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Exam 3: Igneous Rocks

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Question 81

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The average geothermal gradient in the upper crust is about 25° C/km.

A) True
B) False

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Question 82

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The most common ferromagnesian silicate minerals by % in igneous rocks are ________.

A) aragonite, barite, calcite, and diamond
B) feldspar, quartz, and muscovite
C) magnetite, chromite, hematite, and ilmenite
D) olivine, pyroxene, amphibole, and biotite

E) A) and B)
F) B) and C)

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Question 83

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Olivine and quartz commonly crystallize together from mafic (basaltic)magmas.

Earth's crust and mantle are composed predominantly of solid (not molten)igneous rocks.

Which of the following best describes the composition and form of the typical felsic bedrock in the Coast Ranges of BC, highlands of Nova Scotia, or the Sierra Nevada Mountains in California?

How much water does it take to lower the melting point of basalt by 100 degrees?

Glassy pyroclastic deposits that fuse together as they fall are called ________.

The partial melting of a gabbro deep in the crust could generate a felsic (granitic)magma.

Pegmatites consist of what size mineral grains?

As the silica content varies from less than 40% to more than 70% there is a systematic ________.

The most abundant elements in common crustal igneous rocks are ________.

________ typically exhibit pyroclastic textures.

What term denotes the larger mineral grains in a porphyritic igneous rock?

Which of the following is the dominant lava erupted from volcanoes in Hawaii and Iceland?

Examine the words and/or phrases for each question below and determine the relationship among the majority of words/phrases. -Choose the option that does not fit the pattern.

Which of the following igneous rocks is composed mainly of ferromagnesian minerals with less than 20% feldspar?

Basalt is the aphanitic or fine-grained equivalent of gabbro.

How much silica do ultramafic igneous rocks contain?

Which of the following high silica igneous rocks can be of low enough density to float on water?

The aphanitic equivalent of diorite is