EESC Midterm 2 Questions

Which of the following properties does not depend on the chemical composition of an igneous rock?

grain size

Which of the following rocks is deposited only by non-biological, chemical precipitation ?

halite

If a body of magma is subjected to fractional crystallization, the rock that results is expected to be

more felsic than the magma

The two most common elements in Earth's crust are

oxygen and silicon

Which of the following types of currents can transport sand grains?

rivers, wind, ocean waves

The surface part of the rock cycle makes sedimentary rocks

weathering -> erosion -> transportation ->deposition ->burial ->compaction ->diagenesis

3 reasons why rocks in the Earth may melt

1.Increase in temperature to raise it above the melting temperature of the rock. 2.Decrease in pressure causes decompression melting. 3.Addition of water to hot rock deep in Earth lowers the melting temperature. Rocks melt initially by partial melting, because different minerals melt at different temperatures. Felsic minerals and rocks melt at lower temperatures than mafic ones

3 types of reactions from chemical weathering

1.dissolution 2.oxidation 3.hydrolosis

Why can studying the equilibrium mineral assemblage in a metamorphic rock give information about the temperature and pressure conditions under which it formed?

As pressure and temperature change, unstable minerals react to form minerals that are stable under the new conditions

What would you expect to find in rocks formed through contact metamorphism?

Minerals that are stable at high temperatures and low pressures

What is the composition of magma?

Solid, liquid, and gas Solid-solidified mineral crystals are borne by the melt Liquid-the melt itself is comprised of mobile ions Si and O, lesser Al, Ca, Fe, Mg, Na, and K, and some other ions

What makes native elements different than all other elements?

They contain only one element

A metamorphic facies is best defined as a group of rocks that:

Were metamorphosed under similar pressure and temperature conditions

Which list of metamorphic facies is in order from lowest to highest grade?

Zeolite, greenschist, amphibolite, granulite

River sediment transport

- Bedload and suspended load - Sorting

Four categories of igneous rock composition

-felsic, intermediate, mafic, and ultramafic -refers to the different amount of silica, iron, and magnesium in the minerals that make up the rocks

Dark silicate minerals that are black and green have a lot of__________; while light-colored silicate minerals such as quartz and fledspar have abundant

-magnesium and iron (mafic) -Silica (felsic)

Three processes by which minerals are made

-precipitated from water -crystallization -cooling of magma

Why is there so much granite in the crust?

1) rocks in the upper mantle might undergo partial melting to produce basaltic magma 2) mixtures of sedimentary rocks and basaltic oceanic rocks, such as those found in subduction zones, might melt to form andesitic magma 3) mixtures of sedimentary, igneous, and metamorphic continental crustal rocks might melt to produce granitic magmas

3 ways rock is created into molten magma?

1. decompression melting 2.flux melting 3. heat-induced melting

Flux v. decompression melting

Flux melting occurs when volatiles enter a wedge in the mantle, and then the volatiles lower the melting temperature, causing volcanism. Decompression melting occurs when material moves upward and pressure is released. While flux melting happens at subduction zones, where there are convergent boundaries, decompression melting happens at hotspots and divergent plate boundaries. Some rocks that are commonly associated with flux melting are intermediate to felsic rocks, like rhyolite, andesite, tuff, and pumice. Rocks commonly associated with decompression melting include migmatite, phaneritic gabbro, and ultramafic peridotite.

What mineral properties relate to light?

Iridescence, florescence, and phosphorescence

Which best describes the primary association between plate tectonics and sedimentation?

Plate tectonics is responsible for most of the large-scale variations in Earth's topography, which leads to sediment transport downhill via gravity.

What is the chemical formula of the silica tetrahedra, the building block of al silicate minerals?

SiO4

A metamorphic petrologist examines the chemical compositions of several mineral grains and notes that the compositions near the centers of the grains are different from those near the rims of the grains. What is the most likely explanation for this?

The composition of the parent rock was not consistent throughout.

According to Bowen's reaction series, the minerals in the discontinuous series react with the magma to become different minerals as the magma cools. Although this was demonstrated experimentally in the laboratory, some of the minerals that form at higher temperatures have been shown to survive as the magma cools. Which of the following describes a mechanism that allows some of these minerals to be preserved as the magma continues to cool?

The crystals that form first settle out of the magma, becoming physically separated from the magma.

The pressure and heat that drive metamorphism result from which three forces?

The internal heat of the Earth, the weight of overlying rocks, and horizontal pressures developed as rocks become deformed

Give two examples of felsic minerals that occur in igneous rocks.

Two examples of felsic minerals that occur in igneous rocks are quartz and feldspar

A clastic rock

a rock formed from the cementation of transported grains

A sill is

a sheet-like intrusion that lies parallel to surrounding layers of sedimentary rock

In which of the following sedimentary environments would you expect the sand deposits to be poorly sorted?

alluvial fan

Why would one mineral (like pyrite) have several different crystal habits?

atoms in its structure can be arranged differently

How are igneous rocks classified?

based on texture and composition

shale refers to a rock formed from

clay minerals

The most common lithification process for fine clastics is _______ .

compaction

What is crystal size dependent on?

cooling rate, rate to where rocks cool within the Earth

Which of the following bond types produces the hardest minerals?

covalent

Which of the following scenarios would lead to melting of Albite plus Water?

either raise the Pressure (P) or raise the Temperature (T)

Which of the following processes is not an important cause of subsidence during the development of a sedimentary basin?

erosion of sediments

what feature is NOT associated with sedimentary rocks?

exfoliation

Three processes that can change the composition of a magma and lead to magma diversity are:

fractional crystallization, magma mixing, and assimilation

Which of the following rocks can be considered gradational between an igneous rock and a metamorphic rock?

migmatite

What type of fault is characterized by the rocks above the fault plane (the hanging wall) moving downward relative to the rocks below the fault plane (the footwall)?

normal faults

An igneous rock with minerals that can be seen with the unaided eye exhibits:

phaneritic texture

Two distinct minerals that have the same chemical composition, but different crystalline structures are called _________.

polymorphs

Which minerals are composed of 3-D framework of silica tetrahedra?

quartz and feldspar

According to Bowen's reaction series, which of the following pairs of phases are likely to be incompatible?

quartz and olivine

What type of metamorphism is caused by high temperature and high pressure imposed over a large volume of crust?

regional

Incorrect statement about rock deformation

rocks under low pressure are more likely to deform ductily than rocks under high pressure

siliciclastic sediments

sediment formed from clastic particles produced by the weathering of rocks and physically deposited by running water, wind, or ice

Which of the following index minerals forms at the highest metamorphic grade?

silimanite

The tendency for variations in a current velocity to arrange sediments on the basis of particle size is called __________.

sorting

three main locations doe volcanoes or igneous rocks

subduction zones, mid-ocean ridges, hotspots

Which of the sand grains above has been transported the furthest?

the roundest one

Coarse clastic material can be transported into a deep marine environment by ______ .

turbidity currents

What controls a mineral's color?

types of elements in the mineral