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Flashcards in Lab Rock Test Deck (50)
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1

Detrital Texture

Means sedimentary rock
Rock and mineral pieces (detritus) cemented by calcite, quartz or hematite.
“Weather-worn” appearance
Less sparkly than igneous and metamorphic rocks e.g. micas will sparkle

2

Interlocking Texture

Means Igneous Rocks

An igneous interlocking texture is polyminerallic.

Minerals have grown together like a jigsaw puzzle.
The cleavage planes of minerals reflect the light to make these rocks sparkly

3

Foliated Texture

Means metamorphic rock
Foliation means minerals have grown parallel to each other like layers.
Foliated textures are polyminerallic.
The cleavage planes of the minerals reflect the light making these rocks sparkle.

4

Three ways in which sedimentary rocks are formed:

Detrital
Chemical
Bioclastic

5

Detrital Sedimentary Rocks

Detrital rocks are derived from the land
Pieces of detritus mechanically or chemically weather from larger pieces
These pieces are transported by wind, water, ice or gravity.
The detritus is deposited and reworked in some sedimentary environment.
Burial and lithification of the sediments created a detrital sedimentary rock.

6

Well-Sorted Sedimentary Rocks

Grains are all the same size
Indicates a reworking of the materials and/or they have traveled from the source

7

Poorly Sorted Sedimentary Rocks

A range of grain sizes are in the rock
Means that the material is close to the source

8

Fine-Grained Sedimentary Rocks

Smooth to touch
Cannot see individual grains

9

Coarse Grained Sedimentary Rocks

Gritty to the touch
Can see the grains

10

Conglomerate

Sedimentary
Detrital
Poorly Sorted
Coarse Grained with round gravel
Made of quartz and rock clasts
Alluvial Fans, mt. rivers, rocky beaches,

11

Breccia

Sedimentary
Detrital
Poorly sorted
Coarse grained with angular gravel
Can be made of rock, mineral clasts, and chert

12

Sandstone

Sedimentary
Detrital
Well or poorly sorted
Coarse grained
Can be made with quartz, hematite, and feldspar
Can be layered
Alluvial fans, Mt. rivers, sandy beaches, desert, deltas

13

Shale

Sedimentary
Detrital
Well-sorted
Fine-grained
Made of quartz and clay minerals
Deltas, wet lake

14

Chemical Sedimentary Rocks

A chemical sedimentary rock is derived from water on or near the land (think shallow marine or lakes on land)
Detritus has chemically weathered down to ions in water solution.
Chemical sedimentary rocks form in two ways:
1. evaporites
2. precipitates

15

Chert

Sedimentary
Chemical
Precipitate
Made of quartz

16

Micritic Limestone

Sedimentary
Chemical / Bioclastic
Precipitate
Made of Calcite
Very smooth looking
Shallow, warm marine waters

17

Oolitic Limestone

Sedimentary
Chemical
Precipitate
Made of calcite
Bauble looking
Shallow, warm marine waters

18

Travertine (Limestone)

Sedimentary
Chemical
Precipitate
Precipitation of calcite rich groundwater
Look like stalagmites

19

Rock Gypsum

Sedimentary
Chemical
Evaporite
Wet/dry lake beds

20

Rock Salt

Sedimentary
Chemical
Evaporite
Wet/dry lake bed

21

Bioclastic Sedimentary Rocks

These are like detrital rocks but they have a “living” past.
Bioclastic rocks are derived from plant material or exoskeletons of marine organisms (limestones).
Detritus of plants or broken up shells are deposited in a water environment and later (with burial) are lithified to form a bioclastic rock.
Limestones are classified based on size of bioclasts.

22

Fossiliferous Limestone

Sedimentary
Bioclastic
Contains whole or large shells made of calcite
A reef or sandbar

23

Coquina

Sedimentary
Bioclastic
Limestone with coarse shell fragments made of calcite
A reef or sandbar

24

Chalk

Sedimentary
Bioclastic
Fine-grained limestone (finely broken shell parts)
Made of calcite
A reef or sandbar

25

Contact metamorphism

High temp.
Low pressure zones
Can occur along a subducting plate boundary where igneous intrusions occur

26

Magma

Molten rock beneath the Earth’s surface
Contains molten rock, steam and other gases, suspended crystals already formed, caved-in pieces of the chamber walls

27

Lava

Molten rock on the Earth's surface

28

Temperature of magma properties

Hot lavas are less viscous- increased T and decreased V
Cool lavas are more viscous- decrease T and increase V

29

Magma properties: Si/FeMg content

High silica content (more felsic) makes viscous lavas- high Si high V or low FeMg high V
Low silica content (more mafic) means less viscous lavas- low Si low V or High FeMg Low V

30

Igneous Processes

Igneous rock forms in 3 basic ways:
Extrusively
Intrusively
Pyroclasts