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Sedimentary Rocks
sedimentary
40
Geology
Undergraduate 1
11/12/2013

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Term
List key factors of sedimentary rocks.
Definition
-upper part of Earth's crust, cover 80% of Earth's suface, compacted fragments of rocks/minerals/shells, form at Earth's surface, contain historical geology, form through minerals precipitated from water
Term
What are the four classes of sedimentary rocks?
Definition
Clastic, biochemical, organic and chemical
Term
How do clastic sedimentary rocks form?
Definition
originate from weathering and erosion of preexisting rocks (clastic=broken)
Term
what do chem sed rocks originate from?
Definition
from chemical precipitation from water solutions
Term
what do organic sed rocks originate from?
Definition
decompostion of plant material
Term
What do biochemical sed rocks originate from?
Definition
shells
Term
The loose grains of sediment trabsform into clastic sedimentary rock by the process of what five steps? Give an example of a sedimentary clastic rock formed this way.
Definition
Weathering, erosion, deposition, lithification cementation. Ex. Sandstone is formed this way.
Term
What is weathering and erosion?
Definition
The physical processes that break up and corrode solid rock, eventually transforming it into sediment. Erosion is the actually the actual seperation of a rock that forms sediments (like falling, flowing through wind, gravity, or ice)
Term
What is physical and chemical weathering?
Definition
physical weathering is physically breaking down rocks into fragments without changing the chemical make-up of the minerals within it. Chemical weathering is a chemical change within some of the minerals within a rock
Term
Sediment travels by wind, water or ice, what is the process by which sediment settles out of the transporting settlement called?
Definition
deposition.
Term
What is lithification?
Definition
the transformation of loose sediment into solid rock
Term
Explain the process of lithification.
Definition
When the sediment has been buried, pressure caused by the weight of overlying material squeezes out water and air that had been trapped between clasts, and clasts compact together tightly. Then this compacted sediment may then bound together to make sedimentary rock by the process of cementation. (acting like glue to hold clast together)
Term
How can you classifly a clastic/detrial rock? 5
Definition
-clast size, composition, rounding/sorting, and cement
Term
What are types of clastic/detrital sed rocks?
Definition
Breccia, conglomerate, arkose, siltstone, shale
Term
Conglomerate clastic sed rocks are _____ fragments and breccia clastic sed rocks are ____ fragments. (think of shape) Both are course-grained
Definition
rounded, angular
Term
How are conglomerate sed rocks formed?
Definition
Through lithification of layers of river gravel sediments
Term
How do breccia sed rocks form?
Definition
through lithification of an accumulation of angular clast.
Term
medium grained sedimentary rocks include which 3? How are they formed?
Definition

Sandstone-through lithification of layers of beach or dune sand

Arkose-through lithification

Graywacke

 

Term
Fine grained clastic sedimentary rock is?
Definition
Siltstone
Term
Very fine-grained clastic sed rock includes? 3
Definition
claystone, shale (formed through lithification of layers of mud, mudstone
Term
What do biochemical sed rocks form from?
Definition
calcite, aragonite or silicate skeletons of organisms
Term
Biochemical sed rock, limestone is formed through the accumulation of compacted shells. What are types of limestones and what are they made of?
Definition

Fossiliferous limestone-identifyable shells

Micrite very fine carbonate mud

chalk-plankton shells

Coquina-all shell material

Chert-hidden crystalline quarts

Coal-the remains of plant material that died and accumulated on the floor of a forest or swamp

Term
List facts of the biochemical sed rock chert.
Definition
fine-grained, hard, consists of silica, deposition of the remains of siliceous marine organisms, diatomite and radiolarite
Term
Organic sed rocks include (2)
Definition
coal and oil shale
Term
Travertine, chemical sed rocks forms through? Where are examples?
Definition

preciptitaion of ground water in hot or cold water springs or on the surface on the walls of caves

ex. Timpanogos Cave, Utah and Mammoth Hot Springs, Yellowstone Park

Term
What are some types of chemical sed rocks?
Definition
travertine, oolites-small calcite spheres, dolomite, chert, evaportites (gypsum, rock salt)
Term
How are dolomite chem sed rocks formed?
Definition
replacement rection -mg-rich solution replaces part of the Ca in calcite
Term
How are chert chem sed rocks formed?
Definition
replacement reaction-petrifed wood forming into agate
Term
How do evaporites such as gypsum and rock salt (halite) form?
Definition
through evaporation of salt water
Term
What is formed at Death Valley, California
Definition
salt, which is a chemical sedimentary product
Term
What are sedimentary structures? When do they form? What can they help determine?
Definition

bedding and other structures visible in a sedimentary unit, form during or shortly after deposition (after transportation through wind water or ice)

transoport mechanisms, depositional environment, stratigraphy of a sedimentary sequence

Term
Bedding is a type of sedimentary structure. Explain its appearance and what it is caused by.
Definition
Visible layers within rock, horizontally. caused by change in grain size, change in composition and pause during deposition
Term
Describe the appearance of cross bedding, a structure of sedimentary.
Definition
layers at different angles cross each other
Term
Ripple marks, a structure of sed rocks can be described as what. Where can this be found?
Definition
small, no more than a few centimeters high, elongated ridges that form on a bed surface at right angles to the direction of current flow. Can be found on modern beaches and on ancient rocks.
Term
Describe graded beds.
Definition
vertical change in particle size, usually coarse grains at base and fine grains at top, form through turbidity currents
Term
What are the types of sedimentary structures? (4)
Definition
Bedding, cross-bedding, graded beds - turbidity currents, and ripple marks
Term
Describe turbidity currents.
Definition
Loose sediment mixed with water creating a murky cloud that is denser than clear water thus causing it to flow downslope
Term
Bed surface markings include? 3
Definition
mud cracks, scour marks, fossils
Term
what is depositional environment?
Definition
the conditions in which sediment was deposited
Term
What are the three types of depositional environmnets?
Definition
continental, shoreline, and marine
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