Geology - Metamorphism Flashcards

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1
Q

Metamorphism

A

The process physical/chemical weathering of rocks with morphological changes.

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2
Q

What changes occur from metamorphism?

A

Chemical composition, mineraology and texture until temperature/pressure equilibrium reached.

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3
Q

Where does metamorphosis occur?

A

10-30km deep and surfaces.

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4
Q

Where is metamorphism primaritly?

A

mid-low crust due to heat and pressure by Earth interior.

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5
Q

Metamorphic Grade

A

Describes the temperature and pressure conditions where metamorphic rocks form

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6
Q

What does metamorphic grade increase with?

A

Pressure/Temperature

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7
Q

How does heat transform rock?

A

Breaking chemical bonds, recrystallising atoms and molecules when surface rocks transported to depths.

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8
Q

Geothermal Gradient

A

The rate of temperature change with increasing depth in Earths interior.

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9
Q

Types of pressure rocks experience…

A

Confined
Directed

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10
Q

Confined Pressure

A

This is applied equally in all directions, increasing with depth with overlyign mass.

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11
Q

Directed Pressure

A

Exerted in a particular direction, as in the convergence of lithospheric plates.

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12
Q

Hydrothermal fluids affect on metamorphosis…

A

Accelerate metamorphosis chemistry, dissolving soluble chemical substances like Na, K and CO2.

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13
Q

Types of metamorphism…

A

Regional
Contact
Seafloor
Shock

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14
Q

Hydrothermal Fluids

A

These are hot groundwaters circulating within Earths crust.

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15
Q

Regional Metamorphism

A

Occurs where there are high temepratures/pressure over large parts of the crust.

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16
Q

Contact Metamorphism

A

Where igneous intrusions metamorphose a rock immediately surrounding it.

17
Q

Seafloor Metamorphism

A

Is associated with mid-ocean ridges most often, hot basaltic lava spread heats sea water that infiltrates, with convection occuring through the new foreign crust.

18
Q

Shock Metamorphism

A

Collision of meteorites with Earth where energy transmits heat and shock waves to the rock, potentially producing tekties.

19
Q

Foliation

A

These form from directed pressure/temperature deforming igneous and sedimentary rocks.

20
Q

Lowest grade of foliation…

A

Slate

21
Q

Phyllites

A

Higher metamorphic grade than slate, glossier containing mica and chlorite, split in sheets

22
Q

Schist

A

Schiscosity derives from high temperatures and pressure subjected onto minerals, where they become more visible and segregate into lighter and darker bands.

23
Q

Gneiss

A

Have dark and light coloured bands from segregation of amphiboles and quartz/feldspar

24
Q

Migmatite

A

Mix of igneous and metamorphic rock resulting from partial metling of gneiss.

25
Q

Granoblastic

A

Rocks with coarse granular appearnace produced by recrystallisation in metamorphism

26
Q

Porphyroblasts

A

Large crystals having grown in a metamorphic rock

27
Q

Crystallisation

A

The process where a fluids atoms allign in chemical proportions/arrangements to form a solid substance.

28
Q

Example of a crystal…

A

Diamond of carbon tetrahedra bound together.