Geology 1040 Exam 2

(Know This) Sedimentary rocks are usually layered or stratified

(Know This)

Foliation is the alignment of _________ in a metamorphic rock.

(Minerals) (not correct)

Clay minerals within a slate are changed into mica minerals due to the application of heat to a rock. This is an example of ___________.

(Pressure solution) (not correct)

Geologists classify metamorphic rocks according to ___________.

(The size of their crystals) (not correct)

What are the 4 sedimentary rock formations/ classes?

1. Cement looses clasts (Clastic) 2. Cement loose shells and fragments (Biochemical) 3. Accumulation of organic (Organic) 4. Precipitation of minerals in water (Chemical)

Clastic sedimentary rocks are created by :

1. Course clastics - gravel sized clasts - Breccia - Conglomerate - Arkose - Sandstone

Locations where sediments accumulate. They differ in;

1. Energy regime 2. Sediment delivery, transport and depositional conditions 3. Chemical physical, and biological characteristics

What are the 4 major types of magma and their significance?

1. Felsic 2. Intermediate 3. Mafic 4. Ultra-mafic Felsic has the most Silica and ultra-mafic has the least

Magmas vary chemically due to:

1. Initial source composition 2. Assimilation 3. Partially melting 4. Magma mixing

Melting is caused by :

1. Pressure release 2. Volatile addition 3. Heat transfer

What is the metamorphic process?

1. Recrystallization,- minerals change size and shape. Mineral identity does not change 2. Phase Change,- new minerals form with; - the same chemical formula = polymorph - Different crystal structure 3. Neocrystallization,- the creation of new crystals from old crystals, new mineral structure 4. Pressure Solution,- Mineral grains partially dissolve

Igneous activity takes place in 4 plate tectonic settings

1. Volcanic arcs, bordering deep ocean trenches 2. Isolated hot spots 3. Continental rifts 4. Mid-ocean ridges (mostly here)

To show topography in a rugged, mountainous are, the most appropriate counter interval would be

100 feet

A series of concentric contour lines may indicate

A hill and depression

The degree of edge or corner smoothness

Angularity

Alters magma composition

Assimilation

Where do sedimentary rocks form?

At or near Earth's crust

Plutons may amass into a ____________

Batholith

Because the velocity of sediment setting (deposition) is positively related to grain size for waterborne sediments, fluvial deposits are more likely than glacial deposits to ___________

Be well sorted

Geologists call individual layers of sedimentary rocks __________, whereas several of them together are called __________.

Beds; Strata

Sedimentary rocks are arranged in planar, close to horizontal ____________. Several beds together constitute ______________

Beds; Strata

Marble and quartzite are nonfoliated rocks because ___________.

Both are dominated by minerals that produce equant grains

Contour lines on a topographic map

Cannot be drawn below sea level

Meta = ____________ Morphe = ____________

Change Form

Have minerals precipitating from a water solution. Have a interlocking crystalline structure

Chemical sedimentary rocks

__________________ - The diameter of fragments or grains

Clast Size

__________________ - The mineral make-up of sediments

Clast composition

Lithified detritus (breakdown products of preexisting rocks) forms which kind of sedimentary rock?

Clastic

Classification is based on ________ and _________

Composition; Texture

Intrusion of granite into layers of sedimentary rock would cause

Contact metamorphism

The presence of vesicles in an igneous rock is evidence that the source melt ______________

Contained dissolved volatiles

Plagioclase changed from Ca rich to Na rich

Continuous

Slow cooling, crystals have time to grow, intrusive

Course grained

Created by ripple and dune migration

Cross Beds

Interlocking crystals fit like a jigsaw puzzle

Crystalline

If the volatile content of magma is increased, its viscosity will __________

Decrease

Small tick marks (hachure) on contour lines indicate

Depressions

Cuts across rock layers

Dike (dominate in the extrusive setting)

Minerals start and stop crystallizing

Discontinuous

Similar triples except much larger

Dunes

Roughly equal in all dimensions

Equant

The datum on which all latitudes are based is the

Equator

The removal of detritus from weathered rock at an outcrop is termed _________

Erosion

What are the 5 ways sedimentary rocks are created?

Erosion Weathering Transportation Lithification Deposition

What are evaporites?

Evaporated rock from the Sea or Lake

Igneous rocks that cool quickly at the Earth's surface, chills to fast to grow crystals

Extrusive

Lower viscosity

Faster movement

Si rich minerals melt first which is why ______ melts first

Felsic

Which type of magma has the greatest silica content?

Felsic

Removing a partial melt from its source creates..........

Felsic magma and magic residue

Rapid cooling, crystals don't have time to grow, extrusive

Fine grained

___________ melting occurs at subduction zones because the down-going plates ____________

Flux; Contains abundant water

What are the 2 major metamorphic rock subdivisions?

Foliated and Non-foliated

Metamorphism often creates __________

Foliation

Parallel surfaces or layers in metamorphic rocks

Foliation

Distinct rock packages can also be called

Formations

Pieces of pre-existing rock, often shattered

Fragmental

Made of solid glass or glass shards

Glassy

Result from rapid cooling of lava, Fracture os conchoidal

Glassy textures

Distinct compositional bands, often contorted

Gneiss

What are some examples of Hot Spots

Hawaii, Iceland, and Yellowstone

What are the agents of metamorphism?

Heat, Pressure, Hot fluids, Compression of shear

Fine grained Variety of metamorphic minerals

Hornfels

Metasomatism occurs when

Hydrothermal fluids add ions to the rock and/or remove other ions

Formed by cooling from a melt

Igneous rocks

Dimensions are not equal

Inequant

Igneous rocks that cool out of sight, underground. Cooling rate is slower. Grows large crystals

Intrusive

Why does magma rise?

It is less dense than the rock around it and the weight of overlapping rock creates pressure

Within a single mountain range, ____________.

It is possible to find a variety of metamorphic rocks produced in distinct facies, including high-, intermediate0 and low-grade rocks

What does adding volatile do?

It lowers the melting point temperature

________ is on the surface and _________ is below the surface

Lava; Magma

The formation of magma within Earth is NOT caused by which of the following processes

Loss of volatiles to the atmosphere

Hot = __________ and Cool = ___________

Low viscosity; High viscosity

Result is a blob of 1 rock suspended in the other

Magma mixing

The formation of a hotspot is thought to be associated with ____________

Mantle Plumes

Coarsely crystalline calcite or dolomite

Marble

Porphyroblasts are _______________

Metamorphic minerals that have grown larger than the rest of the minerals

____________ can alter any protolith

Metamorphism

Metamorphism changes __________

Mineralogy

No planar fabric evident?

Non-foliated

Thermal (contact) metamorphism produces ________.

Non-foliated rocks only

Contour lines on a map connect points ___________

Of equal elevation

The mantle is made up of ____________ which is ultra-mafic

Peridotite

Fine grained Mica rich rock

Phyllite

An irregular-shaped and blob-like igneous rock body that cooled beneath the surface of Earth is a _____________

Pluton

A mixture of course and fine grained minerals

Porphyritic

An igneous rock with a mixed texture of course crystals (phenocrysts) surrounded by fine crystals (groundmass) is termed _____________

Porphyritic

The primary difference between breccia and conglomerate is that conglomerate ......

Possesses more angular grains than breccia

Cementation of sediments occurs when minerals _____________ the space between sediment grains.

Precipitate in

The application of _______ during metamorphism causes elongated crystals to align parallel with each other. When this happens, the rock develops _______.

Pressure; Foliation

The datum on which all longitude is based is the

Prime Meridian

Preexisting rock that is subsequently altered to form a metamorphic rock is termed a _________.

Protolith

Fragments of violent eruptions

Pyroclastic

Ash, and larger fragments of pumice are all examples of ?

Pyroclastic Debris

Almost put quartz in composition Quartz and sandstone

Quartzite

Collision of two continental plates would cause

Regional metamorphism

Exposure due to sea level fall

Regression

Dynamothermal (regional) metamorphism occurs when ___________.

Rock becomes deeply buried during continental collision and mountain building

Fine to course grain Large micas

Schist

The zero contour line is also known as ___________

Sea level

If mineral grains have been smeared out, the rock was subjected to __________.

Shear

Inject parallel to rock layering

Sill

What makes up an igneous rock?

Size, Shape, and Arrangement

Biochemical limestones are dominantly carbonate mud and fragments of ____________.

Skeletons of marine invertebrates made of calcite and aragonite

Fine grained Low grade metamorphic shale

Slate

The mantle is composed entirely of ___________

Solid peridotite

____________ - The uniformity of grain size

Sorting

The degree to which a class nears a sphere

Sphericity

As compared to metamorphism, diagenesis _______________.

Take place at lower temperatures and pressure

Metamorphic index minerals help geologists determine

Temperature and pressure conditions during metamorphism

Metamorphic changes are due to variations in

Temperature, Pressure, and Reactions with water

Metamorphism changes __________

Texture

Sedimentary rocks are classified on the basis of ____________ and ____________

Texture ; Composition

Protoliths undergo slow solid-state changes in ____________ and _____________

Texture; Mineralogy

The absence of preferred orientation of mineral grains in a metamorphic rock may be due to

The absence of platy minerals like mica, The lack of differential stress (directed pressure) during metamorphism, The absence of elongate minerals like amphibole

The assemblage of minerals in a metamorphic rock helps geologists determine

The chemical composition of the parent rock, The temperature at which metamorphism took place, The pressure at which metamorphism took place

Information on the borders of a topographic map does not include what?

The cost of the map

The term "Metamorphic Grade" refers to

The degree to which it has changed from its original state

The Finer the grain size, _________________

The less energy it took

Foliation and lineation are terms describing

The orientation of minerals in metamorphic rocks

What is an agent that does not cause metamorphism?

Time

Flooding due to sea level rise

Transgression

Grains become rounded primarily during __________

Transportation

This is precipitated from ground water

Travertine

Which of the following does not reflect transport distance?

Type of cement

LIP, or large igneous province's are ..............

Unusually large outpourings of magma

Air pockets

Vesicles

Speed of magma flow governed by ________

Viscosity

A vent where molten rock comes out of Earth

Volcano