CAS ES 142 Lecture Notes - Lecture 8: Himalayas, Fringing Reef, East African Rift
22 Feb 2017
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Document Summary
The layer of the mantle below the lithosphere. It is semi-plastic; the high temperature and pressure causes the rock to partially melt, resulting in about 1-2% liquidity. The partially melted rock allows the asthenosphere to be deformed plastically when stress is applied, allowing the movement of lithospheric plates. Give examples of collision, spreading, and shear zones. Collision zone (convergent boundary) --> himalayan mountains, andes mountains. Spreading zone (divergent boundary or rift zone) --> mid-atlantic ridge. Shear zones (transform boundary) --> san andreas fault between pacific and north american plates. Group of volcanic islands that have a curvilinear arrangement and are associated with the subduction of an oceanic plate beneath an oceanic plate. Ocean-ocean plate convergence: subducted plate descends into mantle. Being less dense than the mantle rock, the magma rises towards the surface, some intruding and solidifying with the overlying ocean crust. A small portion reaches the surface and erupts on the ocean floor, producing island arc.
