CH 04 VISUAL QUIZ

Certain minerals are commonly found together in different igneous rocks. According to the following figure, which two minerals are you unlikely to find forming in the same rock?

quartz and olivine

Geologists use mineral composition to help categorize igneous rocks. From the information provided in the chart, which minerals would you expect to find in granite?

quartz, k-feldspar and plagioclase

Geologists use composition (mineral content) and texture (grain size) to classify igneous rocks. Use the chart below to provide the name of a mafic rock that cooled slowly.

gabbro

Igneous rocks are formed by cooling magma or lava. Whether the rock cools intrusively or extrusively has a profound impact on a rock's texture. Which statement BEST describes the texture and depositional environment of the rocks shown in the figure?

glassy to fine-grained from cooling extrusively

The texture of an igneous rock is dependent on its emplacement mechanism (how and where the lava or magma cooled). Match the following images with their emplacement mechanism;

A - Intrusive, B - Pyroclastic, C - Extrusive

The following image shows samples, both in hand sample and in microscope thin-section views. The textures are the result of their emplacement mechanism (intrusive, extrusive, or pyroclastic). Match the texture term with the appropriate picture set.

A- Crystalline, B - Fragmental, C - Glassy

The following four figures show several different tectonic settings where volcanism is active. Which of the following images shows a tectonic environment where magmas were produced by flux-melting?

B

This is a picture of a basaltic lava flow. Choose the letter on the image that BEST approximates how a rock like this would form.

C

Viscosity is a material's resistance to flow. The pictures below show two types of volcanic eruptions. In the first, lava is fountaining and flowing freely, making a gently sloping volcano. In the second eruption, a thick plug of lava called a dome has emerged in a volcanic crater. Which of the following statements BEST describes the relative viscosity of these two eruptions?

The lava dome (2) is higher viscosity than the fountaining lava (1).

In this image, volatiles that were driven off of the subducting slab have caused the mantle to melt. What kind of melting does this figure show?

flux melting