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Metamorphism & Metamorphic Rocks. The rock that forms depends on: How do Metamorphic rocks form?

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Presentation on theme: "Metamorphism & Metamorphic Rocks. The rock that forms depends on: How do Metamorphic rocks form?"— Presentation transcript:

1 Metamorphism & Metamorphic Rocks

2 The rock that forms depends on: How do Metamorphic rocks form?

3 Why Should You Study Metamorphic Rocks? What are the 3 Agents of Metamorphism?

4 Heat ___________ the rate of chemical reactions. Sources of Heat: How does TIME affect transformations?

5 Lithostatic 

6 Differential __________:

7

8 Types of Metamorphism

9 Regional Metamorphism

10 Contact Metamorphism Alteration occurs because:

11 Aureole  Width determined by:

12 Index Minerals

13 Mylonites  Dynamic / Cataclastic Metamorphism

14 How Are Metamorphic Rocks Classified? Two Groups foliation 

15 Foliated Meta. Rocks Rock Typical Meta. Features Parent Name Minerals Grade of Rock Rock Name Minerals Grade of Rock Rock Slate clays, micas, low fine-grained, shale, chlorite splits uniformly vol. ash chlorite splits uniformly vol. ash Phyllite quartz, micas, low-med fine-gr, glossy shale chlorite “crinkled” chlorite “crinkled” Schist micas, chlorite, med-high distinct foliation shale, talc, garnet visible carbonates, hbl basalt/gabbro Gneiss qtz, feldspar, high light & dark shale, hbl, micas bands sandstone, basalt/gabbro felsic ign. Amphibolite hbl med-high dark, weak fol. basalt/gabbro Migmatite qtz, feldspar, very granite streaks felsic ign. & hbl, mica high in gneiss sed. mixed

16 SLATE (very fine-grained, foliated) formed by ____________, ___________ metamorphism used for

17 PHYLLITE (fine-grained, foliated) glossy sheen coarser-gr. than slate “crinkled” appearance

18 SCHIST (medium-grained, foliated) platy/elongate minerals _________________________ metamorphism Schistose foliation 

19 GNEISS (medium-grained, foliated) ______________ ________________________ metamorphism Light bands  granular minerals. (______________________) Dark bands  platy/elongate min. (______________________)

20 AMPHIBOLITE  (med-gr, foliated) hornblende & plagioclase (___________________ regional meta.) MIGMATITES (mixed rocks) _________________________ metamorphism High-grade meta. rx intermix w/ streaks of granite. Georgian Bay, Ontario, Canada

21 Nonfoliated Metamorphic Rocks

22 Nonfoliated Meta. Rocks Rock Typical Meta. Features Parent Name Minerals Grade of Rock Rock Marble calcite, low-high interlocking limestone, dolomite grains dolostone Quartzite quartz med-high interlocking quartz grains, hard sandstone Greenstone chlorite, epidote, low-high fine-grained mafic ign. hornblende green color Hornfels micas, garnet, low-med fine-grained, mudrocks quartz hard, dense Anthracite carbon high black, lustrous, coal subconchoidal fracture

23 Marble ________________________________ metamorphism Parent Rock = How is Marble used? metamorphism C

24 QUARTZITE _____________________________________ metamorphism Parent Rock = ________________________ Hard & compact w/ uniform strength [breaks across grains rather than around them] used in __________________________________________ metamorphism

25 Greenstone  ( ____________________ meta ) Parent rock = ________________________ (green color from chlorite, epidote, & hornblende) Hornfels  ( __________________________ meta ) Parent rock = __________________________ equidimensional grains Anthracite  Parent rock = ___________________________

26 Isograd  What Are Metamorphic Zones?

27 Does Metamorphism Relate to Plate Tectonics? Low-temp/high-press  _______ part of subducting plate High-temp./high-press  _______ part of subducting plate High-temp/low-press  _________ meta. follows

28 Natural Resources Minerals used: talc  graphite  garnet  kyanite  asbestos  {Chrysotile  silky fibers 95% of all asbestos used in the U.S.} {Crocidolite  long, straight fibers This variety presents a health risk. EPA policies treat all asbestos the same.} Chrysotile

29 Ore Deposits Ore Mineral Formula Uses Copper Bornite Cu 5 FeS 4 transportation, communications Iron Hematite Fe 2 O 3 steel manufacturing Magnetite Fe 3 O 4 Lead Galena PbS batteries, pipes, solder Tin Cassiterite SnO 2 plating, solder, alloys Tungsten Scheelite CaWO 4 metal hardening, Wolframite (Fe,Mn)WO 4 carbide manufacturing Zinc Sphalerite (Zn,Fe)S batteries, brass making, galvanizing iron (hydrothermal contact meta.)


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