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