cpx, 16BA04 Bay Badcall Scourie ox 16BA02 FeTi pl, cpx, g, Scourie ox FeTi 16SC07 pl, hb, opx, cpx, ox FeTi pl, Strome 16SC03 cpx, Ben g, ox ox FeTi FeTi pl, hb, Strome 16BS05 cpx, pl, Ben g, cpx, g, ox FeTi hb, Drumbeg 16BS01 pl, cpx, g, Drumbeg 16DR07 pl hb, opx, cpx, Tarbet 16DR03 Tarbet 16TA08 pl hb, opx, 16TA07 cpx, Achiltibuie g, assemblage Observed 16AC04 Achiltibuie 16AC01 Locality Sample ± hb ± ± eT ox FeTi eT ox FeTi ± ± ± ± ± ± mt ± ± hb hb hb hb mt hb hb al 3: Table 2: Table This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article A4 16ST03 16ST02 16BA04 16BA02 16SC07 H 16SC03 Fig. Sample 16BA04 16BA02 16ST02 apeSatMelt Start Sample A4 xrse sFO soye,wihcmie ihFOvateeuto FO+O=Fe = O + 2FeO Fe equation bulk the to via equal FeO identically with is O combines bulk which hence, oxygen, FeO is oxide). O (mol.% FeO. construction as diagram expressed phase for used compositions Bulk-rock 4Jhsne l 18)i hw o reference. for shown is amphibolite (1987) Gairloch al. subsolidus et undepleted, Johnson for peak A4 of composition conditions bulk the constrain reported to The used was bracketsmetamorphism. that square composition in original Values the from respectively. dierence out, the carried show reintegration-steps of number the and mol.%) and kbar in rein- labelled melt column following The 16ST02 oxides). and (mol.% 16BA04, tegration 16BA02, samples of compositions bulk-rock Calculated . 3 7/545 23 .01.163 08 .329 .12.17 1.21 2.92 1.00 0.63 0.37 10.82 2.03 6.32 0.92 10.31 8.42 8.80 11.29 52.30 9.38 4.52 7.94 53.28 5 / 5.38 27 930 6 / / 8.8 39 920 / 8.8 . 7 75/647 42 .01.91.374 .523 .80.82 0.38 2.39 0.75 7.41 10.03 10.29 8.90 54.23 4.79 6 / 37.5 970 / 9.5 6cd 4d 4b 4a 4e 4c 4f - .55.184 07 00 03 .921 .108 0.16 0.82 0.21 0.91 0.24 1.15 2.15 0.71 1.11 0.41 0.19 0.51 1.64 2.68 0.25 10.38 2.25 1.49 0.19 1.27 10.05 0.24 0.06 2.86 10.87 0.34 10.74 0.47 1.60 0.16 12.57 9.25 1.39 8.46 2.00 0.80 13.38 0.61 12.98 13.25 50.61 0.23 0.95 9.13 12.88 5.65 3.22 7.67 10.29 0.20 50.23 9.06 12.22 0.38 0.14 14.18 13.40 50.97 9.03 11.14 8.15 0.66 15.04 49.99 7.82 13.32 7.99 0.92 50.15 8.70 11.53 2.46 45.67 9.67 0.31 55.15 1.92 ◦ 2 ,respectively. C, SiO O tot .55.184 07 00 03 .921 .10.82 0.91 2.15 0.19 10.38 10.05 10.74 8.46 50.61 5.65 - tp H Steps / 2 Al 2 O .231 .2.6.9.706 .2.0.7] 0.27 0.10 0.02 0.69 1.87 2.89 1.76 0.12 3.13 2.92 [ .023 02 19 13 21 .600 02 05 ] 0.51 0.28 0.06 0.46 2.16 1.35 1.91 0.23 2.31 3.60 [ .432 01 25 32 18 .901 01 02 ] 0.29 0.14 0.14 0.69 1.85 3.21 2.59 0.16 3.26 4.14 [ 3 2 Melt SiO O a g FeO MgO CaO tot 2 and Al 2 Steps 2 O O 3 3 Start hl rebl e sgvnb FeO by given is FeO bulk true while , a g e K FeO MgO CaO ietettlaon fml enertd(in reintegrated melt of amount total the give tot ie h trigpito etreintegration melt of point starting the gives K 2 Na O 2 TiO O 2 Na O 2 2 TiO O O tot 2 X sttliron total is tot Fe O 3+ 2  × 2 O O. 3 ; al 4: Table This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article cuuaino %o ata et opstosaegvna t oxide. wt% as the given after are event Compositions loss melt. melt 6% partial a of isobaric assuming 7% an conditions, of along open-system accumulation performed under were kbar Calculations 9.5 at 1987). melt- path prograde al., of et (Johnson metamorphism Gairloch amphibolite- A4, prograde undepleted, sample and facies during Strathan, 3), Table generated (cf. 16ST02 melt sample granulite-facies reintegrated, partial of compositions Calculated 4601.16.91.910 .100 .75.03 3.17 0.03 0.01 1.07 13.49 62.09 15.11 630 A4 5.05 3.23 0.02 0.00 1.00 13.48 61.96 15.26 625 16ST02* Sample 0011 98 26 .460 25 .84.47 0.08 5.69 22.54 0.15 6.02 14.05 3.24 4.02 12.65 3.00 49.86 14.42 1.13 55.60 1050 3.07 1000 5.26 0.38 5.72 18.05 0.78 6.31 11.13 2.82 3.53 13.50 2.92 52.24 15.10 1.44 57.64 1050 3.17 1000 4 .36.91.131 .658 .85.54 0.28 4.96 5.89 1.16 4.50 1.56 3.33 2.07 4.46 3.10 0.71 1.45 2.60 4.68 15.01 2.85 0.26 0.47 63.49 2.91 4.85 14.59 2.69 5.13 0.08 0.12 66.03 3.36 14.51 940 6.37 2.31 0.02 0.03 66.37 880 14.28 8.15 1.79 0.01 65.66 820 13.97 1.18 10.14 4.69 64.19 760 13.60 12.32 1.38 2.44 62.48 700 14.49 4.23 5.05 2.08 640 1.18 2.53 6.10 2.65 3.19 0.56 1.16 5.70 3.14 15.05 3.03 0.22 0.29 65.68 5.24 4.68 14.96 2.76 0.06 4.61 0.06 67.16 3.67 14.97 2.33 940 4.26 0.01 0.02 67.26 14.63 880 5.46 1.96 0.01 66.49 820 14.26 7.86 1.16 64.77 760 13.64 10.55 62.59 700 14.24 640 T H 2 SiO O 2 Al 2 O 3 a g e K FeO MgO CaO 2 Na O 2 O i.2: Fig. This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article 1: Fig. captions gure and Figures i.3: Fig. i.4: Fig. ae meitl bv tplf fpoorp)aditreit ecsm iheogtdprxnt ip eo bto ih fphoto- ultramac of right the (bottom Note below wisps pyroxenite Drumbeg. elongated with 16DR03, leucosome sample intermediate and in photograph) graph). porphyroblasts of left garnet (top large above immediately around layer coronae rocks. plagioclase-bearing metagabbroic and Lewisian Orthopyroxene- of features Outcrop-scale ecsm ihnmtgbr ape1B0,BdalBay. Badcall 16BA02, sample metagabbro within leucosome citbi A) oie fe ono ta.(03,adcnan rts elgclSurvey Geological British contains (ST), and Strathan (2013), (AS), Scourie al. Assynt (TA), et Loch Tarbet Johnson (DR), materials south: after Drumbeg representative to (BS), Modied north the Strome (AC). from of Ben Achiltibuie names locations (BA), Locality Bay sample Badcall the study. (SC), indicate this stars in Large emphasised southern and samples facies. northern the amphibolite while are central conditions The metamorphic regions facies geology. granulite surrounding younger of the rocks showing comprises also region complex Lewisian mainland the of Map antmnln pqepaei lgols-ihcrn nsml 16ST02. sample in hornblende. corona in oxides plagioclase-rich grained in ne phase of opaque proportion mantling high the Garnet hornblende Note subhedral with assemblage. together garnet-absent a plagioclase in and orthopyroxene without clinopyroxene, but of (a) grains to hedral similar very is mineralogy and Textures hornblende. Strathan. 16ST03, sample in semblage nsml 6C3 cui,gvnb hnqat l nepee ohv rsalsdi h space the in crystallised have to interpreted lm quartz thin a by given Scourie, 16SC03, sample Scourie. opaques. in 16SC07, and sample garnet in of hornblende intergrowths and symplectic garnet Note by mantled being (ilmenohematite) oxide FeTi garnet. around development clinopyroxene, symplectite orthopyroxene, orthopyroxeneplagioclase 120 garnet, showing of amphibole, comprised and Achilitibuie, plagioclase 16AC01, sample rocks. in metagabbroic Lewisian assemblage of features petrographic section-scale Thin onlnebaigasmlg ed r oordb e,bon n re ie,respectively. lines, green and and brown, orthopyroxene-bearing, red, garnet-bearing, by black of coloured thick are limits elds a The assemblage by respectively. hornblende-bearing indicated lines, are dashed contours thin mode and melt line and solidi The gcpxopxplilm. assemblage: gcpxopxhbpl assemblage: Peak Strathan. 16ST02, hb boxes. yellow cpxopxplqilm in gcpxopxplilm outlined assemblage: are Peak granulite-facies sample represent individual Scourie. to each interpreted elds in Assemblage assemblages mol.%. peak in given are Compositions text. Calculated (continued) boundaries. grain its on angles dihedral small forming phases, mac and plagioclase between (d) (c)

c in ape1B0,BdalBy ekasmlg:gcpxopxplilm assemblage: Peak Bay. Badcall 16BA04, Sample EC(2016). NERC - situ (c) eie yoeerc ecsm ngreieosmtgbr rmScourie. from metagabbro garnetiferous in leucosome pyroxene-rich derived yia ekasmlg nsml 6A4 acl a,cmrsdo u osub- to eu- of comprised Bay, Badcall 16BA04, sample in assemblage peak Typical ± hb P (c)  T suoetosfrtesxrpeettv ape icse ntemain the in discussed samples representative six the for pseudosections ape1B0,BdalBy ekasmlg:cpxopxplilm assemblage: Peak Bay. Badcall 16BA02, Sample i.4: Fig. ◦ ato overleaf caption rpejntosbtenpaicaeadprxn,and pyroxene, and plagioclase between triple-junctions (b) ape1S0,Sore ekassemblage: Peak Scourie. 16SC07, Sample (f) ± ergahceiec o ata melting partial for evidence Petrographic ilm (a) (f) antfru eaabosmls1T0 n 6A8 Tarbet. 16TA08, and 16TA07 samples metagabbro Garnetiferous ape1S0,Srta.Peak Strathan. 16ST03, Sample (b) (a) ersnaiepa as- peak Representative (a) ± ersnaiepeak Representative (e) ,hb q, ape16SC03, Sample ag risof grains Large (e) Sample (d) (d) ± lrm evdeaon netdfelsic injected around selvedge Ultramac (b) i.7: Fig. i.6: Fig. 6: Fig. i.5: Fig. This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved.

Accepted comparison for Data (2012). al. (2012). et al. Johnson et after Johnson Modied  complex. J12 Lewisian (1994); region Rollinson central  the R94 from sheets from: felsic of produced. proportions melts to the study to equivalents this lithological intrusive the considering (1994), Middlemost considering after (b) kbar, are 9.5 labels at and amphibolite boundaries Field Lewisian a compositions. and granulite Lewisian melt-reintegrated conditions. a in open-system form to predicted compositions melt Calculated Article enr nArdarmcmaigNgl omtv rprin Ngl,13)epce ofr ncytlie et icse in discussed melts crystallised in form to expected 1936) (Niggli, proportions normative Niggli comparing diagram AnAbOr Ternary etls uigmtmrhs.SeTbe3frbl opsto.Nt h togrsmlneto resemblance strong the Note 6a. composition. Fig. bulk and/or in melting for pseudosection partial 3 the Table experience not See did metamorphism. that during 1987), loss al., melt et (Johnson Complex Lewisian the of gion (lower) open-system and (upper) closed-system a both environment. in 16ST02*, sample of evolution prograde the (continued) 4e). (Fig. equivalent residual as- the dierent for distinctively calculated the those to Note topologies re-integration. eld melt semblage following 16ST02* sample for composition Calculated fec w ape rmSore(6C2ad1S0) acl a 1B0 n 6A4 and 16BA04) inferred and the inferred (16BA02 of of Bay range Compilation the Badcall showing 16SC07), 16ST03) and and (16SC02 (16ST02 Strathan Scourie from samples two each study. of this in emphasized samples of pseudosections Overlapping P (b)  (c) T oeo iga hwn rdce hs sebaecagsa . brduring kbar 9.5 at changes assemblage phase predicted showing diagram Modebox suoetosfrbl-okcmoiin o oie yml loss. melt by modied not compositions bulk-rock for pseudosections suoeto acltdfrapioiesml 4fo aroh otenre- southern Gairloch, from A4 sample amphibolite for calculated Pseudosection (a) oie oa laiv.slc TS iga hwn et rgesn rmgaii ointermediate/basic to granitic from progressing melts showing diagram (TAS) silica vs. alkali total Modied PT (d) agso h he oaiisepaie nti td ((a)(c)). study this in emphasised localities three the of ranges sfrpr b,btfrGilc mhblt A4. amphibolite Gairloch for but (b), part for As PT (a)(c) odtosfrec locality. each for conditions obndpseudosections Combined (a) Bulk (d) i.8: Fig. This article is protected by copyright. All rights reserved. This article is protected rights by All copyright. reserved. Accepted Article comparison. garnet-microstructures. from interpreted as depths, mid-crustal PT peak at after cooling closely by decompression followed isothermal is Near conditions respectively. 16AC01, garnet and retrograde/peak A4 and samples prograde of indicate stability lines red peak solid their and of Dashed interpretation the due assemblages. for here metamorphic uncertainties considered high not to are leading samples recrystallisation Assynt retrograde Loch strong to location. each of pairs sample the from constrained PT PT ahbsdo h nig fti td.Teclue ra lutaethe illustrate areas coloured The study. this of ndings the on based path ah fCrwih n anca 18)adJhsnadWie(01 r lte for plotted are (2011) White and Johnson and (1989) Barnicoat and Cartwright of paths iga umrsn h eut fpaeeulbimmdligadsoigaproposed a showing and modelling equilibrium phase of results the summarising diagram PT conditions This article is protected by copyright. All rights reserved. This article isprotected rights by All copyright. reserved. Accepted Article

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