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40 Cards in this Set
- Front
- Back
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What are sedimentary rocks?
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Rocks formed from pre-existing rocks
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What are the two main types of sedimentary rocks?
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Clastic/Detrital and Chemical
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What are clastic sedimentary rocks?
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Pieces of pre-existing rock, classified based on size of particles.
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What are the three size groups of clastic rocks?
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1/256mm-1/16mm- mud (forms shale)
1/16-2mm- sand (sandstone) >2mm- pebbles, cobbles, and bolders (conglomerate, breccia) |
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What is sorting?
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Size of grains: poorly sorted= sand with gravel
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What is important to the formation of clastic rocks?
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Energy of the environment (wind, water*, gravity)
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Why do sand grains move to the ocean in winter in Maine?
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Nor'easters have more wind, which creates more energy and moves sand out.
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What are chemical sedimentary rocks?
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Rocks formed out of a solution.
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What are the two main classifications of chemical sedimentary rocks?
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Biochemical and non-biochemical
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What are 4 examples of biochemical sedimentary rocks?
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Limestone/dolostone, coquina, chalk, chert
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What are four examples of non-biochemical sedimentary rocks?
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Limestone/dolostone, chert, evaporites (rock salt) and cements (quartz)
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What is lithification? What are the two main types?
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It is a conversion of sediment to sedimentary rocks. The two main types are compaction ("squishing" the H2O out) and cementation (hardening by drying with heat)
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What are the four main sedimentary structures?
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Bedding, cross bands, mud cracks, and fossils.
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What is bedding?
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A sedimentary structure with layers in sedimentary rocks. They interrupt normal deposition and are flat-lying.
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What are cross bands?
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Sedimentary structures at the leading edge of a dune. They determine the direction of energy, or current.
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What is the "fate of the continents"?
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To end up in the ocean, because of sedimentary processes.
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What are three depositional sedimentary marine environments?
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Deep ocean, near shore, and shoreline
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What consists a deep ocean marine environment?
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Clay and organic material
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What consists a near shore marine environment?
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Offshore- mud
Nearshore- sand In between- coral reefs |
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What consists a shoreline marine environment?
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Pebbles, cobbles, mud, and sand
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What determines what is deposited?
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Energy in the environment
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What kind of deposits are in continental deposition?
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Ephemeral deposits
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What are EIGHT types of continental deposition?
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1. alluvial fans (mud and sand)
2. lakes 3. wind deposits 4. base of mountain (gravity, pebbles, cobbles, boulders, sand, mud) 5. rivers (sand & gravel) 6. glaciers 7. evaporites 8. coal deposits |
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What are the four parts to producing coal?
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1. warm, subtropical swamps
2. burial 3. increased heat and pressure (squeeze out water) 4. add heat |
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What is the path of coal?
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Organic material > peat > lignite coal > bituminous coal > anthracite coal > graphite (metamorphic)
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What causes bedding? What are the three changes?
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An interruption of the normal depositional sequence.
1. Grain size 2. composition 3. surface hardens |
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What is a metamorphic rock?
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A change in the texture or mineralogy of a rock IN THE SOLID STATE due to conditions different from those under which the original rock (protolith) formed. NO MELTING INVOLVED
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What are the three main agents of metamorphism?
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1. Heat (primary)
2. Pressure 3. Chemically active fluids |
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Describe the heat agent of metamorphism.
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Consists of geothermal gradient (apprx. 20 deg C/km, based upon radioactive decay) and igneous activity. The net effect of heat is new and larger minerals.
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Describe the pressure agent of metamorphism.
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Consists of burial or hydrostatic pressure (pressure is equal in all directions) or directed pressure (at convergent boundaries, foliated rocks i.e. slate)
SLATE FORMS VERTICALLY! |
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Describe the chemically active fluids agent of metamorphism.
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It is the only agent that changes composition of a rock.
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What are the six main types of metamorphism?
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1. Contact
2. Regional 3. Hydrothermal 4. Burial 5. Fault 6. Impact |
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Describe contact metamorphism.
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Heat only, no directed pressure.
Rocks are adjacent to igneous intrusion Small areas (wolf river batholith, granite) Band extends 10-100 ft |
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Describe regional metamorphism.
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Temperature and pressure are directed, convergent boundaries, produces foliated rocks. Very large area (100s-1000s of sq. mi)
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Describe hydrothermal metamorphism.
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Chemically active fluids. @ hot springs, mid-oceanic ridges
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Describe burial metamorphism.
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Low heat and non-directed pressure
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Describe fault metamorphism.
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Directed pressure only.
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Describe impact metamorphism.
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From meteorite impact. High pressure and temperature.
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What are the steps from mud to granite?
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Mud (sediment)
Shale (sedimentary) Slate (metamorphic, biotite new mineral) Phyllite (larger biotite) Schist Gneiss Granite Composition stays the same |
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What happens to a weathered phyllite?
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Becomes mud!
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