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GLGY 209 > Lecture 11 > Flashcards

Lecture 11 Flashcards

1
Q

What is a rock?

A

Any naturally formed solid material composed of one or more minerals and having some degree of chemical and mineralogical consistency

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2
Q

What are Igneous rocks?

A

Rocks formed from the solidification of molten matter either at the surface or subsurface.

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3
Q

What are the 2 groups of igneous rocks?

A

Intrusive: magma cools and crystallizes within earths crust

Extrusive-Magma cools and crystallizes at earths surface

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4
Q

What is characteristic of intrusive rocks?

A

All minerals making it up are visible with the unaided eye. Light minerals form acidicly in the crust, dark minerals are basic and formed in oceanic crust

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5
Q

What is characteristic of extrusive rocks?

A

Lava that crystallizes incredibly fast (less than 1 week), can’t see each mineral with the unaided eye as they didn’t have time to form.

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6
Q

What are the 4 types of igneous rocks (recognized by crystal sizes)

A

Phaneritic, Aphanitic, Glassy, and Fragmental

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7
Q

What are phaneritic rocks?

A

Occurs in INTRUSIVE rocks only. Crystals can be seen with unaided eye, slow cooling process

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8
Q

What are aphaneritic rocks?

A

Have small sized crystals that can be seen by making a thin section and looking at it under a microscope-indicates fast cooling (extrusive)

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9
Q

What are Glassy rocks?

A

Came from oceanic eruptions. Molten material crystallized incredibly rapidly, no time for elements to arrange selvses into slid crystalline component-amorphous rock (but some do have crystals)

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10
Q

Why do some glassy rocks have crystals (2 Ideas)

A

Calcite crystals are YOUNGER and placed themselves on rock OR
Calcite crystals are OLDER and embedded themselves in rock

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11
Q

What are fragmental rocks?

A

Consist of pyroclastic material ejected as lava from a volcano which falls down at the Earths surface as partlly consolidated rocks. Mixed characteristics between igneous and sedimentary.

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12
Q

What are the different textures of phaneritic rocks?

A

Granular, Porphyllitic, Poikilitic.

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13
Q

What does the granular texture demonstrate?

A

Slow cooling process, crystals had time to grow (But not enough time to become Euhedral). All minerals have comparable sizes but are Anhedral

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14
Q

What does the Porphyritic texture demonstrate?

A

Large sized minerals, occuring in the mantle of crust. Some are truly euhedral or subhedral. Time to grow and develop

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15
Q

What are the 2 types of porphyritic texture?

A

Phenocrysts-Large sized, time to grow and develop

Ground mass- fast forming, looks black as the background

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16
Q

What are the 2 phases of the Poikilitic texture?

A

1) large number of minerals-magma turns them homogenous

2) Small minerals that were formed first are caught in the mass of the larger and become homogenous

17
Q

What are Plutons?

A

General term for body of intrusive rocks (igneous). Process of crystalization happens below ground.

18
Q

What is a batholith?

A

Crystallized magma chamber that reaches the surface (HUGE)

19
Q

What are stocks?

A

Also irregular structures that reached surface, but smaller than batholiths

20
Q

What does it mean that stocks and batholiths are discordant?

A

They pass through preexisting rocks

21
Q

What are the 2 most frequent intrusive igneous rocks?

A

Dike-fracture of igneous rocks cut through preexisting (discordant)
Sill- 2 rock boundaries are parallel, sill sits on top of other rocks (concordant). Sill is younger than rocks above and below

22
Q

What type of igneous rock is volcanic?

A

Extrusive

23
Q

What are basalts?

A

Volcanic igneous rocks-most frequent in the solar system

24
Q

What are the 2 types of volcanic rocks?

A

Lava flows and pyroclastic flows

25
Q

How are rocks formed in lava flows?

A

Solidification of lava

26
Q

What kind of rock is formed from lava flows?

A

Aphaneritic, glassy

27
Q

How are rocks formed in pyroclastic flows?

A

Boulders, rocks, and dust detaching from volcanic mountains-incredibly destructive

28
Q

What kind of rock is formed from pyroclastic flows?

A

Fragmental

29
Q

What type of basalt can be used to tell about the flow it came from?

A

Vesicular basalts-created through low viscosity lava flows, contain air of earths atmosphere at the time of the flow

30
Q

What are pillow basalts?

A

Formed from submarine volcanos-reaches surface at bottom of ocean. High pressure and low temperature creates a fast crystallization process.

31
Q

What is tuff?

A

Solidification of volcanic ash into a fragmented rock

32
Q

What are volcanic bombs?

A

Large sized rock fragments ejected during volcanic eruptions

GLGY 209 (22 decks)

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