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Carbonate units of the intermediate aquifer system in the Suwannee River Water Management District /
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Title: Carbonate units of the intermediate aquifer system in the Suwannee River Water Management District /
Physical Description: 22 p. : ill., maps ; 28 cm.
Language: English
Creator: Groszos, Mark
Florida Geological Survey
Suwannee River Water Management District (Fla.)
Publisher: Florida Geological Survey, in cooperation with the Suwannee River Water Management District
Place of Publication: Tallahassee, Fla.
Publication Date: 1992
 Subjects
Subjects / Keywords: Geology -- Florida -- Suwanne River Water Management District   ( lcsh )
Rocks, Carbonate -- Florida -- Suwanne River Water Management District   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: by Mark Groszos ... et al..
General Note: Florida Geological Survey open file report number 54
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Source Institution: University of Florida
Holding Location: University of Florida
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The author dedicated the work to the public domain by waiving all of his or her rights to the work worldwide under copyright law and all related or neighboring legal rights he or she had in the work, to the extent allowable by law.
Resource Identifier: oclc - 32887017
System ID: UF00099432:00001

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Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Title Page
        Title Page 1
        Title Page 2
    Table of Contents
        Table of Contents
    Main
        Page 1
        Page 2
        Page 3
        Page 4
    Figures 1-10
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
    Back Cover
        Page 24
        Page 25
Full Text






STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Virginia B. Wetherell, Executive Director





DIVISION OF RESOURCE MANAGEMENT
Jeremy A. Craft, Director





FLORIDA GEOLOGICAL SURVEY
Walter Schmidt, State Geologist and Chief






Open File Report No. 54



Carbonate units of the intermediate aquifer system
in the Suwannee River Water Management District

by

Mark Groszos, Ron Ceryak, David Alison,
Renee Cooper, Mike Weinberg, Milena Macesich,
Meryl Martinez Enright, and Frank Rupert






Florida Geological Survey, Tallahassee, Florida, in cooperation
with the Suwannee River Water Management District
1992

UNIVERSITY OF FLORIDA LIBRIAIE;




















Oil


c.^

SCIENCE
LIBRARY






















Contents




Introduction and Hydrostratigraphy ..................................... 1
G eom orphology ...................................................2
R regional G eology .................................................. 2
M apping M methods ................................................... 3
Extent and Thickness ................................................ 3
Upper Carbonate Unit ......................................... 3
M iddle Carbonate Units ........................................ 3
Lower Carbonate Unit .......................................... 4
A cknowledgem ents ................................................. 4
R references ........................................................ 4



Illustrations


Figure 1. Cross section A-A' of the Hawthorn Group in the SRWMD ......... 5
Figure 2. Cross section B-B' of the Hawthorn Group in the SRWMD .......... 6
Figure 3. Top of the Upper Carbonate Unit ............................ 7
Figure 4. Isopach of the Upper Carbonate Unit ......................... 9
Figure 5. Top of the Upper Middle Carbonate Unit ..................... 11
Figure 6. Isopach of the Upper Middle Carbonate Unit ................... 13
Figure 7. Top of the Lower Middle Carbonate Unit ..................... 15
Figure 8. Isopach Data for the Lower Middle Carbonate Unit .............. 17
Figure 9. Top of the Lower Carbonate Unit ........................... 19
Figure 10. Isopach of the Lower Carbonate Unit ......................... 21











Carbonate Units of the intermediate aquifer system in the
Suwannee River Water Management District, Florida

by
Mark Groszos, Ron Ceryak, David Allison,
Renee Cooper, Mike Weinberg, Milena Macesich,
Meryl MartinezEnright, and Frank Rupert, P.G. 149


Introduction and Hydrostratigraphy

The intermediate aquifer system or
intermediate confining unit (Southeastern
Geological Society Ad Hoc Committee,
1986) is a series of artesian freshwater
aquifers and interbedded confining units
underlying the northern and eastern
portions of the Suwannee River Water
Management District (SRWMD). It is used
locally as a domestic and a limited
agricultural water source. Stratigraphically,
it is contained within the Miocene
Hawthorn Group sediments.
Characteristically, the Hawthorn
Group sediments consist of interbedded
sands, sandy clays, clays and carbonates,
commonly containing variable amounts of
phosphate (Scott, 1988). The Hawthorn is
underlain by Eocene to Miocene carbonates
which comprise part of the upper Floridan
aquifer system. These include the Ocala
Limestone, the Suwannee Limestone, and
the St. Marks Formation. The Hawthorn
Group is overlain by undifferentiated Plio-
Pleistocene sands and clayey sands. It
extends laterally northward into Georgia,
eastward into the neighboring St. Johns
River Water Management District, and is
truncated by the Cody Scarp to the
southwest. In general, clay and clayey sand
units within the Hawthorn Group function
as confining units for the water-bearing
units of the intermediate aquifer system as
well as the underlying Floridan aquifer
system.
The primary water bearing units of
the intermediate aquifer system/confining


unit consist of a regionally extensive Upper
Carbonate Unit (UCU), generally situated
near the top of the Hawthorn Group, and
in the northern portion of the District, an
underlying sand unit (Figures 1 and 2).
Most local wells draw from the Upper
Carbonate Unit. In those areas of the
SRWMD where a low permeability clay unit
occurs at the top of the Hawthorn, an
effective confining bed exists between the
intermediate aquifer system and overlying
surficial aquifer system. In areas where this
confining bed is thin or absent, the upper
Hawthorn Group sediments may be in
hydrologic contact with the overlying
surficial aquifer system.
Three additional deeper carbonate
units, consisting of two units
stratigraphically situated approximately
midway in the section, and a basal unit, are
present within the Hawthorn Group in the
SRWMD. Named according to their
respective stratigraphic positions, they are:
the Upper Middle Carbonate Unit
(UMCU), the Lower Middle Carbonate
Unit (LMCU), and the Lower Carbonate
Unit (LCU). The Upper Middle Carbonate
unit extends over most of the SRWMD.
Less data is available for the Lower Middle
Carbonate, and it is probably discontinuous.
Both units may function as water bearing
units within the intermediate aquifer system.
These units are separated from the Upper
and Lower carbonates by interbedded sands,
clayey sands, and occasional dolosilts. The
Lower Carbonate Unit comprises the basal
Hawthorn Group, and it may be in
hydrologic continuity with the underlying









Floridan aquifer system.

Geomorphology

The SRWMD encompasses two
broad geomorphic zones. Spanning the
northernmost counties in the District is the
Northern Highlands (White, 1970), a
stream-dissected remnant of an extensive
highlands that covered much of southern
Georgia, northern Florida, and southern
Alabama. Elevations typically range from
about 100 feet above NGVD (National
Geodetic Vertical Datum of 1929, which
approximates mean sea level) to greater
than 200 feet NGVD.
South and west of the Northern
Highlands is an elevationally-low zone
named the Gulf Coastal Lowlands (White,
1970). This area is characterized by flat,
often swampy, sandy terrain overlying
karstified limestone. Relict marine bars,
dunes and ridges, formed during Pleistocene
sea level highstands, are common features
throughout the lowlands. Elevations in the
Gulf Coastal Lowlands range from 0 feet
NGVD at the current coastline to about 100
feet NGVD at the northern and eastern
edge of the zone.
A prominent relict marine
escarpment named the Cody Scarp (Puri
and Vernon, 1964) forms the boundary
between the Gulf Coastal Lowlands and the
Northern Highlands. The Cody Scarp also
forms an erosional, areal limit for many of
the Miocene and younger strata underlying
the Northern Highlands. As such, it also
functions as a southern and western
boundary to the intermediate aquifer
system/confining unit within the SRWMD.


Regional Geology

Northern Florida is underlain by
thousands of feet of predominantly marine
carbonates, sands and clays (Ceryak et al.,


1983). The near surface units are composed
of Eocene, Oligocene, and Early Miocene
limestones, overlain in turn by Miocene
through Pleistocene carbonates and
siliciclastics. In the Gulf Coastal Lowlands,
near-surface limestones belonging to the
Eocene Ocala Limestone and the Oligocene
Suwannee Limestone form a karstified
limestone plain covered by a thin veneer of
undifferentiated sands and clays. These
limestones comprise the Floridan aquifer
system.
North of the Cody Scarp, in the
Northern Highlands, these same limestones
are overlain by substantial thicknesses of
Hawthorn Group siliciclastics and
carbonates, and, where present, the Pliocene
Miccosukee Formation and/or Plio-
Pleistocene siliciclastics. The intermediate
aquifer system/confining system and the
surficial aquifer system are contained within
the Miocene through Pleistocene strata.
In the SRWMD, the intermediate
aquifer system and the interbedded clays
and clayey sands of the intermediate
confining unit are contained in strata of the
Hawthorn Group (Scott, 1988). The
lithology of the Hawthorn Group sediments
is diverse, composed primarily of
interbedded phosphatic sands, clayey sands,
sandy clays, clays, and carbonates. In
general, the Hawthorn Group ranges in
thickness from 0 feet south and west of the
Cody Scarp, where it has been largely
removed by erosion, to at least 410 feet in
the eastern portion of the District (Groszos
and Rupert, 1992). It underlies the
Northern Highlands geomorphiczone, north
of the Cody Scarp and typically the upper
surface is above elevations of about 110 feet
NGVD (Ceryak et al., 1983).
The intermediate aquifer system is
comprised of four distinct carbonate units
(Upper, Upper Middle, Lower Middle, and
Lower), separated by clays, sands, and
clayey sands (Figures 1 and 2). Throughout
the District, the carbonate units are
predominantly composed of dolomite, with










some localized occurrences of dolosilt or
limestone. The intermediate aquifer
system/confining unit is absent west and
south of the Cody Scarp. Here, the
underlyingFloridan aquifer system functions
largely as an unconfined or semi-confined
artesian system. Northeast of the scarp, the
intermediate aquifer system overlies the
Floridan aquifer system. In some areas, clay
and/or tight dolomite (often called chert by
drillers) sediments in the basal Hawthorn
Group form a confining layer for the
underlying Floridan aquifer system.
Similarly, clay units near the top of the
Hawthorn Group may, in some areas,
support an overlying perched surficial
aquifer system (Ceryak et al., 1983).

Mapping Methods

The tops and thicknesses (isopachs)
of the Upper, Upper Middle, Lower Middle,
and Lower carbonate units were mapped in
this study. Data from well cuttings and
cores, as well as detailed driller's logs were
analyzed to delineate the four distinct
carbonate units within the Hawthorn Group
sediments. Lithologic data were derived
from well and core sample descriptions on
file at the FGS. Driller's logs were supplied
by the SRWMD.
Each carbonate layer was assigned to
the Upper, Upper Middle, Lower Middle,
or Lower Carbonate Unit based on
elevation and stratigraphic sequence. Wells
which did not fully penetrate each unit were
used for construction of the top of unit
maps only. Depths to the top of each unit,
corrected to NGVD, and thicknesses of
each unit were used to construct the top-of-
unit and isopach maps. Well locations and
isolines were digitized using the computer
assisted drafting program AutoCad.
Isolines were constructed at a 20 feet
contour interval, relative to mean sea level
(NGVD). The isolines were truncated at
the District boundary, or where they


intersected an erosional terminus such as
the Cody Scarp, and where data were
sparse. The maps shown were constructed
based on the best available data. Future
studies, benefiting from additional data,
may alter the areal extent and or
configuration of the mapped units.

Extent and thickness

Upper Carbonate Unit

The Upper Carbonate Unit (UCU)
is a water-bearing strata lying near the top
of the Hawthorn Group (Figure 3). It is
utilized as a water source for rural wells.
The UCU is regionally extensive, extending
from southeastern Hamilton County
southeastward through Columbia, Baker,
Union, Bradford, and into Alachua County.
It pinches out to the west in central
Hamilton County, and it is truncated to the
south by the Cody Scarp. The elevation of
the top of the UCU varies between less
than 20 feet and 120 feet NGVD. It
reaches a high of 120 feet NGVD in areas
of Columbia, Bradford, and Alachua
Counties. The surface then dips to the
northeast, dropping to an elevation of 20
feet NGVD or less in Baker County.
Thickness of the UCU ranges from
less than 20 feet at the peripheral portions
of its extent to about 40 feet near the
juncture of Alachua, Bradford, and Union
Counties, and in Hamilton County (Figure
4).

Middle Carbonate Units

Two carbonate units are
stratigraphically situated in the middle of
the Hawthorn Group section. The Upper
Middle Carbonate Unit (UMCU) occurs
throughout most of the SRWMD south and
east of Hamilton County. The top of the
UMCU ranges from a high of about 100
feet NGVD in Alachua County, to deeper








than -60 feet NGVD in northeastern Baker
County (Figure 5). Isopach data for this
unit are sparse, but existing well data
indicates it is about 20 feet thick over much
of the study area (Figure 6). The unit
reaches a maximum recorded thickness of
42 feet in one well in eastern Bradford
County. The UMCU is separated from the
underlying Lower Middle Carbonate Unit by
a sand or clayey sand unit of variable
thickness.
The Lower Middle Carbonate Unit
(LMCU) is poorly represented in wells, with
the bulk of wells containing this unit
concentrated around the City of Gainesville
Figure 7). It may occur only sporadically
throughout the SRWMD. From the existing
well data, the top of the unit varies between
about 40 feet NGVD in the west central
SRWMD to over -190 feet NGVD in
northeastern Baker County. Isopach and
top of unit maps were not constructed for
the LMCU, and only data is shown on the
map in Figures 7 and 8. The known
thickness ranges from about 10 to 90 feet.

Lower Carbonate Unit

The Lower Carbonate Unit (LCU)
occurs in most of District east and south of
Hamilton County (Figure 9). This unit is
situated near or at the base of the
Hawthorn Group, and rests directly on the
Suwannee Limestone or Ocala Limestone
sediments. In portions of the District, the
LCU is most likely in hydrologic continuity
with the underlying Floridan aquifer system,
which may supply much of the water to the
unit. The elevation of the top of the unit
ranges from about 20 feet NGVD in central
Alachua County, southwestern Union
County, and central Columbia County, to
about -280 feet NGVD in northeastern
Baker County. Thickness varies from less
than 20 feet near the Cody Scarp to
approximately 100 feet in northern Baker
County (Figure 10).


Acknowledgements

Mapping of the principle carbonate
units of the intermediate aquifer system was
performed by the Florida Geological Survey
(FGS) under contract with the SRWMD,
and was funded through the Florida
Department of Environmental Regulation
Groundwater Quality Monitoring Program.
The authors extend special thanks to
Nolan Col, SRWMD, and Drs. Tom Scott
and Walt Schmidt of the FGS for critically
reviewing drafts of the maps and text for
this report.

References

Ceryak, R., Knapp, M., and Burnson, T.,
1983, The geology and water
resources of the Upper Suwannee
River Basin, Florida: Florida
Bureau of Geology Report of
Investigation 87, 166 p.

Groszos, M., and Rupert, F., 1992, An
isopach map of the Hawthorn
Group in the Suwannee River
Water Management District:
Florida Geological Survey Open
File Map Series 2.

Puri, H., and Vernon, R., 1964, Summary
of the geology of Florida and a
guidebook to classic localities:
Florida Geological Survey Special
Publication 5 revised, 312 p.

Scott, T., 1988, The lithostratigraphy of
the Hawthorn Group (Miocene) of
Florida: Florida Geological Survey
Bulletin 59, 148 p.

Southeastern Geological Society Ad Hoc
Committee, 1986, Hydrogeological
units of Florida: Florida Geological
Survey Special Publication 28, 8 p.

White, W., 1970, Geomorphology of the
Florida Peninsula: Florida Bureau
of Geology Bulletin 51, 164 p.


















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Figure 3.

TOP OF THE UPPER CARBONATE UNIT,
INTERMEDIATE AQUIFER SYSTEM
IN THE
SUWANNEE RIVER WATER MANAGEMENT DISTRICT

COMPILED BY:
MARK GROSZOS (FGS)
RON CERYAK (SRWMD)
DAVID ALLISON (FGS)
WITH ASSISTANCE FROM:
RENEE COOPER (FGS)
MIKE WEINBERG (FGS)
MILENA MACESICH (FGS)
NETTIE MARTINEZ (FGS)

EXPLANATION
Well Number, Top of Unit in Feet NGVD, P%"
and Location Point
County Boundary
Cody Scarp
Contour Line (Relative to NGVD)
Contour Interval = 20 Feet
MILES


KILOMETERS


Study Area Location





C









13E 14E 15E 16E 17E 18E 19E 20E 21E 22E


2N

P -N- 1N








3S


5S



~' 6 5S




B D R 7S


8s


Y, 9S


10S
GILCHRIS-

11S

MARION
12S










Figure 4.

ISOPACH OF THE
UPPER CARBONATE UNIT,
INTERMEDIATE AQUIFER SYSTEM,
SUWANNEE RIVER WATER MANAGEMENT DISTRICT

COMPILED BY:
MARK GROSZOS (FGS)
RON CERYAK (SRWMD)
DAVID ALLISON (FGS)
WITH ASSISTANCE FROM:
RENEE COOPER (FGS)
MIKE WEINBERG (FGS)
MILENA MACESICH (FGS)
NETTIE MARTINEZ (FGS)

EXPLANATION
Well Number, Top of Unit in Feet NGVD, 83
and Location Point
County Boundary --

Cody Scarp

Contour Line (Relative to NGVD)

Contour Interval = 20 Feet

MILES


KILOMETERS

Study Area Location










I 2N

-N- IN

i s

2S

3S

4S

5S












Figure 5.


TOP OF THE UPPER MIDDLE CARBONATE UNIT,
INTERMEDIATE AQUIFER SYSTEM
IN THE
SUWANNEE RIVER WATER MANAGEMENT DISTRICT

COMPILED BY:
MARK GRSOSZ (FGS)
RON CERYAK (SRWMD)
DAVID ALLISON (FGS)
WITH ASSISTANCE FROM:
RENEE COOPER (FGS)
MIKE WEINBERG (FGS)
MILENA MACESICH (FGS)
NETTLE MARTINEZ (FGS)

EXPLANATION
Well Number, Top of Unit in Feet NGVD, a'p
and Location Point
County Boundary I

Cody Scarp
Contour Line (Relative to NGVD)
Contour Interval = 20 Feet
MILES


KILOMETERS


Study Area Location








13E 14E 15E 16E 17E 18E 19E 20E 21E 22E


t 2N
--N-- 1N






31S
S\ I ---^)9 2s





UNION
-~N / 5 S









Figure 6.

ISOPACH OF THE
UPPER MIDDLE CARBONATE UNIT,
INTERMEDIATE AQUIFER SYSTEM,
SUWANNEE RIVER WATER MANAGEMENT DISTRICT

COMPILED BY:
MARK GROSZOS (FGS)
RON CERYAK (SRWMD)
DAVID ALLISON (FGS)
WITH ASSISTANCE FROM:
RENEE COOPER (FGS)
MIKE WEINBERG (FGS)
MILENA MACESICH (FGS)
NETTLE MARTINEZ (FGS)

EXPLANATION
Well Number, Top of Unit in Feet NGVD, l283
and Location Point
County Boundary --

Cody Scarp

Contour Line (Relative to NGVD)

Contour Interval = 20 Feet

MILES


KILOMETERS

Study Area Location












Figure 7.

TOP OF THE LOWER MIDDLE CARBONATE UNIT,
INTERMEDIATE AQUIFER SYSTEM
IN THE
SUWANNEE RIVER WATER MANAGEMENT DISTRICT

COMPILED BY:
MARK GROSZOS (FGS)
RON CERYAK (SRWMD)
DAVID ALLISON (FGS)
WITH ASSISTANCE FROM:
RENEE COOPER (FGS)
MIKE WEINBERG (FGS)
MILENA MACESICH (FGS)
NETTLE MARTINEZ (FGS)

EXPLANATION
Well Number, Top of Unit in Feet NGVD, Fe'
and Location Point
County Boundary -

Cody Scarp



MILES


KILOMETERS


Study Area Location








13E 14E 15E 16E 17E 18E 19E 20E 21E 22E









NION 2



5S








5. 9S



ALACHUA
S-N- 12S
SLU A,
3 3S

^ BAKE ____

^ ,. -^T_->-- 4

-^\^ CL~i5

p^S^ ^q^S
7 ^3 ':- '7
UFAYETTE~s b ~ / ___ ^-- -- V ---- --- -- j-
w '1 J j ^ x 8









Figure 8.

ISOPACH DATA FOR THE
LOWER MIDDLE CARBONATE UNIT,
INTERMEDIATE AOUIFER SYSTEM,
SUWANNEE RIVER WATER MANAGEMENT DISTRICT

COMPILED BY:
MARK GROSZOS (FGS)
RON CERYAK (SRWMD)
DAVID ALLISON (FGS)
WITH ASSISTANCE FROM:
RENEE COOPER (FGS)
MIKE WEINBERG (FGS)
MILENA MACESICH (FGS)
NETTIE MARTINEZ (FGS)

EXPLANATION
Well Number, Top of Unit in Feet NGVD, '283
and Location Point
County Boundary
Cody Scarp





MILES


KILOMETERS

Study Area Location










13E 14E 15E 16E 17E 18E 19E 20E 21E












Figure 9.

TOP OF THE LOWER CARBONATE UNIT,
INTERMEDIATE AQUIFER SYSTEM
IN THE
SUWANNEE RIVER WATER MANAGEMENT DISTRICT

COMPILED BY:
MARK GROSZOS (FGS)
RON CERYAK (SRWMD)
DAVID ALLISON (FGS)
WITH ASSISTANCE FROM:
RENEE COOPER (FGS)
MIKE WEINBERG (FGS)
MILENA MACESICH (FGS)
NETTlE MARTINEZ (FGS)

EXPLANATION
Well Number, Top of Unit in Feet NGVD, ~s7
and Location Point
County Boundary

Cody Scarp
Contour Line (Relative to NGVD)
Contour Interval = 20 Feet
MILES


KILOMETERS


Study Area Location











13E 14E 15E 16E 17E 18E 19E 20E 21E 22E

HAMILTON

S2N







20 52S




S4S



5S


7 SS



UFAYETTE
DIXIE




S 10S



ALACHUA
---ua -------- I
LEW -- 11 S


12S












Figure 10.

ISOPACH OF THE
LOWER CARBONATE UNIT,
INTERMEDIATE AQUIFER SYSTEM,
SUWANNEE RIVER WATER MANAGEMENT DISTRICT

COMPILED BY:
MARK GROSZOS (FGS)
RON CERYAK (SRWMD)
DAVID ALLISON (FGS)
WITH ASSISTANCE FROM:
RENEE COOPER (FGS)
MIKE WEINBERG (FGS)
MILENA MACESICH (FGS)
NETTIE MARTINEZ (FGS)

EXPLANATION
Well Number, Top of Unit in Feet NGVD, ea
and Location Point
County Boundary

Cody Scarp

Contour Line (Relative to NGVD)

Contour Interval = 20 Feet

MILES


KILOMETERS

Study Area Location











2N

-N- iN

Li

2S

3S




5S

6S