Wikibooks: HKDSE Geography/M1/Constructive Plate Boundaries

• Format: Book
• Language: English
• Subjects: Antarctic; Mid-Atlantic Ridge; Pacific; Antarc*
• Online Access: https://en.wikibooks.org/wiki/HKDSE_Geography/M1/Constructive_Plate_Boundaries

Constructive plate boundaries are almost always under the sea between two oceanic crusts. They move because of tensional force. = Landforms = Mid oceanic ridges Rift valleys Transform faults Volcanoes = Mid Atlantic Zone (N/S American + Eurasian/African) = Landforms at a glance Mid oceanic ridge called the Mid Atlantic Ridge Transform faults Diverging/Rising magma currents cause the North American Cocos Nazca and Antarctic Plates to move away from the Pacific Plate in the Pacific Ocean under tensional force A constructive plate boundary is formed. Magma wells up from the plate boundary to form a bulging zone. As the uprising and solidification of magma continues newly formed crust is gradually pushed away from the plate boundary by ridge push. This is sea floor spreading. Repeated sea floor spreading forms a mid oceanic ridge called the Mid Atlantic Ridge . When the adjacent flows of magma flow at different speeds lateral force is exerted. The force breaks the mid oceanic ridge and displaces the broken ridges relative to one another horizontally forming transform faults . = Southeast Pacific Zone (N American/Cocos/Nazca/Antarctic + Antarctic) = Landforms at a glance Mid oceanic ridge called the East Pacific Rise Rift valley Transform faults Volcanoes such as Easter Island (Pacific + Cocos) Diverging/Rising magma currents cause the N American Cocos Nazca and Antarctic Plates to move away from the Pacific Plate in the Pacific Ocean under tensional force A constructive plate boundary is formed and magma wells up from the plate boundary As the uprising and solidification of magma continues old crust is gradually pushed away from the plate boundary by newly formed crust. Parallel faults are created. This is called sea floor spreading. Repeated sea floor spreading forms a mid oceanic ridge called the East Pacific Rise . When the adjacent flows of magma flow at different speeds lateral force is created. The force breaks the mid oceanic ridge and displaces the broken ridges to one another horizontally forming transform ...