Sedimentary Rocks Fossils - WOU Homepagebrownk/ES105/ES105.2012.0306.SedsFossils.pdf · Shale with plant fossils ... Travertine (calcite) and sinter (silica) from

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Sedimentary RocksFossils

Sedimentary rocks

Two main types

Rocks formed by deposition of sedimentClastic

Rocks formed by precipitation from waterChemical (includes rocks formed by organisms)

Clastic Sediment Grains

Particle loosened from pre‐existing rock

Transported to place of deposition

Shape, size, and sorting of grains can tell about the environment of deposition

Lithification

Process of becoming stone Burial and compaction

Precipitation of cementp

Each reduces ‘pore space’

Cement

Brought in by water

Mineral material between grains

Fills in pore spaces

Commonly calcite, silica, and sometimes iron oxide

Bedding and bedding planes

STRATA• http://www.birdandhike.com/Hike/General_Info/Glossary/Gloss4.htm

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Types of Clastic Rocks

Shale (most abundant)

Sandstone

Conglomerate

Fossils

Traces or remains of prehistoric life

Are the most important inclusions

Help determine past environments p p

Used as time indicators

Used for matching rocks from different places

Shale with plant fossilsShale

Composed of very fine grained sediment

Shows obvious tendency to split along planes (fissile)

Usually gray

Most common type of sedimentary outcrop

Sandstone Sandstone

Composed of sand‐size particles Between 1/16 mm and 2 mm diameter

Particles may be individual mineral grains or rock fragments

Q f i Quartz most common type of grain

Environments include

•Beach,

•river,

•shallow sea,

•sand dunes

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Conglomerate Conglomerate

Composed of particles larger than 2 mm

Usually particles are rock fragments

Clastic rocks

•Shale is the most common one

•Made from solid particles

•Classified by particle size y p

Chemical rocks

Material was once in solution and precipitates to form sediment

•Directly precipitated as the result of physical processes or physical processes, or

•Through life processes (biochemical origin)

Chemical rocksLimestone

Composed of the mineral calcite (calcium carbonate)

Much of this calcite was precipitated by organisms

Considered an ‘organic chemical sediment’ if from gorganisms

Most common type of chemical rock—

second most common type of sedimentary rock

Chalk

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Fossiliferous limestoneCoquina

Close up of coquina Chemical rocksDirect mineral precipitation from water

Evaporites such as rock salt or gypsum

Microcrystalline quartz (precipitated quartz) known as chert, flint, jasper, opal or agate

Travertine (calcite) and sinter (silica) from hotspring deposits

Travertine

• http://njminerals.org/travertine.html

• http://www.gonomad.com/destinations/0409/hot_springs_of_the_sierras.html

• http://www.cis.nctu.edu.tw/~whtsai/World%20Highlights/New%20Side%20Show%20Webpages/imagepages/Turkey%202001‐‐‐Travertine%20stones%20and%20water%20in%20Pamukale.html

Evaporites

• http://www.bonnevillehealeyclub.org/

• http://www.img.uni‐karlsruhe.de/925.php

• http://www.paintersflat.net/saltflat.html• http://www.nv.blm.gov/Winnemucca/blackrock/BRHR_Planning.htm

• http://www.pitt.edu/~cejones/GeoImages/1Minerals/2SedimentaryMineralz/Gypsum.html

• http://www.flickr.com/photos/snogun/191723596/

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Rock salthttp://geomaps.wr.usgs.gov/sfgeo/geologic/stories/marin_sedimentary.html

• http://www.mii.org/Minerals/photochert.html

Chert

• http://homestake.sdsmt.edu/Photos/Surface_geology_photos.htm

Classification of sedimentary rocks Features of sedimentary

rocks Porosity

Permeability

Sedimentary rocks

Economic importance

• Coal

• Petroleum and natural gas

• Precipitation of iron and aluminum

• Deposition of gold and tin

• Sand, gravel, clay

Fossils: evidence of past life

Remains or traces of prehistoric life

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Petrified

Cavities and pores are filled with precipitated mineral matter

Petrified

Formed by replacement

Cell material is removed and replaced with mineral matter

Mold

Shell or other structure is buried and then dissolved by underground water

Shape is preserved in the surrounding sediment http://www.ammonoid.com/Manning.html

Cast

Hollow space of a mold is filled with mineral matter

Carbonization

Organic matter becomes a thin residue of carbon. This is a

f‘compression’ of the original organism

Impression

Replica of the fossil's surface preserved in ffine‐grained sediment

http://www.lfbuffalo.org/exhibitions/map/t/

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Preservation in amber

Hardened resin of ancient trees surrounds an organism

Indirect Evidence Includes

Tracks

Burrows

Coprolites

fossil dung and stomach contents

Gastroliths

stomach stones used to grind food by some extinct reptiles

Tracks

Dinosaur footprint in fine‐grained limestone near Tuba City, Arizona.

Types of fossils

Petrified

Formed by replacement

Carbonization

Impression

i ireplacement

Mold

Cast

Preservation in amber

Indirect evidence

Conditions favoring preservation

Rapid burial

Possession of hard parts

Fossils and correlation

Principle of faunal succession

Index fossils

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Principle of faunal succession

Proposed by William Smith –late 1700s

Fossil organisms succeed one another in a definite and d bl d h fdeterminable order, therefore any geologic time interval can be recognized by its fossil content

http://www.lfbuffalo.org/exhibitions/map/a/

Geologic Time Scale

Archean through Devonian

http://rst.gsfc.nasa.gov/Sect2/Sect2_1b.html

Carboniferous through Quaternary

http://rst.gsfc.nasa.gov/Sect2/Sect2_1b.html

Cambrian Marine Life

http://www.handprint.com/PS/GEO/geoevo.html

Trilobite

http://www.ststephens.it/biology/fossils.html

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Crinoid—380 ma

http://www.lsa.umich.edu/exhibitmuseum/exhibits/temporary_exhibits/

Ordovician sea floor

http://www.uwsp.edu/geo/faculty/hefferan/Geol106/CLASS6/MAIN%20PAGE.htm

Ordovician Invertebrates


Silurian reef

Silurian Reefhttp://hoopermuseum.earthsci.carleton.ca/camex/1rpaleoreef.html

Silurian Landscape

http://www.nasa.gov/worldbook/earth_worldbook.html

Devonian Sea


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Mid Paleozoic

http://www.tufts.edu/as/wright_center/cosmic_evolution/docs/text/text_bio_4.html

Late Paleozoic


Carboniferous Fern Forests


Permian Sea


Permian Reptiles


Permian Extinction

Link to hypotheses of the Permian Extinction

80‐95% of marine species died out

70%+ of terrestrial vertebrates

Largest extinction episode in geologic record

http://en.wikipedia.org/wiki/Permian_extinction

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Geologic Time Scale Mesozoic

http://geography.berkeley.edu/ProgramCourses/CoursePagesFA2002/Geog40/Geog40.Week7.html

Mesozoic

http://serc.carleton.edu/introgeo/earthhistory/dinosaur.html

Mesozoic


Mesozoic


Archeopteryx

http://www.researchcasting.ca/sculpt%20miami.htm

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Mesozoic Mammal

Eomaia

http://www.amnh.org/exhibitions/dinosaurs/diorama/

Mesozoic Mammal

Repenomamus

http://www.amnh.org/science/papers/mesozoic_mammal.php

Jurassic

http://www.worldbook.com/features/dinosaurs/html/world_mesozoic.html

Cretaceous

http://www.worldbook.com/features/dinosaurs/html/world_mesozoic.html

Mesozoic Sea


Mesozoic sea

http://www.uky.edu/AS/Geology/webdogs/time/mesozoic/mesozoic.htm

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Cretaceous Extinction

Perhaps 60% of species died

Result of radical change in environment

Perhaps Earth encountered a large meteorite—

10 km in diameter

90,000 km/hr

Equivalent to 100 megatons of TNT exploding

Cenozoic mammals


Cenozoic


Cenozoic

http://www.uky.edu/AS/Geology/webdogs/time/cenozoic/cenozoic.htm

Cenozoic

http://www.copyrightexpired.com/Heinrich_Harder/cenozoic.html

Geologic Time Scale

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Sedimentary Rocks Fossils - WOU Homepagebrownk/ES105/ES105.2012.0306.SedsFossils.pdf · Shale with plant fossils ... Travertine (calcite) and sinter (silica) from