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1) Name three minerals that will crystallize in a) basalt b) andesite c) dacite

ID: 288415 • Letter: 1

Question

1) Name three minerals that will crystallize in a) basalt b) andesite c) dacite d) rhyolite. In order to evaluate the differentiation of volcanic rocks, you (yes, as in you) can use either compatible or incompatible elements. Determine one compatible major element for each of the minerals in Question #1 that will be removed as crystal fractionation progresses. You should have at least three major elements that will be removed from the melt during crystal fractionation for each magma composition (i.e., basalt, andesite/dacite, and rhyolite) Do not use Si. 2) 3) As such we could use this element as a monitor of the removal of the mineral in question. So plot your "compatible" major elements vs SiO2. Does the chemistry changes in the 1) basalts, 2) andesite and dacites, and 3) rhyolites reflect a depletion in these compatible elements as you would expect if crystal fractionation were involved? Describe what you se changes that result. e chemically and the chemical

Explanation / Answer

1 (a) Basalt- Diopside(clinopyroxene), Anorthite( plagioclase feldspar) and Fosterite (olivine)

(B) Andesite- plagioclase feldspar ( andesine) , biotite, pyroxene/amphibole

(C) dacite- plagioclase ( andesine), amphibole (hornblende), pyroxene (augite), biotite

(D) rhyolite- quartz, k-feldspar( sanidine/microcilne), plagioclase

2. (A) Basalt- compatible elements: diopside- Nb, anorthite- Eu, Fosterite- Cr

(B) andesite- compatible elements: plagioclase- Eu, biotite- Sr, pyroxene- Ti

(C) dacite- compatible elements: plagioclase-Eu, hornblende- Y, pyroxene - Fe, biotite- Sr

(D)rhyolite- compatible elements: quartz- Al, k-feldspar- Rb, plagioclase- Eu