WEEK 4- TECTONIC PLATES Flashcards by Tea Ya

an undifferentiated, homogenous
mass of solid rock when it was formed 4.5 BYA.

Earth

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denser materials sank—less dense materials displaced towards the surface.

Iron Catastrophe

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Liquid layer

Mantle

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Part of mantle with convection currents

Asthenosphere

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solid layer made up of iron and nickel

Inner core

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two types of crust

Oceanic and Continental Crusts

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liquid layer made up of iron and nickel

Outer core

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basalt, 4-7km thickness, much denser(heavier) than continental crust, subducts underneath the continental crust.)

Oceanic

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granite, 20-70km thickness, less dense(will not undergo subduction, lighter.

Continental

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Proposed by Alfred wegener

Continental drfit theory

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he believed that all the continents were connected as one large land mass (Pangea) about 200 million years ago.

Alfred Wegener

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Continents were once a supercontinent called _____ which means “all lands.” Over time, these supercontinents slowly broke apart into what we have today.

Pangaea

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Evidences of continental drift theory:

Distribution of rocks, distribution of fossils, distribution of glacier sediments, paleoclimate, fit of continental shorelines

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these were the main evidence for continental drift during Wegener’s lifetime.

Fossils, rocks, climate clues

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This theory was often rejected because no one could explain how the continents moved. He reasoned that the cause of movements is the Earth’s Rotation.

Continental drift theory

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Why was Wegener’s theory often rejected?

No one could explain how continents are moving

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Some terrestrial organisms are restricted in certain continents because they cannot
swim and cross over the vast oceans that
PRESENTLY separate the continents.

Distribution of fossils

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Coal forms in tropical climates

Paleoclimate

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Orientation of striations or scratches imprinted as glaciers moved along the surface of rocks

Distribution of glacier sediments

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For example, the coast of Africa fits well with the Eastern coast of South America and Southeast coast of North America

Fit of continental shorelines

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Parts of the Appalachian mountains in the
eastern America are like those found in
Greenland and western Europe

Distribution of rocks

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It is the idea that the Earth’s crust and upper mantle are broken into sections called plates that move around on the mantle.

Theory of plate tectonics

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It is the idea that the Earth’s crust and upper mantle are broken into sections called _____ that move around on the mantle.

Plates

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Plate boundaries (3)

Divergent, convergent, transform

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Boundaries between two plates that are diverging or moving away from each other

Divergent

the crust and part of the upper mantle

Lithosphere

the plastic like layer below the lithosphere

Asthenosphere

2 composition of earth's plates?

Lithosphere and asthenosphere

fossils (especially rocks) formed million years ago and contain record of direction of the magnetic poles at the time of formation.

Paleomagnetism

it is the driving force of plate tectonics in which hot, plastic-like material from the mantle rises to the lithosphere, moves horizontally, cools, and sinks back to the mantle.

Convection current

often occur along faults. Faults are breaks in rock mass where plate movement occurred. Faults are associated with plate boundaries.

Erathquakes

Boundaries between two plates that are sliding horizontally past one another.

Transform fault

The crust is broken up into sections that moves on top of liquid mantle

Plates

Boundaries between two plates that are converging or moving towards each other

Convergent

sections or pieces of crusts are called

Tectonic plates

Forms trenches, Destructive Earthquakes, Rapid Uplift of mountain ranges, and building of volcanic arc

Oceanic-continental

Produces trenches and volcanic arcs

Oceanic-oceanic

Produces mountain ranges (himalayas)

Continental-continental

San Andreas fault

Transform

Proposed by Harry Hammond Hess

Sea floor spreading

Presented a mechanism how Pangaea broke apart

Sea floor spreading

Both sides moves away from crust until it sank

Subduction

Recite the 6 stages of Wilson cycle

Embryonic, Juvenile, Mature, Declining, Terminal, Continental collision

seafloor basalts begin forming as continental margins separate. Rift valley deepens and is flooded by seawater.

Juvenile

Wilson cycle begins with-

a rising plume of magma and the thinning of the overlying crust.

The cyclical opening and closing of ocean basins caused by the movement of the Earth's plates.

Wilson cycle

broad ocean basin widens, trenches develop, and subduction begins.

Mature

continents are starting to separate resulting in the formation of rift valleys.

Embryonic

subduction narrows much of the seafloor and oceanic ridge due to converging tectonic plates. This results in the formation of trenches, volcanic island arcs, and coastal mountain ranges.

Declining

ocean basin becomes narrow and shallow due to sedimentation. Young m mountain ranges are formed along the sides.

Terminal

the remaining seafloor is eliminated and continents collide, forming a continental mountain chain.

Continental collision

2 classifications of faults:

Strike slip and dip slip faults

Under dip-slip faults are:

Reverse, normal, and thrust

Faults in which movement is primarily parallel to the dip (or inclination) of the fault surface are called?

Dip-slip faults

Fractures that has no movements

Joints

Fractures in the crust along which appreciable displacement has taken place

Faults

a block that moved down between to subparallel normal faults that dip towards one another

Graben

These are dip-slip faults in which the hanging wall moves down to the footwall

Normal faults

these are dip-slip faults which the hanging wall block moves up to the footwall block.

Reverse faults

consist of two subparallel fault that dip towards each other so that the block between remain high

Horst

Are reverse faults having dips less than 45°, so the overlying block moves nearly horizontally over the underlying block.

Thrust faults

A fault in which the dominant displacement is horizontal and parallel to the trend or strike of the fault surface

Strike-slip faults

The rocks are sliding past each other horizontally, with little to no vertical movement.

Strike slip faults

2 classifications of strike-slip:

Dextral or sinistral

when some strike-slip faults cut through the lithosphere and accommodate motion between two large tectonic plates

Transform fault

Ex. The 1,200 km Philippine Fault Zone (PFZ) that transects the Philippines from Luzon to Mindanao

Left lateral strike-slip or sinistral

A strike-slip fault where the block opposite an observer looking across the fault moves to the left

Left lateral strike-slip or sinistral

A strike-slip fault where the block opposite an observer looking across the fault moves to the right

Right-lateral strike-slip of dextral

EX. San Andreas Fault

Dextral

bending or warping of rock strata caused by compressive stress. The structure that develops is called_____?

Folding, fold

Parts of a fold

Limbs, axis, axial plane

The axes of most folds are inclined. The angle of dip of its axis is the_____?

Plunge

Imaginary plane containing all the fold axes within a deformed layer of rock layers

Axial plane

Two sides or legs of folds

Limbs

Fold types (2)

Anticline and Syncline

Through shaped fold

Syncline

Symmetrical fold in which one limb has been tilted beyond veritcal

Overtuned fold

Arch shaped fold

Anticline

Direction of imaginary line connecting points of maximum flexure of fold

Axis

Bed in a generally flat-lying rock layer

Monocline

If one limb is steeper, the fold is?

Asymmetrical

Anticlines and synclines are ___? if their limbs has approximately equal dips

Symmetrical

A fault in which the axial plane has been overtuned

Recumbent fold

circular or elliptical structural or topographic highs in which beds dip away to all directions; when eroded, the oldest rocks are exposed at the center

Domes

circular or elliptical structural or topographic lows or down warps in which beds dip towards the center; when eroded, the youngest rocks are exposed at the center

Basins

A giant landmass called?

Pangaea

Pangaea means?

All land

When all continents were joined to form pangaea, rest of the earth's surface is covered by a huge ocean called_________

Panthalassa

theory that the outer rigid layer of the earth (the lithosphere) is divided into a couple of dozen "plates" that move around across the earth's surface relative to each other, like slabs of ice on a lake

Plate tectonics theory

Seven major and minor plates: