Pliocene, Miocene, and Oligocene

1
Pliocene, Miocene, and Oligocene

• Jordan Garrard

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Oligocene

• 1993 17 separate lithostratigraphic uints
  formations
• Will only speak about two formations
• Suwannee Limestone Formation
• Lazaretto Creek Formation

3
Suwannee Limestone

• Suwanee Limestone is a widely distributed
  formation underlying the majority of the eastern
  Coastal Plain of Georgia
• Soft, recrystallized, massive bedded and does not
  contain macrofossils
• Dolomite is found in localized areas

4
Lazaretto Creek Formation

• Ranges from unconsolidated, calcareous quartz
  sand to soft, friable, calcareous quartz
  sandstone to friable, unconsolidated, sandy fine
  to medium grained calcarenitic limestone
• Separated by an unconformity producing an early
  Oligocene and late Oligocene formation with a
  phosphate rich lag bed

5
Miocene

• 5.3 to 23 million years ago
• Has been extensively study in the state of
  Georgia
• Stratigraphy of Miocene sediments in Georgia
  consists of one major Group

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Miccosukee Formation

• Has been identified as numerous other formations
• Characterized by thinly-bedded to laminated, well
  sorted, fine to medium grained sand with
  scattered layers of clay

7
Hawthorne Group

• Current studies suggest the Hawthorne Group is
  subdivided into five Formations
• Tiger Leap Formation
• Parachucla Formation
• Marks Head Formation
• Coosawhatchie Formation
• And Ebenezer Formation

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Hawthorne Group

• Covers the majority of the South and Southeastern
  Coastal Plain Province, and progresses into
  Florida
• The Hawthorne is the major upper confining unit
  of the Floridian Aquifer which is the major
  supply of drinking and irrigation water in
  Georgia and Florida

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Hawthorne Group

• Seven major defining characteristics
• argillaceous sand and clay, rarely pure sand
• Dolomite is the prominent carbonate mineral
• lacks macrofossils
• majority of the deposits are phosphatic
• magnesium rich clays
• Chert and diatomaceous sediments are locally
  common
• deposits are marine and relatively shallow

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Tiger Leap Formation of the Hawthorne Group

• Lithology
• limestone, calcareous shelly sand,
  microfossiliferous sand, and noncalcareous sand.
  Dolostone and phosphatic sand and sandstone which
  is fine grained and well sorted
• Stratigraphy
• Is currently identified as a member of the
  Parachucla Formation

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Parachucla Formation of the Hawthorne Group

• Currently consists of two members Tiger Leap
  and Porters Landing
• Is the only formation which carbonates are the
  major constituents
• Porters Landing - fine to medium grained sand and
  clay, and is characterized by thick bedded,
  partially stratified, noncalcareous, and
  nonfossiliferous

12
Marks Head Formation of the Hawthorne Group

• slightly dolomitic, phosphatic, argillaceous sand
  and sandy clay with scattered interbedded
  dolostone and limestone, sands fine grained and
  well sorted, carbonates minor component, similar
  to the characteristic phosphate which rarely
  exceeds a few percent

13
Marks Head Formation of the Hawthorne Group

• Two separate unconformities which are marked by
  detrital lag beds split the Marks Head Formation
  into three lithologically similar beds
• Late early Miocene in age based through numerous
  planktonic foraminifera species such as
  Globorotalia mayeri and Globigernia praebulloides

14
Coosawhatchie Formation of the Hawthorne Group

• Based on the Weems and Edwards study in 2001, the
  Coosawhatchie Formation is subdivided in four
  members
• Tybee Phosphorite Member
• Charlton Member
• Meigs Member
• Berryville Clay Member

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Tybee Phosporite Member

• Composed of quartz sand and phosphate with minor
  clay lenses
• Characteristic of Tybee Phosphorite Member is the
  commercial grade phosphate which is associated
  abundant fine vertebrate debris

16
Charlton Member

• Formly a formation in classification
• Consists primarily of clay, dolostone, and
  limestone, clays - dense, blocky, and are gray in
  color
• Dolomite is the dominate carbonate, but calcite
  found in the extensive fossiliferous limestones

17
Meigs Member

• Originally named by Huddlestun in 1988
• Predominantly clayey silt to very fine sandy
  silt. The sands of the Meigs are thinly bedded
  to laminated and are well sorted
• Dinocysts have dated the Meigs to Middle Miocene

18
Berryville Clay Member

• Originally proposed and named by Huddlestun in
  1988
• Consists of a silty to very fine sandy clay,
  olive-gray in color
• Massive, thick bedded, blocky diatomaceous clay
  is the dominant component

19
Ebenezer Formation

• Ebenezer Formation is currently divided into 5
  members based on four distinct unconformities
• Four members of the Ebenezer consist of fine to
  very fine sands, well sorted which grade
  northward into sandy and clayey silt
• Fifth member of the Ebenezer is similar to
  lithology of the Wabasso Beds in the Pliocene

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Pliocene Epoch

• Pliocene deposits in Georgia are found at
  elevations higher than 300 ft above sea level.
• These elevations provide little evidence of
  tectonic uplifting in the Coastal Plain
• Coastal Plain of Georgia was tectonically stable
  with little uplift and subsidence

21
Raysor Formation

• Dominated by calcite or calcareous material and
  coarse sand in South Carolina
• Formation is less calcareous, more sandy and
  limestone is less noticeable in Georgia
• The majority of the quartz sand is fine-grained
  and well sorted

22
Copperhead Formation

• Characterized by prominently thin to thick bedded
  and massive planar-to cross bedded, variably
  burrowed and bioturbated, fine to fine pebbly,
  coarse sand and moderate reddish-brown to orange
  in color
• Classified as a coastal, beach/sound type deposit

23
Copperhead Formation

• Two distinguishable gross lithofacies
• updip lithofacies is cross-grained, the sand size
  ranged from fine to coarse with pebbly scattered
  gravel, ranging from well-sorted to poorly sorted
  in the coarser grain facies
• downdip consists of fine grained sand and clays
  which are thinly-bedded, well sorted with thin
  layers of clay dispersed through the sand beds

24
Pearson Terrace Unit

• Informal formation which consists of poorly
  sorted silt to clayey sand that ranges in color
  form the pale-olive through yellowish-gray and
  pale-orange to grayish-red
• Found above the youngest member of the Ebenezer
  Formation (Miocene in age), the position
  indicates Pliocene in age

25
Undifferentiated Upper Pliocene Sand

• Outer Continental Shelf Equivalent of the
  Cypresshead Formation
• Massive, structure less, unsolidated,
  macrofossiliferous, calcareous, sandy,
  foraminiferal clay which is olive in color