SCIENCE type of plates boundaries.pdf

SCIENCE -type of plates boundaries- Saturday, 10 August 2024 5:19 pm Sea floor spreading theory - proposed by Harry Hess but fisrt coined by Robert Dietz Continental drift and sea floor spreading theory - conceptual based for development of tectonic plate. Plate Boundaries - bord...

SCIENCE -type of plates boundaries- Saturday, 10 August 2024 5:19 pm Sea floor spreading theory - proposed by Harry Hess but fisrt coined by Robert Dietz Continental drift and sea floor spreading theory - conceptual based for development of tectonic plate. Plate Boundaries - border between tectonic plates. TYPE OF PLATE BOUNDARRIES Consvergence Plate boundarries - "destructive plate boundarries" Consvergence Plate boundarries - when two plates push towards each other that forms either subduction or orogenic belt. Divergent Plate Boundarries - "Constructive plate boundarries" Divergent Plate Boundarries - two plates move away from each other creating a gap or rift between them. - If the gap widens =rift valley - Divergent boun. Between oceanic plates makes mid-ocean ranges > Mid-ocean ridges - mt. ranges formed underwater - As portion of plates moves away from hot spreading center, it cools, contracts and becomes more dense. - Divergent-landmasses are torn apart. - Surrounding waters will fill the gap and later beccame an ocean. - As the two plates move apart, new magma wells up and cools creating new crust.  Ex; Great Esast african rift valley located in sudan,ethiopia,kenya,tanzania Transform plate boundarries - "Conservative bboundarries" Transform plate boundarries - plate slides against each other in opposite direction. No mt./volcanoes are formed instead earthquakes are released from massive energy. KINDS OF CONVERGENCE PLATES BOUNDARRIES Oceanic-to-oceanic convergence - both plates, same density about 3.0 g/cm^3 - When two oceanic plates collide one is uneven totally subducted beneath another. > Long narrow deep sea trenches - mark the zones where plates is subducted. - Plates subducted begins to melt when in contact with the asthenosphere. - Molten material rise, forming volcanic island arc on overriding plate. - Deep sea trench & volcanic island arc = parallel and close to each other.  Ex; formation of hawaiian island Oceanic - continental convergence - Continental crust is less dense = 2.7 g/cm^3. Oceanic crust always subduct. > Trench - will be develop along the zone where the oceanic crust is subducted. - As the oceanic crust descends towards the asthenosphere it began to melt. - Magma rises up through the overriding continental plate forming volcanic mountain ranges at the surface. Volcanic Mountain [ andes, cascades ] > Oceanic trench and volcanic mountains = parallel and close to each other.  EX; formation of volcanic island Continental-continental convergence - Continental plate have low density = 2.7 g/cm^3 - Subduction of continental crust is minimal due to its low density. > During convergence; plate edge are the intensely deformed to construct fold-mountain ranges. - Continents can increase in size during this process by suturing themeselves together along fold-mountain systems.  Ex; himalayas mt. TYPES OF TRANSFORM BOUNDARRIES Ridge-ridge transform fault review for quiz and exam Page 1  Ridge-ridge transform fault - Connects 2 segemet of divergent plate boundarries - Most abundant - Fault cute entire lithosphere - Active displacement occurs only between ridge of segments plate movements in opposite direction - Sustain formidable shearing movement.  Ex; Dead sea Ridge-trench transform fault - Connects reudge and trench - Less common - Longest transform faults are all of this kind. - Form an important connection between spreading and converging plates  Ex; Queen Charlotte, island fault off the western coast of canada. Trench-trench transform boundarries - Pcouple trenches at two different convergent plate boundarries - Rare  Ex; alpine fault in New Zealand. Triple Junction - point at which 3 plate boundarries meet. Triple Junction - involves ridge,trench, transform R ( ridge ) , T ( trench ), F ( fault ) - geologist used this notation to catalogue triple junction. RRR - triple junction, at which plate are moving apart. TTT - plates are pushing together if they are lined up just right. FFF - all of the triple junction, impossible to occur.  Ex; - afar depression triple junction, east african rift system, main ethiopia rift, kenya rift. review for quiz and exam Page 2