Geology Unit 2
silt size
1/16-1/256 mm
turbidite settle debris
greywacke
after 800 C
melt
before 200 C for
sedimentary rocks
protolith
the original rock from which a metamorphic rock formed
Goldich Stability Series
-Bowen's reaction series on its side and relabeled least to most resistant -Relative susceptibility to weathering olivine --> quartz
Gravel
1. Breccia: angular 2. Conglomerate: Rounded both are Chalcedony
erosion
1. clast size 2. clast sorting (well sorted --> travelled further) 3. clast rounding ( further tansport --> greateer rounding)
lithificiation
1. compaction 2. cementation a. calcite CaCO3 b. quartz SiO2 c. hematite Fe2O3 (dry environment)
sand (quartz)
1. quartz arenite: >90% quartz; sand, beach "clean" 2. greywacke" sand + mud "dirty", deep offshore 3. Arkose: quartz + feldspar; sand --> terrestrial (pink + white (can have hematite cement))
depositional principles
1669 1. law of OG horizontality (sediments will be flat from gravitational moving; stratum, strata, stratified) 2. Law of superposition ( bottom rocks are older, evolution and fossils) 3. law of lateral continuity ( layers spread out for a long way)
sand size
2 mm - 1/16 mm
temp for metamorphic rocks
200-800 C
Geothermal gradient
24 C/km
mud/clay size
<1/256 mm
gravel size
> 2 mm
aphanitic texture
A texture of igneous rocks in which the crystals are too small for individual minerals to be distinguished without the aid of a microscope.
mudstone (shale)
A type of fine-grained sedimentary rock that forms in slow-moving water; typical of a lake or floodplain deposit. (feldspars and micas)
hydrolysis
Breaking down complex molecules by the chemical addition of water
clastic sedimentary rock
Clastic Sedimentary rocks
dolostone
Dolomite; CaMg(CO3)2; Mg rich ocean; doesn't fizz with acid; Mg can sub for Ca, add mg and Ca
crystalline limestone
Made up of calcite. Reacts with acid. Coarse-grained
aphanitic
Rhyolite, Andesite, Basalt, komatiite
equation for geothermal gradient
T = 24 C/Km * d (in Km) + 14
frost wedging
The mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices
saltation
The movement of sand or other sediments by short jumps and bounces that is caused by wind or water
thermal expansion and contraction
a type of mechanical weathering in which the volume of rocks changes in response to heating and cooling
phenocryst
any of the large crystals in the porphyritic igneous rock
ventifact
any rock that is pitted, grooved, or polished by wind abrasion
biologic
calcite (shells, chalk, coceolithophoran, coccolith); chalcedony (waxy, radiolaran, silica ooze, SiO2 quarts) ( agate, jasper (green/red), flint (black)); opal (looks like plastic); kaolinite (clay, hydrous Al Silicate)
limestone
calcite; 2 types: biologic (skeletons, bioclasts), nonbiologic (evaporite)
chemical sedimentary rock
chemical sedimentary rock
clay(typeofsediment)
chemical weathering leftovers
dissolution
chemical weathering that creates solutions; calcite + carbonic acid --> ca+2 and co3 -2
hydration
clay + h2o --> greasy
coal
compressed peat needs heat; burning releases CO2 and SOx
peat
compressed plants
welded tuff
compressed volcanic ash, obsidian stripes
jointing
cracking, unloading, stress from below
porphyritic
describing an igneous rock composed of both large and small crystals (phenocrysts + groundmass), porphyry
diatomite
diatoms; quartz skeletion, spongy, absorbs
Precipitation from a solution(typeofsediment)
evaporites and biologic
order
felsic --> ultra mafic
siltstone
fine-grained sedimentary rock generally composed of very small quartz grains; mica rich (biotite + muscovite)
oxidation
formation of rust; hematite Fe2O3; copper rust --> verdigris
chalk limestone
forms skeletons
scoria
frothy bubbly basalt
pumice
frothy, bubbly tuff, foam
Phaneritic
granite, diorite, gabbro, peridotite
Grains that are visibile to the naked eye
gravel and sand
evaporites
halite (NaCl); calcite (fizzes with hydroclauric acid); gypsum (alabaster)
mechanical weathering implies
hardness, cleavage
oxides(typeofsendiment)
hematite: reddish strak, hardness 6 limonite: brown yellow streak, hardness 4-5.5
solid state reaction requires
high T, High P, H2o
pressure solution (metamorphic; texture)
high pressure dissolution, low pressure deposition with water (eg marble)
dunite
igneous peridotite with sugary crystals
phaneritic texture
igneous rock texture in which minerals are easily visible without magnification
pegmatitic
igneous, very large crystals, >1 cm, >2cm, pegmatite, phaneritic
oolitic limestone
is formed into small pearl-like spheres, constructed as concentric layers. This is a chemical rock, precipitated from warm, supersaturated marine water.
micrite
limestone composed of very tiny calcite particles - solidified lime mud, fizzes
530 million years ago
limestone skeleton
fossiliferous limestone
micrite with fossils
where does the geothermal gradient apply
near surface, for 200 km
neocrystallization (metamorphic; mineralogy)
new crystals created (eg Garnet)
pyroclastic
non rocks, glass beads, volcanic ash, tuff
glassy
non rocks, no crystals, flash cooling, obsidian, volacanic glass
granite
orthoclase: weak biotite: weak hornblende: weak quartz: durable
mechanical weathering
physical breakage of rocks into clasts
recrystallization (metamorphic; mineralogy)
rebuilding minerals bigger (eg plagioclase and muscovite)
salt wedging
rock disintegration caused by the crystallization of salts from evaporating water
abrasion
rocks against rocks; h2o, glaciers, wind are agents of transport
root wedging
roots growing under rocks causing it to break
Phase change (metamorphic; mineralogy)
same formula, different mineral (Eg Stishovite; SiO2 but shorter bond links than quartz)
coquina limestone
shell hash
grains that are indistinguishable to the naked eye
silt and mud/clay
tufa limestone
springs, spongy, h2o dissolved limestone
plastic deformation (metamorphic; texture)
squeezing for shearing with heat (eg Metaconglomerate)
tuff
volcanic ash, pyroclastic texture, obsidian droplets
obsidian
volcanic glass, conchoidal fracture
anorthosite
• Ca-rich plagioclase feldspar • mafic/ultramafic • grey • type of gabbro