EOSC 114 Chapter Notes - Chapter 3: Magma Chamber, Pyroclastic Flow, Lava
23 Nov 2017
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Formed by melted pre-existing rocks in earth"s interior. Comprised of melt, crystals of minerals & gas bubbles. Less dense than solid rock (so it rises towards surface of the earth) Some are trapped in the crust & some travel thru fractures in the crust. Magma that travels thru the crust is: less dense than the crust, runny enough to flow (i. e. low viscosity, hot enough to stay liquid. Lava is magma that erupted & cools to form solid rock. 2 primary gases found in magma: co2 & h2o. Most magmas are composed of varying proportions of 8 elements: oxygen (o) greatest amount, silicon (si) greatest amount, aluminum (al, iron (fe, calcium (ca, magnesium (mg, sodium (na, potassium (k) Other elements present but in lesser amounts: titanium (ti, manganese (mn, phosphorus (p, hydrogen (h) Amounts of elements in rocks are reported as weight percentages of oxides e. g: sio2 rather than si & o (bc oxygen bonds with all other common elements)
