Exam 3: Igneous Rocks

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

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?

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

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

How much silica do ultramafic igneous rocks contain?

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

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

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

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

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

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

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 ________.

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.

The aphanitic equivalent of diorite is

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

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

________ typically exhibit pyroclastic textures.

Pegmatites consist of what size mineral grains?

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