Download Sedimentary Rocks

SEDIMENTARY ROCKS
Sire Kassama
2014
Intro to Info
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Sedimentary: fragments of sediment cemented
together
75% land area composed of sedimentary rock
Lithification: conversion of sediment to sedimentary
rock
Sediment deposited in horizontal layers called
strata or beds
Examples are: sandstone, shale, limestone;
Intro to Info
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Stalactites: limestone is left behind when water
evaporates and hang down from the roof; take
thousands of years to form
Stalagmites: limestone is left behind when water
evaporates and forming upward from the floor
Most sedimentary rocks are clastic or made from
pieces of other rocks
Types of Sedimentary Rock
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Clastic: weathering of pre-existing rocks transported to
basin; texture consists of clasts (large pieces such as
sand or gravel), matrix (mud or fine grained sediment),
cement (calcite, iron oxide, or silica)
Organic
Chemical: Also biochemical sedimentary rock;
evaporites, carbonates, and siliceous rocjs; firm within
depositional basin from chemicals dissolved in
seawater; chemicals may be removed and made into
rocks with assistance from shell growth or biological
processes
Clastic Sedimentary Rocks
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Clastic sedimentary rocks are classified according
to texture (grain size):
1. Gravel: Grain size greater than 2 mm
If rounded clasts = conglomerate
If angular clasts = breccia
2. Sand: Grain size 1/16 to 2 mm.
Sandstone (various types)
3. Clay: Grain size less than 1/256 mm Shale (if
fissile)
Identifying Sedimentary Rocks
Rock
Grain
Color
Hardness
Sandstone
Medium
Red or brown
Hard
Mudstone
Fine
Black gray red or
green
Hard
Clay
Fine
Red or brown
Soft
Conglomerate
Mixed
Red or brown
,edium
Shelly limestone
Medium with
shells
Fine
Brown or gray
Medium
White
soft
Chalk
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What would be the four stages in order of making a
sedimentary rock?
weathering, transportation, deposition,
compaction/cementation
Which sedimentary rock is most likely to be
changed to slate during regional metamorphism?
1. breccia
2. conglomerate
3. dolostone
4. shale
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Need To Know on Rocks
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ROCK NAME
TYPE ( Igneous, Sedimentary, metamorphic)
FORMATION
Igneous (Extrusive, Intrusive) (volcanic, plutonic) (felsic or mafic)
Sedimentary ( Clastic, chemical, biochemical, organic)
Metamorphic (Regional, Contact Metamorphism) (low grade-high grade)
ENVIRONMENT
TEXTURE
Igneous (phaneritic, aphanitic, porphyritic)
Sedimentary (grain size)
Metamorphic Foliated or non-foliated
HARDNESS RANGE
MINERALS
PHYSICAL DESCRIPTION
(Color)
USES
OTHER PROPERTIES
Sedimentary Rocks for The Soul
Limestone
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Is composed of calcite
Fossils are likely to be found within limestone; carbonate
sedimentary rock
Hardness: 4
Made from shells and fossils
Shelly limestone full of small shells
Another type of limestone is called coquina that is mostly made from
shells of sea animals including snails
Oolitic limestone: delicately rolled spheres of calcite
White, gray, or black
Found in Belgium, China, England, Egypt, US
Used Egyptian pyramids
Shale
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Not a clastic rock, but rather an organic sedimentary
rock
splintery rock made from weathering of other clastic
rocks
Most common sedimentary rock
Minerals: kaolinite, smectite, and illite
Used for roof tile, bricks, and pottery when ground up
Hardness: 3
Fossil rock
Bauxite
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Main source of aluminum
Contains more than one mineral so is not considered
mineral
Forms because of the weathering process of soils
mostly in tropical regions
Not easily identifiable by streak and hardness tests
Travertine
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Evaporite
Forms in caves around hot springs
Chalk
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Major mineral within is calcite
A type of limestone made from tiny pieces of the
mineral calcite
Coal
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Organic sedimentary rock
With increased pressure, coal becomes blacker,
harder and better for burning
Most coal formed in the swampy Carboniferous
period
Mineral: carbon
Hardness: 2
Used to generate electricity
Anthracite
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Black, shiny
Found in Australia, China, US
Type of coal
Densest type of coal
Sandstone
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A clastic sedimentary rock
Made from grains of sand stuck together
Rough texture like sand paper
Grains are rounded
Made mainly of mineral quartz
Found in Brazil, China, India, US
Used in the making of buildings
Minerals: quartz and feldspar
Gritstone
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Similar to sandstone but has larger particles and is
not rounded and feels rougher
Clay
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Clastic sedimentary rock
Made of small particles of rock that are too small
to see even with a microscope
Becomes sift and easy to break when wet
Used in facial masks
Minerals found within are kaolinite, smecite and
illite
2-3 on hardness scale
Mudstone
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Made of small particles too small to see without
microscope
Black, gray, red, or green
Very brittle
Conglomerate
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Made of a mixture of different sized rounded rock
such as pebbles, boulders, and sand
Coarse grained clastic rock
Found in high
energy environments
Evaporite
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Chemical sedimentary rock
Minerals: qypsum and halite
In dry regions, where limited fresh water flows,
evaporites begin to dry out, as the water
evaporates, minerals dissolved in water begin to
harden and crystallize
Used in chemical industry for hydrochloric acid,
plastics, and plaster of Paris
Chert
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Sedimentary rock with microcrystalline and quartz
Dolostone
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Hard to distinguish from limestone
Carbonate sedimentary rock
Minerals composition includes calcite, dolomite, and
aragonite
Other Resources
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The following questions and answers are from the
New York State Regents Website:
http://www.regentsprep.org/Regents/core/questio
ns/topics.cfm?Course=ESCI
Geology.com
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Carbonate: fossiliferous limestone composed of fossils in
limestone matrix; oolitic limestone is dossil hash cemented
together; chalk made of planktonic organism such as
coccolithophores
Siliceous rocks: dominated by silica; form from silicasecreting organisms such as diatoms, radiolarims, or
sponges; chert is formed through chemical reaction of silica
in solution replacing limestone
Diatomite: siliceous rock; made of diatoms
Coal: electricity: chemicals derived are used in plastics, tar,
synthetic fibers, medicine, and fertilizer
Organic Sedimentary Rocks (Coal)
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Plant fragment rocks accumulate in swamps or marshes
Lack minerals which must be organic
Peat: porous mass of brownish plant resembling moss
Lignite: crumbly and black
Bituminous coal: dull to shiny, black sooty with visible
layers
Anthracite coal: very shiny, slightly golden, low density,
no soot