How can we help?

You can also find more resources in our Help Center.

32 terms

Geology Chp7

Chp7!
STUDY
PLAY
Sedimentary rocks
products of mechanical and chemical weathering
Sedimentary rocks are important for economic considerations because
they may contain
Coal
Petroleum and natural gas
Sources of Fe, Al, and Mn
Detrital sedimentary rocks
transported sediment as solid particles
Chemical sedimentary rocks
sediment that was once in solution
Organic sedimentary rocks
-Coal
detrital rocks include
Clay minerals
Quartz
Feldspars
Micas
Shale
Mud-sized particles in thin layers that are called laminae
Parallel alignment of grains
Barrier to flow of water
Low energy environments of deposition
Most common sedimentary rock--can be shales, mudstones, siltstones
Sandstone
Rock composed mainly of sand-sized particles
Forms in a variety of environments
Described by
Sorting
Particle shape
Composition
Predominant mineral = quartz
Conglomerate consists largely of
rounded gravels
Breccia is composed mainly of large
angular particles
Inorganic processes
evaporation, chemical activity
Organic processes
-life processes of water-dwelling organisms
Limestone
Most abundant chemical rock
Composed chiefly of the mineral calcite
Marine biochemical limestones form as coral reefs, coquina (broken shells), and chalk (microscopic organisms)
Inorganic limestones include travertine and oolitic limestone
Dolostone
Typically formed secondarily from limestone
Chert
Microcrystalline quartz
Varieties include flint, agate, and jasper
Evaporites
Evaporation triggers deposition of chemical precipitates
Coal
Different from other rocks because it is composed of organic material
1. Plant material
2. Peat
3. Lignite
4. Bituminous coal
Diagenesis
Chemical, physical, and biological changes that take place after sediments are deposited and lithified.
Occurs within the upper few kilometers of Earth's crust
Two major textures are used in the classification of sedimentary rocks
Clastic,Nonclastic
Clastic
Discrete fragments and particles
All detrital rocks have a clastic texture
Nonclastic
Pattern of interlocking crystals
May resemble an igneous rock
Types of Sedimentary Environments
Continental
Marine
Transitional
Marine Sedimentary Environments
Shallow ,Deep
Types of sedimentary structures
Graded beds
Ripple marks
Mud cracks
Fossils
A sedimentary facies is the sedimentary rock's ________.
environment of deposition
Which of the following sedimentary rocks would you expect to have originally been deposited by fast-moving streams?
conglomerate
Oolitic limestone is most likely to form in what type of depositional environment?
shallow, clear marine waters with vigorous current activity
If shale is such a common rock in the sedimentary rock world, why isn't it as prominently exposed at the surface as sandstone?
Shale crumbles easily, causing increased mechanical weathering, whereas sandstone resists weathering more effectively.
Which of the following is a feasible explanation as to why quartz sandstone is an excellent use of "uniformitarianism"
Layers of sand-size quartz-rich sediment found today at the beach are virtually identical to layers in a 10-million-year-old sandstone, thus suggesting the location of the sandstone was the location of a beach 10 million years ago.
Many limestones are ________.
biogenic
Which are sedimentary rocks?
Conglomerate and mudstone
How do you classify sedimentary rocks?
Texture and grain size