Geo404C Test 1

Front 1

seismic discontinuities

Back 1

boundaries btw layers of earth where seismic wave velocity changes suddenly due to sudden density changes

Front 2

Moho

Back 2

boundary btw base of crust and mantle

Front 3

Low Velocity Zone (lvz)

Back 3

near top of mantle at depth 100-200 km, seismic waves slow 7%. Rocks here are very close to melting point and are plastic

Front 4

Gutenberg Discontinuity (depth)

Back 4

2900 km below surface, boundary bw mantle core

Front 5

Core density

Back 5

10.8 g/cm^3

Front 6

mantle density range

Back 6

3.3(top) - 5.5(base) g/cm^3

Front 7

lithosphere

Back 7

region above lvz(above depth 100km), forms rigid outer layer including upper mantle and crust

Front 8

asthenosphere

Back 8

plastic area, synonomous with lvz, 100-200km deep

Front 9

mesosphere

Back 9

mantle below asthen, more rigid than asthen, less rigid than litho

Front 10

continental crust (thickness, comp, density)

Back 10

generally 35-40 km thick
beneath mountains ~75 km thick

composed mainly granite related: high Si, Al, O

Densities 2.6 (most) - 2.9

oldest rocks 4.1 ga

Front 11

oceanic crust (thickness, comp, density)

Back 11

6 - 8 km thick

basalt related rocks, high mg, fe, si, o

density 2.9 - 3 (denser than cont)

oldest rocks 200 ma

Front 12

mid-ocean ridge system

Back 12

mountain chain 70,000 km long through pacific, indian and atlanic oceans

Front 13

earth average density

Back 13

5.5 g / cm^3

Front 14

sialic

Back 14

rocks composed high silicon content.

synonomous w/ granitic

Front 15

memorize comparisons at bottom of outline 1

Back 15

http://www.geo.utexas.edu/courses/404C/outlines/outline01.htm

Front 16

principal of faunal succession

Back 16

note that fossils can be found in certain order going down strata layers, can use fossils to match strata w/ similar fossils in other strata - mapping out geologic record

Front 17

index fossils

Back 17

those who existed for only brief period - best for identifying age of strata

Front 18

how to do halflife calculations

Back 18

half life

Front 19

rare samples diamonds mean for earth composition

Back 19

kimberlite, a var of peridotite, has form of pure carbon called diamond - very dense(3.5) and hard

shows high pressureof mantle at depth below 70 km

Front 20

10 light elements that made up mantle, oceans, conts, atmos

Back 20

si, ox, al, k, na, ca, c, ni, h, he

Front 21

magnetic field means what about composition

Back 21

the liquid outer core would be able to maintain electrical currents responsible for mag field

Front 22

triple junction

Back 22

the point where the boundaries of three tectonic plates meet

Front 23

miogeosyncline

Back 23

landward side of geosyncline, no volcanics, no deep sea sediments

Front 24

eugeosynclin

Back 24

seaward side of geosyncline with volcanics and deep ocean sediments

Front 25

apalachian orogeny (formed when?)

Back 25

mid ordovician (also called taconic oregeny) when baltica began to approach laurentai

completed in late carboniferous when gondwana hit laurentia forming pangea

Front 26

ophiolite suite

Back 26

europeans called assemblage of deep ocean sediments found in strata exposed at the alps.

generally deep ocean sediment found in cont mountain belt

Front 27

subsidence & sedimentation

Back 27

esp for shallow marine sedimentation, subsidence would be neccessary for sedimentation to continue (not just filling the basin). The subsidence slows over time and the sediment begins to spread laterally

Front 28

progradation

Back 28

lateral spreading of sediment after basin subsidence becomes slower than sedimentation

Front 29

continental growth

Back 29

geosynclines become mountains, folding deposites on the edges of continents. These folds raise up and add to the size of the continent.

so the conts are growing!

Front 30

sympathetic downward flexing

Back 30

the continental margin where subsidence is occuring due to sediment accumulating, also begins to subside. This tilt of the cont helps sedimentation increase

Front 31

continental drift

Back 31

idea that conts move horizontally over earth surface
- preceeded full blown plate tec theory
- in 40's 50's cont wasn't supported and desire was to abandon it

Front 32

felsic corridors

Back 32

idea that explained away similar extint fossils found on different continents (now known to have resulted from drift)

those opposed to drift said that felsic corrodors of land formed bridges at poles btw conts, and later subsided into ocean crust

Front 33

alfred wegner

Back 33

german meteorologist - 1915 proposed all conts were united in late paleozoic era as single super cont - named PANGEA

Front 34

glossopteris flora

Back 34

type of plant that was found fossils in south america, south africa, india and antarctica

evidence support of super cont and cont drift

Front 35

paleomagnatism (declination)

Back 35

sci found earths pole and magnetic pole not exaclty alligned.

declination - the degrees compass line north is off from absolute north

if compas could move in z axis, it would dip depending on where person was. dip is lowest at the equator

Front 36

polar wandering

Back 36

americans and euros plotted the magnetic pole over time by looking at the magnetism of different ages of rocks

PROBLEM - the paths they plotted didn't match up

realized that pattern didn't reflect polar wandering but the directions and movements of continents over time!

Front 37

Harry Hess - fixed plt tect skepticism

Back 37

suggested cont plates hadn't plowed through ocean plates but that instead, the entire plates themselves had moved!

determined sedminent lvls on sea floor way to thin for it to be very old

also too few volcanoes on sea floor for it to be very old

this along with heat at ridges and convection he deved SEA FLOOR SPREADING

Front 38

fred VINE and drummond MATTHEWS

Back 38

1960s british geophysicist found magnetic reversal stripe in indian ocean, realized it could confirm hess seafloor spreading

found the atlantic rift had magnetic striping, matching on both sides

Front 39

inclination (magnetic)

Back 39

the dip of magnetic angle of rock into the earth vertically. very steep dip -> rock at very high latitude

Front 40

panthalassa

Back 40

universal ocean surrounded super cont pangaea

ancester to pacific

Front 41

tethis sea

Back 41

large triangular shape ocean separated pangaea africa and eurasia

mediteranean is a remnant of tehtis

Front 42

Laurasia

Back 42

northern part of pangaea - north america and eurasia

when breakup started the eurasia portion really didn't have to move much east,just rotated clockwise 20 deg
the NA part moved way West
both parts rotated clockwise before breaking apart

called Laurussia by chicago group when baltica and laurentia colided in late silurian

Front 43

Gondwana

Back 43

southern part of pangaea - south america, africa, india, anarctica australia

(all but north am and eurasia)

Front 44

breakup of pangea

Back 44

diez + holden:
*200 Ma:
- began rifting (large quant of basaltic flows)
*180 ma 2 rifts:
- 1 e-w sep laurasia from gondwana
- 2 y shape sep antarcticUaustralia from india and africa
*65MA - PRESENT conts difted to current positions
- 2 americas joined
- india completed journey to eurasia
- australia rifted from antarctica

Front 45

caledonian orogeny

Back 45

just after taconian, occurred in western baltica during silurian as ocean btw laurentia and baltica closed

Front 46

cache creek terrane

Back 46

located in british columbia (north of washington state), one of first exotic terranes discovered via fusulinids

Front 47

fusulinids

Back 47

marine microfossils dating back to permian widely distributed across north america

those in cache creek exotic terrane were unlike that of rockes and middle of cont, instead more like chinese and jpaanese, helped IDENTIFY THIS AS A TERRANE

Front 48

CHULITNA TERRANE

Back 48

LOOKUP

Front 49

tethyan fusulinids distrib

Back 49

west siberia, new zealand, western hemisphere (from top of alaska down to washington), central america, south america

Front 50

Detrial rocks (4)

Back 50

Conglomerate, Sandstone, Siltsonte, Shale

Front 51

Chem Sed Rocks(6)

Back 51

limestone, dolomite, salt, gypsum, chert, coal

Front 52

arkose

Back 52

low proportion of clay/silt w/ lots of feldspar grains

derived from granitic source areas - mechanical weathering dominant

Front 53

graywack

Back 53

sandstones w/ great deal of matrix - rock frags, felspar and quartz

poorly sorted -> rapid erosion of source deposition

Front 54

limestone

Back 54

chem sed rock

form where large areas of clastic detritus are not available

Front 55

beds

Back 55

strata more than a centimeter thick

Front 56

laminae

Back 56

strata less than a centimeter thick

Front 57

concretion

Back 57

spheroidal mass in sediment formed after deposition as result of chemical reaction (usually w/ organic matter like fecies)

Front 58

diastems

Back 58

small stratigraphic gaps, very numerous

more missing than tthere, diastems account for bulk of elapsed time

Front 59

base level

Back 59

level above which erosion occurs, below which deposition occurs

sedimentation only available in areas that have net subsidence.

when baselevel falls below an old level where deposition occurred the old deposition is whiped out by erosion

Front 60

unconformity

Back 60

very large gap in strata - likely results from uplift

unlike diastem, when deposition occurs again the environment is likely to have have changed greatly

Front 61

cation

Back 61

positively charged particle

Front 62

leached by chem weathering (ion type)

Back 62

cation +

Front 63

epeirogeny

Back 63

broad regional upwarp of the cratonic (stable interior)

Front 64

bedding planes

Back 64

Any of the division planes which separate the individual strata or beds in sedimentary or stratified rock.

very little of section thickness, most of time

Front 65

beds

Back 65

90% of sedimentary structures, most of section thickness, very little time

Front 66

disconformity

Back 66

sedimentary over eroded sedimentary

Front 67

paraconformity

Back 67

sedimentary over parallel sedimentary little apparent erosion, but with
big gap (looks just like normal bedding layer though)

Front 68

brittle deformation (lvl stress speed of app, depth)

Back 68

think "break"

high stress, fast app, shallow depth

base of crust

Front 69

elastic deformation (lvl stress speed of app, depth)

Back 69

low - med stress, fast app, all over

earthquake on sanandreas where land bends then fault shifts and land straight

Front 70

plastic deformation (lvl stress, speed app, depth)

Back 70

low stress, slow speed, very deep
mantle - core

Front 71

ophiolite

Back 71

sections of oceanic crust and upper mantle, along with sedimentary rocks deposited on the sea floor, emplaced as thrust slices onto continental lithosphere, results from continent-continent collision following subduction of oceanic crust and the closure of oceans

Front 72

GreenHouse interval

Back 72

calcite oceans

high speed higher ridges, hotter, lower magnesium, higher calcium

Front 73

icehouse interval

Back 73

aragonite sea

slow has lower sea lvl, lower temp, lower ridges, higher mag/ lower cal

Front 74

island arcs (2 kinds)

Back 74

hot spots (hawaii)
ocean ocean convergance (mariana - japan)

Front 75

most rocks on surface today from what eon?

Back 75

phanerozoic 90%

only 8% precambrian

Front 76

4 plate movement mechanisms

Back 76

push - plates pushed apart at spreading centers

pull - the cold dense slabs sinking into mantle pulling rest of plate along

gravity sliding - as sea floor spreads old lava cools and subsides as its heavier on mantle. this subsidence makes downward angle from ridge on witch plate slides toward low end.


convection in asthenosphere that plates rid on

Front 77

percents of * on earth:
evaporites
cherts
limestones
shales
sandstone

Back 77

evaporits 1
cherts 2-3
lim 14
shale 63
sandstone 21

only evaporites and shales not found in outcrops - they weather too easily

Front 78

still stand

Back 78

when sed suppy and basin sinking equalibrium

facies don't move as seds build up

rare!

Front 79

transgression

Back 79

sea level raising, ss = bs remains same

facies migrate toward land

common

Front 80

regression

Back 80

sea level sinking, ss & bs remain equalib

facies migrate toward sea

Front 81

walters law

Back 81

things deposited lateral of each other end up on top of each other

one layer of

dune beach ocean

*** time ***
***sea lvl incr - transgression **

beach ocean now on top of
olddune oldbeach