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Test II
Chp 6, 7,15,16
88
Geology
Undergraduate 1
05/05/2009

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Term
Detrital, chemical, and organic
Definition
The three categories of sedimentary rock
Term
Sedimentary rocks derived from both chemical and mechanical weathering.
Definition
Detrital Sedimentary Rock
Term
soluble material produced by chemical weathering, are precipitated by either inorganic or biologic processes
Definition
Chemical sedimentary rocks
Term
Sedimentary rock that consists of plant and animal material compacted.
Definition
Organic Sedimentary rock
Term
Main constituents of detrital rock
Definition
Clay and quartz
Term
Why would mica and feldspar be found in sedimentary rock?
Definition
erosion and deposition was fast enough that it preserved some of the primary minerals from the source rock.
Term
Sedimentary rock that consists of silt and clay size particles, account for half of sedimentary rocks, tiny grains indicate that the resulted from gradual setteling from calm sources like swamp, lake, floodplains, or deep ocean basin
Definition
Shale
Term
Thin layers of silt and shale
Definition
lamine
Term
property of shale that seperates it from other fine grained sedimentary rocks like like mudstone or siltstone:  the ability to split into thin lyers along well developed, closely spaced planes
Definition
fissility
Term
accounts for about 20% of sedimentary rocks, consists of sand sized sediments, form in a variety of environments
Definition
sandstone
Term
The degree of similarity in particle size in sedimentary rock
Definition
Sorting
Term
Consists of sphericity and angularity 
Definition
Particle shape
Term
The minerals that sandstone is made of 
Definition
composition
Term
Three ways to derive the way sandstone was formed
Definition
Sorting, particle shpae, composition
Term
Sandstone that contains more than 25% of feldspar
Definition
arkose
Term
Along with quartz and feldspar this dark-colored rock contains abundant rock fragments and matrix
Definition
graywacke
Term
refers to the silt and clay size particles found in spaces between larger sand grains
Definition
Matrix
Term
Poorly sorted, sedimentary rock that consists of gravels. Rounded
Definition
Conglomerate
Term
gravels that are angular rather than rounded
Definition
breccia
Term
life processes of water-dwelling organisms that form chemical sediments
Definition
biochemical origin
Term
about 10% of sedimentary rocks, the most abundant chemically formed, chiefly composed of calcite, and formed from inorganic or biochemical processes
Definition
Limestone
Term
closely related to limestone, instead of calicite it contains calcium-magnesium carbonate
Definition
dolostone
Term
compact hard rocks made of microcrystalline quartz, one well known forms are flint and jasper
Definition
Chert
Term
gypsim and halite (rock salt) are deposited through this process
Definition
evaporation
Term
Deposits that remain after water enters the atmosphere
Definition
evaporites
Term
The most abundant organic sedimentary rock
Definition
coal
Term
the collective term for all of the chemical, physical, and biological changes that take place after sediments are deposited and during and after lithification
Definition
diagenesis
Term
the process by which sediments are transformed into solid sedimentary rocks
Definition
lithification
Term
the most common physical diagenetic change, as sediment accumulates, the weight of overlying material compresses the deeper sediments
Definition
compaction
Term
the most important process by which sediments are converted to sedimentary rock,  a diagenetic change that involves the crystallization of minerals among individual sediment grains.
Definition
cementation
Term
The most common cements
Definition
calcite, silica, and iron oxide
Term
Sed. Rocks that consist of discrete fragments and particles that are cemented and compacted together have this texture.  Includes all detrital rocks
Definition
clastic
Term
sed. rocks that consist of minerals forming a pattern of interlocking crystalline structure
Definition
nonelastic or crystalline texture
Term
the nature of the place where the grains in a sed rock eventually came to rest
Definition
environment of deposition
Term
the layers of sed. rocks
Definition
strata or beds
Term
flat surfaces between beds along which sed. rocks tend to break
Definition
bedding planes
Term
when beds of sed rock are inclined to the horizontal
Definition
cross bedding
Term
the rock from which a metamorphic rock was formed
Definition
parent rock
Term
means to change form 
Definition
metamorphism
Term
Two ways that heat metamorphs rocks
Definition

1. Promotes recrystalization of individual mineral grains, fine particles tend to oalesce into larger grains of the same mineralogy

2. May rise the temperature of a rock to the point where one or more, of the minerals are no longer chemically stable.  Consituent ions arrange themselves into crystalline structures that are more stable in the new high-energy environment.

Term
refers to the increasing temperature with depth of the earths interior
Definition
geothermal gradient
Term
When surface rocks are changed by magma
Definition
contact metamorphism
Term
increased pressure from depth causes spaces between mineral grains close
Definition
confining pressure
Term
rocks subjected to direct pressure,  usually at convergent plate boundaries
Definition
differential stress
Term
The change in composition caused by interaction with fluids
Definition
metasomatism
Term
term used to describe the size, shape, and arrangement of grains within a rock
Definition
preferred orientation
Term
any planar arrangement of mineral grains or structural features within a rock
Definition
foliation
Term
Three ways that foliation can occur
Definition

1. Rotation of platy and /or elongated mineral grains into a new orientation

2. recrystalization of minerals to form new grains growing in the direction of preferred orientation

3. Changing the shape of equidimensional grains into elongated shapes that are aligned in a preferred orientation

Term
closely spaced planar surfaces along which rocks split into thin tabular slabs when hit with a hammer
Definition
rock cleavage
Term
slates display this form of excellent splitting
Definition
slaty cleavage
Term
when under high temperature and pressure mica and chlorite grains in slate grow to a point they can be discernible with the naked eye and exhibit a planar sturcture
Definition
schistosity
Term
during high grade metamorphism ion migrations result in the segragaion of minerals, giving the rock a banded appearance.
Definition
gneissic texture
Term
meta rocks that do not exhibit a foliated texture
Definition
nonfoliated
Term
a common meta texture that consists of particularly large grains
Definition
porphyroblastic textures
Term
marble is foliated or non foliated
Definition
nonfoliated
Term
five foliated meta rocks
Definition
Slate, Phyllite, schist, gneiss, migmatite (in order of metamorphism and foliation
Term
two most common non-foliated rocks
Definition
marble and quartzite
Term
hot ion rich fluids circulate through fissures and cracks that develop in rock, the alteration that occurs is called
Definition
hydrothermal metamorphism
Term
very thick accumulations of sedimentary strata in a subsiding basin causes low grade metamorphic conditions for the deepest layers
Definition
burial metamorphism
Term
rocks and sediments carried to great depths along convergent boundries, differential stresses play a major role in deforming rock as it is metamorphosed
Definition
subduction zone metamorphism
Term
The way most metamorphic rocks are produced, dynamic events  where large segments of Earth's crust are intensely deformed along convergent plate boundaries
Definition
regional metamorphism
Term
coccurs when high speed projectiles such as meteorites strike the earths surface
Definition
impact metamorphism
Term
rocks with chlorite (usually slate) have what grade of metamorphism
Definition
low
Term
rocks with sillimanite are considered what grade of metamorphism
Definition
high
Term
rocks that form from the highest grade of metamorphism
Definition
migmatites
Term
Idea theorized by Alfred Wegener that the  continents  were moving
Definition
continental drift
Term
the supercontinent
Definition
pangaea
Term
three theories that were made to explain plant and animal similarities on different continents 
Definition
island stepping stones, land bridges, and rafting
Term
upermost part of the mantle ,  a strong rigid layer
Definition
lithosophere
Term
parts of the mantle that move
Definition
lithospheric plates
Term
weak region of the mantle directly below the lithosphere,  nearly melted rock that allows the lithosphere to move
Definition
asthenosphere
Term
where two plates move apart resulting in upwelling of material from the mantle to create new seafloor
Definition
divergent boundaries
Term
where two plates move together resulting in oceanic lithosphere dexcending beneath an overriding plate, could create mountains
Definition
Convergent boundaries
Term
where two plates grind past each other without the production or destruction of lithosphere
Definition
transform fault boundries
Term
most divergent boundaries are located where
Definition
along the crests fo oceanic ridges
Term
the mechanism that operates along the oceanic ridge system to create new seafloor
Definition
oceanic spreading
Term
when divergent plate boundaries develop within a continent, forming two or more smaller segments
Definition
continental rift
Term
convergent plate margins occur when two plates move towards each other and one is bent downward, allowing it to slide beneath the other causes
Definition
deep ocean trench
Term
convergent boundries are also called______ because they are sites where lithosphere is descending into the mantle
Definition
subduction zones
Term
mountains that are caused in part because associated with the subduction of oceanic lithosphere
Definition
continental volcanic arcs
Term
Prominent linear breaks in the oceanic crust are known as 
Definition
fracture zones
Term
discovered in 1965 by Tuzo Wilson, plates that slide past each other without production or destruction of lithosphere
Definition
transform faults
Term
This is located under Hawaii
Definition
Mantle plume
Term
the surface manifestation of mantle plumes
Definition
Hot spots
Term
the point at which magnetic material lose their magnatism
Definition
Curie point
Term
rocks that formed thousands or millions of years ago and hold a record of the direction of the magnetic poles
Definition
fossil magnetism, or paleomagnetism
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