Florida Groundwater and Hydrogeology

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Florida Groundwater and Hydrogeology
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The Florida Platform
The edge is defined as where the water depth is
at 300 feet.
100 miles west of Tampa 3-4 miles east of Miami
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The Florida Platform
The Florida platform is a miles-thick carbonate
bank
Freeport
Miami
CaCO3
Ice age
Nassau
CaCO3
Warm period
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Origins of the Florida Platform
Precambian 4.5 Bya to 500 Mya Paleozoic 500
Mya to 248 Mya Mesozoic 248 Mya to 65
Mya Cenozoic 65 Mya to present
(Earth formation, cooling, oceans, atmosphere,
life, oxygen)
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Approximately 250 million years ago
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Breakup of Pangaea
Late Triassic, early Jurassic 200Mya
- 250 Mya
Rifting phase Creation of the Atlantic Ocean
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Approximately 150 million years ago
Late Jurassic
Stable, shallow sea floor Subject to marine
sedimentation
Sedimentation settling of particles from a
fluid due to gravity
For the next several million years the area was
dominated by carbonate sedimentation
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Carbonate Deposition/Sedimentation
Marine Calcium and Magnesium Carbonate
CaCO3 MgCO3
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Between about 150 Mya and 25 Mya
Florida platform was a flooded, submarine plateau
dominated by carbonate deposition
CaCO3
FL platform
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The Eocene and Oligocene Limestone
The Eocene and Oligocene limestone forms
the principal fresh water-bearing unit of the
Floridan Aquifer, one of the most productive
aquifer systems in the world
Eocene 55 34 million years ago Oligocene 34
24 million years ago
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Marine Carbonates
carbonates
Prior to 24 Mya
Between 150 and 25 Mya, Florida was dominated by
carbonate deposition
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Continental Influences
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Sedimentation on the Florida Peninsula
Sediments
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Isolation of the Florida Peninsula
Georgia Channel
Suwannee Current (similar to Gulf Stream)
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Isolation of the peninsula from
continental influences allowed carbonates to
build on the platform for 125 million years
Fundamental change came approximately 25 million
years ago
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Events of the Late Oligocene Epoch, approximately
25 Mya
Raising of the Florida Platform
Lowering of Sea Levels, Interruption of Suwannee
Current
Suwannee Current
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Rejuvenation of Appalachians, increased sediment
load
sediments
Miocene Epoch beginning approximately 24 Mya
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These Sediments were Silicon-based Sands, Silts,
Clays, Rocks, and Rock Fragments
KAlSi3O8 CaAl2Si2O8 NaAlSi3O8 MgSiO4 KAl3Si3O1
0
Feldspars Olivine Muscovite
They are typically called siliciclastics
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Filling in the Georgia Channel
Sediments
Early Miocene ( 24 Mya)
Carried by rivers and longshore currents
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Sediments
Rising sea levels allow sediments to
become suspended in water and drift over the
platform
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Siliciclastics Covered the Peninsula
Silicon-based
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• Deposition of Eocene/Oligocene Limestone (55 24
  Mya)
• Raising of the Florida platform
• Lowering of sea levels, interruption of the
  Suwannee Current
• Infilling of the Georgia Channel with sediments
  derived from
• Appalachian/continental erosion
• Sea level rise, lack of Suwannee current.
• Suspended siliciclastic sediments settle over the
  peninsula
• These sediments blanket the underlying limestone
  forming
• the upper confining layer for the Floridan
  Aquifer.

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Basic Florida Geology
Sands
Confining unit
sands, silts, clays, rock
Water-bearing unit
Limestone
Miocene deposits are siliciclastic sands, silts,
clays, rocks
These deposits are known commonly as the
Hawthorne Formation. They overlie the Eocene and
Oligocene limestone deposits and form the upper
confining unit for the Floridan Aquifer.
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Miocene sediments are non-carbonate marine
sediments
Megalodon MG1Locality Hawthorne Formation,
South CarolinaAgeMioceneVirtually flawless
museum grade specimen. Perfect serrations, black
and gray mottling Price 785.00 SOLD
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In Gainesville, Miocene clays tend to be fairly
thick and, in many cases, close to the surface
13th st.
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Alfred A. Ring Park
1801 NW 23rd Boulevardparking at Elks Lodge
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The thickness of and depth to Miocene sediments
varies
0-500 ft thick in the North-central part of state
Up to 40 phosphorus
Also contains uranium
Uranium decays to Radon
OK
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Generalized Florida Geology
Surface features were shaped primarily during the
Pleistocene
Surface Saliciclastics (sandy)
Siliciclastic sediments from the continent
settled over the limestone beginning 24
Mya. forming the upper confining unit for the
Floridan
Clays and Sands (Hawthorne)
Limestone originating from the Eocene and
Oligocene Epochs forms the water-bearing unit
for the Floridan Aquifer.
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Permeability the ease with which water moves
through material
Surface Siliciclastics (sandy) (highly permeable)
Unconfined aquifer is extensive throughout the
state of Florida
Low Permeability Confining Unit (poor water
movement)
Clays and Sands (low permeability)
The Floridan aquifer is a confined aquifer. The
water-bearing unit is permeable limestone.
Low permeability rock (confining)
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The Floridan Aquifer
The water-bearing unit of the Floridan Aquifer is
a confined, consolidated limestone formation.
How does it contain and release water?