ve,
U. S. Geological Survey.
REPORTS-OPEN FM. SERIES, no. 958: 1967.
Gf_O LOGICAL 1- -01V p. DEC 2 0 1967 -, • '• , '•••• ?. • ;-?,=;Z:." •••••,- ••• • ••• . •
10. 41
( 200 ) 11,290 no.953, 1967 2/(
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DEC 1 9 1967
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UNITED STATES DEPARTMENT OF THE INTERIOR
I-7LA GEOLOGICAL SURVEY
FLORIDA TYPE PHOSPHORITE DEPOSITS--ORIGIN AND
TECHNIQUES FOR PROSPECTING
By James B. Cathcart
U.S. Geological Survey, Denver, Colorado, U.S.A.
sfif\„. D. 0,VIAGTOW
DEG 8 1967
Open-file report R 1967
Report prepared for presentation at ECAFE Seminar on Raw Materials,
Bangkok, Thailand, December 4-11, 1967
Contents Page
2 Introduction 1
3 General geology of the Atlantic Coastal Plain 2
4 Strati graphy 5
5 - Structure 10
6 Phobphorite 11
7 Phosphate pellets 11
8 Mineralogy 12
9 Origin 15
10 - Prospecting techniques 19
11 Literature cited 24
12 Tables
13 Table 1. Known occurrences of phosphate, Gulf and Atlantic
14 Coastal Plain, United States 6
15- 2. Generalized stratigraphy of phosphorite deposits of
16 Tertiary age, Atlantic Coastal Plain-- 8
17 Figure
18 Figure 1. Sketch map of southeastern United States, showing
19 structure of the Coastal Plain and phosphorite
20- deposits of Tertiary age 3
21
22
23
24
25-
U. S. GOVERNMENT PRINTING OFFICE 1959 0 - 511171 a (p. 1 follows) 167.100 Introduction
2 Phosphate particles are widespread in rocks of Cretaceous,
3 Tertiary, and Quaternary ages in the Atlantic and Gulf Coastal Plains
4 of the United States. Sedimentary particles of phosphate are known to
5 - occur in rocks of Cretaceous, Paleocene, Eocene, Oligocene, Miocene,
6 Pliocene, Pleistocene and Recent ages, but known economic deposits are
7 confined to or were derived from rocks of middle Miocene age. Economi
8 deposits occur only in the Atlantic Coastal Plain frOm North Carolina
9 to Central Florida,(fig. 1). Similar deposits are known at Sechura
in Peru in rocks of Miocene age.
The Miocene phosphorite deposits are herein called the "Florida"
type, because the deposits of the land-pebble district of Florida are
the best known.
14 The deposits are unconsolidated, flat-lying, have=been reworked
15- in varying degrees, and all are covered by varying thicknesses of non-
16 phosphatic material called overburden. The overburden, in many cases,
17 completely masks the underlying deposits, and discovery of new
18 deposits depends on an understanding of the origin and geology of the
19 already known deposits. Prospecting must be done by drilling in the
20- deeper deposits or by a combination of drilling or trenching in the
21 shallower deposits. Prospecting can be expensive, and the target are
22 has to be limited so that drilling of blank holes can be held to a
23 minimum.
24
25-
U. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 • 67.100 1 Clues to the location of possible ore bodies and methods of
2 prospecting, or more precisely, the limiting of areas in which to
3 prospect will be discussed in this paper. The clues may be direct,
that is, dependent on the ore body being at or close to the surface,
5 — or the clues may be indirect, and dependent entirely on the theory of
6 origin of the deposits.
7 Some of the geologic factors that control the deposition of the
8 phosphorite ore bodies are the same as tko:=2-ffer,,,--Tr% those that govern
9 the deposition of the marine phosphorite deposits in miogeosynclinal
10- areas, but other factors are different, and a major difference is that
11 the "Florida" type deposits are economic because they have been re-
12 worked and concentrated.
13 General geology of the Atlantic Coastal Plain
14 The Atlantic Coastal Plain is a physiographic province of the
15- eastern United States that is bounded by the Piedmont on the west and
16 by the Atlantic Ocean on the east. The Coastal Plain is underlain by
17 Cretaceous and Tertiary sedimentary rocks that, in general, dip very
18 gently east and southeast toward the sea. The sedimentary rocks are
19 unconsolidated or weakly consolidated, outcrops are poor, and a cover
20- of Pleistocene and Recent deposits obscures much of the geology. The
21 general seaward dips are interrupted by broad, gentle anticlinal and
basinal folds that have northeast and northwest trends (fig. 1).
23
:4 Figure 1.--Near here
C. S. GOVERNS/EST PE:N77.,a; GFF7.7 G - • - '4,-f.‹. 2 A rprox irrocte. ilrni t- of the_ Coos -I Plain
- a- No rfolk. arrh
4r Albemarle embayrneni-
ainsc, FRI'ver ?boilhoritc (6i6son, /91;9 Unnamed
Qfch "1'4 fie-0.1
areek; 'Roger', 19/4) Seal% Caro/,NE (Char/es7An Riagelcand. basin phos.phorift. 9leTohn son , /1") ?ectuforE-1 high (tieron
- Sou4beas+ Ge_.rgia. ern"it ( Herncictvvd,his, 1 etr
Unnamed baks;r Leve, 1 94.5) distract (Se-vet:47*W otAirr;, 4'41)
51tin) dtrictifi - tio.rekrock divir CF.Spenshoele. Sptrazr, icio)
1401412oro I/01 CAOrcAlt I1050 ani,- tat. le. dist/10- Cca-theart, qoa.)
F u1-E - SK ETCH MAP o F EA ST U N D %TA Ts.5 314 NI 6- Cru RE_.5 OF Ti4r coAsTi+/- PL-A-1N) AND F4-05 P4-110T2- ITE. DE. Po i T3 •F T E IZT FR.?) 13-6 E Because of the very gentle dips, the unconsolidated nature of the
2 rocks, the cover of Pleistocene material, and abundant vegetation, not
much of the geology can be seen at the surface, and the stratigraphy,
4 structural relations, and the discovery and delineation of phosphorite
5 - deposits depend. on mapping large areas supplemented by core drilling.
6
7
. 9
10-
11
12
113
14
15-
16
17
18
19
20-
21
22
23
24
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U. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 867.100 4
Stratigraphy
2 Phosphate pellets are widespread in rocks of Cretaceous, Tertiary,
3 and Quaternary ages in the Atlantic and Gulf Coastal Plains of the
eastern United States. A complete discussion of the stratigraphy of
5 - the coastal plains is beyond the scope of this paper, but summary data
6 on all known occurrences of phosphate pellets in sedimentary rocks of
7 the Coastal Plains are given on table 1. Table 1 lists the formations
8
9 Table 1.--Near here
10- in which phosphate occurs and is arranged generally according to age 11 and state, but the table is not a correlation chart, and is not 12 intended to show relations between formations. 13 In general, the phosphatic formations are of two kinds: calcare- 14 ous and quartzose. The calcareous phosphorites are probably primary, 15- while the quartzose phosphorites have been reworked, at least to some 16 degree. 17 Phosphatic sedimentary rocks in the Gulf Coast are confined to 18 the Paleocene and the Cretaceous, and in general are found associated 19 with marls and glauconitic sediments. No phosphate deposits are known 20-
21 in rocks of Tertiary age in the Gulf Coastal Plain, and the occurrenc s
22 of phosphate pellets in these rocks are restricted to a few grains in
23 a few outcrops. A survey of the literature indicates that there is
24 little or no phosphate in rocks of Eocene to Pleistocene age in the
25- Gulf Coast.
U. S. GOVERNMENT PRINTING OFFICE 1959 0 - 511171 667.100 5
Age State Formation Lithology F205 content Refer .Ices
Recent or Florida, Georgia, Bars, floodplains along . Sand of quarts grains and Phosphate pellets ' Mansfield, 1942
Pleistocene South Carolina modern rivers phosphate pelletoY 25 Rogers, 191k
Pleistocene South Caroline Ladson Formation Clay, quarts asnd, 1/ Phosphate pellets Melds, 1959
phosphate pellets 21-29
Pliocene Florida Done 'Atilt,' Formation Clay, sand, phosphate Phosphate grains Cathcart, 1963e pellets and nodules 30-38
•Pliocene North Florida tisnamet.'l do. Phosphate pellets Olson, 1966
South Georgia 20-35
Miocene Florida, Georgia, Hawthorn Formation Clay, sand, calcite, Phosphate pellets in Olson, 1966 nd ()then:. South Carolina dolomite, phosphate veathered rock-25-351 Sever,/ea=als4 1967
in fresh rock-15-25 Heron $rd Johnson, 19.'",6
Cathcart, 1963b
Berth Carolina , Yorktown Formation Clay, ,and, limestone, Phosphate pellets Brown, 1958
some phosphate pellets 30* Kimrey, 1965
and granules 1/ flibson, 1967 Roomy and Kerr, 19(7
'North Carolina Puna° Slyer For. Phosphate pellets, sand, Phosphate pellets • tin.
matron dolomite, clay 1/ 31
• Florida Tampa Limestone" Limestone, clay, ea*, I Phosphate pellets-- Sever and others, 19'1
Georgia some phosphate pellets 10-20 Carr and Aleerson, 1959 —•I Whole rock--2-4
South Carolina Marl Marl, sailor phosphate Phosphate pellets )141.4A, 1959 pellets 10-20 Whole rock--2-9
North Carolina Castle Bayne Limeetgne, some phos- Phosphate pellets Dabney, 1885 Limestone photo pellets and 30 granules Whole rock--6-7
Georgia Tallakusta Quarts sand, some No data Oven, 196 Formation ' phosphate grains 1/ i•••••••••••••••••••., Claiborne Phosphatic shell marl Phosphate pellets Smith, 1892
Group 20
Kidings Phosphate pellets in Phosphate pellets-. Weaver and others, Group greensands and marls 20
Matrix--1-2
!atomise Brightseat Phosphate pellets in No data Adams and others, 194-;
Formation dalcarepus sand 1/
Cretaftone' Alabama :Prairie Bluff Phosphate pellets in Phosphate pellets-- Smith, 1892 Formation of elma Mississippi S 30 McCallie, 1896 Group and equivalents: Alorgla matrix 2-4 Monroe, 19412 Stephenson F I Monroe, 1940
Eagle Ford iPhosphate conglomerate Phoephate--24 Vassar and others, 1963
Formation at base of shale 1/ Whole rock.-5.10 6 1/ levorkeds at least in part, tram 014er rocks. 1 Economic phosphorite deposits of the "Florida" type are found only
2 in the Atlantic Coastal Plain and in rocks of middle Miocene age, or
3 in younger rocks in which the phosphate was derived from rocks of
4 middle Miocene age. Generalized stratigraphy of the phosphate depositD
5- of the Atlantic Coastal Plain is shown on Table 2.
6
7 Table 2.--Near here
8
9 The phosphorite deposits of North Carolina are in the Pungo River Formation of middle Miocene age. The underlying Castle Hayne Limestone 10 -
H contains a few phosphate nodules, and the overlying Yorktown Formation
12 contains some phosphate pellets in the base of the formation, that
13 have been reworked from the Pungo River Formation. The Pungo River
14 Formation consists of phosphate pellets, quartz sand, minor clay, and
15- interbeds of dolomite, diatomaceous clay, and sand. The phosphate
16 pellets show evidence of having been reworked (Rooney and Kerr, 1967).
17 The phosphorite of the Charleston area, South Carolina, is in the
18 base of the Ladson Formation of Pleistocene age (Malde, 1959) and
19 consists of boulders of reworked, phosphatized Cooper Marl in a claye
20- sand. Malde does not propose any source for the solutions that
21 phosphatized the surface of the Cooper Marl. The Hawthorn Formation
22 is present just to the south of the Charleston area, where it contain abundant phosphate (Heron and Johnson, 1966). The source of the P205 23 that phosphatized the Cooper Marl probably was phosphate pellets in 24 the Hawthorn Formation.
25-
U. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 .97-100 SOUTH CAROLINA SOUTH CAROLINA . " --- 130GTH'GEORGIA SOUTH FLORIDA NORTH CAROLINA Charleston area Beaufort County NORTH FLORIDA
Surficial sand Pleistocene and Surficial sand Surficial sand Surficial sand Ladson Formation phos•horite) Bone Valley Formation Unnamed unit Pliocene (phosphorite) 1phosphorite)
Pungo River Hawthorn Formation Hawthorn Formation Hawthorn Formation Formation (phosphate pellets liocene (phosphorite) (phosphorite) (phosphorite) •/ abundant) Tampa Formation Tampa Limestone (trace phosphate) (trace phosphate)
Cooper Marl Cooper Marl Suwannee Limestone Suwannee Limestone Oligocene (trace phosphate)
Ocala Limestone Ocala Limestone Jackson, Claiborne , Eocene Castle Hayne Lime- Castle Hayne Middle and Wilcox Groups Avon Park Limestone Rocks of Claiborne stone (trace Limestone age phosphate) Olson (1966) Cathcart Malde (1959) Heron and Johnson References Gibson (1967) Sever, Cathcart, and, (1963a, b) - (1966) Patterson (1967) 1 The phosphorite deposits of Beaufort County South Carolina
2 are in the Hawthorn Formationjwhich is underlain by the Cooper Marl,
3 and is overlain by surficial sand of probable Pleistocene age
4 (Heron and Johnson, 1966).
5 - The North•Florida-South Georgia deposits are in the Hawthorn
6 . Formation and in rooks of probable Pliocene age. According to Olson
(1966, p. 79) the phosphorite deposit at the mine of the Occidental
Corporation of Florida is Pliocene in age, but the phosphate probably
9 was derived from pre-existing Miocene beds. Much of the phosphorite
10- in this area is in rocks of the Hawthorn Formation (Sever, Cathcart,
11 and Patterson, 1967).
12 The very large phosphorite deposit of South-Central Florida is in
13 the Bone Valley Formation of Pliocene age (Cathcart, 1963a,b;
14 Altschuler, Cathcart, and Young, 1964)0 but much of the phosphate in the
15 - deposit was reworked from the Hawthorn Formation. Some phosphate is
16 mined from the Hawthorn Formation.
17
18
19
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21
22
23
24
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S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 167.100 9 1 I Structure
2 The structure of the Atlantic Coastal Plain is a gentle, seaward-
3 dipping homocline, but the general seaward dip is interrupted by a
4 series of very gentle anticlines and synclines that strike either to
5 - the northwest or the northeast (fig. 1). The phosphate deposits are
6 related to the structures in the Coastal Plain (Cathcart and
7 Osterwald, 1954). Each of the deposits is in a basin on the flank of
8 an anticline, and the anticlinal structures were rising at the time of
9 deposition. The northernmost phosphate deposit' (in North Carolina) is
10 - in a basin on the flank of an unnamed high; the deposit in Beaufort
11 County, South Carolinajis in the Ridgeland basin on the flank of the
12 Beaufort high; the northern Florida-southern Georgia deposits are on
13 the flanks of the Barwick Arch and the Ocala Uplift; and the central
14 Florida deposits are on the flanks of the Ocala Uplift and the
15- Hillsborough high. Each of the deposits is in a position such that
16 deposition could have been from southward flowing ocean currents. The
17 rising domes could have acted as barriers to the southward flow of the
18 currents, possibly leading to deposition in the basins.
19
20 -
21
22
23
24
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U. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 867.100 10 Phosphorite
2 Phosphate pellets
3 The phosphate pellets of all the deposits and occurrences are ve
4 similar. They include internal casts and molds of fossils,
5 - phosphatized bone fragments and teeth (particularly shark's teeth),
6 phosphatized limestone fragments, elongate grains that may be fecal
7 pellets, and rounded, zoned particles that have formed by precipita-
8 tion around a nucleus. Many of the particles show evidence of
9 reworking--there are compound pellets, broken and rerounded pellets,
10 - phosphatized fossils that have a rim of later phosphate, and so on.
11 The phosphate particles are white, gray, tan, brown, red, black, and
12 green. All are rounded, some are spherical, and most have a high
13 luster. Particles that are dull are usually near the surface of the
14 deposit and show evidence of having been altered by solution.
15-
16
17
18
19
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21
22
23
24
25-
U. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 117•t00 11 1 The pellets range in size from less than 0.1 mm to several
2 centimeters inallamstar, and in the deposits in Florida and South
3 Carolina some of the phosphate is in the form of boulders that are
4 as much as tens of centimeters in diameter. In the deposits of the
5- land-pebble district in central Florida, the particle size is very
6 important, and the variation in particle size can be mapped. Coarser
7 particles are found on submarine ridges, from which the fines were
8 winnowed by current action, during and after deposition. Screening
9 is necessary to obtain a uniform size feed for the flotation plants
10- that separate quartz and phosphate grains, and the material coarser
than 1 mm is separated from the flotation feed. In the land-pebble
district, the +1 mm material, called pebble, is a phosphate product.
.3 Elsewhere in the Atlantic Coastal Plain, the coarser sizes contain
A material other than phosphate (quartz, shell material, and limestone
15- or dolomite fragments) and the coarse material is not a product.
.6 Mineralogy
.7 The phosphate mineral of all of the sedimentary phosphorites is
a carbonate fluorapatite that has the formula Ca10(PO4,CO3)6F2_3
9 (Altschuler and others, 1958).
20-
!1
2
3
4
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U. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 667.100 12
The gangue minerals that occur with the phosphate particles are
2 basically of 2 types--calcareous and quartzose, but even the most
3 calcareous of the host materials also contain abundant quartz grains
4 (table 2). Limestones that contain little or no quartz do not
5 - contain any phosphate grains.
6 Silica is present as detrital grains of quartz of varying size,
7 and in some of the deposits as diatoms. Quartz is most abundant in
8 the reworked phosphorite deposits. In these deposits, quartz and
9 phosphate, with minor amounts of clay, may be the only minerals.
10- Carbonate minerals are present as major constituents in all of
.1 the primary phosphatic sedimentary rocks,in the Atlantic Coastal Plain
2 of the United States. Dolomite is the principal carbonate mineral in
3 the phosphorite deposits of North Carolina, while calcite is the
4 principal carbonate mineral in all of the other deposits. Dolomite,
15- probably secondary, is present in the Hawthorn Formation of Florida.
6 The phosphorite deposits also contain one or more clay minerals--
7 Mite, montmorillonite, attapulgite, and sepiolite. Where the rocks
8 are weathered, kaolinite is a prominent clay mineral.
9
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!1
2
3
4
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V. S. GOVERNMENT PRINTING OFFICE : I9S9 0 - S11171 817.100
The clay minerals of the phosphorite deposits of the eastern
United States are different in each of the deposits. The clay minerals
in the phosphorite of North Carolina are illite and montmorillonite
(Rooney and Kerr, 1967); in the phosphorite of the Hawthorn Formation
in Beaufort County, South Carolina, the clay minerals include abundant
6 sepiolite and montmorillonite, and minor illite (Heron and Johnson,
7 1966); in the phosphorite of South Georgia-North Florida, the clay
B minerals are predominantly montmorillonite and attapulgite (Olson,
9 1966); and in the phosphorite deposits of the land-pebble district
10- of Florida, the principal clay mineral in the Bone Valley Formation
1 is montmorillonite but the underlying Hawthorn Formation contains
2. some attapulgite in addition to montmorillonite (Altschuler, Cathcart,
3 and Young, 1964).
Iron minerals are also present in all of the phosphorite deposits
15- in small amounts. The iron minerals include pyrite, and the iron
5 oxide minerals--hematite, goethite, limonite, and in the weathered
7 zones in Florida, the iron phosphate minerals, vivianite and dufrenite.
3 Glauconite, a trace constituent in many of the deposits, is found
almost entirely within the phosphate pellets.
20- Trace amounts of "heavy" minerals--ilmenite, zircon, rutile,
1 staurolite, sillimanite, tourmaline, and several others-!-are present
in most or all of the deposits.
25-
4+ #10::•;4,
U. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 $17 .100 \-t FitY 14 1 Clinoptilolite, a zeolite mineral, that possibly formed as an
2 alteration of volcanic ash (Rooney and Kerr, 1967) is present in small 3 amounts in the Pungo River Formation of North Carolina, and has been
4 reported in one sample from South Carolina (Heron and Johnson, 1966).
Aluminum phosphate minerals (wavellite and crandallite) are
6 important secondary minerals in the Florida deposits.
7 Origin
8 Phosphate pellets are found in the Gulf and Atlantic Coastal
9 Plaina of the eastern United States in marine sedimentary rocks of
10 - Cretaceous to Recent age. In the Gulf Coastal Plain, phosphatic
11 sediments are known only in rocks of Cretaceous and Paleocene age,
12 whereas in the Atlantic Coastal Plain, phosphatic sedimentary rocks
13 are known from rocks of all ages from Cretaceous to Recent.
14 Rocks of Cretaceous age contain phosphate pellets only in the
15- southern part of the outcrop belt in Georgia, Alabama, Mississippi,
16 and Texas. In the northern part of the outcrop belt, in New Jersey,
17 ct,,s VirginialATennessee, and in a part of Texas. the sedimentary rocks
18 contain abundant glauconite, and only trace amounts of phosphate. No
19 economic deposits of phosphorite are known in rocks of Cretaceous age.
20 — Rocks of Paleocene age on the Gulf Coast contain abundant glauconite
21 and only minor phosphate.
22
23
24
25--
I). S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 667.000 15 Phosphate in rocks of Eocene to Recent age is known only from the
2 Atlantic Coastal Plain. Glauconitic sedimentary rocks are present in
3 the northern states of the Atlantic Coastal Plain from Virginia to New
4 Jersey, and in this area, phosphate pellets are scarce. From North
5- Carolina south to the southern tip of Florida, phosphatic sediments
6 are widespread, and glauconite is present only in minor amounts.
7 The economic deposits of phosphorite are all structurally
8 controlled. The deposits are in basins that are on the flanks of
9 domes or anticlines that were rising at the time of deposition. Depth
10 - of water is evidently an important factor in the deposition of the
11 phosphorites.
12 All of the deposits are in areas where deposition of clastic
13 material was at a minimum. They are-sec far from a source of
14 clastic sediment as in south Florida, or am adjacent to very low-lyin
15 - land masses.
16 The phosphate pellets in all of the deposits have very similar
17 forms, and all were deposited in marine sediments, except for the
18 deposits in Pleistocene and Recent sediments, and in these rocks, the
19 phosphate particles were derived from older rocks and were redeposited
20- and concentrated in either marine or continental environments.
21 Phosphate pellets in the surficial materials under the Atlantic
22 Ocean are thought to have been derived from older rocks (Pilkey and
23 Luternauer, 1967).
24
25—
11, S. GOVERNMENT PRINTING OFFICE : 19%9 0 - S11171 eei• too 16 During middle Miocene time abundant phosphate was deposited
2 over most of the Atlantic Coastal Plain, but none was deposited on the
3 Gulf Coastal Plain. The geographic distribution of phosphate is
4 consistent with the source of the phosphorus being currents that moved
5 - southward along the Atlantic coast. These were cool, temperate waters,
6 different from the waters of late Miocene and the present (Gibson,
7 1967), and were probably cooler than the northward moving Gulf Stream.
8 The cooler southerly currents diverted by the rising anticlinal
9 structures of the Coastal Plain (fig. 1), might have been mixed with
10 - the warmer Gulf stream, causing phosphate to precipitate.
11 Pevear (1966) has suggested that the phosphorites of the eastern
12 United States were deposited in an estuarine environment, and it seems
13 likely that the nutrient-laden waters typical of estuaries may have
14 been the loci for the start of precipitation of phosphate. Certainly
15- a part of the land-pebble phosphorite of Florida was deposited in an
16 estuary (Cathcart, 1950). The estuarine environment, however, cannot
17 account for the vast, widespread phosphorite of the middle Miocene
18 throughout the Atlantic Coastal Plain.
19
20-
21
'2
?3
'4
25- ti
U. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 5111 71 667.100 Both Gibson (1967) and Rooney and Kerr (1967) attach great
2 significance in the origin of the phosphorite of North Carolina to
3 clinoptilolite derived from volcanic ash. For example, Rooney and
4 Kerr (1967, p. 747) suggest that: "Widespread ash falls of long
5 - duration killed large numbers of marine organisms whose subsequent
6 decay contributed phosphate." Neither report, however _
7 givany data regarding the amount of clinoptilolite. Work by the preent
writer shows that over the whole deposit clinoptilolite is present in I 6 small amounts and is only in the fine fraction (-200 mesh) of the
10 - phosphorite. The -200 mesh fraction averages 16 percent, by weight
11 of the total rock)and the amount of cliniptilolite in the -200 mesh
12 fraction (based on X-ray diffraction patterns) ranges from a trace to
13 about 30 percent. The amount of clinoptilolite in the whole rock,
14 therefore, ranges from nil to about 5 percent.
15- Elsewhere in the Atlantic Coastal Plain, clinoptilolite has been
16 reported only from one sample from South Carolina (Heron and Johnson)
17 1966). It has not been reported from the offshore deposits in the
18 Atlantic. A 9.0$. peak, present in X-ray diffractometer patterns run
19 by the writer from samples of -200 mesh material from offshore Baja
20- California, may represent clinoptilolite.
21 It seems likely that the small amount of clinoptilolite in the
22 North Carolina phosphorite deposit is merely coincidental and has
23 no necessary relation to the origin of the phosphorite deposits.
24
25--
ZI. S. GOVERNMENT PRINTING OFFICE: 1959 0 - Shill 817.100 18 1 To briefly recapitulate--phosphorite deposits are restricted to
2 rocks of middle Miocene age and were probably precipitated from sea
3 water in areas of favorable structural positions, that is, in basins
4 on the flanks of anticlines that were rising at the time of deposition
5 - Deposits are present only on the Atlantic Coastal Plain because of
6 southerly moving, cool, oceanic currents that were turbulently mixed
7 with warmer waters around the structural highs. The southerly currents
8 could not have moved into the Gulf Coast area of North America, because
9 of the position of the Floridian plateau, which caused the current to
10 - move south and east, away from the Caribbean. This accounts for the
11 absence of phosphate deposits or even occurrences on the Gulf Coast.
12 The deposits are on the stable shelf or foreland, which was low-
13 lying at the time of deposition, and therefore, was not deluged with
14 large amounts of clastic sediments.
15- Many of the deposits are economic only because of later reworking
16 and concentration of the phosphate pellets, and all of the deposits
17 show some evidence of reworking.
18 Prospecting techniques
19 Phosphorite deposits of the "Florida" type are concealed by
20- variable thicknesses of barren overburden, and prospecting must be by
21 some form of drilling or trenching. Actual prospecting is simple,
22 except that core drilling of unconsolidated sediments requires an
23 experienced driller. Trenching of shallow deposits is not a problem
24 in terms of technique, but deposits that are covered by more than a 25- few feet of overburden probably cannot be trenched. The problem in prospecting is to pick the area that is to be examined. P. S. GOVERNMENT PRINTING OFFICE: I9S9 0 - SI1171 867.100 19 1 A generally favorable area might be picked on the basis of a
2 knowledge of the details of local geology, based on the theory of
3 origin of the deposits. That is, the area is structurally favorable,
4 and the knowledge of paleogeography is such that it is possible that
- upwelling or laterally moving oceanic currents are known to have been
6 operative during the time the structures were being formed. This area
might be a basin on the flank of the rising dome, and in the proper
relation to the lateral or upwelling currents, so that it might be
restricted enough so that prospecting could be started on a broad
10- pattern that would ensure discovery of a deposit.
1 If the local geology is not well enough known to predict this
2 type of area, there are certain other techniques that can be used to
3 determine a possibly favorable area.
4 A trave'se of all of the streams can be made to determine if
15- there is any concentration of phosphate particles as bars along the
6 courses of the river. These are the so-called river-pebble deposits,
7 and they are characteristic of all of the Coastal Plain phosphorite
deposits of the eastern United States that are covered by thin over-
9 burden. The presence of river-pebble deposits may indicate an
20- economic phosphorite deposit under the interstream divides.
11, S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 eel. too 20
1 All known marine phosphate deposits contain uranium. The uranium
2 is present in amounts that are large enough to cause radioactive
3 anomalies. Thus, search for deposits of phosphorite can be made with
4 radiation detection equipment. Airborne scintillometers are effective
in the detection of the anomalous radiation caused by a phosphorite
6 deposit, provided the deposits crops out. The thickness of overburden
7 sufficient to mask the radiation is only a few feet.
8 If the deposits are too deeply buried to be detected with surface
9 radiation equipment, gamma-ray logging of drill holes is an effective
10 - method of locating possible phosphate deposits. This is the method
11 used on the deposits of North Carolina, which are so deeply buried
12 that there is no surface indication of their presence. There must be
13 , some drill holes in the area that can be logged, however. Gamma-ray
14 logs of all test holes (water wells, oil wells, and so on) should be
15- made, or examined, to determine whether there is any indication of
).8 anomalous radioactivity.
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,;. S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 197-10o 21
1 Reconnaissance work by the writer and P. F. Fix of the Geological
2 Survey clearly indicated that acid streams that drain phosphatic
terrains contain anomalous amounts of uranium in solution, and Odum
4 (1953) showed that these acid streams also contain anomalous amounts
5- of P 0 in solution. Stream sampling may be an effective way to 2 5 6 outline a potential area that contains a phosphorite deposit. There
7 are disadvantages, however. The analytical techniques required to
8 determine extremely small amounts of uranium and phosphorus are
9 difficult and require special training. Anomalous uranium may
10- indicate concentrations of uranium minerals rather than phosphate
11 minerals)and anomalous phosphate contents may indicate large areas
12 of sedimentary rock that contain small amounts of phosphate nodules)
13 rather than a phosphorite deposit. In either case)anomalies must
14 be followed by other prospecting to determine the source of the
15- phosphorus and uranium. The technique will be effective only in area
16 of acid groundwaters, because the phosphate mineral, that contains
17 the uranium, is soluble only in acid solutions.
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U. S. GOVERNMENT PRINTING OFFICE: 1959 0 - 511171 0117.100
1 The phosphorite deposits of the "Florida" type do not have the
2 unique suite of rock types (black shale and chert) that are
3 associated with marine phosphorites of the geosynclinal type. The
phosphatic sedimentary rocks that form the source of the phosphorite
P - deposits are all marls or impure (sandy and clayey) limestones. Some
6 of the deposits contain beds of diatomaceous earth (North Carolina,
7 USA, and Sechura, Peru), and the presence of diatomaceous material in
8 the section may be a clue to the location of the deposits. The
9 phosphorite deposits are always in sections that are thin--the total
10- thickness of the rocks that contain phosphate grains seldom is
1 measured in more than scores or hundreds of feet, while non-phosphatic
2 sections of the same age may measure thousands of feet. Thus,
3 prospecting in areas where the beds are very thick might be unpro-
4 ductive)and prospecting should be restricted to areas
15- where the beds are thin.
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U. S. GOVERNMENT PRINTING OFFICE 1959 0 - 511171 067.100 23 1 Literature cited
2 Adams, J. K., Groot, J. J., and Hiller, N. W., Jr., 1961, Phosphatic rob1)1(,s from the Brichtseat Formation of Maryland: Jour. Sed.
Petrolocy, v. 31, p. 546-552. Altschuler, Z. S., Clarke, R. S., Jr., and Young, E. J., 1958,
6 Geochemistry of uranium in apatite and phosphorite: U.S. Geol.
7 Survey Prof. Paper 314-D, 90 p.
8 Altschuler, Z. S., Cathcart, J. B., and Young, E. J., 1964, The
9 geology and geochemistry of the Bone Valley Formation and its
10- phosphate deposits, west-central Florida: Guidebook, field trip
11 no. 6, Geol. Soc. America, ann. meeting, Miami Beach. 68 p.
12 Brown, P. M., 1958, The relation of phosphorites to ground water in
13 Beaufort County, North Carolina: Econ. Geology, v. 53, p. 85-
14 101.
15- Carr, W. J., and Alverson, D. C., 1959, Stratigraphy of middle
16 Tertiary rocks in part of west-central Florida: U. S. Geol. Survey Bull. 1092, 111 p. Cathcart, J. B., 1950, Notes on the land-pebble phosphate deposits of
9 Florida; in, Snyder, F. G., ed., Symposium on mineral resources 20- of the southeastern United States/ p. 132-151. '1 , 1963a, Economic geology of the Keysville quadrangle, 2 Florida: U.S. Geol. Survey Bull. 1128, 82 p.
3 , 1963b, Economic geology of the Plant City quadrangle,
4 Florida: U.S. Geol. Survey Bull. 1142-D, p. Dl-D56.
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S. GOVERNMENT PRINTING OFFICE : 1959 0 - 511171 24 807-100
Literature cited--continued
2 Cathcart, J. B., and Osterwald, F. 0., 1954, Relation of structure
3 to phosphate deposition (abs.): Am. Inst. Mining and Metall.
4 Eng. Ind. Min. Div. Meeting)Tampa, Florida, 1954. Dabney, C. W., Jr., 1885, The phosphate exploration: North Carolina
6 Agric. Expt. Sta. Ann. Rept. 1884. C. W. 7 Espenshade, G. H., and Spencer)/1963, Geology of phosphate deposits of
8 northern peninsular Florida: U.S. Geol. Survey Bull. 1118, 115 p.
9 Gibson)T. G., 1967, Stratigraphy and paleoenvironment of the phos-
10 - phatic Miocene strata of North Carolina: Geol. Soc. America
11 Bull., v. 78, p. 631-649.
12 Heron, S. D., Jr., and Johnson, H. S., Jr., 1966, Clay mineralogy)
13 stratigraphy, and structural setting of the Hawthorn Formation)
14 Coosawhatchie district, South Carolina: Southeastern Geology,
15- v. 7, p. 51-63. 16 Herrick, S. M., and Vorhis, R. C., 1963, Subsurface geology of the
17 Georgia Coastal Plain: Georgia Dept. Mines, Mining, and Geol.
18 Inf. Circ. 25, 67 p. 19 Kimrey, J. 0., 1965, Description of the Pungo River Formation in
20- Beaufort County, North Carolina: North Carolina Div. of Min ► 21 Res. Bull. 79, 131 p.
!2 Leve, G. W.)1965, Ground water in Duval and Nassau Counties, Florida:
'3 U.S. Geol. Survey Open File Rept.)102 p.
'4 McCallie, S. W., 1896, A preliminary report on a part of the phosphats 25-- and marls of Geor ia: Georgia Geol. Survey Bull. 5A, 101 p.
U. S. GOVERNMENT PRINTING OFFICE 1959 0 - 511171 U7. 100 27
Literature cited--continued
Malde, H. E., 1959, Geology of the Charleston phosphate area, South Carolina: U.S. Geol. Survey Bull. 1079, 105 p. Mansfield, G. R., 1942, Phosphate resources of Florida: U.S. Geol.
Survey Bull. 934, 82 p. Monroe, W. H., 1941, Notes on deposits of Selma and Ripley age in
Alabama: Alabama Geol. Survey Bull. 48, 150 p. Odum, H. T., 1951i Dissolved phosphorus in Florida waters: Florida
Geol. Survey Rept. Invest. 9, 40 p. Olson, N. K., 1966, ed., Geology of the Miocene and Pliocene Series in the North Florida - South Georgia area: Guidebook, Southenstern Geol. Soc. (12th Ann. Field Conf.), 94 p.
Own. rA'stN. Oe\.7•10:-:Y and groundwater resources of Lee and southwest Sumter Counties, iteorgia: U.S. Geol. Survey Water-Supply Paper 1666, 70 p.
Pevear, D. R., 1966, The estuarine formation of United States Atlanti
Coastal Plain phosphorites: Econ. Geology, v. 61, p. 251-256. Pilkey, O. H., and Luternauerl J. L., 19671 A North Carolina shelf phosphate deposit of possible commercial interest: Southeastern Geology, V. 8, p. 33-51.
Rogers, G. S., 1914, The phosphate deposits of South Carolina: U.S. Geol. Survey Bull. 580, pt. 1, p. 183-220.
Rooney, T. P./ and Kerr, P. F., 1967, Mineralogic nature and origin o
phosphorite, Beaufort County, North Carolina: Geol. Soc. Americ Bull. v. 78, p. 731-748.
U. S. GOVERNMENT PRINTING OFFICE: 1959 0 - 511171 867.100 26 Weld - Int. 2905
GEOLOGIC DIVISION U.S. GEOLOGICAL SURVEY Washington, D. C. 20242
For release DECEMBER 6, 1967
The U. S. Geological Survey is releasing in open files the following reports. Copies are available for consultation in the Geological Survey Libraries, 1033 GSA Bldg., Washington, D. C. 20242; Bldg. 25, Federal Center, Denver, Colo. 80225; 345 Middlefield Rd., Menlo Park, Calif. 94025; and in other offices as listed:
1. Preliminary materials map of the Chester quadrangle, Hampshire and Hampden Counties, Massachusetts, by G. William Holmes. 1 map, scale 1:24,000, 1 table. Massachusetts Dept. of Public Works, 100 Nashua St., Boston, Mass. 02114; and USGS, 80 Broad St., Boston, Mass. 02110. Material from which copy can be made at private expense is available at the Broad St. address.
2. Preliminary materials map of the Massachusetts portion of the Hancock quadrangle, Massachusetts-New York, by G. William Holmes. 1 map, scale 1:24,000, 5 tables. Massachusetts Dept. of Public Works, 100 Nashua St., Boston, Mass. 02114; and USGS, 80 Broad St., Boston, Mass. 02110. Material from which copy can be made at private expense is available at the Broad St. address.
3. Marine phosphorite deposits--economic considerations, by James B. Cathcart. 21 p., 1 table.
4. Phosphate exploration in Colombia--a case history, by James B. Cath- cart. 19 p., 1 fig., 1 table.
5. Florida type phosphorite deposits--origin and techniques for prospect- ing, by James B. Cathcart. 27 p., 1 fig., 2 tables.
6. Distribution and geologic habitat of marine halite and associated potash deposits, by Robert J. Hite. 35 p., 11 figs.
Literature cited--continued
2 Sever, C. W., Cathcart, J. B., and Patterson, S. H., 1967, Phosphate deposits of South Central Georgia and North Central Peninsular
Florida: Georgia State Div. of Cons. South Georgia Minerals
5 - Program Project Rept. no. 7., 62 p. Smith, E. A., 1892, On the phosphates and marls of Alabama: Alabama
7 Geol. Survey Bull. 2, 82 p.
8 Stephenson, L. W., and Monroe, W. H., 1940, The upper Cretaceous
9 deposits: Mississippi State Geol. Survey Bull. 40, 296 p.
10 Weaver, H., Campbell, D., and Northcutt, N., 1963, Phosphate explora-
. k '-(1'-40\A#A A VI\_\, ,I.w-<_•4 Rept., la p.
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U. S. GOVERNVCNT PV.N.Tek: CIFIXE: 1.59 0 - 511:71 4147-100 27
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