Question

question 29
2 pts
which of the following can be described as an aphanitic crystalline rock containing plagioclase, amphibole, and pyroxene?
rhyolite
basalt
granite
andesite
gabbro
diorite
question 30
2 pts
true or false: many volcanoes exhibit a close temporal association between seismicity and volcanic eruption cycles.
true
false

Explanation:

• For Question 29: Andesite is an aphanitic (fine - grained) igneous rock that commonly contains plagioclase, amphibole, and pyroxene. Rhyolite is usually felsic and may not have all these minerals in significant amounts. Basalt is also aphanitic but has a different mineral - chemical composition. Granite is phaneritic (coarse - grained). Gabbro is phaneritic and more mafic. Diorite is phaneritic.
• For Question 30: Many volcanoes do exhibit a close temporal association between seismic activity and volcanic eruption cycles. Seismicity can be an indicator of magma movement and pressure changes beneath the volcano, which are precursors to eruptions.

Answer:

• Question 29: Andesite
• Question 30: True