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Atoms to volcanoes - 33739 > Mock up of revision missed > Flashcards

Mock up of revision missed Flashcards

1
Q

What system is used to classify sedimentary rocks?

A

Wentworth size classes

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2
Q

What are the 3 main categories on the Wentworth size classification?

A

Gravel
Sand
Mud

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3
Q

On the Wentworth classification what is the description for gravel size? (largest to smallest)

A

Boulder
Cobble
Pebble
Granule

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4
Q

On the Wentworth classification what is the description for sand size? (largest to smallest)

A

Very coarse sand
Coarse sand
Medium sand
Fine sand
Very fine sand

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5
Q

On the Wentworth classification what is the description for mud size? (largest to smallest)

A

Silt
Clay

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6
Q

What is basal cleavage?

A

minerals with one cleavage

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7
Q

What is prismatic cleavage?

A

when the planes of breakage occur along 2 non parallel planes and are perpendicular (90*)

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8
Q

What is non-prismatic cleavage?

A

when the 2 cleavage directions are not perpendicular

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9
Q

How do cleavages in potassium feldspar intersect?

A

90*

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10
Q

How does the prismatic cleavage in hornblende intersect?

A

56* and 124*

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11
Q

What is cubic cleavage?

A

when 3 cleavages intersect at 90*

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12
Q

What terms can be used to describe singular crystals?

A

Acicular (needle like)
Columnar
Tuberose
Tabular
Equant (equal dimensions)
Bladed (long flattened blades)
platy
foliated (easy separated into sheets)

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13
Q

What terms can be used to describe aggregates?

A

Fibrous
Radiating
Dendritic (tree/ moss like)
Granular
Botryoidal
Massive (no distinct form)

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14
Q

what does botryoidal mean for aggregate description?

A

bubble like surface (AKA reniform)

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15
Q

What are the properties of quartz in thin section for PPL?

A

low relief
colourless

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16
Q

What are the properties of quartz in thin section for XPL?

A

Birefringence first order greys up to first order yellow
Extinction might be sweeping

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17
Q

What are the properties of muscovite (mica) in thin section for PPL?

A

Colourless
Moderate relief
perfect cleavage

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18
Q

What are the properties of muscovite (mica) in thin section for XPL?

A

High birefringence (3rd order)

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19
Q

What are the properties of chlorite in thin section for PPL?

A

green and pleochroic
moderate relief

20
Q

What are the properties of chlorite in thin section for XPL?

A

1st order birefringence
anomalous interference colours

21
Q

What are the properties of plagioclase in thin section for PPL?

A

Colourless
non-pleochroic
low relief

22
Q

What are the properties of chlorite in thin section for XPL?

A

1st order greys
polysynthetic twinning (multiple parallel twins)

23
Q

What are the properties of microcline in thin section for PPL?

A

Colourless
Non pleochroic
low relief

24
Q

What are the properties of microcline in thin section for XPL?

A

1st order greys
cross hatched twinning

25
Q

What are the properties of calcite in thin section for PPL?

A

Colourless (May exhibit pale pastels)
Low to moderate relief

26
Q

What are the properties of calcite in thin section for XPL?

A

Extremely high birefringence (may look pastel)
Polysynthetic “calcite” twinning in coarse grain- fine grain may be colour swirl

27
Q

How much silica will be basalt and rhyolite?

A

Basalt <50% SiO2 (low silica)
Rhyolitic 75% SiO2 (silica rich)

28
Q

How is olivine best recognised?

A

High relief
Shape = sub-equant and sub rounded
Cleavage - none but curved fracture
Birefringence - high
Alteration- common on fractures

29
Q

How does the pleochroism change for biotite?

A

brown pleochroism (pale yellow brown to dark brown)

30
Q

What is quartz made of?

A

SiO2 (silicon dioxide)

31
Q

What are 2 types of plagioclase feldspar?

A

Albite (NaAlSi3O8)
Anorthite (CaAl2Si2O8)

32
Q

What are 2 examples of alkali feldspars?

A

Orthoclase - (KAlSi3O8
Albite - (NaAlSi3O8)

33
Q

What type of zoning can occur in plagioclase feldspar?

A

Oscillatory zoning due to growth ring variation of CA and Na compositions)

34
Q

How will plagioclase appear in hands specimen?

A

white blocky grains

35
Q

How will plagioclase composition change between mafic and granite?

A

Mafic = Ca rich
Granite= Na rich

36
Q

How will plagioclase feldspar grains appear in volcanic rocks?

A

lath-shaped

37
Q

What is the real name for white and dark mica?

A

White = muscovite
Dark= biotite

38
Q

What will acidic evolved magmas be like?

A

75wt% silica
Relatively rich in Si, Na and K

39
Q

What are plutonic rocks?

A

ones formed from a large magma body which take a long time to lose heat

40
Q

What will plutonic rocks generally be like?

A

granular texture due to large interlocking crystals

41
Q

What type of volcanic rock will form from slow cooling from a magmatic body like a batholith?

A

Gabbro

42
Q

What type of volcanic rock will form from fast cooling from lava or effusive process

A

basalt

43
Q

What process starts metamorphism with temperature range?

A

diagenesis at around 100-150*

44
Q

What leads to an end of metamorphism in terms of temp and process?

A

anatexis at ~900*

45
Q

What is a typical product of diagenesis?

A

Zeolites

46
Q

What is associated with low pressure high temp metamorphism?

A

contact or regional metamorphism associate with volcanism and plutonism

47
Q

What is high pressure low temperature metamorphism linked to?

A

Regional metamorphism in rapidly subsiding areas of subduction zone

Atoms to volcanoes - 33739 (16 decks)

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