Earth Sciences 1023A/B Lecture Notes - Lecture 16: Andesite, Oceanic Crust, Continental Crust
25 Mar 2016
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Document Summary
The degassing of magma through volcanism created both the atmosphere and the hydrosphere. 3 ways that earth melts rock: plume heating (intra-plate: hot spots, decompression melting (divergent boundaries, hydration melting (convergent boundaries) Depth zone of partial melt depends on where the geotherm intersects the solidus. The geotherm compared to the mantle solidus is key. If the asthenosphere becomes hot enough, it will start to melt. This can happen with the arrival of a mantle plume, which can be > 1400oc. Intra-plate (hotspot volcanism: thought to arise from warm material (plumes) originating at the core/mantle boundary, plumes are warmer than the surrounding mantle which causes them to rise. Volcanism: thought to arise from warm material (plumes) originating at the core/mantle boundary, plumes are warmer than the surrounding mantle which causes them to rise. The rising plume is hot enough to melt the rocks in the crust and uppermost mantle. Location of hotspots do not closely coincide with plate boundaries.
