ASBOG - Association of State Boards of Geology Mineralogy and Petrology Questions and Answers

Question 1

A geologist is mapping a regional metamorphic terrain and identifies two parallel belts of metamorphic rocks of the same age.
Belt A is characterized by blueschist and eclogite facies rocks.
Belt B, located continent-ward of Belt A, is characterized by amphibolite and granulite facies rocks.
What is the most likely tectonic setting that produced this 'paired metamorphic belt'?

Accepted Answer

A convergent plate boundary with subduction

Answer

A continental rift zone

Answer

A transform plate boundary

Answer

A mid-ocean ridge spreading center

Question 2

According to the discontinuous series of Bowen's reaction series, which of the following sequences represents the correct order of mineral crystallization as a magma cools?

Accepted Answer

Olivine, Pyroxene, Amphibole, Biotite

Answer

Pyroxene, Olivine, Amphibole, Biotite

Answer

Biotite, Amphibole, Pyroxene, Olivine

Answer

Amphibole, Pyroxene, Biotite, Olivine

Question 3

Which of the following silicate mineral groups is characterized by a framework structure of silica tetrahedra, where all four oxygen atoms in each tetrahedron are shared with adjacent tetrahedra?

Accepted Answer

Quartz and Feldspars (Tectosilicates)

Answer

Pyroxenes (Inosilicates)

Answer

Micas (Phyllosilicates)

Answer

Olivines (Nesosilicates)

Question 4

A coarse-grained igneous rock is composed of 40% quartz, 35% plagioclase feldspar, and 25% alkali feldspar. Using the QAPF classification diagram, this rock would be identified as:

Accepted Answer

Granite

Answer

Granodiorite

Answer

Tonalite

Answer

Quartz Monzonite

Question 5

A geologist is examining a core of clastic sedimentary rock. They note that the loose sand grains from a similar recent deposit have been converted into a solid rock through compaction and the precipitation of calcite between the grains. Which term best describes the overall processes that have occurred after deposition to turn the sediment into rock?

Accepted Answer

Diagenesis

Answer

Metamorphism

Answer

Weathering

Answer

Erosion

Question 6

Which of the following physical properties is LEAST reliable for identifying most minerals, especially varieties of quartz?

Accepted Answer

Color

Answer

Hardness

Answer

Cleavage

Answer

Specific Gravity