Metamorphic Rocks Francis, 2014

1. Metamorphic RocksFrancis, 2014

2. Metamorphic Minerals AFM projection for Metapelites andalusite sillimanite kyanite paragonite NaAl2(AlSi3O10(OH)2 muscovite KAl2(AlSi3O10(OH)2 pyrophyllite Al2Si4O10(OH)2 andalusite Al2SiO5 or Al2OSiO4 kyanite Al2SiO5 or Al2OSiO4 sillimanite Al2SiO5 or Al2OSiO4 staurolite (Fe,Mg)2Al9O6(SiO4)4(O,OH)2 chloritoid (Fe,Mg)2Al4O2(SiO4)2(OH)4 cordierite (Fe,Mg)2Al3(Al,Si5)O18.nH2O garnet (Fe,Mg)3Al2(SiO4)3 chlorite (Mg,Fe)3(Al,Si3)O10(OH)2(Mg,Fe)3(OH)6 biotite KFe3(AlSi3O10(OH)2 zoisite - epidote Ca2(Fe,Al)3O(SiO4)(Si2O7)(OH) tremolite/ actinolite Ca2(FeMg)5Si8O22(OH)2 staurolite

3. Andalusite Cordierite / Pyrox Garnet /Biotite Chlorite Kyanite Sillimanite Staurolite ActinoliteHornblende Muscovite K-Spar

4. Metamorphic Facies : A metamorphic facies is the set of mineral assemblages that are stable over a given range of P and T. The actual mineral assemblage within this set that a given rock exhibits is a function of its chemical composition. The delineation of the metamorphic facies commonly used today is a matter of historical development that predates actual experimental determination of pressures and temperatures. The division of the P-T metamorphic regime into the following metamorphic facies developed from field observations on the persistence of certain mineral assemblages for specific bulk compositions in geographic and thus P-T space: Zeolite - zeolites or clay minerals, calcite and/or quartz-filled amygdules Greenschist - green minerals: chlorite, actinolite, epidote Blueschist - blue amphibole, aragonite Amphibolite - dark amphibole (hornblende), garnet Granulite - absence of hydrous minerals and thus schistoscity, granular Eclogite - pyropic garnet & jadeiitic clinopyroxene – high pressure

5. Slate vs Shale Harder and cleavage at an angle to bedding bedding bedding Extremely fine-grained rock exhibiting a perfect planar cleavage defined by the alignment of sub-microscopic phyllosilicates grains. Distinguished from shale by its greater hardness and the fact that cleavage is generally at an angle to bedding. bedding

6. Phylites to Schists micaceous foliation with sheen or visible mica xyls cordierite muscovite schist garnet muscovite schist

7. Schists

8. garnet staurolite schist kyanite staurolite schist andalusite sillimanite Metapelites in the Amphibolite Facies kyanite No amphiboles because of the lack of Ca

9. amphibolites basaltic bulk compositions garnet Hornblende Plag Typically characterized amphibole-defined lineation, rather than mica-defined foliation

10. Amphibolites Hornblende garnet Plag

11. Gneissosity: Compositional layering produced by metamorphic (solid-state) segregation into alternating felsic (leucosomes) and mafic (melanosomes) layers. Gneiss

12. Gneiss

13. Feldspar is granular rather than lath-like. garnet-orthopyroxene-cordierite granulite garnet sillimanite gneiss granulite andalusite sillimanite kyanite

14. partial melting migmatites and diatextites

15. diatexite, Hortavaer Complex, Norway partial melting migmatites and diatextites

16. Metamorphosed Carbonates • marble: crystalline metamorphosed limestone. • skarn: calcium-rich contact-metasomatic rock – contains abundant • calc-silicate minerals ± carbonate formed at the contacts • between magmatic intrusions and dirty carbonate rocks. Diopide CaMgSi2O6 Grossularite Ca3Al2(SiO4)3 Calcite CaCO3 Gross

17. High-pressure rock of basaltic composition dominated by pyropic garnet (Mg3Al2(SiO4)3) and jadeitic (NaAlSi2O6) clinopyroxene  kyanite (never sillimaniteassociated, with of diamonds. More mafic compositions of with similar mineralogy are termed garnet clinopyroxenites. Eclogite andalusite sillimanite kyanite

18. Mylonite / Tectonite Extremely fine-grained rock exhibiting fine parallel gneissic banding over extensive strike lengths, produced by extreme strain. Typically possess a pronounced mineral lineation parallel to the transport direction, commonly have rotated porphyroblasts

19. Metapelites AFM Projections Shales are typically depleted in Ca and Na because they were lost to solution during the breakdown of tecto-, ino-, and orthosilicates to clay minerals during weathering. Furthermore, quartz and muscovite are typically ubiquitous phases in metapelites. As a result, we can project the compositions of metapelites into a simplified ternary system (end-members: Al2O3* (A), FeO (F), and MgO (M)), assuming that quartz and muscovite are always present. Components = 6: K2O, Al2O3, SiO2, FeO, MgO, H2O With excess quartz & water: C = 4 and F = 4 - P + 2 If muscovite is present, we can project the mineral assemblages onto the Al2O3 – FeO – MgO plane, where: C = 3 and F = 3 - P + 2 thus F = 0 for P = 3, if Press & Temp are fixed

21. Metapelite Minerals: quartz, muscovite, and : andalusite Al2SiO5 or Al2OSiO4 kyanite Al2SiO5 or Al2OSiO4 sillimanite Al2SiO5 or Al2OSiO4 pyrophyllite Al2Si4O10(OH)2 paragonite NaAl2(Al,Si3)O10(OH)2 muscovite KAl2(Al,Si3)O10(OH)2 staurolite (Fe,Mg)2Al9O6(SiO4)4(O,OH)2 chloritoid (Fe,Mg)2Al4O2(SiO4)2(OH)4 cordierite (Fe,Mg)2Al3(Al,Si5)O18.nH2O garnet (Fe,Mg)3Al2(SiO4)3 chlorite (Mg,Fe)3(Al,Si3)O10(OH)2(Mg,Fe)3(OH)6 biotite K(Mg,Fe)3(Al,Si3)O10(OH)2 K-feldspar KAlSi3O8

22. F = C - P

23. F = C - P