Science Study For Tectonic Plates and STUUFSS

5 Mechanical layers of Earth, and composition

Lithosphere (solid, stronk)

Asthenosphere (plastic, weak and deformable)

Mesosphere (solid)

Outer Core (molten, flowing)

Inner Core (Solid)

Tectonic Plates

\-Massive slabs of thin broken apart solid rock

\-Usually composed of both continental & oceanic lithosphere

\-They move across the mantle

7 Major Plates

North American

South American

Pacific

Eurasian

African

Australian

Antarctic

5 Minor Plates

Nazca

Caribbean

Indian

Arabian

Cocos

Rate of Movement of plates

5-10 cm/yr

Divergent

\-plates move apart

\-make rifts from upwelling of magma in crack of lithosphere

\-convection cell for each plate

\-rift gets bigger and when filled forms lakes, seas & oceans

\-sometimes volcanoes

Transform

\-Tectonic plates slide past each other

\-Stuck & build tension & pressure

\-Shallow earthquakes

\-Strike-slip fault: The area between two plates that are split apart

\-no volcanoes

Convergent CC

\-plates collide & crumple

\-possibly forms folded mountain ranges

\-suture zones from deformation & mountain building

Convergent CO

\-oceanic crust denser so subducts under continental crust

\-pushes continental up

\-Continental volcanic arc forms on continental side

\-Trench forms where subduction begins (ocean)

\-Explosive volcanoes from water melting certain minerals (silicates)

\-Earthquakes, tsunamis

Convergent OO

\-denser (older) slab of crust subducts under

\-creates volcanic arc island & trench where subduction begins

\-Tsunamis, explosive volcanoues, & earthquakes

Wegener Continental Drift Evidence

1. Continents fit together like puzzle
2. Fossils match
3. Rock & mountain ranges match
4. Paleoclimate

Plate tectonic theory

\-Tectonic plates with continents & ocean crust move as 1 slab across the asthenosphere

\-Driven by convection from mantle plumes, slab pull & ridge push

Plate tectonic theory evidence

1. Seafloor spreading

\-continental plates older cuz no subduct

\-youngest→oldest matches mid ocean ridge generation

\-more subduction in pacific so younger seafloor

\-ridge pull doesn’t affect sea floor age/speed as much


2. Hotspot chains

\-volcano no occur at boundary, then cuz of hotspot

\-hotspots occur as plate moves over lava plume

\-no plate movement than just 1 island


3. Earthquakes & volcanoes occuring on plate boundaries

\-they follow location of convergent & divergent boundaries

\-deeper earthquakes only occur at subduction boundaries


4. Magnetic stripping

\-polarity changes in bands across the seafloor mirrored on both sides of the rift

\-shows formation of new oceanic crust

Continental Drift vs. Plate Tectonic Theory

\-Wegener’s idea: Pangea, continents moved

\-Plate tectonics explained plate spreading with evidence (constant movement, convection, plate tectonics)

Seafloor spreading

\-Ridge=spreading center

\-Magma upwelling forms new oceanic crust

\-Plates driven apart by convection & divergence

Driving mechanisms of plate motion

Ridge push:

Slab pull:

Plate Suction:

Relation to convection with mantle:

Oceanic vs. Continental

Oceanic denser cuz composition so at convergent, it subducts under continental

Reminder to practice Map

\

CC features

Growing: Himilayas, zagros

Locked: Alps & appalacians

OO features

Mariana islands & trench, aleutian islands & trench, japan trench & islands

OC features

Andes mtns, peru chile trench, cascade mts and cascadia trench

Transform Features

Saint Andreas Fault

Diverging features

East African Rift Valley, east pacific ridge, Indian ridge, mid atlantic ridge