Please enable JavaScript.
Coggle requires JavaScript to display documents.
Plate Techtonics (DESTRUCTIVE PLATE BOUNDARY- Intermediate magma is formed…
Plate Techtonics
DESTRUCTIVE PLATE BOUNDARY- Intermediate magma is formed by wet partial melting of the asthenosphere in the subduction zone. Acid magma is formed by wet partial melting of the continental crust
-
-
accretionary prism- massive zones of upthrusted oceanic sediments scraped off the surface of the subducting plate
-
volcanoes- melting of the descending plate triggers volcanism directly above the subduction zone. Andesitic volcanoes
-
Types
-
continental-oceanic- occur along continental margin where they converge e.g along the wear margin of South America
-
-
Continental Plate
Upper- all rocks
Lower- Schist, Gneiss, Granite
-
-
-
-
Causes of plate movement
MANTLE CONVECTION- magma that is hotter and less dense rises at the mid-ocean ridge and cooler, denser magma sinks
RIDGE PUSH- molten magma rises and heats the rock around it which expands and becomes elevated which produces a slope down away. Colder, denser rocks further away slide away due to gravity
SLAB PULL- one plate is denser than the other at a subduction zone. As it sinks, it pulls the rest of the plate with it
-