GEOL 1 Lecture Notes - Lecture 7: Oceanic Crust, Partial Melting, Peridotite
Document Summary
Gold has a very low melting point- similar to quartz- the last things that crystalizes. Partial melting: melt part of the rock, and fractional crystallization: big thig of magma and cool it down and you start crystalizing from the top-down. Partial melting: as a rock heats up and begins to melt, bowen"s reaction series operates from the bottom up. The most silica-rich end of the rock"s composition begins melting first. Magma tends to be more silica-rich than the parent rock that it was generated from. Peridotite: 45% silica, rich in fe, mg, ca. Basalt/ gabbro: 50% silica, rich in fe, mg, ca. Starting with the mantle: peridotite: 45% silica, rich in fe, mg, ca partially melts along rising plumes in convection cells in the mantle. Basalt/ gabbro: 50% silica, rich in fe, mg, ca- it forms oceanic crust- and eventually bump into another oceanic crust and gets subducted back in.
