Lab 1 Flashcards by Iviana Chmielowski

Q

Sediments

A

form from the breakdown of pre-existing rocks
1. igneous
1. metamorphic
1. sedimentary

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Q

How are sediments made?

A

rocks are broken down by chemical and physical weathering and erosion into particles called “clasts” and into ions in solution.

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Q

Chemical Sedimentary Rocks

A

form when dissolved ions percipitate out of solution

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Q

Biochemical Sedimentary Rocks

A

form when organisms use materials dissolved in water or air in order to build their tissue and “hard parts”
(e.g. bones, shells)

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Q

Clastic Sedimentary Rocks

A

are composed of lithified detrital sediments

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Q

Lithification

A

is the process that transforms loose sediments into solidified rocks
* occurs through compaction and cementation

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Q

Detrital

A

particles of rock derived from pre-existing rock through weathering and erosion

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Q

Clast

A

a fragment of rock that was broken from a larger rock or rock unit

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Q

Common Cements

A

calcite
quartz
clay minerals
iron oxides

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Q

Lithology

A

the mineralogical composition and textural charecteristics of sedimentary rocks

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Q

Categories of Sedimentary Rock Textures

A

Grain Size
Rounding
Sorting
Grains and Matrix

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Q

Pebbles

Grain Size of Sedimentary Rock

A

4-64 mm
coarse grained: > 2 mm

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Q

Granules

Grain Size of Sedimentary Rock

A

2-4 mm

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Q

Coarse Sand

Grain Size of Sedimentary Rock

A

0.5-2 mm

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Q

Medium Sand

Grain Size of Sedimentary Rock

A

0.25-0.5 mm

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Q

Fine Sand

Grain Size of Sedimentary Rock

A

0.06-0.25 mm

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Q

Clay

Grain Size of Sedimentary Rock

A

< 0.004 mm
very fine grained: <1/256 mm

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Q

Silt

Grain Size of Sedimentary Rock

A

0.004-0.06 mm
fine grained: 1/256 to 1/16 mm

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Q

Grain Size Categories

A

Pebbles
Granules
Course Sand
Medium Sand
Fine Sand
Silt
Clay

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Q

Rounding Categories

A

Angular
Sub-Rounded
Well-Rounded

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Q

Sorting Categories

A

Poorly Sorted
Well-Sorted

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Q

Grains

A

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Q

Matrix

A

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Q

Mineral

A

homogeneous naturally occuring crystalline solid with a definite crystal structure

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Rocks

made up of 1 or more minerals

Rocks are made up of ____ or more ____.

1, minerals

Fracture

When minerals tend to break along rough or uneven surfaces

Cleavage

the tendency of a mineral to split along flat surfaces or planes of weakness

Luster

the way the surface of the mineral reflects lightw

Examples of Luster

* metallic * glassy * dull * pearly * greasy * earthy

Depositional Environments

Deposited at the Earth's surface by wind, water, glacier ice, or biochemical processes

Sedimentary rocks are typically deposited where?

In strata (layers) under cool surface conditions

Clastic Sedimentary Rocks

made up of **clasts** (broken off particles) and **cement** (typically calcite, quartz, or hematite)

Examples of **clastic** sed. rocks:

* conglomerate * shale

Chemical Sedimentary Rocks

depositied by inorganic means such as precipitation or evaopration

**Chemical** sed. rocks commonly consist of how many minerals?

1

Examples of **chemical** sed. rocks:

* rock salt * oolithic limestone

Biochemical Sedimentary Rocks

formed through the actions of living organisms

Examples of **biochemical** sed. rocks:

* bituminous coal * chert

High Energy Environment

can carry large and small particles

Examples of **high energy environments**:

dunes

Low Energy Environment

can carry small particles

Examples of **low energy environments**:

swamps

Particle size indicates?

indicates the energy of the transportation medium

larger grain size = ........... | Particle size

more energy needed

# what is the sediment maturity of: Arkose

immature

Arkose is:

poorly sorted & poorly rounded

# what is the sediment maturity of: Quartz Sandstone

mature

Quarts Sandstone is:

well sorted & well rounded

Textural Maturity

* angulatiry * sorting | maturity does not refer to "older" or "younger" rock

Angulatity

degree to which the individual sedimentary particles are rounded 1. well rounded 2. sub rounded 3. angular

Sorting

degree to which the sedimentary particles are the same size * well sorted * poorly sorted

Well Sorted

all particles are the same size all grains are nearly the same size

Poorly Sorted

different sizes together large and small grains jumbled together

As sediments get more mineralogically mature...

* unstable minerals such as feldspars are removed * stable minerals as quartz are left alone

Well Rounded

all corners of a grain are rounded off

Angular

all corners of the grain are relitively sharp (pointed)

Poor sorting suggests?

that the particles have not been trasported very far

Particle size indicates?

the energy of the transporting medium

The larger the size of grains in a clastic rock, the ................ energy it took to move that particle to the place of deposition

more

# Identify the **clastic** sedimentary rock * Coarse Grains >2 mm * Any rock type * Rounded clasts, varied clast size

Conglomerate

# Identify the **clastic** sedimentary rock * Coarse Grains >2 mm * Any rock type * Angular clasts, varied clast size

Breccia

# Identify the **clastic** sedimentary rock * Fine Grains 1/16 to 2 mm (can be seen with naked eye) * Quartz with minor accessory minerals * White, tan, brown; sandpapery feel, well sorted

Quartz Sandstone

# Identify the **clastic** sedimentary rock * Fine Grains 1/16 to 2 mm (can be seen with naked eye) * Quartz with at least 25% potassium feldspar * Often reddish because of potassium feldspar, made of poorly sorted sand

Arkosic Sandstone

# Identify the **clastic** sedimentary rock * Fine Grains 1/16 to 2 mm (can be seen with naked eye) * Rock fragments, mica, clay, quartz * "Dirty" looking, dark colored; sandpapery feel

Graywacke

# Identify the **clastic** sedimentary rock * Very Fine Grains <1/16 mm (can NOT be seen with naked eye) * Silt and clay mixture * Smooth 1/16-1/256 mm, some grains may be seen with a hand lens

Mudstone

# Identify the **clastic** sedimentary rock * Very Fine Grains <1/16 mm (can NOT be seen with naked eye) * Quartz and clay minerals * Gritty, 1/16-1/256 mm, some grains may be seen with a hand lens

Siltstone

# Identify the **clastic** sedimentary rock * Very Fine Grains <1/16 mm (can NOT be seen with naked eye) * Clay sized particles; <1/256 * Compact, may split easily

Shale (can be classified by color)

# Identify the **chemical** sedimentary rock * Crystalline * Calcite (CaC03) * Fizzes with dilute HCl, crystalline

Crystilline Limestone

# Identify the **chemical** sedimentary rock * Generally very fine grained * Calcite * Fizzes with dilute HCl, Ooids (tiny spheres)

Oolitic Limestone

# Identify the **chemical** sedimentary rock * Crystalline * Halite (NaCl) * Evaporite, tastes salty

Rock Salt

# Identify the **chemical** sedimentary rock * Crystalline or very fine grained * Gypsum * Evaporite, hardness of 2

Gypsum

# Identify the **biochemical** sedimentary rock * Crystalline and/or bioclastic * Calcite * Abundant fossils, fizzes with dilute HCl

Fossilferous Limestone

# Identify the **biochemical** sedimentary rock * Varied, course to fine * Calcite * Fossils, fossil fragments, and shells; loosely cemented, fizzes rapidly with dilute HCl

Coquina

# Identify the **biochemical** sedimentary rock * Varied * Carbonaceous material * Plant remains, brown, soft, porous

Peat

# Identify the **biochemical** sedimentary rock * Varied * Carbonaceous material * Plant remains, brown

Lignite

# Identify the **biochemical** sedimentary rock * Varied * Carbonaceous material * Plant remains, black, sooty, blocky

Bituminous Coal

# Identify the **biochemical** sedimentary rock * Crystalline * Calcite * Non-friable; fizzes with dilute HCl

Crystalline Limestone

# Identify the **biochemical** sedimentary rock * Crystalline * Dolomite * Non-friable; fizzes with dilute HCl only when powdered

Dolostone

# Identify the **biochemical** sedimentary rock