TCNJ GCH Physics 120 Introduction to Geology … GCH Physics 120 Introduction to...TCNJ Physics 120...

TCNJ Physics 120 Introduction to Geology

Professor Gregory C. Herman [email protected] Manual

GCH 2018-01

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Sources notes within

GCH 2016-17

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TCNJ Physics 120 Introduction to Geology Lab Manual GCH 2018-01

Laboratory 1.

Time-Life-Man.jpg

• One page, hand-written essay

on your interpretation of the

handout.

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Laboratory 2. Minerals and Spectroscopy

• This lab is an introduction to minerals and spectroscopy, the latter being the

scientific study of how light interacts with solid matter.

• The Ward’s mineral sets contain different mineral samples that are found in all

different rock types, including those formed during 1) the cooling of molten

magma into igneous rock, and others from 2) the precipitation of minerals from

a) saturated, briny fluids or b) biological processes.

• By the end of this lab you should have a working familiarity with the 5 most

common rock-forming minerals (quartz, feldspar, mica, amphibole, and

pyroxene) and be able to identify them separately from other minerals that

appear similar but are usually softer and formed from precipitation ((b) above)

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Laboratory 2. Minerals

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• Carbonates (CO3)-2

•Sulfates (SO4)-2

•Phosphates (PO4)-3

Calcite (CaCO3) is the

main constituent in the

sedimentary rock

limestone

Gypsum (CaSO4 . H4O) is a main

constituent in drywall

Turquoise CuAl6(PO4)4(OH)8·5H2O

derived from the shells and hard parts of marine organisms or are precipitated

as seawater evaporates

derived from hydrothermal activity or

are precipitated as saline-water

evaporates

derived from hydrothermal

activity and igneous processes


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http://slideplayer.com/slide/8711262/26/images/9/Types+of+Cleavage.jpg

Laboratory 2. Mineral Cleavage Types


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TCNJ Physics 120

Introduction to

Geology Lab Manual

Laboratory 2.

Minerals

From Cronin, V. S., and

Tasa, D., 11th Laboratory

Manual in Physical

Geology: Pearson, New

York, NY, 426 p.

Mohs Hardness Scale


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Laboratory 2.

Minerals

Adapted from Cronin,

V. S., and Tasa, D.,

11th Laboratory

Manual in Physical

Geology: Pearson,

New York, NY, 426 p.


Silicate Minerals


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GCH Rev. 1.0 12-2015

Quartz – No. 2 of the 5 most common rock-forming (silicate) minerals


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• Identify quartz, calcite, and gypsum by checking the type of habit, cleavage,

and visual aspects that you observe

Quartz (silica SiO4)

Calcite (carbonate CaCO3)

Gypsum (sulfate SiO4)

NOTES:


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• Group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust.

•Two cleavage directions at 900.

•Hardness of 6 – 6.5.

•Will not scratch glass or quartz.

•Microcline and orthoclase

•Not usually clear.

•Often salmon pink or white and milky.

•Can also be aqua blue.

•Can have wavy stripes of similar color that go through the mineral.

Alkali feldspars (K,Na)AlSi3O8

Plagioclase feldspars (Na,Ca)AlSi3O8

•Albite to Anorthite solid-solution series

•Individual crystals a range of colors between white and dark gray.

•Exhibits striations

•Can have wavy stripes of similar color that go through the

mineral.

www.earthguide.ucsd.edu/mystery_detectives/media/flash/minerals_igneous/minerals_igneous.swf

FELDSPAR – No. 1 of the 5 most common rock-forming (silicate) minerals


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• Identify plagioclase and alkali feldspar by color, microscopic twinning, and

mineral habit, hardness with respect to quartz and metal. Note any visual

and physical aspects that you observe.

Plagioclase feldspar (silicate (Na,Ca)AlSi3O8)

Twinning seen on face of large plagioclase sample

Alkali feldspar (K,Na)AlSi3O8)

NOTES:


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• Identify the following minerals by color, and mineral habit, hardness with

respect to quartz and metal and one another. Note any distinctive visual and

physical aspects that you observe.

Mica (biotite and muscovite)

Pyroxene

Amphibole

Olivine/peridotite

NOTES:


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1) Igneous are derived from the hardening of

molten magma (intrusive or volcanic, with felsic,

intermediate, and mafic varieties)

2) Sedimentary are derived from detrital or

chemical sediment, the products of mechanical

and chemical weathering and chemical

precipitation.

3) Metamorphic are the result of burial,

increasing temperature and pressure, and fluid

transfer processes during recrystallization

(low, medium, and high grade)

• Igneous rock forms when hot magma cools and solidifies. Sedimentary rocks form when

sediment is compacted and cemented together (lithified), or when minerals precipitate from

solutions. Mechanical weathering and physical breakdown of a parent material (usually rock)

produces clastic or detrital sediment, whereas chemical sediment is accreted through

biological processes or precipitates directly from hydrothermal or briny waters. Metamorphic

rocks are compacted, heated, pressurized, and altered from burial, thermal contact, and fluid

transfer during recrystallization and alteration.


• Rocks are identified by their textures, colors, and other physical

properties like hardness, weight (density or specific gravity), magnetism

(magnetite), and reactivity with acids (limestone and marble).

• Two rock sets are presented for this lab.

• The Green buckets contain intrusive and extrusive samples of felsic,

intermediate, and mafic igneous rocks.

• The Ward’s mineral sets contain different mineral samples that are found

in all different rock types, not just igneous ones.

• By the end of this lab you should have a working familiarity with the 5

most common rock-forming minerals (quartz, feldspar, mica, amphibole,

and pyroxene) and be able to identify them both in mineral form and in

some of the felsic, intermediate, and mafic igneous rocks.

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GCH 2016-17


Laboratory 3. Igneous Rocks

+1 os

+2 os

os – oxidation state

An element having a

+2 os (or charge) has

a higher electron

affinity because it has

twice the charge than

one with a +1 os.

• Calcium and magnesium (+2) are proportionately more abundant in mafic rocks

that crystallize form magma first with slow cooling and crystal growth.

•Parent magma composition largely determines the composition of igneous

rocks but a single magma can, however, yield different rock types.

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Texture in igneous rocks is related to cooling history; the slower the

magma cools, the more coarse-grained the rock becomes.

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•Typically, the coarsest-grained rocks formed in deep crustal chambers after rising out of the

mantle where it can accumulate and pond at the base of the crust or in the crust, or deep in

the roots of crustal mountain where rocks begin to melt from burial and heat. They become

exposed at the surface Eons after formation from crustal tectonics.

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GCH 2016-17



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_____ SS - red sandstone _______ B - basalt dike leading to basalt flow ______ D - diorite stock and sills

______Gr – granite ________ Pg – pegmatite ______ Gb – Gabbro


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NOTES:

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Laboratory 5. Sedimentary and Metamorphic Rocks

• LAB 5 provides samples of all three principal groupings of rocks including:

1) Igneous (plutonic and extrusive felsic, intermediate, and mafic varieties)

2) Sedimentary (detrital and chemical) and

3) Metamorphic (low, medium, and high grade)

• Because we studied igneous rocks in LAB3,

this will serve as a review for those, but

our focus in this lab will be the different

types and subtypes of sedimentary and

metamorphic rocks and how they

compare to igneous rocks, to one another,

and with respect to the rock cycle.

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• LAB 5 is set up with all three groups of rocks arranged on laboratory tables 1 to 6.

•Each group will systematically move to adjacent tables in a clockwise rotation to study the rocks

at each station for ~20-minute intervals.

VOLCANIC IGNEOUS

DETRITAL

SEDIMENTARY

CHEMICAL

SEDIMENTARYLOW-GRADE

METAMORPHIC

MEDIUM- TO HIGH-GRADE

METAMORPHIC

123

4 5 6

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•The two primary types of sediment are chemical (table 1) and detrital (table 2)

•Sediment becomes lithified into sedimentary rocks by cementation and

compaction.

•Chemical sediment consists of minerals precipitated from solution by

inorganic processes and by the activities of biological organisms.

•Chemical sedimentary rocks (limestone, coal, microcrystalline quartz) are

formed from chemical sediment.

•Detrital sediment consists of solid particles, products of mechanical

weathering.

•Detrital sedimentary rocks are formed by the compaction and cementation,

or lithification of detrital sediment.

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Laboratory 5. Sediment and Sedimentary Rocks

Laboratory 5. Table 1, Chemical Sedimentary Rocks

Chemical sedimentary

rocks are:

a) Precipitated directly

from fresh or sea water

by biological

accumulation,

b) Precipitated from

saturated water (fresh,

marine, and

hydrothermal), or

c) Formed in bogs or

swamps from the

accumulation of dead

organic matter (animal

and vegetation)

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Laboratory 5. Table 1, Chemical Sedimentary Rocks

Checklist:

Limestone (CaCO3 in it’s pure form) is generally soft, gray to cream colored, will

react with HCL, and is softer than metal, and can contains marine fossils.

Dolomite is similar to limestone but is commonly has some Mg+2 replacing Ca+2, can

have an orange tint from also having some Fe+2, is slightly harder than limestone, is

less reactive to HCL

For coal, recognize the peat lignite coal transition and the bituminous versus

anthracite types. Bituminous is lower grade, has more sulfur (yellow mineral) and is

not as shiny. Antracite of higher ‘grade’ as it burens cleaner and gives off more

energy.

Differentiate among cryptocrystalline quartz and limestone that are precipitated

out of hydrothermal solutions or saturated waters.

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Laboratory 5. Table 2, Detrital Sedimentary Rocks

Detrital sedimentary

rocks are transported

and deposited by

running water, wind,

or glacial ice.

Most are composed of

silica grains and/or

mineral and rock

fragments, and are

therefore

differentiated using

grain size.

Common cementing

agents are silica and

calcium carbonate.

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Checklist:

Recognize increasing grain size of mudstone siltstone sandstone conglomerate.

Conglomerate contains rounded grains whereas breccia contains angular grains

The degree of rounding and sorting of grains in the various samples and discuss the

significance with respect to transport distance.

Those cemented with calcium carbonate are commonly more friable and can react

with dilute HCL whereas silica-cemented ones are harder and nonreactive to HCL.

Mudstone and shale differ because the latter has initial layering, or fissility, by the

preferred alignment of play minerals during early phases of burial and compaction.

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Note:

Metamorphic rocks form when minerals in a sedimentary or igneous rocks rock

begin to recrystallize into ne mineral forms when it is subjected to changes (usually

increases) in temperature and pressure from burial or through interaction with

groundwater.

The transition from sedimentary rocks into low-grade metamorphic rocks is gradual

as rocks become more deeply buried and heated through time, therefore it is

sometimes difficult to tell if a mudrock is sedimentary or low-grade metamorphic

without microscopy. Similarly the transition from limestone into a marble

sometimes requires microscopic work.

Generally speaking, metamorphic rocks are more compact and dense than their

sedimentary precursor rocks, have foliation caused by mineral banding or layering

that can be seen with the naked eye. But this isn’t the case for pure quartz or

limestone rocks that can be mono-minerallic and therefore locally lack visible

foliation.


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Laboratory 5. Table 3, Low-grade Metamorphic Rocks

Metamorphic rocks are a

result of new mineral growth

as a result of changing

temperature and

temperatures during burial,

tectonism, and plutonic

igneous activity.

Mostly foliated to

non-foliated silica and lime

rocks that are more dense,

hard, and mineralized than

sedimentary rocks.

Do not ordinarily include

plutonic igneous rocks

because igneous minerals

form at relatively high T & P’s.

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Checklist:

The transition of lime rocks to different types of

marble (foliated and non-foliated)

Hornfels are sedimentary rocks that have been altered

and mineralized by hydrothermal solutions percolating

through them.

The transition from sandstone to quartzite (foliated

and non-foliated).

The transition of mudrock from

mudstone argillite phyllite

Those cemented with calcium carbonate are

commonly more friable, are softer than steel, and

react with weak acid, whereas silica-cemented ones

are harder than metal and don’t react with acid.

Laboratory 5. Table 3, Low-grade Metamorphic Rocks

Quartzite and marble can look very similar, but metal

scratches marble but not quartzite.

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Schist is a medium-grade metamorphic rock with medium to large, flat, sheet-

like grains in a preferred orientation (nearby grains are roughly parallel). It is

defined by having more than 50% platy and elongated minerals, often finely

interleaved with quartz and feldspar.

Laboratory 5. Table 4, Medium-grade Metamorphic Rocks

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Gneiss is a high grade metamorphic rock, meaning that it has been subjected to higher

temperatures and pressures than schist. It is formed by the metamorphosis of granite,

or sedimentary rock. Gneiss displays distinct foliation, representing alternating layers

composed of different minerals.

Laboratory 5. Table 4, High-grade Metamorphic Rocks

Migmatite is a rock that is a mixture of metamorphic

rock and igneous rock. It is created when a

metamorphic rock such as gneiss partially melts, and

then that melt recrystallizes into an igneous rock,

creating a mixture of the un-melted metamorphic part

with the recrystallized igneous part.49


Laboratory 5 Crustal rocks

garnet

A.

B.

C.

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Laboratory 8. Geological Primary and Secondary Structures

• The first exercise for this lab is to study and become familiar with different

sets of secondary structures that I supply from my personal rock collection.

• Different rocks containing examples of rock fractures, cleavage, folds, and

faults will be placed on lab tables to study and discuss.

• After an introductory lecture about the different classes of structures,

groups of four students will rotate to each table in about 10-minute

intervals to inspect an discuss each set of rocks.

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Laboratory 8. Primary and Secondary Rock Structures

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Laboratory 8. Primary Rock Structures

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Laboratory 8. Secondary Rock Structures

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Laboratory 8. Fault Strains and Fabrics

• A cleaved slab of rock with

lithons rotated 30o from simple

shear resulting in lengthening

(~10%) and flattening (~2%).

Rocks can become faulted with planar discontinuities that separate individual lithons, or fault slices

that nestle among themselves with 3D geometries resembling slip cleavage. The transition from slip

cleavage to faulting is a matter of scale and definition.

L2

H3 < H2

• Progressive strains from

shearing, rotation,

flattening, and

imbrication of lithons

occur in fault zones or

shear zones.

• In 3D, faulted lithons

become nestled together

like bunches of aligned

watermelon seeds

slipping past each other.

Shortening, shearing, and flattening

• In reality, lithons are elliptical in profile and terminate in 3D at tip lines.

Smaller lithons from

~20% volume loss

(area reduction in profile)

Larger fault planes

Apparent normal slip (flattening and lengthening)

Apparent reverse slip (thickening and shortening)

OR lithon

Small-fault planes appear as tip lines in profile


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Laboratory 8. Fault Strains and Fabrics

• A cleaved slab of rock with

lithons rotated 30o from simple

shear resulting in lengthening

(~10%) and flattening (~2%).

Rocks can become faulted with planar discontinuities that separate individual lithons, or fault slices

that nestle among themselves with 3D geometries resembling slip cleavage. The transition from slip

cleavage to faulting is a matter of scale and definition.

L2

Shortening, shearing, and flattening

• Cleaved and faulted Lithons are elliptical in profile and terminate in 3D at tip lines.


• Progressive strains from

shearing, rotation,

flattening, and

imbrication of lithons

occur in fault zones or

shear zones.

• In 3D, faulted lithons

become nestled together

like bunches of aligned

watermelon seeds

slipping past each other.

Lithons become

progressively smaller

with higher strains

Larger faults

Apparent normal slip (flattening and lengthening)

Apparent reverse slip (thickening and shortening)

OR lithon

Fault planes appear as tip lines in profile

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TCNJ GCH Physics 120 Introduction to Geology … GCH Physics 120 Introduction to...TCNJ Physics 120...

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