Geology Exam 2 Review

Geology Exam 2 Review - Geology Exam 2 Sparknotes okay....

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Geology Exam 2 Sparknotes GossamerOvenMitt : okay. .. well the rock cycle goes something like this. sedimentary and metamorphic rocks are melted in batholiths (large bodies of magma) and some hardens underground, forming intrusive igneous rocks. some goes up to the surface through sills (horizontal magma plumbing) and dikes (vertical magma plumbing) and eventually comes out of a volcano through a pipe. magma becomes lava once it comes out of the earth's surface, and the lava, ash, and tuff that land on the earth's surface eventually harden into igneous rocks. weathering causes sediments to come off these rocks, and water mixing with the sediments causes the sediments to shed minerals, which in turn harden and form a cement around the sediment grains, making sedimentary rocks. GossamerOvenMitt : extreme heat and pressure bend and fold sedimentary and/or igneous rocks and creates metamorphic rocks. These sedimentary rocks and metamorphic rocks eventually become magma again. GossamerOvenMitt : intrusive (formed in the earth) rocks can be exposed at the surface by weathering GossamerOvenMitt : controls on magma viscosity include the silica content (the more silicic the magma- aka felsic- the more viscous it is), the temperature (the hotter the magma, the less viscous). low-silicic magma is called mafic. ultramafic is even less silicic than mafic, and intermediate is between mafic and felsic GossamerOvenMitt : bowen's reaction series GossamerOvenMitt : the lower the silica content, the higher the melting point. olivine is at the top of the discontinuous branch. .. fractional crystallization means that when a body of magma is cooling from a really high temperature, olivine cools first because it melts at the highest temperature, so olivine drops out of the mix like raisins in pudding. then pyroxene, etc. but fractional crystallization means that the cooled olivine reacts partially with the still melted magma to create pyroxene. this creates reaction rims, where the center is still olivine, but a rim of pyroxene is around it, and then so on and so forth until the silicic minerals are reached and cool. GossamerOvenMitt : the continuous branch starts with K feldspar and goes to Na Feldspar at the end GossamerOvenMitt : zones form within the chamber of the continuous branch becuase the minerals form at different temperatures. magma becomes more viscous as it cools because the silica concentration increases as the other minerals separate, and the silica structure becomes more complex as it separates and the magma gets thicker GossamerOvenMitt : partial melting is the reverse of fractional crystallization- different minerals melt at different temperatures, so the silicic minerals melt first GossamerOvenMitt : magma evolution in tectonic settings. .. well, magma is mafic (not so silicic) at divergent boundaries, because it's coming straight up from the mantle, which is ultramafic. it then hardens and forms a mafic oceanic crust. when the oceanic crust meets continental crust at a convergant
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Geology Exam 2 Review - Geology Exam 2 Sparknotes okay....

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