Exam 2 Flashcards
diaganesis
the physical and chemical changes caused by pressure, heat and chemical reactions
clastic sediments
formed from the result of physical and chemical weathering of preexisting rocks
siliciclastic sediments
formed from sediments from clastic sediments
biological sediments
result of mineral precipitation by organisms
bioclastic sediments
formed from broken shells
how are most sediments transported?
air and water
strong currents
carry gravel (boulders, cobbles, and pebbles).
moderately strong currents
carry sand
most common
weak currents
carry mud composed of the finest particles
subsidence
a broad area of the crust sinks
sedimentary basins
thick accumulations of sediments and sedimentary rock
rift basins
deep, narrow, and long with thick succession of sedimentary and igneous rocks
how does a rift basin form?
when plates separate, the thin lithosphere between the two plates fills with hot mantle
thermal subsidence basins
develops in the later stages of plate separation
when lithosphere that was thinned and heated becomes cooler and more dense
continental shelf
a broad, flat, submerged platform with a thick layer of shallow-water sediment
from shoreline to the edge of the continental slope
flexural basins
at a convergent boundary where one lithospheric pushes over the other and causes the lower one to bend and flew
sedimentary environments
continental shoreline marine siliciclastic chemical
continental sedimentary environments (4)
lake environments
alluvial environments
desert environments
glacial environments
lake environments
fresh or saline water
transport agent: small waves and currents
alluvial environments
a river and its floodplain
shoreline sedimentary environments (3)
deltas
tidal flats
beaches
marine sedimentary environments (4)
continental shelf environments
organic reef environments
continental margin and slope environments
deep-sea environments
terrigenous environments
sediment eroded from the land surface
cross-bedding
beds deposited by wind or water with degrees up to 35
graded bedding
bedding where the large particles are at the bottom and smaller particles are at the top
ripples
very small ridges of sand
bioturbation
when organisms like clams or worms dig vertically through sand and mud
lithification
hardening of soft sediment into rock
conglomerate
lithified gravel
What mineral would you find at a site with heavily weathered materials?
quartz
what mineral would you find at a site near rapidly eroding granitic and metamorphic zones where physical weathering is more common?
arkoses (25% feldspar)
what is shale composed of?
silt and a significant amount of clay
what rock is formed from lithified carbonate sediments?
limestone
what rock is the dominant biological sedimentary rock?
limestone
what is dolostone composed of?
dolomite (calcium-magnesium carbonate)
what is chert composed of?
silica
at what depth are metamorphic rocks formed?
10-30km
at what rate does Earth’s temp decrease with depth?
30 degrees Celsius per km
geothermal gradient
the increase in temperature with increasing depth
confining pressure
a general force applied equally in all directoins
directed pressure
a force exerted in a articular direction
metasomatism
the change in a rock’s composition by fluid transport of chemical substances
what are 6 types of metamorphism?
shock regional high-pressure contact burial seafloor
regional metamorphism
high temperatures and high pressures imposed over large parts of the crust
contact metamorphism
the heat from igneous intrusion metamorphoses the rock
seafloor metamorphism
a form of metasomatism, where lava heats the seawater which drives chemical reactions
burial metamorphism
the progressive increase in pressure as more layers are on top of the rock
shock metamorphism
when a meteorite collides with Earth
foliation
a set of flat or wavy parallel cleavage planes
slates
very fined grained and lowest grade
phyllite
slightly higher grade than slates
schist
intermediate-grade rock
most abundant metamorphic rock
gneiss
lightly-colored with coarse bands of light and dark minerals throughout the rock
migmatite
mixture of igneous and metamorphic rock
granoblastic rock
grow in the shape of cubes and spheres
hnornfels
high-tempurature contact metamorphic rock of uniform grain size that has undergone little to no deformation
examples of granoblastic rock
hornfels quartzite marble granulite amphibiolite
examples of foliated rocks
slate
schist
gneiss
exhumed
transported back to Earth’s surface
P-T path
history of a metamorphic rock
strike
the compass direction of a rock layer
dip
amount of tilting of a rock measured at right angles
strike-slip fault
movement or rocks next to each other is horizontal
thrust fault
low-angled reverse fault
anticline
upside down u
syncline
U-shape
principle of original horizonality
sediments are deposited as horizontal beds
principle of superposition
each layer of rock is younger than the one beneath it
stratigraphic succession
chronologically ordered set of strata
principle of faunal succession
sedimentary strata in an outcrop contain fossils in a definite sequence
isotopic dating
the use of naturally occurring radioactive elements to determine the ages of rocks
ductile
undergoes smooth and continuous deformation without fracturing
brittle
undergoes little deformation until it breaks suddenly
nebular hypothesis
the origin of the solar system can be traced to a cloud of rotating gases and fine dust
solar nebula
a disk of gases and dust
When did the big bang take place
about 13.7 billion years ago
key features of venus
hell-like
atmosphere is mostly carbon dioxide
covered by 85% lava flows
mountainous
key features of mercury
thin atmosphere made up of helium
very hot during the day and very cold at night
