1. Intersecting Isograds at Whetstone Lake Dugald Carmichael (1970) Journal of Petrology, 11, 147-181. l Pelitic and calcareous rocks l Wide range of chemical compositions l Textures indicate 1 metamorphic episode l Lowest grade rocks in the area are already in the garnet zone

2. E. pluton is pre-met (has sl. phengite S 1 || regional S & across contact) Central pluton is syn-met metasediments metagabbro

3. Components = K 2 O-Al 2 O 3 -MgO-FeO-SiO 2 -H 2 O How many? 5 (H 2 O is mobile)  nice AKFM diagram (proj. from Q and Mu) Expect 5-phase assemblages (6 phases = univariant if eqm), but will see only 3 in projection Extra components: Phase-makers TiO 2 & P 2 O 5 can be ignored as add 1 component and only 1 phase (Il & Ap) Partitioners- instead of new phase will act as solute and make solid solutions

4. 5 reactions occur in the area: 1. Chl + Ms + Grt = St + Bt + Qtz + H 2 O 2. Chl + Ms + St + Qtz = Ky + Bt + H 2 O 3. Ky = Sill 4. St + Ms + Qtz = Sill + Grt + Bt + H 2 O 5. Bt + Cal + Qtz = Ca-amphibole + Kfs + CO 2 + H 2 O These can be documented texturally across each isograd

5. 1. Chl + Ms + Grt = St + Bt + Qtz + H 2 O  = 6, so univariant in KFMAS-H Below the isograd Above the isograd What isograd would you call this? What minerals appear and disappear? At A, B, C, D, E?

7. Within the "St-Bi" zone get a Continuous Reaction: Chl + Ms = St + Bt + Qtz + H 2 O  = 5 (divariant in KFMAS-H)

9. 2. Chl + Ms + St + Qtz = Ky + Bt + H 2 O  = 6, so univariant in KFMAS-H Below the isograd Above the isograd

10. 3. Ky = Sill Polymorphic transformation- univariant in Al 2 SiO 5 Polymorphic transformation- univariant in Al 2 SiO 5 Above the isograd

11. 4. St + Ms + Qtz = Sill + Grt + Bt + H 2 O  = 6, so univariant in KFMAS-H

12. 5. Bt + Cal + Qtz = Ca-amphibole + Kfs + CO 2 + H 2 O This reaction is not a pelitic one, but occurs in more calcic rocks