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Metamorphic Rocks.

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Presentation on theme: "Metamorphic Rocks."— Presentation transcript:

1 Metamorphic Rocks

2 Rock Cycle


4 Objectives 14 – Describe the types of changes associated with metamorphic rocks. 15 – Contrast regional and contact metamorphism.

5 Metamorphic Rocks Pre-existing rocks changed by heat and pressure

6 Different Types of Changes
Compaction Grains move closer. Rock becomes more dense. Porosity reduced. Example: clay to shale to slate Recrystallization- Growth of new crystals. No changes in overall chemistry. New crystals grow from the minerals already present Foliation Minerals separate into bands New minerals form from heat and pressure

7 Types of Metamorphism: Contact
Contact (thermal) Small scale Associated with igneous intrusions

8 Types: Regional Metamorphism
Regional (dynamic) Large scale Associated with mountain building

9 Foliated vs. Non-foliated
Foliated – has bands or layers Non-foliated - No banding Form from rocks made up of single minerals

10 Rank The degree of metamorphism required to change a rock


12 Quartzite Non-foliated Visible minerals grains Low-high metamorphisis
Parent - Sandstone

13 Marble Non-foliated Usually visible grains – granular
Will effervesce in HCl Calcite Parent - Limestone

14 Anthracite Non-foliated Black color Metamorphosed Coal Peat→Lignite→
Bituminous coal→ Anthracite

15 Slate Foliated Small grain size Low metamorphism Visible layering
A metamorphosed shale

16 Phylite Foliated Small-visible grains Low-medium metamorphism Sheen
Crenulations- slight wavy appearance A metamorphosed slate

17 Schist Foliatied Visible grain size Medium metamorphism
Biotite, Garnet A metamorphosed phylite Basalt may change into schist

18 Gneiss Foliated Large visible grains High degree of metamorphism
Definite banding and recrystallization Horneblende, Quartz Metamorphosed schist


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