Earth Sciences 1022A/B Lecture 6: Earth Science Lecture January 26 2016
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7 Aug 2016
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JANUARY 26 2016 LECTURE
SEDIMENTARY ROCKS
Weathered material from various rocks forms sedimentary rocks that comprise 75% of
all rocks on the continents
The word sedimentary means the settling of particles
Diagenesis and Lithification
After deposition, sediment undergoes physical, chemical and biologic changes as it gets
turned into rock
oHardened and consolidated
Lithification includes
oCompaction
Pore space is reduced and particles are pressed closer together
oCementation
Precipitate from solution onto grains fills in the pores and cements the
grains together
Mainly calcite, silica and iron oxides
Detrital Sedimentary Rocks
Formed from rock fragments and minerals deposited by rivers, glaciers, wind and gravity
Mainly made of clay material and resistant quartz
Three main types
oShale
The most abundant sedimentary rock made of slit and clay deposited in
quiet water in lakes, river floodplains and lagoons
Grains are packed together which means water and oil cannot flow
through
Makes a good cap rock for oil and gas
oAlso used for pottery, bricks and tiles
S-7
oSandstone
S-11
Made of sand grains of mainly quartz
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