CAMBROORDOVICIAN - PowerPoint PPT Presentation

Title: CAMBROORDOVICIAN


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CAMBRO-ORDOVICIAN

• FORMATIONS BETWEEN 500-470 MYA

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LAURENTIA
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NEWALA LIMESTONE

• Overlies Longview Limestone
• Beneath Hiatus
• Member of the Knox Group(Chickamauga Super Group)
• 300 Feet Thick
• Limestone, Dolomite, Chert and Shales
• Fossils include Gastropods and Cephalopods
• Newala Problem

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GASTROPODS
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HIATUS
Due to either erosion or non-deposition an
unconformity occurred in Georgia, Butts and
Gildersleeve state that the Buffalo River group
belongs here. So what happened?
My theory is...
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LOWER ORDOVICIAN
Beginning of the Stones River group -Murfreesboro
Limestone -Mosheim Limestone -Lenoir
Limestone -Lebanon Limestone
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MURFREESBORO LIMESTONE

• Murfreesboro Tennessee
• Oldest of Stones River group
• 425 feet thick
• limestone, chert and shales
• Variance in character
• Brachiopods and Trilobites

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BRACHIOPODS
TRILOBITE
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MOSHEIM LIMESTONE

• Mosheim Tennessee
• Extends from Alabama to Maryland
• 100 feet thick
• Pure CaCO3
• Two outcrops in Georgia
• No fossils found!

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LENOIR LIMESTONE

• Lenoir, Tennessee
• 100 feet thick
• Limestone with interbedded fossiliferous chert
• Only outcrops in Tennessee
• Fossils Found!

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LEBANON LIMESTONE

• Youngest of Stones River group
• Named for exposures near Lebanon, Tennessee
• Estimated thickness of 200 feet
• Fossiliferous limestone with evidence of
  argillaceous or dolomitic fucoids
• Medium gray to dark gray
• Brachiopods and Bryozoans!

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MIDDLE ORDOVICIAN

• Blount Group
• Holston Marble
• Athens Shale - Rockmart Slate
• Tellico Formation
• Ottoossee (Sevier) Shale

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HOLSTON MARBLE

• Located in Georgia and Tennessee
• Found next to Rome Fault
• Reddish, coarsely crystalline limestone
• Approximately 50 - 100 feet thick
• One outcrop!
• Little use in Georgia but exploited in Tennessee
• No Fossils!

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ATHENS SHALE

• Athens Shale located in NE Georgia to parts of
  Tennessee
• Named after Athens, Tennessee
• Gray, sandy layers interbedded with coarse
  sandstone
• One outcrop in Eton, Georgia
• 3,500 feet thick

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ROCKMART SLATE

• Named after Rockmart, Georgia
• Found only in Polk and Bartow Counties
• Clay rock with layers of sandstone
• Interbedded chert, argillaceous limestone and
  limestone conglomerates
• Both Athens and Rockmart are mapped together
• Graptolitics found!

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TELLICO FORMATION

• Not of much importance!
• Located in thin belt from Tennessee to Eton,
  Georgia
• Sandstone with interbedded calcareous shales,
  conglomerates and impure limestones

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OTTOOSSEE (SEVIER) SHALE

• Youngest member of Blount group
• Not much seen in Georgia
• Fossiliferous shale
• Is a deep water facie with fossils of ostracodes,
  brachiopods, bryozoans and trilobites

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LOWVILLE-MOCCASIN LIMESTONE

• Both deposited above the Blount group and below
  the Trenton Limestone
• Lowville, New York and Moccasin Creek, Virinia
• Both are of the same facie
• Lowville, a bluish color, thin bedded limestone
• Moccasin, apart of red bed sequence, red
  argillaceous calcareous rock
• Fossils of Bryozans, Brachiopods and Trilobites

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REFERENCES
Http//home.att.net/cochran3/rocks3/rocks01/gmn4e
301.htm http//www.westga.edu/geosci/GeoClub/Geos
ciences20Trips2020Events/GGS2004 http//www.
beepworld.de/members55/kanada-2003-015/index.htm h
ttp//digilander.libero.it/ufo_zone/gif-eng.htm ht
tp//www.visualsunlimited.com/Images/Watermarked/4
19/419620.jpg http//www.fossilmuseum.net/fossil_G
alleries/USTrilobites/Bathyurellus_teretus/TR016b.
jpg http//www.gly.edu/railsback/BS/Rockmart04.jpe
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