[SOLVED] CS chain EESA06 Lecture 1

EESA06 Lecture 1
Planet Earth 2011
Earth is 4.5billion years old
Geography of planet has changed, Plate Tectonic Movements
Rocks can tell us the history of the planet where water was, where land ones
Glacial erratic large boulders
o Marble altered limestone
Super-continent Pangaea Great all together in one place
Amnesia Continent Pangaea # 2 will become a super continent once again
Stratigraphy putting rocks in their relative age organizing history
o Aka Historical geology
Vector Map direction of movement and velocity of movement of land masses
Next super continent clustered around southeast china
Ring of Fire most dangerous place to live, the outline of pacific
Geophysical Equipment cameras etc. go underwater
Derrick drilling tower
o The Resolution drill ship can drill 7km underwater
Scope of Course
Earth history: Application of plate tectonics to the ancient past to reconstructing past
continents/oceans
Paleo-environment reconstruction (ex: climate) and paleo-biology
o Paleo = old
Geographical evolution of Canada over 4 billion years
Environmental issues and hazards (earthquakes etc) resources (mineral, water, oil)
Lecture 1 and 2:
How Planet Earth Works: Plate Tectonics (Chapters 1 and 2 in textbook) Key concepts to read up for the First Two Quizzes:
Formation of planet Earth 4,500 million years before present Continental drift and Pangaea: 1912 (Alfred Wegner)
o He proposed that craters on the moon were caused by meteor impact Sea Floor Spreading: 1960 (Harold Hess)
o Oceans are widening, pushing the continents around
Magnetic stripes on the ocean floor and wander paths for continents: 1965 (Fred Vine)
Mid-ocean ridges and hot spots: 1965 (Tuzo Wilson)
Plate Tectonics and Wilson Cycle: 1967 (Tuzo Wilson)
o Continental drift (continents are moving around) vs. Plate tectonics (whole of earth surface can be broken up into plates and those plates are moving due to mantel movement)
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Change in the Earths Interior Differentiation caused by gravity [diagram]
Differentiated into a core, mantel and crust
Degassing Minerals break down in volcanoes, created water vapor, accumulated on earths surface as oceans
Plumes the uneven core, composed of plastic rock that is hotter than surrounding mantel, want to rise Brittle crust being moved around by plumes in mantle
Old crust sinking back into the mantel
Mantel Convection continuous stirring of mantel hot rock (plumes) coming up, cold hard rock going
down
Heat source is from radioactive decay of uranium
However, over time earth is cooling
Diamonds come from the layer immediately around the core about 2billion years old
The United Plates of Planet Earth
Biggest plate Pacific Plate
Mid-ocean ridge row of volcanoes running thru the middle of the Atlantic ocean
John Tuzo Wilson is the father of Plate Tectonics
Type of Crusts:
Oceanic crust 5-8km thick 7km/sec higher density sink lower into mantel
o Made up of basalt rock
Continental Crust <70km thick 6km/sec low densityo Dominantly made out of Granite- Mohorovicic (Moho) the base of the crust- Asthenosphere low velocity zone, very weak, plasticGeothermal energy heat coming from the mantelDownloaded by ashna vithu ([email protected])EESA06 Lecture 1 Page 2lOMoARcPSD|7033340EESA06 Lecture 2The deepest mine in the world is 4km underground, any deeper it will be too hot, hole will begin to close due to temperature and movementGeophysics application of physics to the worldEarthquakes generate energy- Fault plane surface (between moving bocks) which blocks have moved, we feel as anearthquake- Focus is where the energy is released, the trigger of the earthquake, always underground, canpredict how much damage it can do how deep down the focus is- Epicenter directly above the focus on the earths surface- Seismic risk assessment gauge any movement along any fault, looks at fault scarp & fault trace- Fault scarp cliff, bluff, the steep slope that results after earthquake (ex: 1891 Japan)- Fault trace fairly straight lines, many river valleys along traces of faultso Morphological what shapes on earths surface created by faults- Not all faults create earthquakes, some creep dont result in earthquake, the lock onescreate earthquakes Waves:- Body waves goes thru the interioro Primary and Secondary waves- Surface waves go around the surface- Primary waves the quickest 7km/sec, compression + extension (spring)o can go thru fluidso go all the way thru the interior of planet, thru the coreo Refraction effects create shadow zones no direct P waves- Secondary waves – are smaller 5km/sec, wave on a rope o Cannot go thru fluidso stops at coreo very large shadow zone Earth Core:- Outer most part of core is liquid preventing s-waves, refracting p-waves- Inner core is solidSeismograph station closer to focus = time lag of arrival of P&S waves not much, farther from focus = time lag from P&S wave is bigger- Allow to determine where the epicenter was- Networks was setup to determine nuclear bomb testingMajor Epicenters Circum-Pacific belt (most damaging, deepest), Indonesian belt, Mediterranean- Himalayan belt (where India is colliding with China)- Deep focus earthquakes – Along the plate margins- Deepest earthquake is 7km down- Shallow-focus earthquakes, where plates are diverging, mid ocean drifts- Low magnitude earthquakes, magma coming up- Earthquakes can be in the middle of continents- Intracratonic earthquakes are very difficult to explain and predict (ex: Toronto)Ancient China used missing farm animals to predict earthquakesUsing Heat Flow measurements to map mantle structure and plumes (very hot rock)- Black lines are continents cooler areasEESA06 Lecture 2 Page 1 Downloaded by ashna vithu ([email protected])lOMoARcPSD|7033340- White lines are the plate boundaries higher heat flow below the oceansPicture of the Core by Julain Lowman- Large plumes protruding from the core- Green slabs going down into core- Plates are moving around due to convection in this interiorRift valley on ridge crest (in textbook!) seems like a conveyer belt- Hot mantle rising and cold mantle sinking- Oceanic trench – Oceanic crust meeting oceanic crust (Older oceanic crust more dense goesunder less dense, younger oceanic crust, continental crust goes on top, least dense)- Island arc considered continental crust- Andesitic volcano- Mid-oceanic ridge Rift valleyFinger nails grow at average of 3.7cm/year, Atlantic ocean opening growing at 3.7cm/yearCrust types: two (continental and oceanic) and so plate interact in four ways: 1) divergent plate boundaries (mid ocean ridges, continental rifts)2) oceanic crust converging with oceanic or continental (subduction)3) continental crust converging with continental (obduction)4) Both types of sliding past each other (transform boundaries)Continental Drift: (Alfred Wegener)- 1912 published theory of continental drift- Proposed a supercontinent Pangea fitting the continents togetherPangea consists of:- Laurasia (N.America & Asia)- Gondwana (Southern continents)- Wegner suggested continents moved by plowing thru sea floor but this mechanism was rejectedby most scientists…- Put a map together, by identifying rocks of the same age, evidence that the plates were once togetherStriation – Scratches in rocks made by glaciers (thick mass of ice that is flowing, usually has rock debris)- Tell us about the direction of ice flow in the last ice age about 10thousand years agoOcean floor gets mapped- Sound source – mimics energy that is produced by earthquakes generate seismic signals- Hydrophone picks up the bounced off energy from the ocean floor, reconstruct ocean floor- Swath Bathymetry higher frequency waves, bounce off the surface of ocean floor- Can map subduction zones, mid-ocean ridgesThe Challenger Deep aka Marianna trench deepest point of Pacific ocean, 11km deep, just above a subduction zoneTopography of the ocean floor- Fractures transformed faults, horizontal lines offsets mid-ocean ridgesDownloaded by ashna vithu ([email protected])EESA06 Lecture 2 Page 2Harold Hess (1962) introduced the idea of the sea floor spreading- Sea floor created at Mid-Ocean Ridges (MOR)s recycled into mantle at trenchesPaleomagnetism- Periodically the Earths magnetic field flips- North magnetic pole changes to south- Geographical pole and magnetic pole do not coincideDirection of Earths magnetic field- Cooling lava <- Magnetic alignment preserved in magnetic records orientation of Earths fields- Geomagnetic Time scale – Layers of rocks lava flows showing reverse magnetismPaleomagnetism- Magnetic reversals in lavas average every 500k years- Takes 10k years or less for a reversal to occur- Magnetic epochs: Brunhas -> Matuyama -> Gausis -> Gilbert
Magnetic Stripes
Magnetometer tow behind ship, measure magnetism on ocean floor (cannot see)
Magnetometer survey of ocean floors identified patterns of anomalies on each side of MORs
Symmetric pattern on either side of the ridge
Patterns Matched pattern of magnetic reversals
Proved the sea floor spread
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EESA06 Lecture 3
How continents Break Up and Oceans Open
Mantle movement creates Triple junctions 3 major fractures
o Middle of continent, dome forms above plume, o Outward flow from plume creates rifts
o Only one rift develops into an ocean
Failed rifts are preserved in modern continents from the breakup of Pangea they just sit there and may fill up with sediments
Example of failed rifts in Canada: Ottawa river valley and St. Lawrence river valley
o Control river flow, generate earthquakes
Stage 1: East African Rift
Continent undergoes extension, the crust is thinned and a rift valley forms
Stage 2: Red Sea
Continent tears in two, continent edges are fractured and uplifted, Basalt eruptions form
oceanic crust Stage 3: Atlantic Ocean
Continental sediments blackout the subsiding pressure margins to keep continental shelves, the ocean widens and a mid-ocean ridge develops as in the Atlantic Ocean
Difference between a Sea and an Ocean
Ocean has a mid-ocean ridge, and always widening
Seas do not widen
East African Rift System
Continental breakup and birth of a new ocean
Somalian plate the horn of Africa will break away and become an ocean
Triple Junction Gulf of Aden, Red Sea, Lake Turhana (one of these will become an ocean)
Arabian Plate
Pushed north by the widening of the red sea
Fissures cracks in the earths crust
Basaltic magma comes out thru the fissures, generates flood basalts
Ash layers can put an age on it
Early hominids started in East African Rifts Kariandusi (layer of ash founder hammers)
Homohabilis tool maker hominids
Where is an ocean opening today?
When there are lots of oceans there is lots of food rich ecosystem, key step of human
evolution took place when there were large oceans
Afar Triangle Rift widening, famous for human evolution (Lucy australopicthin)
Thinned crust, Flood Basalts
Danakil Desert
Shield Volcano low slope tips, source of flood basalts, basalt eruptions (building oceanic crust)
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Pointy Volcanoes have more violent eruptions , gas doesnt come out as readily, magma is more stiff
Deccan Lavas cause extinctions
Margin of the Red Sea Egypt
Nile river flowing from East African Rift, Ethiopia, Parallels Red Sea
Giza (old period pyramids made out of limestone) and Luxor (new period temples made out
of granite) population clustered around these two places Pyramids: all constructed approx 4,500 years ago
1) Great Pyramid of Khufu (Cheops) Tura limestone facing stone
2) Khafres Pyramid (Chephren)
3) Menkaures Pyramid
the idle and foolish exhibition of royal wealth
soliders, forty centuries of history look down upon you
Bioclastic Limestone made up of broken fossils (foraminifera nummulites organisms)
Numismatics study of coins, they look like coins hence the name
Mokkatam Limestone Thin bedded worlds first stone building stripped of its Tura limestone Tura limestone polished, mirror like
Electrum the gold caps on pyramids
Pylon at Karnak temple complex: made out of Nubian sandstone
Hypostyle hall in Luxor: made out of Nubian sandstone
Tors granite (igneous rock) rots along fractures when it is in a warm climate
Regolith clay material, rotten granite
Canada does not have Tors because of glaciers, knocked them down and moved boulders all around
Erratic boulders glacial transported boulders, remains of tors
Obelisk tall towers of limestone
Gold is an igneous rock was thought to be the skin of the gods, Nubians bringing tributes of gold
The oldest known Geological Map: 3150 years old
Written on papyrus for Ramesses IV by Ammenakhate (Scribe of the Tombs) and portrays
Wadi (Canyon) Hammamat in the Eastern Desert
Where gold veins were etc.
William Strata Smith the map that changed the world
Smith was a canal engineer and made the first geology map in Britain in 1815
Industrial revolution the need to find coal etc
William Logan the First Canadian Geology Map 1866
No coal problem Nova Scotia Confederation to get coal from others
Daily reminders of an ancient past
Rock names having an ancient Egyptian source:
1) Porphyry igneous rock with very large crystals, deep red almost purple color (mined in egypt and exported by Romans for coffins)
2) Basalt
3) Alabaster
4) Syenite type of granite, common in southern Egypt
5) Ophiolite
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Red Sea is opening up Mountains are result of Arabian plate crashing into European plate:
Arabian Plate is Pushed North Along the Dead Sea Fault Zone as the red Sea Opens
Turkish Plate is escaping Westward along the North Anatolian Fault
North Anatolian Fault major fault and major earthquakes
Dead Sea Fault Zone Arabian plate sliding past crust to the west, major earthquakes
Dead Sea a lot of evaporation produces brine
Brine concentrated salty water, At least 10x denser than normal sea water, unable to swim
Lowest Place on Earth subsiding rift, well below sea level
Level of Dead Sea is lower commercial use of salt
Lisan formation sediments looking for evidence of ancient earthquakes, major earthquakes disturb layers of rock formations, earthquakes falls in cycles, may give clue to next earthquake
Seismites layers of sediment of rock that have been deformed by major earthquakes
Comparing written records of earthquakes (the dead sea scrolls) and information from
seismites to find frequency of earthquakes
Crusader Fortress of Ateret on the Jordan River: Built on a Plate Boundary
Earthquakes of 1202 and 1759 moved 2.1m North
Wall offset by slip along plate boundary
Sinai-Israeli Plate on left and Arabian Plate on right
Petra, Jordan city built into rocks (was in Transformers) Abandoned due to an earthquake
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EESA06 Lecture 4
Topics for Lecture 4 and for Quiz 3 on Thrusday Feb 10th
1) Introduction to mid-ocean ridges: Modern and Ancient Fossil MORs (Called Ophiolites)
2) Why are more MORs Fractured? The role of transform faults
3) Iceland: Walking over a Mid-Ocean Ridge
4) Magnetic Stripes Recorded in Ocean Floor Crust and The Age of Ocean Floors
5) Basalt Lava Flows: Fissure Eruptions
6) Volcanic Activity Under Glaciers: Jokulhlaups!
7) Geothermal Energy
Oceans only widen(rift) to a certain width then they start to close subduction
cooling away from ridge and thickens at sides
It wants to sink back down to the mantle
History of continent is dictated by ocean history
Ophiolites Ancient pieces of ocean crust
Combining the information can put a picture of
history of MORs
Contain rocks that are very mineral-rich
Mid Ocean Ridge
Middle of Atlantic, constantly volcanic eruptions
Are not continuous, are fractured
Fractures horizontal lines on MORs
enable ocean floor spreading on a curved earth
surface
Dykes result of hot magma intruding into older rock, sheeted Dykes surrounding rock will be extended
basic fuel behind plate tectonics Plumes supply the large amounts of magma How Oceans Widen: Continuous intrusion of dykes
continuous cooling of margins of magma chamber and continuous intrusion of new magma at center
symmetrical distribution on each side
Pillow Basalt pillowed lava, rounded masses where basalt magma was cooled very quickly Gabbro chemically equivalent of basalt but has larger crystals since it cools slowly, igneous rock Peridotite dominant mineral is olivine (Peridot), the mantle is made out of peridotite
Distill Gabbro and Basalt is distilled from huge
mantle plumes
Ridge Push- Hot magma pushes up and dykes intrude Slab pull Ocean floor sinks under its own weight Continental crust is the product of melting ocean crust plus sea water
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Ma Mega-annum (million)
Ga Giga-annum (billion)
ka kilo-annum (thousands of years) 750Ma to 350Ma
closing of an ocean aiapotis
oceanic crust some gets subducted, some gets
pushed up onto land (Himalayas)
Ophiolites ancient ocean crust that is now on
land, fossil ocean crust preserved on land Eastern Canada:
Chert (Flint) sediments that were being slowly deposited on top of MORs, igneous processes, and accumulates
Sheeted Dykes continuous intrusion of basalt
Pillow Lava igneous rock, cooled very quickly
Oceanic crust is made of:
Mafic and Ultra-Mafic rock magnetism and iron,
pre-dominant in olivine Contiential crust is made of:
Acidic Rocks more silica Red is young Green + Blue is old Youngest Rocks are all along the MOR
Pacific ocean can see old rock but not along south American coast
Oceanic crust has already been subducted
Feeding Andian Volcano, has been recycled
Maximum age of oceanic crust is:
Late Jurassic (150 mill. years ago) Pangea broke up
Continent underlay by two plumes, push two contintents apart,
flood basalts develop into oceans
fractures allow spreading on curved surface or when there is weakness in the crust
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Fractures a crack or break
Black arrows moving in the same direction
Transform Faults movement of rock on either side of a fracture (can be small or big San Andres Fault)
Black arrows moving opposite each other
Hydrothermal Processes Super heated water
Vents carrying minerals in suspension, looks
cloudy and opaque
Ancient ocean crust is a major source of metals
Iceland is an example of a hotspot
Hotspot = a narrow plume (the red dots)
Hotspots are stable (40 in the world)
Volcano is above the hotspot
Crusts are moving, volcano dies but a new one
forms
End up with a chain of volcanoes
Older volcanoes are smaller due to erosion
Distillation Melting of Plumes withdrawing fluid from what was plastic
Iceland is slowly being torn into two
Sitting on a MOR
West on north American plate
East on European plate
Rate at which plates are moving in Ontario = 3cm/year
Fissure Swarms group of cracks (2 pictures)
These cracks wells up magma
Krafla Central Volcano overdue for a major
eruption, huge amounts of ash in air Symmetrical: very young island ->
lots of small earthquakes
Transform Faults Zone (TFZ) Iceland region
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Magnetic Stripes

Thingvillir
Switches through time
Ocean crust is being pushed away, acquire magnetic strip along the edge Confirms sea floor spreading
Dangerous to walk over magnetic stripes
plate boundary for north America
First Iceland parliament held there natural amphitheatre
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Measuring the Jerky movement of plates using a GPS Ultra-Mafia Rock Shield Volcano
Acidic Rock Pyroclastic Cone
Eruptions shape volcanoes and what rock is formed
Mid-Ocean Ridge
Mining heat in the circle in the form of hot water
Geothermal energy
Spatter cone:
Cinders large pieces of rock, rapid cooling of lava that
is hot up into the sky
Ropey Lava A cooled lava flow
Very fluid magma looks like when its cooled
Pahoehoe lava
Sharp/ Jagged (cooler) -Aa lava
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Quiet Volcanism
Basaltic lava flows easily
(low viscosity) water moves easily
Two types of lava
o Pahoehoe ropey (hot lava)
o Aa cinders, sharp, jagged (cooler)
Oil thick = high viscosity, use in high temperatures Oil thinner = low viscosity, use in low temperatures
Flow = used to be a lava flow, ropey surface Dykes feeding to magma surface
Basaltic Flow that has cooled inside Paligonal rocks
Contracted and then broken
In Iceland are said to be trolls
Tephra Volcanic Dust, can affect climate Glacier sitting on a dormant volcano
Tuya Flat-top mountain, erupted underneath ice made of basaltic
Sub-glacial volcanic eruptions under ice
Pillow lava from erupting in water
Jokulhlaups (Joo-kulh (mountain) laups (leap))
Big Floods coming out below ice-caps (Similar to flash floods)
Geysir water goes down gets heated above boiling point, under pressure, form spray of water Happens every 10-15 mins
Boiling mud pits
The Blue Lagoon hot water, contains algae (fine rock particles), distinctive blue color
Icelandic Deep Drilling Project
Geothermal Energy draw hot water for energy Can grow bananas wells in yard
Earthquake proof pipes
Reykjavik Smokey Bay capital of Iceland
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District Heating Project steam, free hot water
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EESA06 Lecture 5
When oceans close is the dangerous volcanoes because of subduction.
Raeology ability to flow, how easy does that magma flow?
Iceland is very fluid not that dangerous, all gases come out
More viscosious dangerous, stuff comes out pyroclastic
Pyroclastic broken by fire, rocks are shattered by eruptions and thrown up into air
Volcanic bombs or ash(is a misnomer named improperly)
o Italy thought it was coal burning
The Green Areas subduction back into the mantle
Friction (earthquakes), melting (volcanoes)
Similar to lava lamp
The Pacific Ring of Fire: Tectonics of a closing ocean
Pacific Rim Dense concentration of volcanes, major
earthquakes, tsunamis
Subduction:
The stars marks earthquakes The deepest earthquakes are
700km down
We know that slabs dont melt till after 700km down
Magmatic Arc a line of volcanoes directly above
subduction zone
Oceanic crust made out of basalt
Silicic magma Sediment + seawater melted, reducing
viscosiy of magma
Deep water trenches ocean floor going down into
subduction zone
New Zealand: small island, exposed tip of a much larger land mass (Zealandia)
Red Boundary Pacific plate and Austrailian Plate
o Bottom: Austrailian Plate is being subducted under
Pacific Plate
o Top: Pacific Plate is being subducted under
Austrailian Plate (older oceanic crust is heavier) o Middle: Obduction Colliding continental crust
together
Obduction Himalayas, creating high mountains
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Continential Crust Collides with Continenetial Crust:
The Southern Alps Mt.Cook in New Zealand
White Island young volcano
Lateral (side) blast highly dangerous
Caused by sector colapse
Sulfuric acid natural pollution
Merapi Volcano Indonesias most dangerous
Killed the gate keeper that protected the volcano
Subduction: Older oceanic crust going under younger crust
Japan & Indonesia
When you collide two oceanic crust,
creates continential crust, generates new
lands
Proto-continents first continents
Model of Merapi Steep Volcano very susceptible to sector collapse
Eruption:
1) Pyroclastic Flow White areas with gas and boulders
2) Lahars debris flow similar to concrete
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Merapis sister stable
Top of Merapi very unstable because has thick plug of magma being pushed up, building a cap and its beginning to fall off Large cracks
When erupts gase and large masses of rock rolling down Pyroclastic flows
Rich soils farming at base of volcano
After the pyroclastic flows the large boulders Mt.Winson killed 30 journalists
Flow deposits burnt stuff buried Charred woods dark oval
Japan: Volcanic arc
Earthquake nation, most danergous place on pacfic rim
More volcanoes, active faults
Tokyo four plates combined here
Arc of volcanoes becomes an island
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Chikyu the earth
Drill ship can drill 7km down into ocean floor
Made out of derrick the drilling apparation
Riser system can withstand high gas pressures
Want to drill down into mantle new source of energy +
mineral deposits etc.
Want to find an early warning system for earthquakes
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Mount Fuji and the City of Fujioshida
Famous for fire festival
Make offerings to the volcano
Pyres light these for celebration
Mount Unzen of Japans Deadliest Volcanic Disater in 1792
Green patches from sector collapse
Under pyroclastic flow is the older city
fishing ports
Islands as a result of sector collapse
Sector collapse triggers a tsunami double whammy
The Legend of the giant kashima (cat fish)
Geo-methology how they used to explain earthquakes
Nobi Earthquake of 1891
1868 western technology in japan
1891 All the western building fell down
Neodani Fault
Earthquake museum
Fell 6metres
Tokyo after the great Kanto Earthquake of September 1st 1923
Kill people by fires + buildings coming down
Survivors of 1944 earthquake
Earthquake prevention day Sept 1st
San Francisco
San Andreas fault transform fault
From Plates sliding past each other
Connects sea floor spreading in south
and trench forming in the north
Baja is on its way north to Vancover
Western Canada (Yukon, Alaska, California)
Made up of pieces of crust come up from
south and got stuck at Western America
Making way up from San Andreas Fault Creeping Segment (Blue) fault is continuously
moving , release of stress
1906 break (red) locked fault 1857 break (green) locked fault
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San Francisco Bay Area
Hayward Fault-along shoreline, where San Andreas splits into 2
Building that survived the 1906 earthquake Because built on rock not sediment
Effect of Liquefaction: Subsidence of Houses
Anything solid when shaken turns into liquid
Houses sunk down, second floor became main floor
University of California in Berkley
Hayward Fault runs right in the middle of centerfield
Standford is built on the San Andreas Fault
when shaken the left statue fell, memorial arch damaged
Hollister Creeping Plates
San Andreas Fault Creeping Fault Line:
Not dangerous
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Cobija: Devastated by a Tsunami in 1877
In a James Bond Movie
Used to be part of Boliva but now its part of Chile
Concepcion Earthquake of 1835 Witnessed by Charles Darwin
Land was raised up several metres
Darwin Made connection how earthquakes and how
mountains are pushed up
Andes Mountains have been jacked up by earthquakes
Salt Flats Salars in Atacama Deserts
Driest Desert on the planet
Contain Lithium used for batteries
Nitrate Mining in the Atacama Desert
Fixation of nitrogen from the air by bacteria
Nitrate Deposits for fertilizers, expolsives
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Chile: Strato-Volcanos the dangerous ones
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Lascar Volcano: Chiles most Active
Farmland over pyroclastic flow
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Lava Flow coming down the valley
Chaiten
Chaiten Volcano
Pyroclastic Material coming up
Very stiff magma
Caldera hole left from previous eruption
Growing of volcanoes
Old Volcanic Glass Rhyolite Obsidian, used for
arrowheads, knives
Can fingerprint Rhyolite trade between ancient people
Plume of ash: coming away from Chaiten Volcano What it looks like today
Forests blown away but pyroclastic flow
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Small city of Chaiten
Gases wiped out vegetation
Town of Chaiten Devastated by a Lahar in 2008 Lahar River of mud
1) Subduction Oceanic and Oceanic
Older goes below younger
2) Subduction Oceanic and Continential
oceanic goes under continential
3) Obduction: Continential and Continential pushes land up into mountains
4) Sliding: no subduction or obduction
San Fran: Locked
Hollister: Creeping
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EESA06 Lecture 6
Fossils
Step 1: The earliest Bacteria: 3.8 Ga(?)
Step 2: The Cambrian Explosion: 542 Ma (multicellular animals with shells, backbones etc)
Step 3: Diversification During the Paleozoic: c.400-250 Ma
Step 4: Role of Meteorites
Nova DVD: Becoming Human
Evolution of Earth:
Hadean Period hell on earth Rocks was molten, no water no atmosphere
Diversification heavier elements sank to the middle
Magnetic field to hold on to the gases which build up atmosphere + oceans
How are fossils formed?
Shells buried and preserved unaltered (<100 million years)- Mineralization – Cavities are filled with silica, calcium carbonate, iron (ex: tree stumps)- Most fossils are found in sedimentary rocko Exception: Pompeii people covered by pyroclastic flow and fossilized in ash Per-mineralization- Die in or near water- Soft parts consumed by bacteria- Sedimentation (fine grained =more detail, chemical makeup of rock = color)- More sediments pile on = pressure rock- Mineral rich water = changes to the shell- Uplift by continental crusts coming together (plate tectonics)- Erosion wear away rocksAmmo an organic gemstoneAmmo fossils iridescent aragonite with trace elements(Fe, Mn, Al, Ba)Trace Fossils- Preserved tracks, trails, burrows (protection/food), borings- Ichnology study of trace fossils- Bioturbation process of disturbing sedimentFossils as clues to ancient environments- Palaeocology study of ancient organisms and their environmentso (St.Cuthbert rings, Sea Lily – Crinoide)o Clues from: fossil types, assemblages (group offossils tend to be found together), fossilmorphology, trace fossils Fossils and stratigraphy- How do we use fossils in stratigraphy?o to establish relative age of rock units, correlate units- What information do we need to do this? o Relative age of rock unitso Fossil species present in each unitlOMoARcPSD|7033340EESA06 Lecture 6 Page 1lite niteDownloaded by ashna vithu ([email protected])lOMoARcPSD|7033340EESA06 Lecture 6 Page 2 o Geologic range – Establish time of first and last appearance of each speciesWilliam Smith Principal of Faunal Succession fossils appear in layersWhat kinds of Fossils are most useful for stratigraphic work?- Index Fossils (ex: Ammonites) – Are Short-lived and widespread- Assemblages (groups) of speciesTrilobite Growth- Trilobites molted regularly shed skin- Thus very abundant in the fossil recordThe evolution of Life on Earth…- Intense bombardment from 4.5 to 4 Ga prevented life becoming established- No magnetic field to prevent oceans and atmosphere being stripped off the planets surface bythe solar wind?Sir James Dawson was wrong.- Thought to be the oldest fossil Eozoon Canadense (1868) the dawn of animal of Canada now recognized as mineral not organic dubiofossilStep 1: The Earliest bacteria 3.3 Ga (?)- Prokaryotes some are photosynthetic (called cyanobacteria: blue/green algae)o Microscopic, single-celled, lacking a nucleus- The earliest prokaryotes (the Archaea) lives around superheated waters near submarinevolcanic vents (hyperthermophilic)o Simple bag-like cellso Only life forms between 3.8 and about 2 GaWhere on Earth did early life forms flourish?- Probably in oceans salts, solvents, mixing of elements to create organic compounds Downloaded by ashna vithu ([email protected])lOMoARcPSD|7033340- Life forms may have first developed at hydrothermal vents (mid-ocean ridges) At Modern Hydrothermal vents (called smokers) on mid-ocean ridges:- Microbes hydrothermophiles- Live at temps > 100C
No light
Energy from chemosynthesis ex: sulfur
Gunflint Formation (in Ontario) prokaryotes
1.9 billion once thought to be the worlds oldest fossils
Oldest Cyanobacteria are thought to be 3.5 billion years old from the Apex Chert in Western Australia
They may be dubio-fossils entirely of mineral origin, not organic
Stromatolites (Gk for stoney carpet)
most common Proterozoic fossils made up of colonies of prokaryotic bacteria trapping fine sediment on sticky bacterial mats
Modern relatives still survive in hyper-saline lagoons in western Australia
The Rusting of the Earth c. 2.8 Ga
Hydrothermal Delivery of Dissolved Ferrous Iron at Mid- Ocean Ridges
Cyanobacteria created oxygen as waste
Oxygen oxidized ferrous iron
Ferric iron oxide droplets landed on bottom
Turbidity Current
Deposition of iron oxides as banded iron formation (BIFs)
o No longer made Cyanobacteria created the Worlds Iron Ore
Banded iron ore alternating layers of magnetite (greyish black) and hematite (red iron rich mineral ) + red jasper (quartz)
Largest deposits are in Canada (Labrador) shipped to steel plants in great lakes (ex: Hamilton)
The Rise of the Eukaryote Bacteria
First developed at c. 2.8 Ga as single cells (protists) with thick protective walls (their fossil
remains are called achritarchs)
They reproduced sexually which allows genetic mutations to be inherited from one generation
to another
Mobile and actively sought food using their hairs (cilia)
The first multi-celled eukaryotic organism (called metazoans) were the Ediacara that developed
about 630million years ago, these are the earliest true animals (resemble jellyfish and worms) Mistaken Point NFLD
Mistaken Point formation, NFLD has one of the earliest multi-cellular animals known
Between 635 and 543 million years old
Soft bodied very hard to fossilize, buried quickly
May have been like a jellyfish
One of the Ediacaran biota
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Step 2: The Cambrian Explosion 542 Ma (Multi-cellar animals) The breakup of Rodinia between 750 and c.600 Ma
New habitats shallow waters near continents
Sudden appearance of principal animal groups between
600 to 542 Ma
Shelled forms capable of burrowing into sediment for
food and shelter
(bad news for geologists: why?) Bioturbation
Cambrian North America period of tectonic stability
Atlantic coast in modern day Maritimes east coast have a passive margin
Modern day west coast is active margin due to subduction
Divergent passive margins carbonates, sands deposited in shallow inlands seas
o Clastic things sands, clays, silts, carbonates (coral reefs) etc.
o Many habitats for animals to develop Cambrian Explosion
Metazoans Multi-cellular creatures appeared ~630 million years ago Ediacaran fauna (ex: Kimberella, Sprigginia)
o Complex forms discoidal, frond-like, elongate
o Soft-bodied
May be related to accumulation of free oxygen in atmosphere
Mistaken Point Formation: Newfoundland
A united nations biosphere reserve
Earliest multi-cellular life forms at 575 Ma (faun like)
The Burgess Shale
Discovered by Charles Walcott near Field British Columbia
in August 1909
In 3 field seasons he collected over 60,000 specimens
Now a UNESCO World Heritage Site
Strange Creature of Burgess Shale
Hallucigenia (40cm)
Anomalocaris (60cm)
Pikaia earliest chordate (4cm) creature with a backbone
Opabinia (7cm)
Step 3: Diversification During the Paleozoic c.400-250 Ma Palcozoic = Old Life
Families of marine organisms increased from 160 to 530
o Diversity among trilobites, brachiopods, bivalve mollusks, gastropods (snail-like)
What caused this increase in diversity?
o Mountain building, volcanism starting to build Pangea o Increased habitat diversity?
Typical Reef Community Limestone Builders
Coral reefs the hard parts builds limestone
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Step 4: Mesozoic middle life period
around Cret-Tert time Major extinction of dinosaurs (around 65 million years ago)
o Due to a meteorite hitting earth near mexico?
Around Pr-Tr time Major major extinction 90% of marine families went extinct during
o Due to flood basalts?
After extinction of dinosaurs, mammals became dominant
Human Evolution and the Onset of Ice Ages
NOVA: Becoming Human Unearthing Our Earliest Ancestors
Nothing is more fascinating to us than, well, us. NOVAs groundbreaking investigation explores
how new discoveries are transforming views of our earliest ancestors. Featuring interviews with renowned scientists, footage shot as fossils were unearthed, and stunning computer-generated animation, Becoming Human brings early hominids to life, examining how they lived and how we became the creative and adaptable modern humans of today
http://www.pbs.org/wgbh/nova/evolution/becominghuman-part-1.html
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