Earth Sciences 1022A/B Lecture Notes - Lecture 3: Gabbro, Oceanic Crust, Subduction
17 Jan 2017
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Document Summary
Igneous rocks are crystallize from molten silicate mineral (magma) Magma - forms at high temperatures and pressures deep in the earth. Magma rises through the crust and either reaches the surfaces by volcanoes (extrusive) or cools below surface (intrusive) Extrusive (volcanic) rocks includes pyroclastic material and lava. Intrusive (plutonic) rocks form over millions of years. Bowen"s reaction series - crystals settle in a magma chamber (figure. Earlier dark crystals remove heavy elements, leaving melt with lighter ones (magmatic differentiation) Bowen discovered 2 different series: discontinuous and continuous. Magm a composition can also change through . Assimilation - pieces of host rock falls and melts in magma. Magma mixing - where one body of magma invades another, producing a composition intermediate between the two. Dark (mafic, less silica) vs light (felsic, more silica) mineral content - fe, Igneous textures: size, shape, arrangement of mineral crystals. Aphanitic - small crystals formed by fast cooling magma.
