GEOS 2104 Exam 1 - Geologic Time, Plate Tectonics, Minerals

what is a silicate tetrahedron?

isolated connected sheets

sulphide: uses?

metallic ores

what are the important characteristics of Oceanic Crust?

thinner and heavier than Continental Crust, 5-7 km

what are the important characteristics of Lithosphere?

Cold => strongest part of mantle <50-250 km thick = crust + uppermost mantle Uppermost rigid rocky crust

what happens at a continent-continent collision zone? explain processes

Collision between two converging continent fragments ensues, This causes mountain belts to form.

Compare to continental drift:

Continental Drift is just about moving plates whereas plate tectonics incorporates oceans and the idea of lithosphere.

What was evidence for plate tectonics from 1910s?

Continental Drift: Similar geologic features across some oceans continental drift proposed...but rejected

collision:

Continental-Continental convergence. This causes mountain belts to form.

define mineral

A natural, inorganic solid with characteristic chemical composition and normal structure.

Plate tectonics was a scientific revolution a...

A new theory, new paradigm

what is an island arc?

A string of islands formed by the volcanoes along a deep ocean trench produced by subduction.

Third most common element in crust

Aluminum

what happens at a transform fault?

Earth quakes Minor extension Minor compression

define mafic

Has more magnesium and iron

define felsic

Has more silica(SiO2)

what are the processes that form sedimentary rocks?

Erosion, deposition, and cementation

describe global patterns of: earthquakes(where?)

Mediterranean-Himalayan belt Circum-Pacific Belt

what are the processes that form igneous rocks ?

Melting and cooling of rock

What is study of minerals?

Mineralogy

Olivine

Most common mineral in upper mantle(70%) Make up Upper mantle, can exist in Crust

mineral: apatite

Most common phosphate.

subduction:

Convergent boundaries where lithosphere is descending into the mantle.

what are the important characteristics of Earth's interior layers?

Core, Mantle, Crust

plate boundaries: what are the types?

Divergent Boundary, Convergent Boundary, Transform

minerals: hematite, magnetite

Fe2O3, Iron Ore

what evidence is used to understand Earth's deep interior?

Geologists record the seismic waves and study how they travel through Earth. Meteorites are also used to examine and compare structure to Earth.

mineral: sylvite(potash)

Halide - KCL, K - used for fertilizer

where on Earth does continent-continent collision zone occur?

Happens at Himalaya, Appalachians(ancient, western North America (old micro-continent collisions)

Oxides: what elements?

Mineral Group: O2- + cations(especially Fe, other metals

sulphide: what elements?

Mineral Group: S2- + cations(especially Fe, Cu, Pb, Zn, other metals)

Hydroxides: Uses?

Mineral Group: minerals that are used to make rust, ex: goethite, FeOOH makes bad iron ore and rust

isolated

No sharing of oxygen SI, 4O. Olivine (common in mantle)

Hydroxides: what elements?

OH- cations(especially Fe, other metals)

When does subduction occur?

Occurs when Lithosphere plates density is greater than underlying asthenosphere. Continental Lithosphere resists subduction.

At what geologic feature do earth quakes occur?

Occurs when there is continent to continent collision Also occurs on faults

what happens at a subduction zone? explain processes

Ocean-Ocean plates moving towards one another sending plate back down to mantle. Earthquakes, tsunamis, volcanic eruptions.

Size of the Core?

More than 1/2 of Earth's Radius but less than 1/6th of Earth's Volume

superposition:

Most basic principle of relative dating. Each bed is older than the one above. Younger than the one below.

what is a continental arc?

Mountain systems produced in part by volcanic activity associated with subduction of oceanic lithosphere

how is ocean-continent subduction different?

Oceans will always subduct Continents cannot subduct

Continental drift:

Older incomplete idea that continents are moving around the world but ignores oceans which lay an important role. Idea created by Alfred Wegener.

list 5 most common elements in crust, in order.

Oxygen Silicone Aluminum Iron Magnesium

Second most common element in Earth

Oxygen 30%

phosphates: what elements/chemistry?

PO43-

describe global patterns of: volcanoes(where?)

Pacific "ring of fire"

sediment: what is it? what shape of rock? how?

Particles and rock deposited by wind, ice, water, sand, gravel, etc.

What is study of rocks

Petrology

relate patterns to plate tectonics: volcanoes:

Plate boundaries

relate patterns to plate tectonics: earthquakes:

On transform faults where they slide

what are the important characteristics of Mantle?

Solid But Warm Enough to Float like glacier

what are the important characteristics of Inner Core?

Solid and very dense. Sank to bottom of earth early in Earth's history

Composition of Crust?

Solid coldest part of earth because it is exposed to space. Silicone and Aluminum rich minerals, and lighter minerals floating on top.

carbonates, sulfates, phosphates: uses?

Soluble in Water. ( dissolve slow relative to humans but fast at a geological rate/scale) Uses: chemicals like carbonates, sulfates, phosphates

asbestos: discuss regulation

Spent trillion of dollars removing it because it was used for insulation and fireproof materials even though it wasn't hazardous in these cases

what is a plate? what part of the Earth?

Strong lithosphere, floating on (weak, solid) asthenosphere. These things are continentst and oceans.

Another name for Convergent Boundaries?

Subduction Zone

where on Earth does ocean-continent subduction occur?

Subduction zones occur all around the edge of the Pacific Ocean, offshore of Washington, Canada, Alaska, Russia, Japan and Indonesia. Called the "Ring of Fire

where on Earth does compression occur between plates?

Subduction, collision

what principles do geologists use to measure relative time?

Superposition, Original Horizontality, Uniformitarianism

most common elements in crust

Oxygen

what is Plate Tectonics?

Plates a part of the lithosphere move around, on edges of plates the global patterns happen, relative direction.

Fossils

Remains or traces of prehistoric life, are inclusions in sediment and sedimentary rocks.

sulphates: what elements/chemistry?

SO42-

relate patterns to plate tectonics: mid-ocean ridges:

Sea floor spreading brings up material creating these underwater mountain ranges

what is mantle convection?

The entire mantle is in motion, driven by the sinking of cold oceanic lithosphere back into the deep mantle. The Upward flow occurs through a combination of mantle plumes and upwelling of hot mantle rock at oceanic spreading centers.

What proves Evolution?

The existence of fossils.

what happens as plates move through geologic time?

The move away from each other

why is it impossible to determine the absolute age of many rocks?

The rocks must contain the right amount of a radioactive isotope and many don't. Too young = no daughter isotopes, Too Old = Parent can't be dated.

What happens to Olivine and Pyroxene at high pressure?

They change into Bridgmanite

what are the important characteristics of Continental Crust?

Thicker and lighter than Oceanic Crust, 20-70 km

Most Common Mineral on the planet?

This Mineral is Bridgmanite

Most Important Mineral on the planet?

This Mineral is Bridgmanite

why do geologists use relative time?

To get approximate dates on rocks we can't date

where on Earth does plate boundary-parallel motion occur?

Transform Fault

Another name for transform fault?

Transform boundary

relate patterns to plate tectonics: ocean trenches:

Two plates converging

Native elements: uses:

Using the element itself.

Elements in Silicate?

Varying amounts of Silicon and Oxygen

halides: chemistry?

Very Soluble in Water.

what happens at a seafloor spreading center? Explain the process

Where two plates are coming apart. A new Oceanic lithosphere is created.

Divergent Boundary

Where two plates move apart, resulting in upwelling and partial melting of hot material from the to mantle to create sea floor.

Convergent Boundary

Where two plates move toward each other causing ocean lithosphere to descend, be reabsorbed into mantle or collision of continental blocks creating mountain regions.

what is the geologic time scale?

Whole of geologic time usually plotted on non-linear time scale. Oldest Geologic processes at bottom.

law

a fundamental, universal, thoroughly tested theory

theory

a hypothesis accepted after thorough testing

silicosis: cause, discuss regulation

a lung disease that occurs when silica is ground up. Not dangerous by itself and even occurs in beach sand, glass, and quartz.

hypothesis, model

a proposed explanation of data; makes predictions that are testable should be simple (Occam's razor)

What created he rocks in the modern Blue Ridge of Virginia (the much-later Appalachian collisions brought these rocks to the surface)

a series of collisions happen to the modern-east coast (then south) of the USA ~1180 Ma, ~1020 Ma, until ~900 Ma. these collisions formed a major mountain chain called the Grenville Mountains, that created this

What was evidence for plate tectonics from 1960s?

earthquake mechanisms (= rock movement directions)compression at Benioff zones left/right lateral motions at ocean fracture zones seismic wave speed: cold Benioff zones => subduction accepted; transform faults accepted

what was Rodinia?

from ~950 to ~750 Ma, there was one super-continent

cross-cutting relationships:

geologic features that cut across rocks must form rocks after the rocks they cut through.

What was evidence for plate tectonics from 1960s?

global earthquakes clustered at plate boundaries mountain-building and continental geology explained by nearby plate boundary motions =>collision accepted

What was evidence for plate tectonics from 1930s?

gravity at ocean trenches indicates active pulldown => subduction and convection proposed... but ignored

what is convection?

heat transfer when hot materials rising displacing cold materials and vice versa.

asbestos: uses

insulation and fireproof materials

Types of Silicate Structures

isolated - No sharing of oxygen SI, 4O. Olivine (common in mantle) chain - sharing oxygen with next tetrahedra. double-chain - two chains shared in line and between two chains. sheet - sharing of oxygen within two directions. Weakness between sheets. framework - shared oxygen in all directions. Covalent bond persists. Strongest silicate structure possible.

original horizontality:

layers of sediment are generally deposited in a horizontal position

Hand sample

methods used to identify minerals

Thin section

methods used to identify minerals Cut Thin section 1/1000th of an inch with diamond saw to examine under microscope.

define magma

molten rock below Earth's surface

mineral: halite

most common halides. Takes the form of table salt, ocean salt, road salt.

fact, data

objectively measurable

transform fault: what happens?

plates slide horizontally past one another without the production or destruction of lithosphere.

how do geologists measure absolute time?

radioactive dating techniques

asbestos: discuss hazards

risk comes from high concentrations breathed in for long periods of time which has caused lung cancer for mine workers.

igneous rocks

rocks formed by the cooling of molten rock (either magma or lava)

What was evidence for plate tectonics from 1950s?

seafloor bathymetry (= under-water topography)mid-ocean ridges, deep ocean trenches large fractures offset the ridges very thin sediments in oceans, except at margins

What was evidence for plate tectonics from 1960s?

seafloor sampling and dating: near-zero age at mid-ocean ridge; gets older with distance from ridges => seafloor spreading accepted, but expanding Earth puzzling

framework

shared oxygen in all directions. Covalent bond persists. Strongest silicate structure possible.

sheet

sharing of oxygen within two directions. Weakness between these

Chain

sharing oxygen with next tetrahedra.

define sediment

small, solid pieces of material that come from rocks or living things

geochemistry

the study of the chemical composition of the earth and its rocks and minerals.

geophysics

the study of the forces that affect Earth

double-chain

two chains shared in line and between two chains.

where on Earth does ocean-ocean subduction occur?

Along "Ring of Fire" which is all along the edge of Pacific Ocean

define rock

An assemblage of minerals.

carbonate: what elements/chemistry?

CO32-

where on Earth does a transform fault occur?

California( an occur on ocean and continents)

what are the processes that form metamorphic rocks?

Changing temperature and pressure

halides: what elements?

Cl-, F-, Br- + cations(especially Na, Ca, K).

Amphibole (e.g., hornblende)

-Found in Crust -Hornblende - most common of this type -silicate

Fourth most common element in crust

Iron

Quartz

-Commonly found in continental Crust(not Ocean) -Commonly found in beach sand -SiO2 -silicate

Mica

-Found in Earth's crust -(e.g,. biotite, muscovite) -silicate

Garnet

-Make up Upper mantle, can exist in Crust -Fe, Mg, Al, Mn, Ca, Cr -MgAl garnet common in upper mantle -silicate

Oxides: Uses?

-Mineral Group: These minerals are magnetic. -Magnetite is the most common magnetic Mineral(Fe3O4).

mineral: gypsum

-Most Common Sulfate. -Used to make plaster.

mineral: calcite

-Most common carbonate. -Common in upper crust -Used to make organism's shells.

Clay

-Most common mineral group at Earth's surface -Created by weathering -important in soil, sediment -silicate

Feldspar

-Most common mineral in crust(ocean and continental) -Al, K, Ca, Na -silicate

Bridgmanite:

-Most of the lower mantle -Unstable at Surface -Most Common Mineral On Earth -More than 1/3 of planet

How fast do plates move? in which direction(s)?

-Moving apart on mid ocean ridges(gap) -Moving together where mountains are being built -Moving at speed of Centimeters per year -Direction and speed - move relative to each other

What silicates make up crust?

Amphibole, Mica, Clay, Feldspar, Quartz

structure: give examples of processes that deform rocks

-Rocks can be broken(faulted) -Rocks can be bent(folded) -Erosion can cut off Rocks -Liquid rock(magma) can push into(intrude) on older rocks

silicates: what elements/chemistry?

-Silica Octahedra or Tetrahedra + cations (e.g. Fe, Mg, Al, Na, Ca, K, etc.) <-- positively charged ions -Connecting to Silicones

mineral: pyrite

-most common Sulphite, -useless FeS2, -fools gold

What was evidence for plate tectonics from 1950s?

-oceanic crust much thinner than continental crust -"Wadati-Benioff zone" earthquakes are shallow at ocean trenches and get deeper in land under volcanoes -paleomagnetic "polar wandering"(explain) rocks can record magnetic field when created different continents' apparent Northpole moved differently in the past => seafloor spreading& expanding Earth(?)proposed... but rejected

What was evidence for plate tectonics from 1960s?

-paleomagnetic stripes on seafloor paleomagnetic N-S -reversals, dated globally -symmetric magnetic N-S pattern across ridges

how old is end of last ice age?

0.01 million years (10,000 years)

how old is Homo sapiens (humans)?

0.2 million years to now (200,000 yrs - now)

heat: what were/are the heat energy sources?

1) Occurred at Earth's formation, rapid increase in internal temp by countless collisions with planetesimals 2) radioactive decay

why might your major require this course?

1) Your building on Geology 2) Hazards 3) To talk and communicate with Geologists 4)Geotechnical, resources, environment

goals of this course: in your profession:

1) know when to consult a geoscientist 2) know how to communicate with a geoscientist (not how to be a professional geologist)

how old is oldest Virginia rocks?

1.1 billion years old

what is absolute time?

Actual time of something, an actual number,

What percent of earth is metal core?

15%

when & where did North America break from South America?

150 Ma

when & where did North America break from Africa?

170 Ma

when & where did North America break apart from Pangaea?

170 Ma from Africa

when & how did the Atlantic Ocean form?

170 million years ago when North America separated from Africa

how/why & when & did the western North America mountains form (the "North American Cordillera", which includes the Rocky Mountains but is much broader)?

170-40 Ma, Pacific and North American Plate collided

When were subduction accepted

1960's

When were transform faults accepted

1960's

When was collision accepted

1960s

When was seafloor spreading accepted?

1960s

When was plate tectonics accepted

1970

when was the ice age?

2.4 million - 10,000 years ago

When was Pangaea

290 million years ago

how old is earliest fossil cells?

3.5 billion years old

How old is the Earth?

4.6 billion years old

when & how did the Himalaya mountains form?

40-50 million years ago, plate movement between india and Eurasia

how old is Appalachian mountains?

400-300 million

When did the Appalachians form?

470-350 million years ago

asbestos: discuss toxicity

6 different minerals, 95% usage in Chrysotile which is least toxic. Not toxic in most cases except for prolonged exposure (ie, occupational exposure)

when & where did North America break apart from Greenland?

60 Ma

how old is extinction of dinosaurs?

65 millions years ago

when & where did North America break apart from from northern Europe?

80 Ma

What percent of time is unknown?

80%

radioactive decay

A spontaneous process in which unstable nuclei lose energy by emitting radiation

what was Pangea?

A supercontinent

relate geologic provinces of Virginia to plate tectonics

Applachian Plateau - Valley & Ridge - Blue Ridge - Piedmont - Coastal Plain

Explain relationship of parent and daughter atoms on graph related to time

As Parent atoms exponentially decrease, Daughter atoms exponentially increase

relate the sequence of silicate minerals to silica(SiO2)

As you go down the order the silica content gets higher and as you go up the silica content gets lower.

relate the sequence of silicate minerals to silicate structure?

As you go down the order the structures get more complex

relate the sequence of silicate minerals to mafic and felsic

As you go down the order they go from Ultramafic to felsic. Olivine is ultramafic while Feldspar and Quartz are felsic.

relate the sequence of silicate minerals to element composition?

As you go up the order the composition gets more Iron and magnesium rich and as you go down the order gets more Aluminum, Sodium, and Calcium rich

what modern ocean formed when North America broke apart from Pangea?

Atlantic Ocean

native elements what elements/chemistry?

Au, Ag, S, C, etc. Gold almost always by itself whereas silver and other elements are with other elements. Carbon: based on structure can be graphite or diamond, both are pure carbon.

relate patterns to plate tectonics: mountain ranges:

Built when plate boundaries collide

what is uniformitarianism?

By understanding today's processes and how they age rocks, we can understand old rocks.

what drives plate tectonics? (why do the plates move?)

Heat escaping from the planet

what are the important characteristics of Asthenosphere?

Hot => weakest part of mantle hot almost entirely solid 50-250 km thick flows a response to stress

Where are active volcanoes?

Hot Spots

What are the three rocks types?

Igneous, Metamorphic, and Sedimentary rock

importance of silicates:

Make up >80% Of Earth

Pyroxene

Make up Upper mantle, can exist in Crust Fe, Mg, Ca, Al silicates

define half-life

Interval of time required for one-half of the atomic nuclei sample to decay. Rate of radioactive disintegration.

most common element in Earth

Iron 35%

list 4 most common elements in Earth, in order.

Iron 35% Oxygen 30% Silicon 15% Magnesium 13%

Composition of the Core:

Iron and Nickel

what are most common elements in core?

Iron and Nickel

How did the Appalachians form?

Island Arc off coast of North America over millions of years these collided to make mountains.

Size of Mantle?

Less than 1/2 of Earth's Radius but more than 5/6th of Earth's Volume

what are the important characteristics of Outer Core?

Liquid

where on Earth does seafloor spreading occur?

Lithosphere

heat: what is the temperature inside Earth?

Lithosphere: Around 0 C Asthenosphere: 500 C Upper Mantle: 900 C Lower Mantle: 1960 C Outer Core: 4000 C Inner Core: 6000 C

describe global patterns of: mid-ocean ridges (what are they & where?)

Longest mountain range in world that extends around the world

Fifth most common element in crust

Magnesium

Fourth most common element in Earth

Magnesium 13%

Composition of Mantle?

Magnesium and Iron

what are most common elements in mantle?

Magnesium and Iron, Silicate Minerals

importance of silicates:

Make up more than >80% of Earth

uses of silicates:

Many industrial rocks and minerals Used in building b/c it is so common clays gems

sedimentary rocks

Rocks formed from the weathering, erosion, depostion, and compaction of other rocks

metamorphic rocks

Rocks formed when other rocks are put under extreme heat and pressure

where on Earth does extension occur between plates?

Seafloor spreading

what is relative time?

Sequence of formation: which formed 1st, 2nd, 3rd

what covered the Great Plains ~90 to ~80 Ma?

Shallow Water

What was evidence for plate tectonics from 1600-1900s?

Shape of Continents Across Oceans -Africa of South American plate looked like they fit lie a puzzle

what is a silicate

Silicates are the most abundant Mineral Group.

Second most common elements in crust

Silicon

Third most common element in Earth

Silicon 15%

what are most common elements in crust?

Silicon and Aluminum(Less Magnesium and Iron) Lighter Silicate Minerals

Occam's Razor

Simpler explanations are more likely to be true than complex ones.

how big is Earth?

Since it spins it is wider at equator and is 6,371 km

Seafloor Spreading

builds mid-ocean ridges by bringing up material creating new oceanic lithosphere. Creates raised area.

paradigm

change through a revolutionary new theory or law

halides: uses?

chemical(salts), fertilizer

what is a silicate octohedron?

complex framework

describe global patterns of: ocean trenches (what are they & where?)

deepest part of oceans that are on the coast relative to Volcanoes

geology is the study of...?

earth