Module 2 Flashcards
Geoligical cycle is made up of a group of 4 sub-cycles
Tectonic cycle
rock cycle
hydrological cycle
biogeochemical cycle
Rock Cycle
.
Rock Cycle
.refers to the worldwide recycling of three major groups of rocks, driven by earths internal heat and by energy from the sun
- depends on tectonic cycle for heat and energy
- biogeochemical cycle for materials
- hydrological cycle for water which plays an essential role in weathering, erosion, transportation, deposition, and lithification
- the rock cycle refers to the continuous transformation of 3 classes of rocks: igneous, sedimentary and metamorphic
rocks are..
aggregates of one or more minerals
-minerals are naturally occuring crystalline substance with a specific elemental coposition and a narrow range of physical properties
3 types of rock, describe rock cycle like on diagram
- igenous rock-formed by the crystalization of molten rock beneath and on earths surface
- Sedimentary rock-sediment is converted to sedimentary rock by lithification which takes place by compaction and cementation of sediment during burial
- Metamorphic rock- may be buried to depths where pressure and temp coonditions cause them to melt, beginning the entire rock cycle again
1.Magma becomes lava and cools becoming extrusive igneous rock
2.Exogenic(from outside earth) sun energy weathering, erosion, and transportation
-causes lithification transforming sediments into sedimentary rock
3. Generally at rock boundaries, high pressure transforms sedimentary to metamorphic rocks
-igneous can also become metamorphic rock
4. Fate of all rocks to be deeply buried and returned to plasticity and eventually magma to enclose rock cycle
.weathering and erosion effects all steps
Hydrological Cycle
the cycling of water from the oceans to the atmosphere, to continents and islands, and back again to the oceans
-driven by solar energy and operates by way of evaporation, precipitation, surface runoff, and subsurface flow
Biogeochemical Cycle
is the transfer or cyclingof an element(s) through the atmosphere, lithosphere, hydrosphere, and biosphere
- photosynthesis and respiration
- remember that some portions of rock and soil have important portions which are organically sourced like carbon
_______, _______, and ______influence the type, location, and intensity of earth processes
geology, topography and climate
Tectonic Cycle
tectonic activity refers to large-scale earth processes that cause the movement and deformation of Earth’s lithospheric plates
these processes create landforms and landscapes at a variety of spatial scales (e.g., orogenic mountain ranges and ocean basins to individual faults).
tectonic processes are driven by energy generated deep within Earth: original heat of formation of the planet, heat generated by crystallization of the core, and heat supplied by radioactive decay of elements in the mantle – endogenic processes
endogenic processes vs. Exogenic proccesses
energy generated deep within Earth: original heat of formation of the planet, heat generated by crystallization of the core, and heat supplied by radioactive decay of elements in the mantle
-endogenic processes (e.g., melting rocks to form magma)
exogenic processes driven by energy from Sun (e.g., weathering)
__% of water is in the oceans
97
Internal Structure of earth is based on..4 things
chemical composition of rock;
physical state – solid vs. liquid;
density;
rock strength
Describe internal structure of earth(4)
1.Solid inner core
-6000 to 5000 km down
> 1300 km thick
-extremely hot temperatures
-primarily metallic; consists mostly of iron (Fe) with minor amounts of nickel (Ni), sulphur (S), and oxygen (O)
-average density – 10,700 kg m-3
- Liquid outer core
- 5000 to 3000 km down
- over 2000 km thick
- composition and density similar to inner core
- movement within the outer core generates Earth’s magnetic field
3.Solid mantle
~3000 km thick
-composed largely of iron (Fe) and magnesium (Mg)-rich silicate minerals – ferromagnesian minerals
-average density – 4,500 kg m-3
- Solid crust
- thickness ranges from 6-7 km beneath ocean basins to ~70 km beneath mountain ranges of continents
- continental crust composed largely of silicate minerals rich in aluminum (Al) – aluminosilicate minerals
- average density of continental crust – 2800 kg m-3
- composition of oceanic crust similar to underlying mantle
- average density of oceanic crust – 2900 kg m-3
Average densities of:
Continental Crust=
Oceanic Crust=
Mantle=
Core=
- 8 g/cm3
- 9
- 5
- 7
(oceanic lithosphere is composed of these)
continental lithosphere is composed of these
.Solid Mantle: ferromagnesian minerals.
Solid Crust: aluminosilicate minerals
lithosphere
cool, strong outermost layer of Earth is termed the lithosphere – crust + rigid uppermost portion of mantle
-lithosphere varies in thickness: few km beneath mid-oceanic ridges; ~120 km beneath ocean basins; 20-400 km beneath continents
Aesthenosphere
a mass of hot, relatively weak rocks (i.e., magma) capable of slow movement
- lies just underneath lithosphere
- .capable of flowing
- .movement of material in this level is the cause of movement of plate tectonics
_______ apparently operates to move materials within the mantle;
convection apparently operates to move materials within the mantle; convection is driven by heat from Earth’s core
-convection is driven by heat from Earth’s core
Plate Tectonics
.processes involved in the creation, movement, deformation and destruction of plates
lithosphere is broken into larger and smaller pieces called lithospheric plates
plates may include a continent and parts of ocean basins, or may be restricted to only ocean basins
plates move relative to one another at rates of several cm per year
Alfred Wegener
historic development of plate tectonic theory:
.continental drift - Alfred Wegener (1912)
-coastline fit – Southern Hemisphere continents
-similarities in Paleozoic geology and palaeontology
-single continental landmass – Gondwanaland
theory lacked a convincing mechanism capable of moving continents across surface of Earth
-sea floor spreading eventually became accepted mechanism
Mid-oceanic ridges
subduction zones
oceanic trenches
Mid-oceanic ridges= plates are diverging(moving away from eachother)
Subduction zones(convergence)= where plates collide and one plate is driven upwards by the other
oceanic trenches(subduction)-oceanic plates subducted because of higher density
Transform Plate Boundaries (located on western N.A coastline): name of fault there
San Andreas Fault
describe ocean-continent collision generally
.ocean-continent collision which lies above subduction zone
.continental crust folded and faulted
.oceanic crust subducted(ocean basin to mantle)
-material from ocean including water(hydrated sediments) is subducted also and becomes magma which eventually turns into extrusive and intrusive igneous rock
Describe magnetic stripping
.the formatiion of magnetic strips by the conveyor like movement of new crust away from the Juan de Fuca spreading ridge
.Divergent plate boundaries, oceanic ridges
-ages get older as you move away from crest
Oceanic crust is generally less than ________ years old, whereas some of the continental crust is _______ years old
200 million
severel billions
Active Plate Boundaries vs. Passive Continental Margins
Active Plate Boundaries: Volcanism and Earthquakes are ongoing along subduction zone
.
Passive Continental Margins: Volcanism and Earthquakes are really irrelevant now(non-active)
Hot spot volcanism
Hot Spot Volcansism: An unusual upflow of material from the mantle which stays in place while surface moves above it
Hawaiian island chain formed when a lithospheric plate moved over a stationary “hot spot” in the mantle; provides explanation for occurrence of active volcanoes 1000’s km from plate boundaries (Figure 2.19)
Tuzo Wilson(Canadian)
came up with idea of Hot Spot Volcanism and transform vaults
transform boundary
transform faults joining segments of mid-oceanic ridges associated with horizontal motion
Define Geomorphology
Geomorphology: from the Greek (gē: earth; morphē: form; and logos: discourse) refers to the study of the morphology of the surface of the Earth and the processes operating on it, in the present, past, and the future. (Alan S. Trenhaile 2013)
Geomorphology seeks to:
understand the sequence of landscape development
understand the dynamics of physical, chemical, and biological processes that create landforms
predict the nature of future change based on field observations, physical experiments, and numerical modelling
-geomorphology is used in a wide spread of fields of knowledge
The morphology of the Earth’s surface is created by the constant interaction of _______ processes, those processes that create topographic relief, and ________ processes, those processes that reduce topographic relief.
endogenic
exogenic
Landforms and landscapes resulting from the movement and deformation of the lithosphere are classified into three basic styles
- Tension: lithospheric plates are pulled apart – divergent plate boundaries
- dominated by normal faulting(rocks fail along a steeply inclined surface, typically sloping at an angle of between 45° and 70°)
- these processes occur at mid-oceanic ridges (spreading centres) and contribute to seafloor spreading
- rift valleys and grabens
2.Compression: lithospheric plates are pushed together – convergent plate boundaries
-compression results in shortening of the lithosphere, a combination of folding and faulting, resulting in an increase in elevation and thickening of the lithosphere
– creates orogenic mountain chains
offshore, subduction of oceanic lithosphere creates deep, narrow depression in the seafloor – an oceanic trench
3.Lateral movement: lithospheric plates move horizontally past each other – transform plate boundaries.
two normal faults sloping in opposite directions, create a _____ _____ that flanks a structural depression termed a ._____
rift valley
graben
Pillow lava is made up of _____(extrusive/intrusive) rock
extrusive
BASALT IS AN ________ ROCK(Fine textured igneous rock)
GABBRO IS AN ________ ROCK(coarse textured igneous rock)
extrusive
intrusive
Types of Faults:
- Normal fault
- high angle:one side sliding up while the other slides down
- vertical displacement - Strike-slip fault
- one side sliding in one direction and the other side sliding in the opposite direction
- horizontal displacement - Reverse Faulting
- low angle: one sliding up while the other slides down
- vertical displacement
- common in landscapes marked by compression
mid-oceanic ridges form where magma from the mantle rises and is erupted as _____ lavas forming broad ridges with a central rift valley where plates break apart and move apart
pillow
newly formed oceanic lithosphere, composed largely of basalt and gabbro, moves away from the ridge crest
e.g., Mid-Atlantic Ridge and Þingvellir Graben, East African Rift Valleys
Describe spreading centre of a divergent mid oceanic ridge
new oceanic ridge is created by upwelling of basaltic magma along fractures beneath mid-oceanic ridges. The newly formed crust moves away from the ridge, forming the trailing edges of two oceans plates.
The Þingvellir Graben
example in iceland of
mid-oceanic ridges form where magma from the mantle rises and is erupted as pillow lavas forming broad ridges with a central rift valley where plates break apart and move apart
The _____-______ Graben Rifted margin at Ottawa and st.Lawrence river valley called ______ faulting
Ottawa-Bonnechere
normal
Earthquakes that most commonly occur in the Ottawa area are called ________ earthquakes
intraplate
convergent plate boundaries consist of 3 types: explain each
- oceanic-continent collision
- when they converge. the oceanic plate must subduct beneath the continental plate because the density of thick continental crust is too low to permit it to sink into the aestenosphere - oceanic-oceanic collision
- when a convergent boundary forms between plates of oceanic lithosphere, the plate that is older, thicker, and denser subducts the less dense plate
- can result in volcanic island arc like in Japan
- example in phillipines
3.continent-continent collision
-when subduction brings two continents together limited subduction may occur but the buoyancy of continental crust eventually stops the subduction. The contraction of crust in the collision zone doubles the thickness of continental crust and creates high mountains. Silvers of oceanic crust are commonly uplifted in the mountain range and record the basin consumed by subduction prior to collision of the continents
Ex: india running into china and creating himilayas
-no volcanism just earthquakes
Synchline Vs. Anticlines
Syncline-topographic depressions
Anticlines- topographic relief
Landscapes of compression
Features developed in landscapes marked by compression of rock units include folding and reverse (thrust) faulting.
Folded terrain results from alternating of down-warped synclines and up-warped anticlines—often leading to the development of ridges (anticlines) and valleys (synclines).
A cuesta is a ridge composed of sedimentary bedrock, where one side dips at a gentle angle and the opposite side forms a steep escarpment.
reverse faulting is associated with _________.
explain reverse faulting and the most common one
compression
.Reverse faults move rocks on the upper side of the fault (called the hanging wall) up and over those on the underside of the fault (the footwall). -Thrust faults are the most common class of reverse faults, involving movement over gently inclined surfaces. thrust-faulting is characteristic of compressive terrain associated with subduction zones. the major mountain chains of the eastern Canadian Cordillera, including the Richardson, Mackenzie, and Rocky mountains, are products of thrust-faulting from southwest to northeast, generated by plate tectonic activity.
Where did a continental-continental collision occur that is still shown today?
Appalachians along the eastern seaboard
Granite becomes what kind of rock after metamorphic change
Gneiss- foliated(layered) texture developed from granite in metamorphic change
explain transform( _____-____) faults
rock units are split horizontally by transform (or strike-slip) faults and displaced laterally.
a sharp, clean break occasionally results, with essentially no difference in relief between the two blocks. More commonly, the moving blocks are forced into contact, fracturing rock faces and grinding the contact surface under high pressure.
transform faults are most common on the ocean floor, but some occur on continents; e.g., San Andreas Fault in California, Queen Charlotte Fault west of Haida Gwaii (see Figures 2.12 and 2.15)
PUT THEM IN ORDER AND GIVE TIME PERIOD
Cenozoic
Mesozoic
precambrian
paleozoic
c=66 million to prsent day
m=225 to 66 million
pa=542 million to 225
pr=4.6 billion
Canadian Shield
Canadian Shield was created between 1.96 and 1.81 billion years ago through the collision and welding together of at least six ancient microcontinents
.divided into structural provinces consisting largely of Archean granite (igneous) and gneiss (metamorphic) rocks, welded together by orogenic mountain belts consisting largely of Late Proterozoic volcanic (i.e., greenstones) and metamorphosed sedimentary rocks
landform comprising the exposed part of the North American craton
covered with younger sedimentary rocks in most of United States and Western Canada
craton: refers to old continental crust preserved deep within the centres of continents
North American craton
large continent-sized block of Archean and Proterozoic rock stretching from Mexico to USA, Canada, and Greenland
granite is _______ rocckwhile gneiss is ________
igneous
metamorphic
craton
craton: refers to old continental crust preserved deep within the centres of continents
graben defined
Grabens: faulting defines parts of the Shield boundary and it has brought different rock types into contact with each other within the Shield. Valley-like depressions, or grabens, have been created when a block subsides between two parallel faults.
Appalachian Mountains
rocks range in age from the Precambrian to the Mesozoic
mountain building was associated with the opening and closing of the Iapetus Ocean
closure of the Iapetus Ocean was associated with subduction of oceanic lithosphere and extensive volcanism; an ocean-continent collision
closure was terminated by a continent-continent collision accompanied by folding, thrusting and metamorphism of sedimentary rocks along the continental margin
in the Early Mesozoic continental rifting along the eastern border of this mountain system was associated with the creation of the Atlantic Ocean basin
canadian cordillera
this region includes the mountains of British Columbia, Alberta, Yukon, and Northwest Territories
these mountain ranges have resulted from plate collision and crustal shortening
the eruption of basaltic lavas, the construction of composite volcanoes, the intrusion of granite batholiths, and the folding and overthrusting of continental lithosphere have accompanied ocean-continent collision during the Mesozoic and Cenozoic
Innutian Mountains
this region of Canada experienced rapid deposition of sedimentary rocks and continuous subsidence throughout the early Paleozoic (Cambrian-Devonian)
orogeny in the Late Paleozoic (Devonian-Carboniferous) involved the eruption of basaltic lava and the folding and faulting of the overlying sedimentary rocks
further uplift of the region was associated with the emplacement of granite batholiths (epeirogeny)
subsequent weathering and erosion (Carboniferous-Cretaceous) heralded the return to rapid sedimentation and subsidence
orogeny in the Early Paleogene involved the uplift, folding and faulting of the sedimentary rocks and the intrusion of igneous dykes.
