Supplementary Table 1. Compositional groups, typical sample numbers and location with their bulk compositional, mineralogical and petrographic characteristics at different metamorphic grades.
Sample #s, Mineral assemblage, Compositio N/E Traverse, Texture Metamorphic Bulk Chemical mode nal GPS and grade Characteristics and Group coordinates other comments mineral chemistry
Ms-Chl-Qtz-Ilm-Mag-Gr ± Kfs ± Pl
Mode: (Qtz 35-42%, Ms 30 - 33%, Chl 25 - 30%, Pl 5-7%).
#1/00, E, Lithology: Chlorite quartz phyllite (minor white 27 o11.268, mica), white mica quartz phyllite (minor chlorite) /88 o38.581 Two compositional and chlorite bearing quartzite. Millimeter to centimeter groups (one richer in scale banding into M- Al 2O3 ~25 wt.%, Muscovite: domain (mica + chlorite Chlorite Normal #187/01, another ~20 Wt.%). rich), grain size 2 - 20 m 187/3, Rocks richer in Paragonite 5%, Pyrophyllite 19%, Celadonite 12%, and Q - domain (quartz - 187/3/ CHAKRA Al 2O3 are relatively Fe-celadonite 13%. feldspar rich), grain size 10 , N, GPS not less ferruginous (see - 50 µm. known Fig 3). Chlorite:
XMg (Mg/(Mg+Fe(tot)) = 0.37 - 0.41.
Plagioclase:
XAn = 0.03
#ID/00,E, Ms-Chl-Qtz-Bt - Pl ± Ilm ± Tur ± Gr 27 o11.268, /88 o38.581 Chl - Qtz - Ms - Ilm -Gr - Tur - Bt - Pl
#2/00, E, Two subgroups - 27 o11.465, high Al, low Fe (18 o /88 38.650 - 24 wt% Al 2O3, - Mode: (Qtz 35-42%, Ms 30 - 33%, Bt 15 - 18%, Chl 4.5-5 wt% Fe 2O3) 10 - 12%, Pl 5-7%). Pervasive foliation defined #3/00, E, and low Al, high Fe by biotite, white mica, 27 o11.465, (14.5 - 17 wt% chlorite and occasional o /88 38.692 Al 2O3, 6.0 - 8.0 wt% Muscovite: ilmenite (S 2) almost parallel Fe 2O3). to compositional banding #4/00, E, Some with high Paragonite 10 -15%, Pyrophyllite 22 - 28%, (S 0). S 2 is crenulated to S 3 27 o11.484, MnO (0.37 - 0.59 Celadonite 6 -9%, Fe-celadonite 6-14%. defned by new generation Biotite Normal o /88 38.858 wt%). SiO 2 variable of biotite, ilmenite and indicating Biotite: elongated quartz in Q - #167/01, N, interbanding of domains. Some coarser o 27 26.092, variable amounts of XMg = 0.38, X Fe = 0.45, X Ti = 0.03, X (AlVi) = 0.14. biotite, chlorite as well as /88 o30.888 psammitic material, plagioclase cross cut all TiO 2 relatively Chlorite: foliations and appear to be #176/01,N, constant (0.55 - 0.8 post-tectonic. o 27 24.809, wt% for most XMg (Mg/(Mg+Fe(tot)) = 0.45. /88 o30.935 samples). Plag: #170/01,N, o 27 24.809, XAn = 0.03 /88 o30.925
Chlorite - quartz - plagioclase ± muscovite
Muscovite:
Paragonite 7 - 12%, Pyrophyllite 16 - 33%, #1/00/A, E, Celadonite 11 - 13%, Fe-celadonite 12%. Foliation defined by chlorite Magnesian 27 o11.268, and white mica; crenulation (Normal - /88 o38.581 MgO ~ 5 wt%. Chlorite: Biotite by second generation white biotite) mica. XMg (Mg/(Mg+Fe(tot)) = 0.65.
Plagioclase:
XAn = 0.1
Ms - Chl - Qtz - Pl - Grt - Mag - Ilm - Gr.
Garnet: Concentric growth zoned with Mn and Ca decreasing to rim compensated by increase of Fe and Mg.
Core: Sps 50 Alm 34 Prp 3Grs 13 150 - 200 µm euhedral garnet porphyroblasts set in Rim: external S 2 fabric defined Sps 20 Alm 63 Prp 07 Grs 10 by white mica. Elongate quartz and opaque Muscovite: inclusions near core of garnet define an internal Mn-rich # 1C/00/3, E MnO ~ 0.4 wt%, ~ Paragonite 14%, Pyrophyllite 15%, Celadonite 6%, fabric (? S ) at high angles (Normal + 27 o11.288, 10 x other bulk 1 Biotite Fe-celadonite 15%. to the external fabric. Grt) /88 o38.619 compositions. Coarse plagioclase as well Chlorite: as later generation of mica and chlorite cut across main XMg (Mg/(Mg+Fe(tot)) = 0.47; Mn-rich with 0.5 - foliation. Quartz is coarse, 0.6 wt% MnO (= 10x other rocks). polygonal in Q-domains and elongate in M-domains. Plagioclase porphyroblasts reverse zoned, unlike in other rocks, from An 26 (core) - An 10 (rim).
Ms - Qtz - Chl - Bt ± Pl - Ilm ± Grt ± Gr
Mode: (Qtz 26-30%, Ms 35-40%, Bt 8-15%, Chl 8%, Grt 1-3%, Pl 5-8%)
Garnet preferentially Garnet: Concentrically zoned, typical core: develops in graphitic Alm Prp Grs Sps , typical rim: 72 05 06 17 schists. S2 defined by Alm Prp Grs Sps . Total range found: Alm 81 05 04 10 68- Muscovite, chlorite and Prp Grs Sps . In rocks without plagioclase, #8/00, E, 80 4-16 6-16 2-17 biotite wrap around garnet garnet is more calcic: 27 o11.616, porphyroblasts. Marked Low alumina as well Alm Prp Grs Sps . /88 o39.131; 65-68 03 18-21 14 decrease in modal Normal as high alumina abundance of chlorite in compositions Biotite at contact with garnet: X = 0.28, X = #158/01, N, Mg Fe garnet rich areas. S often represented; some 0.47, X = 0.01, X = 0.24. 2 27 o27.711, Ti (AlVI) forms sigmoidal inclusion Mn rich and Mg rich /88 o31.400 trails in garnet, some Garnet bulk compositions Ilmenite included in garnet has higher Mn content garnets include an inner found without (= 5 mol% pyrophanite vs. 3mol% in matrix). trail of S that is straight profound effects on 1 and truncated by S . mineral assemblages Chlorite: XMg = 0.36 - 0.39, lower than in lower 2 #24/99/1, N, Aluminous, at these grades. grades. 27 o27.292´, Magnesian bulk high Fe /88 o31.63 compositions (e.g. #19/99) Muscovite: have lower modal
abundance of garnet Paragonite 11%, Pyrophyllite 21%, Celadonite 6%, compared to Fe-rich (e.g. Fe-celadonite 6%. #24/99) samples.
Plagioclase:
XAn = 0.1
Ms - Cld - Qtz - Chl - Bt - Ilm ± Gr ± Grt
Chloritoid porphyroblasts Mode: (Qtz 35-40%, Cld 12 - 16%, Grt 4-8%, Chl 8 Similar in Mn and may be aligned along S or #7/00/R4 - 16%, Ms 20 - 22%, Bt 8-10%, Pl 6-10%). 2 even lower in Al S foliation. Ilmenite is & 7/00/R/6, E, 3 content to garnet often included in chloritoid. 27 o11.616, Cld: bearing rocks from In one case chloritoid and Ferruginous /88 o39.131 the same outcrop garnet occur in the same (Normal + X = 0.1 Garnet (e.g. #8/00). Fe/Mg Mg thin section but in different Chltd) ratio - higher Fe domains - chloritoid occurs #135/01, E, Chlorite: contents - favor in more muscovite rich GPS not appearance of domains. There is a single known X = 0.25 chloritoid. Mg chloritoid inclusion in a
garnet in #135/01. Biotite: X Mg = 0.39, X Ti = 0.04, X (AlVI) = 0.18.
Chl - Qtz - Grt - Pl - Bt - Ap - Ilm
Garnet:
Alm 80 Prp 12 Grs 04 Sps 04 , even richer in almandine (82) Low at the rim. Chlorite - garnet - #10/00, E, Potassic plagioclase rich rock with 27 o11.628, (semi - Biotite: chlorite and biotite defining /88 o39.459; Garnet pelite) S foliation. Euhedral garnet 2 (Normal - X = 0.28, X = 0.55, X = 0.03, X = 0.14. overprints, and sometimes Mg Fe Ti (AlVI) Musc deflects, this foliation. Chlorite: XMg = 0.36.
Plagioclase:
XAn = 0.15 - 0.17. Ms - Qtz -St - Pl - Bt - Ilm - Grt Muscovite and biotite define foliation (S2). Mode: (Qtz 35 - 44%, Ms 15 - 17%, Bt 18 -22%, St Sigmoidal inclusion trails of 9 - 11%, Grt 5-10%, Pl 5 - 10%). S2, including ilmenites, within staurolite and garnet. Garnet: Foliation wraps around porphyroblasts. Core: Alm 63 Prp 12 Grs 08 Sps 17 , with well preserved growth zoning. Increase of Mn content at the very rim. #17/00, E, Equivalent of low Staurolite Normal 27 o12.064, alumina pelites from Muscovite: /88 o41.397 lower grades. Paragonite 17%, Pyrophyllite 12%, Celadonite 5%, Fe-celadonite 10%.
Biotite:
XMg = 0.4, X Fe = 0.42, X Ti = 0.02, X (AlVI) = 0.16.
Staurolite:
XFe = 0.78.
Ms -Bt -Grt -St - Ky - fibrolite -Grt - Ilm – Qtz ± Cld, secondary Chl. Some locations contain abundant and strongly zoned Tur.
Garnet:
Core: Alm 83 Prp 09 Grs 06 Sps 02 , distinctly poorer in Mn and only weakly zoned Muscovite and biotite (XAlm ~ Xprp ~ 0.02). define S 2, garnet and staurolite include sigmoidal Muscovite: trails of S 2, kyanite is coarse prismatic. Paragonite 18%, Celadonite 4.5%, Rare chloritoid inclusion in Fe-celadonite 7.5%. garnet coexisting with Aluminous staurolite. (Normal + #11/00, E, Staurolite Biotite: Tourmaline can define kyanite) folded inclusion trails in XMg = 0.34, X Fe = 0.45, X Ti = 0.05, X (AlVI) = 0.16. staurolite sometimes.
Plagioclase: Fibrolite often surrounds garnet, biotite with ilmenite, XAn = 0.2. can be folded into crenulations occasionally. Staurolite:
XFe = 0.82 - 0.86 (included chloritoid has X Fe = 0.85).
Ms - Bt - Qtz - Pl - Grt - Ilm
Garnet: Abundant garnet and Exceptionally rich in Sps and Grs in plagioclase; in spite of high CaO = 3.7 wt% Core: Al as well as Zn content, Calcic #14/00, E, compared to general Staurolite does not appear, (Normal - 27 o12.174, Staurolite range of 0.15 - 0.52 Alm Prp Grs Sps , indicating that its Staurolite) /88 o41.026 50 09 14 27 %. with well preserved growth zoning. appearance is controlled by Ca (e.g. Spear and others Plagioclase rich in An: 1995).
XAn = 0.34
Ms - Qtz -St - Pl - Bt - Ilm - Grt
Garnet: Core: Alm 73 Prp 05 Grs 13 Sps 09 ,
Rim: Alm 84 Prp 10 Grs 5.5 Sps 0.5 .
Muscovite: #15/00, E, Mn - poor 27 o12.157, Paragonite 17%, Pyrophyllite 12%, Celadonite 5%, (Normal, /88 o41.137 Fe-celadonite 10%.
Staurolite with Mn #16/00, E, poor garnet) 27 o12.100, Biotite: /88 o41.250 XMg = 0.4, X Fe = 0.42, X Ti = 0.02, X (AlVI) = 0.16.
Staurolite:
XFe = 0.85.
Plagioclase:
XAn = 0.2.
Ms - Qtz - St -Pl - Bt - Ilm.
Ms & Bt similar to normal pelite.
Fe-rich ? Staurolite, highly abundant: #129/87, GPS (Normal - Staurolite not available garnet) XFe = 0.83.
Plagioclase: XAn = 0.2 - 0.22.
Grt - Bt - Pl - Qtz - Ms ± St (only as included phase) - Ky - Ilm. Low Al, high Fe as #19/00, E, well as high Al, low Mode: (Qtz 42-45%, Ms 15-17%, Bt 12 - 20%, Ky Kyanite, muscovite and 27 o12.135, Fe groups are 4-8%, Grt 4-8%, Pl 10 - 15%). biotite define foliation (S ) /88 o41.778 2 represented. Bulk that is folded (S ) at places. 3 composition shows Garnet: Modal abundance of garnet #SIN8,N,GPS the widest spread in varies widely. Sigmoidal not available this zone. One Core: inclusion ridden garnet
exceptionally Mn Alm Prp Grs Sps , cores are overgrown by #27/99/1,N, 72 16 11 01 Normal rich (MnO = 1.1 euhedral garnet. Biotite- Kyanite 27 o30.906, wt%) sample was Rim: fibrolite mattes are locally /88 o33.981 found. Three Alm Prp Grs Sps . found. Rare staurolite 83 06 05 06 samples (#Sin8, inclusions in garnet. #27/99/3,N, 19/00/1, 18/00) Large variations, with nearly homogeneous grains to 27 o30.906, contain high CaO complexly zoned crystals, where internal S-shaped Modal abundance of kyanite /88 o33.981 (1.2 - 1.4 wt% compositional zoning bands follows inclusion trails, correlates with Al content,
compared to 0.4 -0.8 surrounded by an external concentric zoning . that of garnet with Fe
wt% for the rest). Overall range in garnet composition: content of bulk rock.
Alm 70-85 Prp 04-16 Grs 03-11 Sps 01-06 .
Muscovite: (Note low paragonite content)
Paragonite 9%, Pyrophyllite 3%, Celadonite 9%, Fe-celadonite 4%.
Biotite:
XMg = 0.5, X Fe = 0.4, X Ti = 0.05, X (AlVI) = 0.05.
Plagioclase:
XAn = 0.44.
Included Staurolite: Quartz - plagioclase bearing XFe = 0.73. leucosomes develop often with a biotite rich restite Qtz - Plag bearing leucosomes with garnet: part. In one case, euhedral garnets are found in the Garnet: leucosome (with different composition and zoning Concentric zoning, Mg increases from core to rim from the usual garnets), compensated by Fe; growth zoning of Mn partly when there are none in the preserved, sharp increase of Mn at rim. biotite rich restitic part. The plagioclase in this part is Alm 76-81 Prp 9-12 Grs 05-10 Sps 02-05 . also more sodic than usual.
Plagioclase: X An = 0.2.
Biotite in restitic part:
1.8 wt% TiO 2. XFe = 0.50 - 0.55, X Mg = 0.32 - 0.28, XTi = 0.03, X Al(VI) = 0.15 - 0.18.
Other than absence of garnet, similar to above. Widespread and occurs in close proximity with the Aluminous #19/00/1, E, Qtz - Ms - Bt - Pl - Ky - Ilm normal pelites. In (Normal - 27 o11.955, Kyanite compositional space a Grt) /88 o 41.514 Mineral chemistry similar to above. continuum is found, where the boundary has been drawn here based on appearance of garnet. Qtz - Pl - Ms -Bt - Grt - Ilm ± Ky ± St. Micas define foliation (S 2). #18/00, E, Unique texture with many 27 o11.955, Garnet: euhedral to subhedral /88 o 41.514 MnO highly garnets dotting the quartzo- Kyanite Mn - rich enriched, upto 1 Alm 57 Prp 13 Grs 08 Sps 17 . feldspathic as well as #18/00/2, E, wt%. micaceous layers giving the 27 o11.955, appearance of post-tectonic /88 o 41.514 growth.
Qtz -Bt - Ms - Sil ± Grt - Pl ± Ky - Ilm
Garnet: (Absent in high Al, Fe poor bulk compositions) Nearly homogeneous crystals, with prominent increase of Mn near rim. Sometimes compositional zones show sigmoidal patterns mimicking the inclusion pattern.
Typical Core: Segregation of leucocratic Alm 80 Prp 15 Grs 4.5 Sps 0.5 and more mafic layers, no modal abundances obtained. #20/00, E, Typical Rim: 27 o12.195, Alm 84 Prp 12 Grs 3Sps 01 . Prismatic sillimanite, rare Both low Al, high /88 o42.29; kyanite, and frequent Sillimanite Fe and high Fe, low Total spread: presence of fibrolite Normal Al groups - muscovite #29/99 & M4, Alm 76-84 Prp9-15 Grs 3-11 Sps 0-6. (replacing muscovite and represented. No Mn N, biotite). Muscovite, biotite rich samples found. 27 o31.757, Biotite: and sillimanite define main o /88 36.369 foliation (S 2). Garnet has XFe = 0.49, X Mg = 0.31, X Ti = 0.04, X (ALVI) = 0.16. inclusion ridden cores and inclusion free, idioblastic Muscovite: rims.
Paragonite 11%, Pyrophyllite 13%, Celadonite 8%, Fe-celadonite 7%.
Plagioclase: XAn = 0.16. Qtz - Bt - Kfs -Pl - Sil ± Grt - Ilm.
Garnet:
Alm 60-79 Prp 11-25 Grs 2-14 Sps 2-5.
Garnets preserve some growth zoning, with diffusion zoning at the rims. Many garnets have grown by coalesence from several nucleii (seen in element maps, e.g. Fig. 5d). Therefore, difficult and Migmatitic rock with not meaningful to provide geometric core and rim leucosomes (quartz - K- compositions. feldspar - minor plagioclase Both low Al, high - occasional small euhedral Sillimanite #29/00, E, Fe and high Fe, low Small, resorbed garnets from leucosomes are garnets) and mesosomes Normal 27 o12.695, Al groups exceptionally enriched in Mn: - K- (garnet - biotite - /88 o43.436 represented. No Mn Feldspar sillimanite). rich samples found. Alm Prp Grs Sps . 60 17 03 20
Biotite and sillimanite Biotite (adjacent or removed from garnet): define main foliation (S ). 2 XMg = 0.39, X Fe = 0.42, X Ti = 0.05, X AlVI = 0.14.
K-feldspar (sometimes pethitic, re-integrated):
Or 66-73 Ab 27-34 .
Plagioclase:
XAn = 0.24.