Rocks Flashcards
How did igneous rocks form?
from the crystallization of molten material melted from the mantle and crust (mostly mantle)
intrusive igneous rocks vs extrusive igneous rocks
aka
intrusive formed from the crystallization of magma in earth
extrusive formed from the crystallization of lava at the surface of the earth
volcanic rocks and plutonic rocks
Slow cooling
Fast cooling
instant cooling
few but large crystals
more but small crystals
won’t form crystals, randomly distributed atoms, volcanic glass (ash)
What minerals are igneous rocks mostly composed of?
silicate (dark and light)
what is the most distinguishing feature of most igneous rocks?
the interlocking arrangement of their mineral crystals
What rocks are part of the light silicate group? comp
muscovite, feldspar, quartz
high in silica
what rocks are part of the dark silicate group? comp
olivine, pyroxene, amphibole, biotite
high in mg and fe
texture
size, shape, and arrangement of mineral grains
composition
abundance and type of minerals it contains
how are igneous rocks identified
texture and composition
list all the textures pls
glassy, coarse-grained (phaneritic), fine-grained (aphanitic), vesicular, porphyritic, pyroclastic (fragmental)
fine grained texture (aphanitic)
formed at a place where cooling is rapid (at surface- extrusive igneous rock) or in upper crust
crystals are too small to see w/ naked eye
coarse-grained texture (phaneritic)
magma crystallizes at depth (intrusive igneous rocks) that have intergrown crystals of equal size that can be seen
vesicular texture
what part of the lava flow
extrusive rock w/ voids (vesicles) from escaping gas bubbles as lava soldified
upper, where cooling is rapid to preserve it
Porphyritic texture
cooling in two different environments:
minerals in magma crystallizes (cools first) before others - phenocrysts (large crystals)
eruption or movement to cooler location, rest of lava will cool faster - small crystals (matrix, groundmass)
Glassy
instant cooling (molten rock ejected from eruption and solidifies in air)
pyroclastic (fragmental) texture
consolidation of fragmentss ejected from eruptions (ash, molten blobs, angular blocks from vent walls)
description of the env where coarse grained igneous rocks form
when molten rock solidifies (at great depth or on the surface), it cools (rapidly or slowly) and produces an (extrusive or intrusive) igneous rock
great depth
slowly
intrusive
description of the env where fine grained igneous rocks form
when molten rock solidifies (at great depth or on the surface), it cools (rapidly or slowly) and produces an (extrusive or intrusive) igneous rock
on the surface
rapidly
extrusive
granitic/felsic
do they have dark colored silicates
composition and melt.temp
color
dominent minerals
only 15%
high in silica, potassium, and sodium
lowest melt. temp
light
quartz and potassium feldspar (light colored silicates)
feldspar crystals vs quartz crystals
rectangular,flat
rounded/irregular, glassy
Mafic/basaltic
composition and melt.temp
color
dominent minerals
45-85% olivine and pyroxene (dark colored silicates)
high in iron, mg, and calcium
higher melt. temp
darker
pyroxene and plagioclase feldspar
direction of melt temp and elements
increasing melt temp from grantitic to andesitic to mafic to ultramafic
increasing mg, iron, and calcium from grantitic to andesitic to mafic to ultramafic
increasing potassium and sodium from ultramafic to mafic to andesitic to granitic
intermediate/andesitic
melt.temp
dominent mineral
composition btw granitic and basaltic
light colored silicates and dark colored silicates (15-45%)
higher than granitic
amphibole, plagioclase feldspar
ultramafic
temp
comp
dominent minerals
almost all dark silicates
highest melt temp
high in iron, mg, and calcium
olivine and pyroxene
Granite
coarse-grained
granitic/felsic
(intrusive)
obsidian
glassy
granitic/felsic
conchoidal
only black granitic/felsic rock
rhyolite
extrusive equivalent of granite
fine-grained
granitic/felsic
pink to gray
can have glass fragments or voids
pumice
vesicular
frothy and floats in water
granitic/felsic
(extrusive)
gray
diorite
ixtrusive equivalent of andesite
coarse-grained
salt n pepper
andesitic/intermediate
basalt
basaltic/mafic
fine-grained
extrusive
dark green, brown, black
andesite
andesitic/intermediate
fine grained
extrusive
can be porphyritic (crystals of feldspar or hornsblende
gabbro
intrusive equivalent of basalt
coarse-grained
basaltic/mafic
periodite
ultramafic
coarse grained
scoria
red rock like pumice
vesicular
basaltic/mafic
did pumice and obsididan cool from the same material but at differnt rates
yes, granitic/felsic but dif textures
if somethinting cool at a loww temp, does tha mean it will cool first or last
last
what are the sources of materials that accumulate as sediment
- solid particles from weathered rocks (detritus)
- precipitation of dissolved material in solution
what are detrital rocks?
mineral grains or rock fragments from chemical and mechanical weathering that are transported and deposited as solid particles
what is the residual product of feldspars? what happens to the si? residual product of quartz?
clay minerals
carried away by ground water
quartz is resistant to chem.weathering
residual product of amphibole and olivine
what are the most abundant solid particles of chemical weathering?
quartz (resistant to weathering) and clay minerals (residual product of feldspars)
On what feature of detrital sedimentary rocks is their classification based on?
particle size
what are the four categories of particle size
coarse, medium, fine, very fine
what is more fine: silt or clay
clay
Breccia
angular fragments
coarse
gravel
Angular vs round fragments indicate
angular: didn’t travel far
rounded: traveled far
Siltstone
fine
silt
dusty
breaks into blocks/layer
quartz and clay
conglomerate
coarse
gravel
round fragments
Quartz sandstone
well sorted, sand, medium, rounded
can scratch galss (quarts)
shale
clay/mud
very fine
splits into layers
fossils
can be scratched by iron nail
arkose
medium
sand
poorly sorted
angular fragments
calystone
mostly clay
clay/mud
very fine
crumbles easily
can be scratched by iiron nail
graywacke
medium
sand
sand and mud
poorly sorted
what are the two textures of fsedimentary rocks and defintion
clastic: discrete particles cemented tog
nonclastic: crystalline
chemical and biochemical sedimentary rocks
chemicaol: precipitated from ophysical process such as evaportion and temp change
biochemical: life processes/animals that forrm shells called biochemical sediments
compositions of all limestone
calcite fizzz
examples of biochemical sedimentary rock
coquina, chalk, fossiliferous limestone
chalk
biochemicala from the hard skeletons of microscopic organism
fossileiferous limestone
shells and shell fragmentof dirrent sizes
biochemicall
travertine
limestone
decorates caverns
faint layering
pores
crystalline limestone
fien to coarse crystalline
micrite
no visible grains, may be conchoidal
chert
will sratch glasss
microcrystalline
may be conchoidal
light colired
looks greasy
rock salt
fine to coarrse crystalline
salty
himilayan pink salt
rock gypsum
fine to coars crystalline
soft
what are metamorphic rocks produced from? thus
any kind of rock, each metamorphic rock as a parent rock
low grade metamorphism
example with parent rock
slight changes
shale (parent) to slate
high grade metamorphism
example
substantial changes
granodioorite to gneiss
Which metamorphic process is mostly closely related to changes that occur because of heat? What is the source of this heat?
foliation
nearly flat arrangement of mineral grains (strongly deformed during folding)
layered or banded look
What metamorphic rock has slaty or rock cleavage? meaning
slate
flat, dull surface that can shatter into thin slans
phyllitic texture meaning and what rock
phyllite
mica crystals in slate grow so shimmers and has wavy surface
parent rock of slate
shale
parent rock of phyllite
slate
what grade is phyllite
medium low
Schistosity
schist
scaly layering of glittery platy minerals (micas) with deformed quartz and feldspar
gneissic texture
uion migration results in segregation of light and dark minerals
what is the grade and parent rock if a schist
medium high
shale
what is the grade and parent rock of gneiss
high
granite and schist
whatkind of metamprphism create schists
regional
gneiss characteristicss
banded or lines of white and black
what aare the minerals that comprise of mostly nonfoliated metamorphic rocks
quartz
calcite
marble crystalline
parent rock is limestone
calcite crystals (very crystally)
pink
quartzite
from quartz sandstone (deep pink)
Anthracite
shiny very, very glossy
parent rock: bituminous coal (less glossy)
serpentinite
dull edges with greenish color
