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The lithostratigraphy of the Hawthorn Group of peninsular Florida ( FGS: Open file report 36 )

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Title:
The lithostratigraphy of the Hawthorn Group of peninsular Florida ( FGS: Open file report 36 )
Series Title:
( FGS: Open file report 36 )
Creator:
Scott, Thomas M
Florida Geological Survey
Place of Publication:
Tallahassee
Publisher:
Florida Geological Survey
Publication Date:
Language:
English
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327-336 p. : ill., maps ; 28 cm.

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Subjects / Keywords:
Geology, Stratigraphic -- Miocene ( lcsh )
Geology -- Florida ( lcsh )
Hawthorne Group ( lcsh )
City of Ocala ( local )
Miami metropolitan area ( local )
City of Jacksonville ( local )
Town of Suwannee ( local )
City of Sanford ( local )
City of Tampa ( local )
Sediments ( jstor )
Carbonates ( jstor )
Phosphates ( jstor )
Quartz ( jstor )
Valleys ( jstor )
Genre:
bibliography ( marcgt )
non-fiction ( marcgt )

Notes

Bibliography:
Includes bibliographical references (p. 336)
General Note:
Cover title.
General Note:
Originally published as chapter 26 in: Phosphate deposits of the world / by William Burnett and S.R. Riggs. New York : Cambridge University Press, 1990.
Statement of Responsibility:
by Thomas M. Scott.

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University of Florida
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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:
027794601 ( aleph )
25643119 ( oclc )
AJG4826 ( notis )

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Full Text
State of Florida
Department of Natural Resources Tom Gardner, Executive Director
Division of Resource Management
Jeremy Craft, Director
Florida Geological Survey
Walt Schmidt, State Geologist and Chief
Open File Report 36
The Lithostratigraphy of the Hawthorn Group
of peninsular Florida by
Thomas M. Scott in
Phosphate Deposits of the World
Published by Cambridge University Press by
William Burnett and S. R. Riggs
Florida Geological Survey
Tallahassee, Florida 1990




26
The lithostratigraphy of the
Hawthorn Group of
peninsular Florida
T.M. SCOTT
Abstract Introduction
The Hawthorn Group has been a problematic unit since it was The sediments of the Hawthorn Group represent a dramnamed by Dall & Harris (1892). It is acomplex unitconsisting of
interbedded and intermixed carbonate and siliciclastic sediments
containing variable concentrations of phosphate. Scott (1988)
upgraded the Hawthorn to group status in Florida and delineated wIth a very minor siliciclastic component dominated the deposiits component formations ional environments of peninsular Florida. During the Early
The Hawthorn Group in northern Florida has been subdi- Miocene, siliciclastics. derived from the southern Appalachians, vided. in ascending order, into the Penney Farms, Marks Head. filled the Gulf Trou2h and encroached into the carbonateCoosawhatchie and Statenville Formations. These units range in
age from Early Miocene (Aquitanian) to Middle Miocene (mid
Serravalian) (Huddlestun. pers. comm., 1983). Lithologically, producing environments were gradually pushed further south as the Hawthorn Group in northern Florida is made up of a basal siliciclastic deposition increased. During the Miocene. carbonate with interbedded siliciclastics (Penney Farms), a com- phosphogenesis became an important depositional-diaenetic plexly interbedded siliciclastic-carbonate sequence (Marks process. Phosphate grains occur within the Hawthorn sediments Head), a siliclastic unit with variable concentrations of carbonate in amounts ranging from trace to 60%. Palvwrskite. sepiolite. in the matrix and individual beds (Coosawhatchie), and a
crossbedded, predominantly siliciclastic unit (Statenville). Phos- smectite and minor i11ite are the clay minerals associatedwith the phate grains are present throughout most of these sediments, Hawthorn sediments. varying in concentration from absent to as much as 60% of the The lithostratigraphv of the Hawthorn Group throughout sediment.
In southern Florida, the Hawthorn Group is comprised of, in pin o rapd the reginal fame forpatascending order, the Arcadia and Peace River Formations. The
Tampa Formation or Limestone of former usage is included asa bearing Miocene sediments. lower member of the Arcadia Formation due to the Tampa's There have been numerous investigations of the Hawthorn limited areal extent, lithologic similarities and lateral relationship sediments during the last century. Scott (1988) provides a with the undifferentiated Arcadia. Similarly, the Bone Valley lengthy discussion of these previous investigations and as such Formation of former usage is incorporated as a member in the
Peace River Formation. The southern Florida Hawthorn Group
sediments range in age from Early Miocene (Aquitanian) to Early
Pliocene (Zanclean) (Hunter. pers. comm., 1985). Lithologically, Structure the Arcadia Formation is composed of carbonate with varying The Hawthorn Group is present throughout much of amounts of included and interbedded siliciclastics which are most peninsular Florida (Figs. 26. 26.2) except on top of the Ocala prevalent in the Nocatee Member (basal Arcadia). The Peace
River Formation is predominantly a siliciclastic unit with some
interbedded carbtnates. The carbonates are often dolostone or non-deposition. The main structures which controlled the Phosphate grains are virtually ubiquitous in the south Florida deposition and present distribution of the Hawthorn Group are Hawthorn sediments with the exception of the Tampa Member shown on Figure 263. These features have been considered where it is often absent. structural in origin: hover, there is considerable discussion
The Hawthorn sediments of peninsular Florida reflect a series
of sea-level events and phosphogenic episodes. These sediments
are characterized as being deposited in inner shelf, nearshore tural. Nonetheless, the features were topographically expressed environments. Erosion and reworking of pre-existing sediments on the surface underlying the Hawthorn Group. The two major played an important role in the development of the Miocene positive features were the Ocala Platform with the Central Florsediment packages- ida Platform and the Sanford High with the St Johns and




T.M. Scott 326
150.
FACIESCL a 100'
CHANGEE;
-SO'
I0
05 .1 50 000
TOP OF HAWTHORN GROUPe*
i6
APPROXIMATE LIMITS OF THE HAWTHORN GROUP 0q0
CONTOUR INTERVAL SOFT.
-50'
-150'
-00, 1503
-100'
, o'C'.07 Fig. 26.1, Top of Hawthorn Group in Florida based on cores and well cuttings.




Hawthorn Group:. lithostratigraphy 327
-c,, -400'
500'
S 400'
FACIES 300'
CHANGE
9 200
0
10
200 0 00
ISOPACH OF THE HAWTHORN GROUP 300 -- 300
se 400' so 0 a o a"400' 5 0
450- 500'
APPROXIMATE LIMITSOTH HAWTHORN GROUP40O
500' *---- 700'
CONTOUR INTERVAL SOFT.- 7,50' 6 / ,800'
- 750' 700' _a 700'
r 7500
50
- 900' 800
850, 900
Fig. 26.2. Isopach of the Hawthorn Group in IFlorida based on cores and well cuttings.




T.M. Scott 328
JACKSONVILLE
BASIN
NASSAU NOSE
ST. J(THNS
PLATFORM
LL SANFORD
HIGH
B
-t-CA-." T LTFOR.
FLORIDA OSVEOLA ---__VATFOR LOWV
0ECHOBEE
--BASIN
Fig. 26.3. Structural features which affected the deposition and present occurrence of the Hawthorn Group.
Brevard platibrms (Riggs. 1979), The major negative features The sediments of the Hawthorn are litholoaically, defined b% include the Jacksonville Basin, the Oseola Basin and the broad the occurrence of variable amounts of phosphate. quartz sand. Okeechobee Basin. These basins contain significant thicknesses dolomite and pulygorskite. The Hawthorn Group is most easily of Miocene sediments ranging from 250 ft (76 m) in the Osceola discussed in the context of northern and southern areas divided Basin to 900 ft (275 m) in the Okeechobee Basin (Fig, 26.2)- by an east-w est line between the southern erosional limit of the Hawthorn on the Ocala Platform and the Sanford High. respecLkthostratigraphy tively (see Fig. 26.4). Lateral and vertical variabiliti is most
Previous Investigations considered the Hawthorn sedi- pronounced in north Florida. ments as a single formation which displayed great variability throughout Florida. The resulting confusion is evidenit In the North Florida literature. Elevating the Hawthorn to group status eliminates The Hawthorn Group in north Florida contains signifimuch of the confusion. candy higher percentages of siliciciastic sediments than in south
t y j




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Fig. 26.4. (;eneralized st.-atigraphic c4Ir dIaOmis fromn Firiula to North Carolina (niodifid fromu unputblished Cult Coast CONtINA chart and Ailantic Coastal Plain chart, American Assoceiation (if Petroleums Georlogists, 19N3).




T.M. Scott 330
Florida since it is closer to the siliciclastic source area in the
Piedmont and southern Appalachians. In north Florida, the Statenville Formation Ina limited area of north Florida.
Hawthorn is subdivided as shown in Figure 26.5. Definitions of the Statenville Formation replaces the Coosawhatchie Formathese formations including type sections, detailed lithologic de- tion as the uppermost Hawthorn Group unit (Scott. 1988). The scriptions, stratigraphic relationships, structure and isopach Statenville consists of thin-bedded, often cross-bedded, clayey, maps and discussions of the formational ages are presented in phosphatic, quartz sands interbedded with thin dolostone beds Scott (1988). and clays. The phosphatecontentis great enough in limited areas
to be an economically important deposit (e.g. Occidental PetroPenney Farms Formation The basal, carbonate-rich leur's north Florida deposit).
Hawthorn Group sediments have been assigned to the Penney The Statenville Formation unconforrably overlies the Farms Formation (Scott, 1988). The carbonates are variably Marks Head in some areas and conformably overlies the lower quartz sandy, phosphatic and clayey dolostones. Carbonate part of the Coosawhatchie in other areas. The Statenville is beds are thicker and more common in the lower portion of the laterally equivalent to at least the upper part of the Penney Farms. Interbedded siliciclastic units become thicker Coosawhatchie, It is unconformably overlain by post-Hawand more abundant upward in the formation. The siliciclastic thorn undifferentiated sediments. The thickest known section of sediments consist of dolomitic, clayey, phosphatic quartz sands Statenville is 87 ft (26 i). Correlation of the Statenville with the and dolomitic, phosphatic, quartz sandy clays. Coosawhatchie suggests a Middle Miocene age (Huddlestun.
The Penney Farms Formation unconformably overlies the peers. comm., 1983). There also is a zone of reworked Statenville Eocene Ocala Group throughout most of northern Florida. exposed in the north Florida phosphate pits that contains a Late Occasionally it overlies the Oligocene Suwannee Limestone. It is Miocene vertebrate fauna (Webb, peers. comm., 1985. overlain unconformably by the Marks Head Formation (Figs.
266, 26,7; Fig. 26.5 shows location of cross-sections). The Penny South Florida Farms reaches a maximum thickness of 230 ft (70 m) in the The Hawthorn Group of southern Florida generally conJacksonville Basin. Palaeontologic evidence suggests that the sits of a basal carbonate unit and an upper siliciclatic unit and Penney Farms is Early Miocene (Early-Middle Aquitanian) is subdivided as shown in Figure 26.4, Complete definitions of (Huddlestun, pers. comm., 1983). the formations are available in Scott (1988).
Marks Head Formation The complexly interbedded Srcadia Formation The lower Hawthorn carbonate secsiliciclastics and carbonates overlying thePenney Farms Forma- tion in south Florida has been assigned the name Arcadia tion have been referred to as the Marks Head Formation ( Scott. Formation (Scott, 1988). The carbonates are characteristically 198 8). This unSit is the most lithologically variable section of the quartz sandy, phosphatic. sometimes clayey doostones to Hawthorn Group. The carbonates are variably quartz sandy. liinestones Quartz sandy non-phosphatic-slightl. phosphatic clayey. phosphatic dolostones. The carbonates are interbedded limestonespredominate intheTampa MenberFign 26.4). Phoswith dolomitic, phosphatic, clayey quartz sands and dolomitic, phatic siliciclastic beds occur sporadically throughout the Arcaphosphatic, quartz sandy clays. Often the Marks Head clays dia Formation,. becoming the dominant lithologv only in the may contain only minor amounts of the other constituents. Nocatee Member (Fimr 26.4).
The Marks Head Formation unconformably overlies the The Arcadia Formation unconformably overlies the Eocene
Penney Farms Formation and unconformably underlies the Ocala Group. Crystal River and Williston Formations, in the Coosawhatchie Formation (Figs- 26.6. 26.7). The Marks Head north-central and northeastern portions of south Florida. It reaches a maximum thickness of 130 ft (4Gm) in the Jacksonville unconformabl overlies the Oligocene Suannee Limestone Basin. Limited paleontologic evidence suggests a mid-late Early elsewherein this area. TheArcadia is overlain unconfor Hably by Miocene (Burdigalian) age (Huddlestun, peers. comm. 1983). the Peace River Formation (Figs. 26.8 and 26.9). The Arcadia reaches a maximum thickness of narly 600tft 183in) in the
Coosawbhatchie Formation The upperCmost sediments of Okcechobee Basin. Few datable fossils have been found in the the Hawthorn Group in much of north Florida have been placed Arcadia. Limited data suggest that this Formation ranges in age in the Coosawhatchie Formation (Scott, 1988). Sediments of the from very earliest Miocene (early Aquitanian) to late Early Coosawhatchie are characteristically less variable than the Miocene (Late Burdigalian) (Hunter, pers. comm. 1985). Marks Head, consisting of very quartz sandy. phosphatic, clayey
dolostones to dolomitic, phosphatic. clayey quartz sands. The Peace RiverFormation a upper Hathornsiliciclastic base of this formation in the Jacksonville Basin often is a section in south Florida has been assigned to the Peace River dolositic, silty clay. Formation (Scott, 988 The siliciclastics are typically
The Coosawhatchie Formation unconformably overlies the dolomitic. phosphatic. clayey quartz sands. Clay beds occur Marks Head and is unconformably overlain by post-Hawthorn infrequentl throughout the section. Carbonate beds are comundifferentiated sediments (Figs. 26.6. 26.7). The thickest mon within the Peace River Formation and are generally quartz Coosawhatchie section encountered was 222ft 68 ) in the sandy, phosphatic clay dolostones. Jacksonville Basin. Paleontologic evidence suggests a Middle The Peace River Formation unconforably overlies the ArMiocene (Early Serravalian) age (Huddlestur, pers. comm., cadia and is unconformably overlain by post-Hawthorn undif1983)C ferentiated sediments (Figs. 26.8 and 26.9). The Peace River
reaces maimumthiknes ofI 3 ft(40 ) i th Jacsonill




Hawthorn Group: lithostratigraphy 331
A
B N
B
0 50 miles
RTH o so kmr
A
D
CC
'CC'
O UTH
Fig. 26.5. Subdivision of north and souih Florida and location of cross- 'd
sections.
Formation reaches a maximum known thickness of 650 ft phosphate-producing horizon in the Central Florida Phosphate (198 m) in the Okeechobee Basin. Faunal evidence suggests that District. the Peace River Formation ranges in ace from Middle Miocene The boundaries of the Bone Valley Member are complex. In (Serravalian) to no younger than earliest Pliocene (earliest some areas of the district it unconformably overlies the Arcadia Zanclean) (Hunter, pers. comm., 1985). Formation while in other areas the Bone Valley conformabir to
Scott (1988) reduced the status of the former Bone Valley unconformablv overlies the undifferentiated Peace River Formation to Member. The status reduction was due to the Formation. The Bone Valley Member is unconformable limited areal extent of this unit and the lithologic relationship overlain by post-Hawthorn undifferentiated sediments (Figs. and demonstrated time equivalence to tbe undifferentiated 26.8 and 26.9)- The maximum recognized thickness for this unit Peace River Formation. Lithologically. the most important fac- is approximately 50 ft (15 m). The age of the Bone Valley Memtor for separating the Bone Valley from the remainder of the ber is derived entirely from vertebrate fossils collected from this Peace River Formation is the occurrence of phosphate gravel in until MacFadden & Webb (1982) and Webb & Crissinger (1983) the Bone Valley Member. Phosphate gravel and sand are mixed suggest that the Member ranges in age from as old as latest Early with quartz sand and clay in proportions that vary from bed to Miocene (latest Burdigalian) to as young as Early Pliocene bed vertically, and within beds laterally. This unit is the main (Zanclean).




T.M. Scott 332
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Hawthorn Group: lithostratigraphy 333
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Fig. 26.7. Cross-section B-B' showing the relationshiip or the
Starenville Formation to the remainder or the Hawthorn Group in
north Florida.
Florida. If sediments of this age are to be round onshore. it may or the Sanrord High. However. the present distribution and be in the thick Arcadia Formation section in south Florida's thickness of these sediments suggest that more of the strue:ures
Okeechobee Basin. It is not known whether the absence of these were covered than earlier in the Early Miocene.
sediments is due to non-deposition or erosion. but it is helpful to Middle Miocene sediments disconformablv overlie the note that they are not recognized in Georgia. South Carolina or Lower Miocene throughout much of the State. The North Carolina. unconformity is often marked by a bored. phosphatized. A elLower Miocene (Mid-Burdigalian) sediments of the Marks lithified carbonate bed or a rubble resulting from the rip-up oi
Head and upper Arcadia formations were deposited on the mid- this bed. Deposition of the mid-NIiocene sediments may hav e Lower Miocene unconformity. Siliciciastic sedimentation domi- beien as early as very early Middle Miocene (Langbian) I Snvnated in northern Florida while carbonate deposition, mixed der. pers. comm. 1985) to mid-Middle Miocene (Early.
with variable amounts of silicicdastics. continued in southern Serravalian) (Huddlestun, pers. comm., 1985j. The deposition of Florida. Once again apatite is present. but not in economically the Middle Miocene Hawthorn sediments covered the entire important quantities. In north Florida. the Lower Miocene peninsula (Scott. 1988). There, sediments were later removed by .sediments were probably not deposited over the Ocala Platform erosion from the crest and upper flanks or the Ocala Platform.
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T.M. Scott 336
leaving only isolated outliers as evidence of at least part of its The amount of phosphate present in the post-Middle Mioformer extent. scene Hawthorn Group sediments (except the Bone Valley MemThe greatest accumulation of phosphate in Florida appears her) is considerably less than in the Lower and Middle Miocene to have occurred during this Middle Miocene depositional cycle. portion. averaging <3/. This suggests that with the lowering of Much of the phosphate currently being mined in northern, anda sea level in the Late Miocene. the major Miocene phosphogenic portion of that mined in central Florida. is thought to have been episode ended. Minor amounts of phosphate may have been deposited in the Middle Miocene. These phosphorites were deposited in these youngersediments, however. much of itcould
deposited during a high stand of sea level in response to the be the result of reworking of the older phosphatic sediments. impingement of topographically-induced upwellings (Riggs,
1984) onto the Ocala Platform and lesser positive features.
Subsequent reworking of the phosphorites has also been quite
important in development of the deposits. The Bone Valley
Membr o th Pece ive Foratin povies he est American Association of Petroleum Geologists. (1983) .4 A an tic Coastal Member of the Peace River Formation provides the Correlation of Straigraphic Unis of North merica
example of the importance of this reworking in that it contains (COSLNA) ed. A. Lindberg. large quantities of phosphate gravel reworked from pre-existing Dal, WH. & Harris, 0.0. (1892). Correlation paper-Neocene. US phosphate deposits. The reworking of these deposits has been Geological Survey Bulletin, 84. 85-15& multicyclic, occurring primarily from early Middle Miocene HuddlesrunP.F.Hoenstine. R.W. Abbott. WH&Wosley. R,(1982). through Early Pliocene. The stratigraphic definition of the Lower Pliocene Indian River beds
of the Hawthorn in South Carolina, Georgia and Florida. In .Viocene
Upper Miocene sediments in the Hawthorn Group occur of the Southeastern United States.ed.T. Scott&S. Upchurch. pp. 184primarily as zones of reworked, older sediments dated by the 5. Florida Bureau of Geology. Special Publication 25. Tallahassee. occurrence of vertebrate remains (Webb & Crissinger, 1983). MacFadden. B-I. & Webb. S.D. (1982). The succession of Miocene These occur at the top of the Statenville Formation in northern Arikarecan through Hemphillian terrestrial mammal localities and Florida and in the Bone Valley Member of the Peace River faunas in Florida. In Miocene of the Southeastern United Stes.
Florda nd i th Bon ValeyProceeding of the Symposium. ed. T_ Scott & S. Upchurch. pp. 186-9, Formation in southern Florida. Although it has not yet been Florida Bureau of Geology. Special Publication 25. Tallahassee.
fully documented, other sediments of Late Miocene age Riggs. SR. (1979). Phosphorite sedimentation in Florida a model
(Tortonian) occur in southern Florida in the Peace River Forma- phosphogenic system. Economic Geology. 74, 185-314. tion. These sediments contain only minor (<5%) concentra- Riggs. SR (1984). Paleoceanonographic model of Neogene
tons of phosphate grains. phosphorite deposition. US Atlantic Continental Margin. Science.
Sediments of the uppermost Bone Valley Member and the 223(4632), 123-31.
Sedient of he pperostBoneValey MmbeScott, T. (1983)- The Hawthorn Formation of northeast Florida: Part informal Wabasso beds (Huddlestun et al., 1982) are the only I The geology of the Hawthorn Formation of northeast Florida. documented occurrences of Pliocene-age sediments in the Haw- Florida Bureau of Geology. Report of Investigations. 94. 1-43. thorn Group. The Bone Valley sediments are reworked from Scott.T.M.(1988).The lichostradgraphy ofthe Hawthorn GrouptMioolder Hawthorn beds and deposited in fluvial to tidal channels. scene) of Florida, Florida Geological Surrey Bulletin, 59.
Webb. S.D. & Crissinger, D.B. (1983). Stratigraphy and vertebrate
The Wabasso beds were deposited under more open marine paleontology of the central and southern Phosphate District of Florconditions (Huddleston, pers. comm., 1985). Deposition of the ida, In Central Florida Phosphate District. Geological Society of youngest Hawthorn Group sediments (the Wabasso beds) ended America Southeast Section Field Trip Guidebook. March 16. 1983.
in late Early Pliocene.
episde eded Minr aount of hoshatemayhavebee




Full Text

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State of Florida Department of Natural Resources Tom Gardner, Executive Director Division of Resource Management Jeremy Craft, Director Florida Geological Survey Walt Schmidt, State Geologist and Chief Open File Report 36 The Lithostratigraphy of the Hawthorn Group of peninsular Florida by Thomas M. Scott in Phosphate Deposits of the World Published by Cambridge University Press by William Burnett and S. R. Riggs Florida Geological Survey Tallahassee, Florida 1990

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26 The lithostratigraphy of the Hawthorn Group of peninsular Florida T.M. SCOTT Abstract Introduction The Hawthorn Group has been a problematic unit since it was The sediments of the Hawthorn Group represent a dramnamed by Dall & Harris (1892). It is a complex unit consisting of atic change in sedimentation in Florida. From the end of the interbedded and intermixed carbonate and siliciclastic sediments Mesozoic to the beginning of the Neogene, carbonate sediments containing variable concentrations of phosphate. Scott (1988) apgraded the Haw thorn to group status in Florida and delineated with a very minor siliciclastic component dominated the deposiits component formations. tional environments of peninsular Florida. During the Early The Hawthorn Group in northern Florida has been subdiMiocene, siliciclastics. derived from the southern Appalachians, vided, in ascending order, into the Penney Farms, Marks Head, filled Gulf Trough and encroached into the carbonateCoosawhatchie and Statenville Formations. These units range in age from Early Miocene (Aquitanian) to Middle Miocene (mid produc Serravalian) :Huddlesiun. pers. comm., 1983). Lithologically, producing environments were gradually pushed further south as the Hawthorn Group in northern Florida is made up of a basal siliciclastic deposition increased. During the Miocene. carbonate with interbedded siliciclastics (Penney Farms). a comphosphogenesis became an important depositional-diagenetic plexly interbedded siliciclastic-carbonate sequence (Marks proces Head i. a s5IUlI ljti C '-nit h ar LAile concentr:ions of carbonate in amounts ranginc from trace to 60%. Palygorskite. Sepiolite, in the matrix and individual beds (Coosawhatchie), and a in an crossbedded, predominantly siliciclastic unit (Statenville). Phossmectite and minor illite are the clay minerals associated with the phate grains are present throughout most of these sediments, Hawthorn sediments. varying in concentration from absent to as much as 60% of the The lithostratigraphy of the Hawthorn Group throughout sediment peninsu In southern Florida. the Hawthorn Group is comprised of, in tenptin t e na e at ascending order, the Arcadia and Peace River Formations. The Tampa Formation or Limestone of former usage is included as a bearing Miocene sediments. lower member of the Arcadia Formation due to the Tampa's There have been numerous investigations of the Hawthorn limited areal extent, lithologic similarities and lateral relationship sediments during the last century. Scott (1988) provides a with the undifferentiated Arcadia. Similarly, the Bone Valley lengthy discussion of these previous investigations and as such Formation of former usage is incorporated as a member in the they w Peace River Formation. The southern Florida Hawthorn Group sediments range in age from Early Miocene (Aquitanian) to Early Pliocene (Zanclean) (Hunter, pers. comm.. 1985). Lithologically. Structure the Arcadia Formation is composed of carbonate with varying The Hawthorn Group is present throughout much of amounts of included and interbedded siliciclastics whichare most peninsular Florida (Figs. 26.1, 26.2) except on top of the Ocala prevalent in the Nocatee Member (basal Arcadia). The Peace Platform and the Sanford Hih where it is missindue to erosion River Formation is predominantly a siliciclastic unit with some interbedded carbonates. The carbonates are often dolostone. or non-deposition. The main structures which controlled the Phosphate grains are virtually ubiquitous in the south Florida deposition and present distribution of the Hawthorn Group are Hawthorn sediments with the exception of the Tampa Member shown on Figure 26.3. These features have been considered where it is often absent. structural in ori2in: however, there is considerable discussion The Hawthorn sediments of peninsular Florida reflect a series ..c of sea-level events and phosphogenic episodes. These sediments concer are characterized as being deposited in inner shelf, nearshore tural. Nonetheless, the features were topographically expressed environments. Erosion and reworking of pre-existing sediments on the surface underlying the Hawthorn Group. The two major played an important role in the development of the Miocene positive features were theOcala Platform with the Central Florsediment packages, ida Platform and the Sanford High with the St Johns and

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T.M. Scott 326 7rb 'A I, Tim S& ---r 1 050 .100 TOP OF HAWTHORN GROUP CONTOUR INTERVAL SOFT. ---------110o Fig. 26.1. Top of Hawthorn Group in Florida based on cores and well cuttings.

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Hawthorn Group: lithostratigraphy 327 b ~400. 500' --3 0' ......H --F TH ATONGOP SO^" 100 ^ i^J^'-30 S, 200' .... ... 450 .... --, CO TUR INTERVAL 50FT. x ^'* ^ -:? 70 .-.0 -00 e100 N 2 ---/ 10000* fthe Hawthorn Group in Florida based on cores a nd el cut0 0400. APPO~MAT LMIS OF THE HAWTHORN GROUP 500' 700 CNOR INTERVAL SOFT. 70 7000 .. .750 750' 8000' 8000' 8550 Fig 262. sopch f te Hawthorn Group in Florida based on cores

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T.M. Scott 328 JACKSONVILLE r----" -" r~-. BASIN NASSAU NOSE iy, ,v LT V 'ik i -7 SANFORD <-) -HIGH SBASIN Fig. 26.3. Structural features which affected the deposition and present occurrence of the Hawthorn Group. Brevard platforms (R]i 2s. 1979). The major negative features The sediments of the Hawthorn are lithologically defined b', include the Jacksonville Basin, the Osceola Basin and the broad the occurrence of variable amounts of phosphate, quartz sand. Okeechobee Basin. These basins contain significant thicknesses dolomite and palygorskite. The Hawthorn Group is most easily of Miocene sediments ranging from 250 ft (76 m) in the Osceola discussed in the context of northern and southern areas divided Basin to 900 ft (275 m) in the Okeechobee Basin (Fig. 26.2). by an east-west line between the southern erosional limit of the Hawthorn on the Ocala PLut.,-rnr, and the Sanford High. respecLithostratigraphy tively (see Fig. 26.4). Lateral and vertical variability is most Previous investigations considered the Hawthorn sedipronounced in north Florida. ments as a single formation which displayed great variability throughout Florida. The resulting confusion is evident in the North Florida literature. Elevating the Hawthorn to group status eliminates The Hawthorn Group in north Florida contains signifimuch of the confusion, cantly higher percentages of siliciclastic sediments than in south

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EASTERN EASTERN SE AND E NW FLA. NORTH SOUTH SE ANDE AND NORTHERN SOUTHERN CAROLINA CAROLINA GEORGIA SW GA. FLORIDA FLORIDA YORK TOWN FM. RAYSOR CYPRESSHEAD FM. MICCOSUKEE FM. CYPRESSHEAD FM. TAMIAMI FM PLIOCENE PLIOCENE YORK TOWN FMS /DUPLIN FM. / CITRONELLE FM, I NASHUA FM. REWORKED UPPER SEDIENT j UPPER C3 PEACE COOSAWCOOSAW-RIVER 0 STATENVILLE C< HATCHIE HATCHIE L STATENVILLE 3 U SFM COOSAWPUNGO 0 cc HATCHIE O RIVER Z 0 Fm .r S FM. M HEAD FM. HEAD FM. FM. < HEAD FM. X_______ 4 1_ NOCATEE MBR. PARACHUCLA PARACHATTAPENNEY TAMPAMBR. SFM CHUCLA HOOCHEE AND FARMS I *FM. ST. MARKS fms. FM. I_ /I *COOPER SUWANNEE RV COOPE SUWANNEE SUWANNEE A SUWANNEE OLIGOCENE LS. LS. LS. LS. OLIGOCENE COOPER FM. OCALA GP. OCALA GP. OCALA GP. OCALA GP. UPPER E CENE SANTEE AVON CASTLE HAYNE SANTEE LS. I PARK AVON PARK FM. AVON PARK FM. AVON PARK FM. MIDDLE FM. Fig. 26.4. Ge-neralized %raligraphic correlations from Florida to North Carolina (nmodified from unpublished Gulf Coast COSJNA chart and Atlantic Coastal Plain chart, American Association of Petroleum Geologists, 1983).

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T.M. Scott 330 Florida since it is closer to the siliciclastic source area in the Piedmont and southern Appalachians. In north Florida, the Statenvile Formation In a limited area of north Florida. Hawthorn is subdivided as shown in Figure 26.5. Definitions of the Statenville Formation replaces the Coosawhatchie Formathese formations including type sections, detailed lithologic detion as the uppermost Hawthorn Group unit (Scott, 1988). The scriptions, stratigraphic relationships, structure and isopach Statenville consists of thin-bedded, often cross-bedded, clayey, maps and discussions of the formational ages are presented in phosphatic, quartz sands interbedded with thin dolostone beds Scott (1988). and clays. The phosphate content is great enough in limited areas to be an economically important deposit (e.g. Occidental PetroPenney Farms Formation The basal, carbonate-rich leum's north Florida deposit). Hawthorn Group sediments have been assigned to the Penney The Statenville Formation unconformably overlies the Farms Formation (Scott, 1988). The carbonates are variably Marks Head in some areas and conformably overlies the lower quartz sandy, phosphatic and clayey dolostones. Carbonate part of the Coosawhatchie in other areas. The Statenville is beds are thicker and more'common in the lower portion of the laterally equivalent to at least the upper par of the Penney Farms. Interbedded siliciclastic units become thicker Coosawhatchie. It is unconformably overlain by post-Hawand more abundant upward in the formation. The siliciclastic thorn undifferentiated sediments. The thickest known section of sediments consist of dolomitic, clayey, phosphatic quartz sands Statenville is 87 ft (26 m). Correlation of the Statenville with the and dolomitic, phosphatic, quartz sandy clays. Coosawhatchie suggests a Middle Miocene age (Huddlestun. The Penney Farms Formation unconformably overlies the pers. comm., 1983). There also is a zone ofreworked Statenville Eocene Ocala Group throughout most of northern Florida. exposed in the north Florida phosphate pits that contains a Late Occasionaill it overlies the Oligocene Suwannee Limestone. It is Miocene vertebrate fauna (Webb, pers. comm., 1985). overlain unconformably by the Marks Head Formation (Figs. 26.6,26.7; Fig. 26.5 shows location of cross-sections). The Penny South Florida Farms reaches a maximum thickness of 230 ft (70m) in the The Hawthorn Group of southern Floridagenerally conJacksonville Basin.'Palaeontologic evidence suggests that the sists of a basal carbonate unit and an upper siliciclastic unit and Penney Farms is Early Miocene (Early-Middle Aquitanian) is subdivided as shown in Figure 26.4. Complete definitions of (Huddlestun, pers. comm., 1983). the formations are available in Scott (1988). Marks Head Formation The complexly interbedded Arcadia Formation The lower Hawthorn carbonate secsiliciclastics and carbonates overlying the Penney Farms Formation in south Florida has been assigned the name Arcadia tion have been referred to as the Marks Head Formation (Scott, Formation (Scott, 1988). The carbonates are characteristically 1988). This unit is the most lithologically variable section of the quartz sandy, phosphatic. sometimes clayey dolostones to Hawthorn Group. The carbonates are variably quartz sandy, limestones. Quartz sandy. non-phosphatic-slightly phosphatic clayey, phosphatic dolostones. The carbonates are interbedded limestones predominate in theTampa Member (Fig. 26.4). Phoswith dolomitic, phosphatic, clavye. quartz sands and dolomitic, phatic siliciclastic beds occur sporadically throughout the Arcaphosphatic, quartz sandy clays. Often the Marks Head clays dia Formation, becoming the dominant lithologv only in the may contain only minor amounts of the other constituents. Nocatee Member (Fig. 26.). The Marks Head Formation unconformably overlies the The Arcadia Formation unconformably overlies the Eocene Penney Farms Formation and unconformably underlies the Ocala Group, Crystal River and Williston Formations, in the Coosawhatchie Formation (Figs. 26.6, 26.7). The Marks Head north-central and northeastern portions of south Florida. It reaches a maximum thickness of 130 ft (40 m) in the Jacksonville unconformably overlies the Oligocene Suwannee Limestone Basin, Limited paleontologic evidence suggests a mid-late Early elsewhere in this area. The Arcadia is overlain unconformably by Miocene siBurdiealiani age iHuddlestun, pers. comm., 1983). the Peace River Formation (Figs. 26.8 and 26.9). The Arcadia reaches a maximum thickness of nearly 600ft (183m) in the Coosawhatchie Formation The uppermost sediments of Okeechobee Basin. Few datable fossils have been found in the the Hawthorn Group in much of north Florida have been placed Arcadia. Limited data suggest that this Formation ranges in age in the Coosawhatchie Forma lion (ScoIt, 1988). Sediments of the from very earliest Miocene (early Aquitanian) to late Early Coosawhatchie are characteristically less variable than the Miocene (Late Burdigalian) (Hunter, pers. comm. 1985). Marks Head, consisting of very quartz sandy, phosphatic, clayey dolostones to dolomitic, phosphatic, clayey quartz sands. The Peace River Formation The upper Hawthorn siliciclastic base of this formation in the Jacksonville Basin often is a section in south Florida has been assigned to the Peace River dolomitic, silty clay. Formation (Scott, 1988). The siliciclastics are typically The Coosawhatchie Formation unconformably overlies the dolomitic. phosphatic, clayey quartz sands. Clay beds occur Marks Head and is unconformably overlain by post-Hawthorn infrequently throughout the section. Carbonate beds are comundifferentiated sediments (Figs. 26.6, 26.7). The thickest mon within the Peace River Formation and are generally quartz Coosawhatchie section encountered was 222 ft (68 m) in the sandy, phosphatic, clayey dolostones. Jacksonville Basin. Paleontologic evidence suggests a Middle The Peace River Formation unconformably overlies the ArMiocene (Early Serravalian) age (Huddlestun, pers. comm., cadia and is unconformably overlain by post-Hawthorn undif1983). ferentiated sediments (Figs. 26.8 and 26.9). The Peace River (p

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Hawthorn Group: lihioraiI rIph331 A B OUTH Fig, 26.5. Subdidision of north and south Florida and location of crosssections. Formation reaches a maximum known thickness of 650 ft phosphate-producing horizon in the Central Florida Phosphate (198 m)in the Okeechobee Basin. Faunal :. idence suye-t that District. the Peace River Formation ranges in age from Middle Miocene The boundaries of the Bone Valley Member are complex. In (Serravalian) to no younger than earliest Pliocene (earliest some areas of the district it unconformably overlies the Arcadia Zanclean) (Hunter. pers. comm., 1985). Formation while in other areas the Bone Valley con]o.nbi-. to Scott (1988) reduced the status of the former Bone Valley unconformably overlies the undifferentiatd Peace River Formation to Member. The status reduction was due to the Formation. The Bone Valley Member is unconformably limited areal extent of this unit and the liihcologic relationship overlain by post-Hawthorn undirlereniied sediments (Figs. and demonstrated time equivalence to the undifferentiated 26.8 and 26.9). The maximum recognized thickness for this unit Peace River Formation. Lithologically, the most important facis approxmrnaTel, 50 ft (15 m). The age of the Bone Valley Memtor for separating the Bone Valley from the remainder of the ber is derived entirely from vertebrate fossils collected from this Peace River Formation is the occurrence of phosphate gravel in until MacFadden & Webb (1982) and Webb & Crissinger (1983) the Bone Valley Member. Pho;phaie gravel and sand are mixed suggest that the Member ranges in age from as old as latest Early with quartz sand and clay in proportions that vary from bed to Miocene (latest Burdigalian) to as young as Early Pliocene bed vertically, and within beds laterally. This unit is the main (Zanclean). .7

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T.M. Scott 332 A A S7 WC e 75-26E736.1 27 P 13S 2SE 07 a 100 30 WNa-3N.24£-.2aa 4.5 a --wP -155-276-4' 5-100 W ,14193 w.1 476 I 75ST JOHNS RIVER C. 14 V:. .:75 20 50 4,8 20 50 WD-tS-27E 2 50 10 ST JOHNS RIVER UNDIFF 2-j UNDIFFERENTIATED ......-.r...... .. --'. ....::::::::: ::::: ...... ....... .... ...... ..... ...... ...................... ........... ...::::: .:::: :::.:. :: :::: :P... ................. A.. ........ ..... ................ .. .... .. ....... .. ..... :: : :: ::;:::: ::: : ::: :::::: : ...... :To....... ......."E::::b:r::' 1: :: :::111 ::. :;. ....... i O -. ......-. -3. ...†.. ..-: ::: -::: :::;: -::: ::::::::: R ::.....:: :::::::::: ',::...::::...::.: :::': .. :::: :" ;: ^1ce of:::::::: .Florida: Thes : sedJiment HAWThORN GRcOUP 50UNOARoES .................... ....::.. ..::: :: ::::: : : :.: : ::: : -:: : ...... ..-30 n::::::::::::::: : : ::: ::::::::: A 1 5 ......i., indica.... ._ i ::::::::n ::e 10 5 1 -450:: i:^::: ;:: :::i :::. ......... .. ::: ... .. .. ... .. .. ...53 111 k .........::: :: :::.:::::::. ::. -: : : :::::::: 4: Fig 26. Cross-section AA showing the depositional and erosional pinlhout of Hawthorn Group sediments southward from Jacksonville Basin onto the Sanford Hugh. Geologic history mentation may have been the result ofeperiogenic uplilt in the Durina the Miocene, peninsular Florida was subjected to Appalachians. possibly coupled with a climatic change. The numerous major and minor sea-level fluctuations and penodidramatic influx of siliciclastic sediments filled the Gulf Trough cally subaerially exposed. The sedimentsofthe basal Hawthorn which had effectively isolated the carbonate bank from Group are the first record of Miocene transgressions upon the siliciclastic input from at least Early Paleocene through Late eroded. karstic, limestone surface of Florida. These sediments, Oligocene. Siliciclastic deposition was very important in norhcarbonates and silicclastics of the Penney Farms and lower ern Florida in the Lower Miocene but did not dominate in Arcadia. Formations. contain significant but not economisouthernmost Florida until possibly as late as early Lace Miocally important amounts of apatite, indicating the Miocene cene (Scott, 1983). Phosphate occurs as discrete apatite grains phosphogenic episode had begun, and as rims on and replacement of carbonate inraclasts SediCarbonate sediments dominated deposition in the Early ments deposited during the early part of the Lower Miocene Miocene, although they contained a siinificanr siliciclastic com(Early Aquitanian) probabl'. did not completely cover the Ocala ponent. The siliciclastics present in the earliest Miocene reprePlatform or the Sanford High. sent the first recorded Cenozoic influx of siliciclastics onto the Sediments deposited in the mid-Lower Miocene (Late carbonate bank of peninsular Florida. This major shift in sediAquitanian-early Burdigalian) have not been recognized in ..

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Hawthorn Group: lithostratigraphy 333 0 Su u f-4-22E-25bd WW-15' W-138210 WHr-2N-12E3b W-15162 60E-200 WCo-2S17E23dc WBk-2S.19E-30ac W-683 175 UDIFF -NE36CSUWANNEE RIVER 50 ALAPAHA RIVER UNOIFF 400 30:: a::: UNDIFFERENTIATED 3 100 MAJ( .E.. .M.... ........ ...................... 75 .......... -.... : ': A5 ..... .. .. .:::::: £ 20 Z -CHARLTON 20 ........ MEMBER1...:SUWANNEE LS ::::::10 ..--OCALA GRDOUP \:':: ::0::::::::::::" 20 ....... ..... ... ... .... ... ..:F : : -30 -100. /sHAWTHORN GROUP BOUNDARIES SCALE 1 250.000 ..0:: :::::: 5 0 5.MILES :::::::: 5 0 5 O 15km::: :::: S ::::::: -2o .... ..-250 Fig. 26.7. Cross-section B-B showing the relationship of the Statenville Formation to the remainder of the Hawthorn Group in Florida. If sediments of this age are to be found onshore, it may or the Sanford High. However, the present distribution and be the thick Arcadia Formation section in south Florida's thickness of these sediments suggest tha more of the strucures OkeechobeeBasin It is not known whether the absence of these were covered than earlier in the Early Miocene. eimnis due to non-deposition or erosion, but it is helpful to Middle Miocene sediments disconformabl overlie the note that they are not recognized in Georgia. South Carolina or Lower Miocene throughout much of the State The ~North Carolina.~ unconformit. is often marked by a bored, phosphatized. wellLower Miocene (idBurdigalani sediments of the Marks lithified carbonate bed or a rubble resulting from the rip-up o Head and upper Arcadia o '.rs were deposited on the midthis bed. Deposition of the mid-Miocene sediments ma ha Lower Miocene unconformity. Siliciclastic sedimentationdomibegun as early as very early Middle Miocene (Lanhian) Snnated in northern Florida while carbonate deposition, mixed der. pers. comm.. 1985) to mid-Middle Miocene (Earl :with variable amounts of siliciclastics, continued in southern Serravalian)(Huddlestun. pers. comm.. 1985). The deposition of Florida Once again apatite is present, but not in economically the Middle Miocene Hawthorn sediments covered the entire mportant quantities. In north Florida, the Lower Miocene peninsula(Scott, 1988). There, sediments were later removed by sediments were probably not deposited over the Ocala Platform erosion from the crest and upper flanks of the Ocala Platform. 3

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c C HIlltBOROUGH CO. POLK CO POLK CO OSCEOLA CO OSCEOLA CO BI REVAYD CO INDIAN RIVER CO W 14883 W FI79 30S 2 04b 152 295 24F 24cb 0S 28E 12cc M5t411S ItET 3 1E METERS FEET llt IJ E \ W 9150 M TERS 50 40 WS I G41/ W 13942 40 30S 18[ 1I l I -^'29S 33E 23ad W 13958 30 100 4 W13964 32S 39E-16b 30 -100 20 ..... 3-35E!?b 20 UNOFENTATED 10 .CSTAl IVER -150 2O. 0ORMATION ARCA :I: A.FIMAT 50 .. ......... .. .... S ..WA AVON PA5-s 90300 L.M.S.. ..-.. LIMESTONE ....O 200 -3.50 i10 AON P ...... A D FO -O A 30 0 4 I 210 0 0 0MIES .221 .5 1. ...5 ..kicn Fig. 26.8. Cross-seclIion CC-C ...howinig 1. .soIIlhcrn. Florida Hawthorn (irou s dimnents from west I ..a.i across .t .s.llI.rni nos orf O(ala llalfrmn In tilt Itrevard PIlatforni.

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ll t SBOHOUG~l CO MANATEE CC MANATEE CO SARASOTA CO SARASOTA CO CHARL OTTE CO CHIARLOTTE CO LEE CO METERS FEET 150 411 1941 T520 1 2w 1 466 W9 19348 2 3,11 b. 152896 W 152 30. ... .--.. .... -.. :::I:U._: ........ 20 -METERS FEET S50 -0 19) 10 0-MLUDFfHNIT 0 --MSL 10...... ._... .... ............ .......... .. .....................--. ............. ..... : .. .... .. ..... .. .. 20 '.. .............:.:::.: ::: .,, :0: :::0:: :::::::: ::: 0 ja .-10 'i,1:: ::: ; ;::::: :::::::::::::: : : -,li : t, :: : ::i:;:! : !:: :;:: : : :;:::::::::i::":::: ii :^ ; ^ ::::::::::::::::::::::::: ::::::: :::::: ============================== 30 .== ::50 .l" ; -,; : .:^; ^ ^ : ^ ^:. : ':::::, .,' : i:::: ;:::::::: :::: ::.: :::.:^ ::i: :: i :::::::: [ i : :! :1:^: 1:!:::: :: 1::: :: :::::: :^ ================ ================ -40 s 60 Ty ::::::;:^ :;;::::;:;::^;: ^ :^ : [:^ m ^i:;:;;^;i~ ii; :^ ;::::::::::::: :::::::::::::^ ;^:: ;::: ::::::::::::::::: :::::::::::::!::6 -5o '^ :: :::: ::: i;:: : :: .:. ::.. .: .... .... .^ f^ ^ ..-^ ^ .^ ^ :: ::: :::: ::::: : :::::: ::::4LIA::::: ::::::::::: :::: ======= ::=== := ::==== :=== ::== :::= 20 .......::::: ;: : :.i. : :::1::::::: : ,j::^ ....::: .... ::: :::: ^ ::: ^ : .......... ::::... .......4 -..2o..:::: : ::: -::::* -7 30....... 100 0 10 ^::" : :" : ": ::::: :'" '":: : '::;'"::: : : ": :ii i !i i i i i i~ ii ii ii ii }!i: : ::'::; :'::";: '"; : ':: :t ; : i :::ii iiiii i :ii i :::: : iii ] i: i :iii i :: :iii :i : :i i i i: :i ii i :;::::ii i. -: --::i :: :: i :; :: : 120: .: :0: ::,:;,;::;:;;,::.-:,::;:,::::,, :;::::::::::;;::rf H *:::;:' ;:;::;::: :::::::;:;::i ^ ;::::;: i ;;;:;; ii:^ ::^ ::ii::i:::i ^ :;:i:::i:ii 120 i 4-" i30 ^^ si-^!^:^ :^! :i:::i;:;^ :: :;: !!!!!!!!!I !!iiiiiiiiiiii^;:^!:: !;;:^ ;:::::;: ^ S ::i^^ :: ^:^ ^^ -l 40! } !} } i : ............... .... ............................... -40 405 150. 61111200 lEO" 1 00 9'^ ; _L --"'k .;: ::^ :;:: 1::: i:! ^ ^ ::::: ^ ^ :'0 -3500 100 bo ================ 100 1.0 0 350 410' 40 12^mlmlH^I~~~llHi~ij; 0 -400o • ........G ............ 130 > n :;::^ : :1;:^::;;;: 0 -13 50 140 451 490l ioOO' ;;;;:^ :;::;:::; 170 T70 *)3 180 1 M IS**::::::::::::: X T W .O....) 1.0 .250 1)0~-9 SEA EI'0002 0 0 0 0 O .......... 100 (1 $ TOOES1 00 SUWtN 750 iH. 26.9. Cross-sect ion 1)-I)' showing Ihickening oF the I lawthorn iroup stiulhwardl intoi I keer-holwlre Basin.

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T.M. Scott 336 leaving only isolated outliers as evidence of at least part of its The amount of phosphate present in the post-Middle Mioformer extent. cene Hawthorn Group sediments (except the Bone Valley MemThe greatest accumulation of phosphate in Florida appears ber) is considerably less than in the Lower and Middle MiocenI to have occurred during this Middle Miocene depositional cycle, portion. averaging < 3%. This suggests that with the lowering of Much of the phosphate currently being mined in northern, and a sea level in the Late Miocene, the major Miocene phosphogenic portion of that mined in central Florida, is thought to have been episode ended. Minor amounts of phosphate may have been deposited in the Middle Miocene. These phosphorites were deposited in these younger sediments; however, much of it could deposited during a high stand of sea level in response to the be the result of reworking of the older phosphatic sediments. impingement of topographically-induced upwellings (Riggs, 1984) onto the Ocala Platform and lesser positive features. Subsequent reworking of the phosphorites has also been quite important in development of the deposits. The Bone Valley References Formation provides the best American Association of Petroleum Geologists. (1983). Aatic Coastal Plain, Correlation of Stratigraphic Unis of North America example of the importance of this reworking in that it contains :COSUNA) ed. A. Lindberg. lare quantitlies of phosphate gravel reworked from pre-existing Dall, W.H. & Harris, G.D. (1892), Correlation paper-Neocene. US phosphate deposits. The reworking of these deposits has been Geological Survey Bulletin, 84. 85-158 multicyclic, occurring primarily from early Middle Miocene Huddlestun, P.F..Hoenstine,R.W.,,AbbottW.H. &Wosley.R.(982). through Early Pliocene. The stratigraphic definition of the Lower Pliocene Indian River beds of the Hawthorn in South Carolina, Georgia and Florida. In Miocene Upper Miocene sediments in the Hawthorn Group occur of the Southeastern United States, ed T. Scott & S. Upchurch. pp. 18primarily as zones of reworked, older sediments dated by the 5,. Florida Bureau of Geology, Special Publication 25. Tallahassee. occurrence of vertebrate remains (Webb & Ctissinger. 1983). MacFadden, B.J. & Webb, S.D. (1982). The succession of Miocene These occur at the top of the Statenville Formation in northern Arikareean through Hemphillian terrestrial mammal localities and Sd in a Member of the Peace River faunas in Florida. In Miocene of the Southeastern United States. Proceeding of the Symposiumn. ed. T. Scott & S. Upchurch. pp. 186-9. Formation in southern Florida. Although it has not yet been Florida Bureau of Geology. Special Publication 25, Tallahassee, fully documented, other sediments of Late Miocene age Riggs, S.R. (1979). Phosphorite sedimentation in Florida -a model (Tortonian) occur in southern Flortd. in the Peace River Formaphosphogenic system. Economic Geolgy. 74. 185-314. tion. These sediments contain only minor (<5%) concentraRiggs. S.R. (1984). Paleoceanonographic model of Neogene tions of phosphate grains. phosphorite deposition, US Atlantic Continental Margin. Science. 223(4632), 123-31. Sediments of the uppermost Bone Valley Member and the Scott. T.M.(1983). The Hawthorn Formation of norheast Florida: Part informal Wabasso beds (Huddlestun et al,, 1982) are the only I -The geology of the Hawthorn Formation of northeast Florida. documented occurrences of Pliocene-age sediments in the HawFlorida Bureau of Geology, Report of Investigations, 94, 1-43. thorn Group. The Bone Valley sediments are reworked from Scott, T.M. (1988). The lithostratigraphy ofthe Hawthorn Group(Mioolder Hawthorn beds and deposited in fluvial to tidal channels. cene) of Florida .Florida Geological Sure Bulletin. 59. Webb, S.D. & Crissinger. D.B. (1983). Stratigraphy and vertebrate The Wabasso beds were deposited under more open marine paleontology of the central and southern Phosphate District of Florconditions (Huddleston, pers. comm., 1985). Deposition of the ida. In Central Florida Phosphate District. Geological Society of youngest Hawthorn Group sediments (the Wabasso beds) ended America Southeast Section Field Trip Guidebook. March 16. 1983. in late Early Pliocene. It-


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xml record header identifier oai:www.uflib.ufl.edu.ufdc:UF0000103500001datestamp 2008-12-05setSpec [UFDC_OAI_SET]metadata oai_dc:dc xmlns:oai_dc http:www.openarchives.orgOAI2.0oai_dc xmlns:dc http:purl.orgdcelements1.1 xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.openarchives.orgOAI2.0oai_dc.xsd dc:title The lithostratigraphy of the Hawthorn Group of peninsular FloridaOpen file report -- Florida Geological Survey; no. 36dc:creator Scott, Thomas M.dc:subject Geology, Stratigraphic -- Miocene.Geology -- Florida.dc:description Cover title.Originally published as chapter 26 in: Phosphate deposits of the world / by William Burnett and S.R. Riggs. New York : Cambridge University Press, 1990.Includes bibliographical references (p. 336)dc:publisher Florida Geological Surveydc:date 1990.dc:type Bookdc:format 327-336 p. : ill., maps ; 28 cm.dc:identifier http://www.uflib.ufl.edu/ufdc/?b=UF00001035&v=00001AAA0682 (notis)AJG4826 (notis)49783372 (oclc)dc:source University of Floridadc:language Englishdc:coverage Hawthorne Group.12000