Term
| Detrital Sedimentary Rocks |
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Definition
Nonorganic, solid particles put through both mechanical and chemical weathering. Clay minerals and quartz are the chief constituents of most detrital rocks. 85% of all sedimentary rocks. chemical resistant. Composed of minerals with slow rates of chemical weathering, or the products of chemical weathering. Composition varies with weathering intensity or length of transport.
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Term
| Chemical Sedimentary Rocks |
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Definition
| When ions in solution are precipitated by either inorganic or biological processes, the material is known as chemical sediment, and it makes these rocks. |
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Term
| Organic Sedimentary Rocks |
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Definition
| Coal is a prime example; when carbonic plant matter is cemented left over from swamps. |
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Term
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Definition
| variety of minerals and rock fragments. |
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Term
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Definition
| Store solar energy and provide a look into the past. |
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Term
| Depositional Environments |
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Definition
| from Glaciers, rivers, dunes are created from wind, shores, both from ocean and river |
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Term
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Definition
| making sedimentary rocks through compaction and cementation |
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Term
| Common cementation elements |
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Definition
- silica (SiO3)
- calcium carbonate (CaCO3)
- iron oxide (Fe2O3-H2O)
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Term
| Compaction relative to clay |
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Definition
| Clays may be compact up to 40% |
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Term
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Definition
| all low-temperature chemical changes that happen under the surface |
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Term
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Definition
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Term
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Definition
- Quartz sandstone-mostly quartz
- arkose sandstone- angular grains, feldspars and rock fragments
- graywacke-dirty sandstone, has quartz, feldspar, clays
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Term
| Difference between breccia and conglomerate? |
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Definition
| conglomerate uses rounded grain, breccia-angular |
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Term
| Siltstone, mudstone, shale |
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Definition
- Siltstone-mostly silt
- Mudstone- silt and clay, not shale-like layers
- Shale- red means oxygen present
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Term
| Precipitation sequence from seawater: |
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Definition
1) Calcite (CaCO3)
2) Gypsum (CaSO4·2H2O)
3) Halite (NaCl) |
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Term
| Chemical Sedimentary Rocks |
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Definition
Biochemical sedimentary rocks = biogenic
precipitates
» biogenic = originates from life
Limestone - mostly calcite; often composed
of biogenic grains which may recrystallize
» Typically deposited where there is little or no
clastic sediment
» Can vary from of fossil-free to fossiliferous |
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Term
| Cementation differences between chemical rocks |
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Definition
| coquina-badly cemented, chalk is good |
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Term
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Definition
–Formed by trapping of sediment by algae
*Evidence for shallow water
–Some of the earliest fossils |
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Term
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Definition
- biogenic buildup; carbonate secreting organisms; marine
–Evidence for shallow water |
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Term
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Definition
SiO2, micro- or cryptocrystalline
»Remains of silica-secreting microorganisms living in ocean (diatoms, radiolaria)
»Also forms from silica precipitation in pores after burial |
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Term
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Definition
asymmetrical-waves go 1 way
oscillatory-goes both ways |
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Term
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Definition
grain size decreases upward
»Caused by slowing of current |
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Term
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Definition
| burrows, footprints, root traces |
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Term
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Definition
| major parts of shields and mountain belts |
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Term
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Definition
| Process whereby preexisting rock undergoes pronounced changes in texture and mineralogy at T > 200-300ºC while in the solid state |
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Term
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Definition
| heat, pressure, chemically active fluids, heat gets greater as you go down |
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Term
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Definition
Increased ductility
– Change in mineral
assemblage |
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Term
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Definition
Confining pressure - felt
equally in all directions
» Differential stress - added
pressure from tectonic activity
(tension, compression, shear) |
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Term
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Definition
Favors minerals with
dense, compact crystal
structures
» Minerals grow
perpendicular to
maximum pressure
– Produces a parallel
arrangement of platy
minerals called
foliation
– Gives rock layered or
banded appearance |
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Term
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Definition
| shallow crustal rocks are metamorphosed by increasing T. |
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Term
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Definition
| sediments are metamorphosed by increasing P and T |
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Term
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Definition
| sedimentary strata are meta-morphosed by moderately increasing P and T |
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Term
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Definition
| Hydrothermal fluids (hot water); important for ion transport |
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Term
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Definition
»Rock or slaty cleavage - parallel alignment of microscopic platy minerals
»Schistosity - parallel alignment of visible platy minerals |
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Term
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Definition
| banded; layers of light and dark minerals |
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Term
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Definition
Lineation - parallel alignment of needle-like grains
Porphyroblastic - larger crystals (porphyroblasts) in a finer matrix |
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Definition
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Term
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Definition
| Supplies ions/atoms; can alter composition inherited from protolith |
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Term
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Definition
very fine grained, clay rich
»Slaty cleavage
»Bedding often present
»Metamorphic grade: low |
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Term
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Definition
Cleavage surface has sheen
»Mica and/or chlorite grains
Figure 8.14
AN07_004. |
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Term
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Definition
50% visible platy minerals; may have layers or qtz and/or feldspar
»Bedding rare
»Grade: medium to high
»Rock name based on predominant mineral
–Ex: muscovite schist (clay |
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Term
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Definition
Fine to coarsely crystalline calcite
»Parent: limestone or dolomite |
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Term
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Definition
| Metamorphosed qtz sandstone; almost all qtz |
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Term
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Definition
| Metamorphosed conglomerate - breaks through pebbles |
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Term
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Definition
»Contains glaucophane (amphibole)
»High pressure, relatively low temperature |
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Term
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Definition
| pyx, garnet; high P, moderate T |
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Term
| three types of metamorphism |
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Definition
»Contact - associated with plutonism; small scale
»Cataclastic - occurs within fault; very small scale
»Regional - associated with mountain-building; large scale |
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Term
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Definition
| zone of metamorphosed rock around pluton; non-foliated |
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Term
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Definition
| unique rock formed from metamorphism of protolith of silicate and carbonate (limestone or dolomite) rocks |
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Term
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Definition
| broken and crushed rock in fault |
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Term
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Definition
| hard, fine-grained rock formed from grinding within fault |
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