Uranium Provinces of North America—

Their Definition, Distribution, and Models

By Warren I. Finch

U.S. GEOLOGICAL SURVEY BULLETIN 2141

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1996
For sale by U.S. Geological Survey, Information Services

Box 25286, Federal Center

Denver, CO 80225

Any use of trade, product, or firm names in this publication is for descriptive purposes only and

does not imply endorsement by the U.S. Government

Library of Congress Cataloging-in-Publication Data

U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Gordon P. Eaton, Director

Finch, Warren Irvin, 1924–

 Uranium provinces of North America : their definition, distribution, and models / by 

Warren I. Finch.

 p. cm. — (U.S. Geological Survey bulletin ; 2141)

Includes bibliographical references.

 Supt. of Docs. no.: I 19.3:2141

 1. Uranium ores—North America. I. Title. II. Series. 

QE75.B9 no. 2141

[QE390.2.U7]

557.3 s—dc20

[551.4′932′097] 95-37553

CIP
III

CONTENTS

Abstract ........................................................................................................................... 1

Introduction..................................................................................................................... 1

Methods of Study .................................................................................................... 2

Acknowledgments................................................................................................... 2

Brief Review of Concepts of Metallogenic and Mineral Provinces ............................... 2

Definition of a Uranium Province................................................................................... 3

Description of Uranium Province Model........................................................................ 3

Definitions and Models of North American Uranium Provinces ................................... 4

Athabasca Basin Uranium Province, Canada ......................................................... 4

Definition ........................................................................................................ 4

The Model ....................................................................................................... 4

Blind River–Elliot Lake Uranium Province, Canada.............................................. 5

Definition ........................................................................................................ 5

The Model ....................................................................................................... 5

Colorado Plateau Uranium Province, United States ............................................... 6

Definition ........................................................................................................ 6

The Model ....................................................................................................... 7

Rocky Mountain and Intermontane Basins Uranium Province, United States ....... 7

Definition ........................................................................................................ 7

The Model ....................................................................................................... 8

Gulf Coast Uranium Province, United States and Mexico ..................................... 8

Definition ........................................................................................................ 8

The Model ....................................................................................................... 9

Basin and Range Uranium Province, United States and Mexico............................ 10

Definition ........................................................................................................ 10

The Model ....................................................................................................... 10

Florida Phosphorite Uranium Province, United States, by Warren I. Finch and

James B. Cathcart.................................................................................................. 11

Definition ........................................................................................................ 11

The Model ....................................................................................................... 11

Distribution of Uranium in North America..................................................................... 12

Tectonostratigraphic and Plate Tectonic Perspective of the Distribution of 

North American Uranium Provinces........................................................................... 13

References Cited ............................................................................................................. 15

PLATES

1. Map showing locations of uranium provinces and the major uranium clusters in North America.

2. Map showing details of the Colorado Plateau, Rocky Mountain and Intermontane Basins, and Basin and Range

Uranium Provinces.
IV CONTENTS

FIGURES

1–3. Maps showing:

1. Details of the Athabasca Basin Uranium Province, Canada ..................................................................................... 5

2. Details of the Blind River–Elliot Lake Uranium Province, Canada ......................................................................... 6

3. Details of the Gulf Coast Uranium Province, United States and Mexico ................................................................. 9

4. Graph showing distribution of uranium in North America....................................................................................... 12 

TABLE

1. Distribution of uranium in North America...................................................................................................................... 13
1

URANIUM PROVINCES OF NORTH AMERICA—

THEIR DEFINITION, DISTRIBUTION, AND MODELS

By Warren I. Finch

ABSTRACT

Uranium resources in North America are principally in

unconformity-related, quartz-pebble conglomerate, sandstone, volcanic, and phosphorite types of uranium deposits.

Most are concentrated in separate, well-defined metallogenic provinces. Proterozoic quartz-pebble conglomerate

and unconformity-related deposits are, respectively, in the

Blind River–Elliot Lake (BRELUP) and the Athabasca

Basin (ABUP) Uranium Provinces in Canada. Sandstone

uranium deposits are of two principal subtypes, tabular and

roll-front. Tabular sandstone uranium deposits are mainly in

upper Paleozoic and Mesozoic rocks in the Colorado Plateau

Uranium Province (CPUP). Roll-front sandstone uranium

deposits are in Tertiary rocks of the Rocky Mountain and

Intermontane Basins Uranium Province (RMIBUP), and in a

narrow belt of Tertiary rocks that form the Gulf Coastal Uranium Province (GCUP) in south Texas and adjacent Mexico.

Volcanic uranium deposits are concentrated in the Basin and

Range Uranium Province (BRUP) stretching from the

McDermitt caldera at the Oregon-Nevada border through the

Marysvale district of Utah and Date Creek Basin in Arizona

and south into the Sierra de Peña Blanca District, Chihuahua,

Mexico. Uraniferous phosphorite occurs in Tertiary sediments in Florida, Georgia, and North and South Carolina and

in the Lower Permian Phosphoria Formation in Idaho and

adjacent States, but only in Florida has economic recovery

been successful. The Florida Phosphorite Uranium Province

(FPUP) has yielded large quantities of uranium as a byproduct of the production of phosphoric acid fertilizer. Economically recoverable quantities of copper, gold, molybdenum,

nickel, silver, thorium, and vanadium occur with the uranium deposits in some provinces. 

Many major epochs of uranium mineralization occurred

in North America. In the BRELUP, uranium minerals were

concentrated in placers during the Early Proterozoic

(2,500–2,250 Ma). In the ABUP, the unconformity-related

deposits were most likely formed initially by hot saline formational water related to diagenesis (≈1,400 to 1,330 Ma)

and later reconcentrated by hydrothermal events at

≈1,280–≈1,000, ≈575, and ≈225 Ma. Subsequently in North

America, only minor uranium mineralization occurred until

after continental collision in Permian time (255 Ma). Three

principal epochs of uranium mineralization occurred in the

CPUP: (1) ≈ 210–200 Ma, shortly after Late Triassic sedimentation; (2) ≈ 155–150 Ma, in Late Jurassic time; and (3)

≈ 135 Ma, after sedimentation of the Upper Jurassic Morrison Formation. The most likely source of the uranium was

silicic volcaniclastics for the three epochs derived from a

volcanic island arc at the west edge of the North American

continent. Uranium mineralization occurred during Eocene,

Miocene, and Pliocene times in the RMIBUP, GCUP, and

BRUP. Volcanic activity took place near the west edge of the

continent during and shortly after sedimentation of the host

rocks in these three provinces. Some volcanic centers in the

Sierra de Peña Blanca district within the BRUP may have

provided uranium-rich ash to host rocks in the GCUP. 

Most of the uranium provinces in North America

appear to have a common theme of close associations to volcanic activity related to the development of the western margin of the North American plate. The south and west margin

of the Canadian Shield formed the leading edge of the

progress of uranium source development and mineralization

from the Proterozoic to the present. The development of

favorable hosts and sources of uranium is related to various

tectonic elements developed over time. Periods of major

uranium mineralization in North America were Early Proterozoic, Middle Proterozoic, Late Triassic–Early Jurassic,

Early Cretaceous, Oligocene, and Miocene. Tertiary mineralization was the most pervasive, covering most of Western

and Southern North America.

INTRODUCTION

The uranium provinces of North America have been

defined, described, and modeled in order to demonstrate the

distribution of uranium resources, identify regional aspects

of the genesis of uranium deposits, identify broad exploration guides, and provide a basis for the assessment of environmental impacts of natural concentrations of uranium and
2 URANIUM PROVINCES OF NORTH AMERICA

attendant exploration, mining, and milling activities. The

provinces are identified by the distribution of major uranium

clusters,1

 generally of a size of 500 tons and more U3O8,

commonly of only a few types of uranium deposits related

genetically in time and space. Their boundaries are defined

on regional geotectonic features related to the distribution of

uranium clusters and their host rocks. The uranium province

model format presented here for the first time is designed to

provide the major characteristics of the province in brief concise descriptions. 

The study of the plate tectonic history of North America

has revealed that most of the uranium provinces appear to

have been related to the tectonic evolution of the western

active margin of the North American plate. Volcanic activity

along the western margin of the plate has contributed both

direct and indirect sources of uranium for the uranium clusters in the provinces.

METHODS OF STUDY

In order to identify, define, describe, and model the uranium provinces, a compilation was made of large uranium

clusters, specifically those with a size of 500 or more tons

U3O8, in the United States, Canada, and Mexico. 

The uranium cluster data consisting of name, country,

State or Province, latitude and longitude, size, grade, and

deposit type are compiled into a computer data base. The

sources of the size and grade data include published reports,

U.S. Department of Energy and U.S. Geological Survey file

data, Nuclear Fuel and Rocky Mountain Scout newsletters,

company press releases, and data files of the German Federal

Institute for Geosciences and Raw Materials; many of these

data are part of the International Atomic Energy Agency

“Working Material for the World Atlas of Uranium

Deposits” (Finch and others, 1995). The maps in plates 1 and

2 and figures 1–3 were made using the GSMAP software

package (Selner and Taylor, 1992).

From the distribution of large uranium clusters, the

provinces were identified and defined by the tectonogeologic features related to the distribution of host rocks and

the genetic history of the formation of the clusters of uranium deposits. Although large uranium clusters were

mainly used to identify uranium provinces, the borders of

the provinces are extended beyond the major clusters by

the distribution of smaller clusters, for example, the

Colorado Plateau Uranium Province (CPUP) as shown by

Finch (1991). Detailed studies underway for the Rocky

Mountain and Intermontane Basins Uranium Province

(RMIBUP) and Gulf Coast Uranium Province (GCUP),

and Basin and Range Uranium Province (BRUP) provided

the distribution of smaller clusters needed to fully define

these provinces.

The initial study of uranium provinces in North America was conducted mainly in the summer of 1992 to prepare a poster for the 29th International Geological

Congress held in Kyoto, Japan, August 26–September 5

(Finch, 1992a). The study has provided input data for the

“Consultancy on the Preparation of World Atlas of

Uranium Deposits” (International Atomic Energy Agency,

Vienna, Austria).

ACKNOWLEDGMENTS

The preparation of the cluster and province outline data

files for using the GSMAP software was greatly aided by

Richard B. Taylor. Charles T. Pierson was very helpful in

plotting the final maps. 

BRIEF REVIEW OF CONCEPTS OF 

METALLOGENIC AND MINERAL 

PROVINCES

Traditionally, a metallogenic province is generally

defined by the occurrence of one or more specific kinds of

mineral deposits in a region with distinct petrographic and

tectonic features, commonly related to the history of the

Earth’s crust. A metallogenic province is commonly referred

to as a mineral province. An early reference to uranium provinces was by Klepper and Wyant (1956), who pointed out

that exploitable uranium deposits resulted from original

inhomogeneities of uranium in the Earth’s crust that commonly persisted through long periods of time, and later interplays of orogenic, metamorphic, and sedimentary processes

produced rocks with enriched uranium. The initial enriched

uranium was successively remobilized and concentrated into

new enrichments of one or more magnitudes above normal

background forming uranium ore deposits. The source of the

uranium and the geologic and geochemical processes were

generally closely related; this concept is commonly thought

of as a metallogeny.

In 1985, a “Technical Committee Meeting of the International Atomic Energy Agency on the Recognition of

Uranium Provinces” held in London, England, reviewed

concepts of Uranium Provinces (International Atomic

______________ 1

A uranium cluster is defined as the group of all the uranium deposits

(properties) within an area of about 25 square miles (about 64 square kilometers) (Finch, 1991). A cluster commonly consists of more than one deposit and is named for the largest deposit, most well known deposit, district

name, or geographic name. Ideally, the size and grade of a cluster are the

total tons of U3O8 and the average grade of the “geologic” deposit based on

uranium endowment at a cutoff of about 0.03 percent U3O8. In practice, the

size and grade are based on reserves and production data that are in turn

based on higher grade cutoffs.
DESCRIPTION OF URANIUM PROVINCE MODEL 3

Energy Agency, 1988). As part of the meeting, panel members defined a uranium province as “A region of the Earth’s

crust in which rocks of one or more successive ages are

enriched in uranium above normal abundance, generally as

distinct deposits***” (Ferguson and others, 1988, p. 439).

As a member of that panel, I pointed out the anomalous Colorado Plateau Uranium Province where the most likely

source of uranium was far removed from the western boundary of the province (Granger and Finch, 1988). Study of

other sedimentary uranium provinces in North America has

revealed similar situations. 

DEFINITION OF A URANIUM 

PROVINCE

The “traditional” concept of a uranium province is

modified for this study. A uranium province is defined

more narrowly as a large geologically and tectonically distinct region where substantial uranium is concentrated into

clusters and the uranium is recovered either economically

as the sole commodity or as a byproduct of another commodity, such as gold and phosphate. For purposes of this

study, the clusters must have a minimum of 500 tons of

contained U3O8. The province can be defined geologically

as a structural or tectonic unit, such as a very large prominent basin, a group of interrelated basins, orogenic belt,

geophysiographic province, or granitic massif. The underlying crust need not be enriched in uranium. The source of

the uranium may be from outside the province a considerable distance and geologically and tectonically separate

from the province. Mineralization may have taken place in

one or more episodes producing one or more types of uranium deposits. 

Some deposits of 500 tons or more U3O8 occur outside

the defined uranium provinces, and they probably are indicators of other poorly defined provinces. The unconformity-related Kiggavik cluster, Canada; Swanson cluster,

Virginia, U.S.A.; and isolated clusters in Mexico (pl. 1) are

examples.

There are several notable concentrations of uranium

where uranium either has not been recovered in economic

amounts or cannot be recovered at all in the foreseeable

future. The most prominent example is the uraniferous

Chattanooga Shale in Tennessee in the United States

(Swanson, 1961), which is a metallogenic uranium province but because of its grade of 0.007 percent uranium

has little economic potential and thus is not included as a

uranium province in this report. Likewise, the uraniferous Phosphoria Formation in Idaho and adjacent States,

which has yielded very little uranium, is not considered

in this report.

DESCRIPTION OF URANIUM 

PROVINCE MODEL

For this study, a descriptive model for uranium mineral

provinces was designed to capture the broad tectonogeologic setting of spatially and genetically related uranium

deposits. The format of this model differs from that of the

mineral deposit model of Cox and Singer (1986) with the

emphasis on larger scale attributes of a group of deposits

(clusters) rather than attributes related to individual deposits. In this regard, the province model probably has wider

application for exploration in large regions and the discovery of new districts and provinces throughout the world.

Sixteen descriptive attributes are listed. The descriptions of

these attributes define the Uranium Province Model in the

following format:

Uranium Province Model

Brief Description. Describe in telegraphic style the

province’s uranium deposit cluster distribution relative to

regional features that define the natural boundaries of the

province.

Key Deposit Clusters, Districts, Mineral Belts. Name

examples of the prominent clusters, districts, and (or) mineral belts.

Types of Deposits. List names of world deposit types

given in Nuclear Energy Agency and International Atomic

Energy Agency (1992).

Cluster Size and Grade Ranges. Express total of clusters in short tons U3O8 and average grades of clusters in percent U3O8.

Total Resource Magnitude. Express total of production and reserves in short tons U3O8.

Tectonostratigraphic Setting. Summarize briefly the

formational history of the host rocks and concentration of

uranium into deposits relative to tectonic history.

Host Rocks. Name rock types that contain the uranium

minerals in decreasing order of importance.

Principal Ages of Host Rocks. Express the geologic

age and numerical age range in brackets.

Epochs of Mineralization. Express the time intervals

of mineralization from oldest to youngest in same format as

ages of host rocks.

Ore Mineralogy. Name the primary uranium ore minerals in decreasing order of abundance; if important, name oxidation uranium minerals separated from primary mineral list

by a semicolon. +, mineral always present; ±, mineral; may

be absent.

Associated Ore Elements. Name primary ore elements

that have been recovered or are economically recoverable in

decreasing order of importance.
4 URANIUM PROVINCES OF NORTH AMERICA

Alteration. Where significant, describe alteration relative to preparation of the host rock, uranium mineralization,

and post-mineralization where appropriate.

Probable Sources of Uranium. List proposed

source(s) with evidence; add references if more than one

proposal.

Mineralizing Solutions. Give general term(s) with

main chemical composition; if more than one solution give

relation to each other.

Plate Tectonic Relations. Give plate tectonic history

relative to formation of host rock, source of uranium, and

time of mineralization.

Principal References. List principal references in

alphabetical order by author name.

DEFINITIONS AND MODELS OF 

NORTH AMERICAN URANIUM 

PROVINCES

Seven uranium provinces are recognized, defined, and

modeled for North America: Blind River–Elliot Lake Uranium Province, Canada (BRELUP); Athabasca Basin Uranium Province, Canada (ABUP); Colorado Plateau Uranium

Province, United States (CPUP); Rocky Mountain and Intermontane Basins Uranium Province, United States

(RMIBUP); Gulf Coast Uranium Province, United States

and Mexico (GCUP); Basin and Range Uranium Province,

United States and Mexico (BRUP); and Florida Phosphorite

Uranium Province, United States (FPUP) (pl. 1). These

provinces contain more than 95 percent of identified potential uranium resources in North America. Several other uranium provinces are suspected but are not defined here

because they contain too few known large deposits. Two

potential uranium provinces are Thelon Basin, Canada, and

the Appalachian Piedmont in Eastern United States (Rast,

1989), which possibly extends into Canada. Extensive

exploration in the Thelon Basin, whose geologic history is

analogous to that of Athabasca Basin, has disclosed one

(Kiggavik, pl. 1; Fuchs and Hilger, 1989) and possibly several more large deposits (Rocky Mountain Scout, 1993; Vlad

Ruzicka, Geological Survey of Canada, written commun.,

1993). The Appalachian Piedmont region contains large

potential uranium resources (U.S. Department of Energy,

1980). A large deposit, the Swanson deposit (pl. 1; Halladay, 1989), is known in the Virginia portion of the Appalachian Piedmont, but others in the region have not been

publicly disclosed for political and business reasons. Some

of these are economically viable, but concern over uranium

mining in Virginia led to laws that, in effect, banned the mining of the Swanson deposit, and this probably curtailed any

plans for developing other deposits in this region. 

These definitions and models of uranium provinces are

two-dimensional; examination in three dimensions and age

slices by GIS (Geographic Information Systems) would further refine our understanding of the provinces. 

ATHABASCA BASIN URANIUM PROVINCE, 

CANADA

DEFINITION

The Athabasca Basin Uranium Province is defined by

the deep localized basin that formed on the Early Proterozoic

Laurentian craton (Hoffman, 1988) at the west edge of the

Precambrian Shield. The uranium deposits are of the unconformity-related type. In 1988, they yielded about 65 percent

of Canadian production and over 20 percent of Western

World output (Sibbald and others, 1991). Veins in the

Beaverlodge District to the north just outside the Province

occur in older rocks (1,930 Ma) and were mineralized earlier

(≈1,750 Ma) than the unconformity-related deposits (Sibbald and others, 1991; Cumming and Krstic, 1992). The

genetic relations of the two types are controversial (Parslow,

1989). The Beaverlodge District is not considered here to be

part of the Athabasca Basin Uranium Province. The internal

structure of the Athabasca Basin is complex with many

northeast-trending faults and shear zones related to positive

basement elements that divide the main basin into

“sub-basins” in which the Athabasca Group was deposited

(Ramaekers, 1981; Sibbald, 1988; Sibbald and others, 1991).

The uranium clusters are concentrated in two areas, the

major Cluff Lake cluster in the Paleozoic Carswell impact

structure and a single cluster of the north edge in the western

part of the basin and numerous clusters along the southeastern boundary (fig. 1).

THE MODEL

Brief Description. Defined by the outcrop of the Athabasca Group of Middle Proterozoic (Paleohelikian, ≈1,450

Ma) age within the Athabasca Basin, uranium deposits

related to sub-Athabasca Group unconformity occur as vein

structures in fluvial quartzose sandstone of the Athabasca

Group but mostly in underlying Early Proterozoic (Aphebian, 1,750 Ma) basement rocks within the Hearne province,

a part of Churchill Structural Province, of the Canadian

Shield.

Key Deposit Clusters, Districts. Cluff Lake, Key Lake,

Cigar Lake, Rabbit Lake, Collins Bay–Eagle Point,

McArthur River (P2 North), McClean Lake–Sue zone,

Alberta and Saskatchewan Provinces.

Types of Deposits. Unconformity-related deposit.

Cluster Size and Grade Ranges. 650–195,000 tons

U3O8, 0.30–16.5 percent U3O8.

Total Resource Magnitude. 5.5×105 tons U3O8.
DEFINITIONS AND MODELS OF NORTH AMERICAN URANIUM PROVINCES 5

Tectonostratigraphic Setting. The complex, locally

disturbed Athabasca Group consisting of four marine transgressive sequences and thick fluvial fans overlies thick

regolith on metamorphic and granitic basement rocks of the

Hudsonian Western craton and Cree Lake mobile zone. Sedimentation took place in three northeast-trending sub-basins,

the Jackfish Basin in the west, the central Minor Basin, and

the Cree Basin in the east, each bounded by major faults and

(or) positive basement elements.

Host Rocks. Pelitic graphitic gneiss, meta-arkosic

sandstone, and pegmatitic granite.

Principal Ages of Host Rocks. Middle Proterozoic,

Paleohelikian Athabasca Group, ≈1,450 Ma; Aphebian basement, ≈1,750+ Ma.

Epochs of Mineralization. Initial episodic mineralization ≈1,330–1,380 Ma (1,514±18 at McArthur River); remobilized ≈1,280, ≈1,000, ≈575, ≈225 Ma.

Ore Mineralogy. Uraninite (pitchblende), coffinite,

brannerite, Ni-Co sulfides and arsenosulfides.

Associated Ore Elements. Ni, Co, Au.

Alteration. Sub-Athabasca weathering profile (chloritization, tourmalinization, hematization, illitization, silicification, dolomitization); strong diagenesis, mainly

kaolinization and hematization, of Athabasca Group. 

Probable Sources of Uranium. Heavy minerals in

Athabasca sandstone; graphitic pelitic (marine black shale)

gneiss in Aphebian crystalline basement.

Mineralizing Solutions. Hot (150°–225°C) saline, oxidizing formational water related to diagenesis; hydrothermal

fluids.

Plate Tectonic Relations. Unconformity developed on

rocks of the Hudsonian orogeny (1,850–1,550 Ma) in the

Churchill Province as part of a worldwide orogenic event

(1,300–1,800 Ma), uplift and erosion followed to fill depressions (sedimentary basins) in the level shield within the

north-northeast aligned Athabasca, Thelon, and Borden

plates.

Principal References. Bally, 1989; Cameron, 1983;

Davidson, 1972; Hoffman, 1989; Lainé and others, 1985;

Ramaekers, 1981, 1990; Sibbald, 1988; Sibbald and others,

1991.

BLIND RIVER–ELLIOT LAKE URANIUM 

PROVINCE, CANADA

DEFINITION

The Blind River–Elliot Lake Uranium Province, the

smallest province in area, is defined by the part of the Southern Structural Province (Card and others, 1972) within

Ontario at the southern margin of the Canadian Shield. The

uranium clusters are in a Huronian pericratonic sedimentary

basin in the Penokean Fold Belt, which is the western part of

this selected portion of the Southern Structural Province; the

fold belt extends into the United States, but neither favorable

host rocks nor uranium deposits are present there. The

deposits are placer concentrations of uranium-bearing minerals in quartz-pebble conglomerate beds formed under

anoxyenic conditions near and at the base of the Early Proterozoic sediments. The quartz-pebble conglomerate deposits are very large but generally quite low grade (fig. 2; table

1).

THE MODEL

Brief Description. Defined by a pericratonic sedimentary basin north of the Murray Fault zone in the western portion of Southern Structural Province at the southern margin

of the Canadian Shield; host fluvial conglomerate reefs form

basal Huronian sedimentary-volcanic pile unconformably

mainly on Archean granite.

Key Deposit Clusters. Pronto, Stanleigh, Denison,

Agnew Lake (fig. 3).

Types of Deposits. Quartz-pebble conglomerate.

Figure 1. Details of the Athabasca Basin Uranium Province,

Saskatchewan and Alberta, Canada. See plate 1 for location of area

and for complete list of uranium cluster types in uranium provinces

of North America.
6 URANIUM PROVINCES OF NORTH AMERICA

Cluster Size and Grade Ranges. 3,000–240,000 tons

U3O8, 0.04–0.125 percent U3O8.

Total Resource Magnitude. 3×105 tons U3O8.

Tectonostratigraphic Setting. Host conglomerates

(Matinenda Formation) formed under oxygen-deficient conditions in major channel systems in Early Proterozoic basins

(now Quirke and Lake Agnew synclines) initiated by crustal

extension (rifting) in a cratonic setting at the boundary

between the Archean Superior and Grenville structural

provinces.

Host Rocks. Quartz-pebble conglomerate and

quartzose arenites.

Principal Ages of Host Rocks. Early Proterozoic,

2,500–2,250 Ma.

Epochs of Mineralization. Placer concentration

≈2,250 Ma; diagenetic modification ≈1,850 Ma.

Ore Mineralogy. Placer: uraninite, monazite, zircon;

authigenic: brannerite, coffinite.

Associated Ore Elements. Th, Y.

Alteration. Post placer concentration of ore minerals–low-grade metamorphism of quartz, chlorite, muscovite,

and pyrite matrix.

Probable Sources of Uranium. Pegmatitic granite of

Archean Kenoran orogeny (2,750–2,650 Ma) to the north of

the sedimentary basin.

Mineralizing Solutions. Stream water carrying detrital

uranium-bearing minerals under oxygen-deficient conditions.

Plate Tectonic Relations. Host formation developed in

intracratonic rift near volcanic centers south of the basin at

the passive continental margin.

Principal References. Card and others, 1972; Robertson, 1976; Roscoe, 1969; Roscoe and Card, 1992; Ruzicka,

1988; Sims and others, 1981.

COLORADO PLATEAU URANIUM PROVINCE,

UNITED STATES

DEFINITION

The Colorado Plateau Uranium Province was first formally described in 1985 (Granger and Finch, 1988) and later

described with more emphasis on tectonics (Finch, 1991).

There are 310 uranium clusters in the province of which 53

are large enough to qualify for this study. The large clusters

are in the central part of the province so that they in themselves do not define the boundary of the province (pl. 2).

The boundaries of the province are drawn on changes in

regional structures that bound the Colorado Plateaus physiographic province. These structures expose older sedimentary and Precambrian metamorphic rocks outside the stable

plateau block and were in part coeval with widespread Tertiary volcanic activity (Granger and Finch, 1988, fig. 2). The

uranium province is bounded on the east by the Laramide

Rocky Mountain deformational structures that contrast

markedly with the flat-lying formations of the stable Colorado Plateau craton (Bayer, 1983). It is bounded on the north

for the most part by the Precambrian Uinta uplift. The western boundary is drawn along the thrust faults and related

monoclinal folds and normal faults that define the Basin and

Range province. The southern boundary with the Basin and

Range is more subtle and broadly defined, especially along

the Mogollon Rim. 

Within the uranium province, most of the clusters are

tabular sandstone deposits hosted by Upper Paleozoic and

Mesozoic fluvial sedimentary rocks. They were formed in

three major epochs of mineralization: Late Triassic–Early

Jurassic, Late Jurassic, and Early Cretaceous. Most of the

remainder of clusters are solution-collapse breccia pipes that

developed in Pennsylvanian and Permian limestone,

Figure 2. Details of the Blind River–Elliot Lake Uranium Province, Ontario and Quebec, Canada. See plate 1 for location of area

and for complete list of uranium cluster types in uranium provinces

of North America.
DEFINITIONS AND MODELS OF NORTH AMERICAN URANIUM PROVINCES 7

sandstone, and shale formations and were mineralized with

high-grade uranium mainly in Late Triassic time, but two

deposits apparently formed in Permian time (260–254 Ma)

(Ludwig and Simmons, 1992). Many ores, for example, tabular deposits in the San Juan Basin, were redistributed into

roll-front deposits and in veins along faults in Late Cretaceous and early Tertiary time in conjunction with the Laramide deformation. The sources of the uranium for the

tabular sandstone and most breccia pipe ores are thought to

have been various volcanic arcs to the west and south at the

edge of the North American plate, which provided silicic ash

for the thick fine-grained units lying above the major Triassic and Jurassic host sandstone layers. The uranium ores in

sandstone beds were most likely precipitated by reduction

between uranium-bearing ground water and an underlying

saline brine.

THE MODEL

Brief Description. Occupies large part of the Colorado

Plateaus physiographic province, an isolated block of the

Proterozoic craton since late Paleozoic; contains major uranium deposits in Upper Mississippian to Lower Permian

breccia fill in Supai Group and Lower Permian Hermit

Shale, and in rocks of the Lower Permian Cutler Group,

Upper Triassic Chinle Formation, Middle Jurassic Todilto

Limestone Member of the Wanakah Formation, and Upper

Jurassic Morrison Formation; bounded by Tertiary volcanic

rocks, older sedimentary rocks, and outcropping Precambrian basement rocks.

Key Deposit Clusters, Districts, Mineral Belts. San

Juan Basin, Uravan, and Lisbon Valley mineral belts, New

Mexico, Colorado, and Utah, respectively; Orphan Lode,

Grand Canyon region, Arizona (pl. 2).

Types of Deposits. Tabular sandstone,

solution-collapse breccia pipe, limestone.

Cluster Size and Grade Ranges. 500–200,000 tons

U3O8; 0.05–0.60 percent U3O8.

Total Resource Magnitude. 6×105 tons U3O8.

Tectonostratigraphic Setting. Fluvial host sandstone

facies and overlying thick fine-grained volcaniclastic facies

deposited in intracratonic sedimentary basins.

Host Rocks. Quartzose to arkosic sandstone, conglomerate, flow-sand, breccia, limestone.

Principal Ages of Host Rocks. Pennsylvanian/Permian, Early Permian, Late Triassic, Middle and Late

Jurassic.

Epochs of Mineralization. Late Triassic–Early Jurassic ≈210–200 Ma, Late Jurassic ≈155–150 Ma, Early Cretaceous ≈135 Ma; redistribution Tertiary ≈60 Ma.

Ore Mineralogy. Uraninite, coffinite, montroseite,

chalcocite.

Associated Ore Elements. V, Cu.

Alteration. Tabular sandstone ore: bleaching of host

sandstone and mudstone by organic reduction of iron

minerals. Breccia pipe ore: bleaching by reduction, common calcification, local dolomitization and kaolinization.

Probable Sources of Uranium. Thick volcaniclastic

beds overlying ore-bearing horizons, ash derived from volcanic arcs west of the province.

Mineralizing Solutions. Ground water.

Plate Tectonic Relations. Near southwest boundary of

the North American plate, and sediment and uranium

sources associated with volcanic arcs to west and south during Late Triassic and Late Jurassic; deep burial Cretaceous–early Tertiary as plate developed westward.

Principal References. Finch, 1991, 1992b; Granger

and Finch, 1988; McCammon and others, 1986; Wenrich,

1985.

ROCKY MOUNTAIN AND INTERMONTANE 

BASINS URANIUM PROVINCE,

UNITED STATES

DEFINITION

The outline of the Rocky Mountain and Intermontane

Basins Uranium Province (RMIBUP) is a modification of

the Rocky Mountain structural province, which is a reactivated craton characterized by uplifts of the basement and

reverse faulting as defined by Bayer (1983). The uranium

province is essentially defined by the extent of the Laramide

uplifts and basins. Roll-front sandstone uranium deposits

formed in the basins, and vein uranium deposits formed in

fractured rocks of the uplifts. The Laramide fluvial-lacustrine basins acquired their individuality in latest Cretaceous

to Eocene (Gries, 1983). The southern part of the western

boundary coincides with the northeast side of the Colorado

Plateau Uranium Province, and the north edge of this boundary coincides with the Phanerozoic western Cordilleran of

North America. The Rocky Mountain front as shown by

Bayer (1983) forms the eastern and northern boundaries of

the RMIBUP. The intermontane Powder River Basin lies

between the Black Hills and Bighorn Mountains and is

included in the uranium province; however, the Williston,

Crawford (DeGraw, 1971), and Denver Basins on the High

Plains are not intermontane basins and lie outside of the

RMIBUP. Large low-grade (0.01 percent uranium), uneconomic lignite uranium deposits occur in the southwestern

part of the Williston Basin in South and North Dakota (Denson and Gill, 1965) . The large roll-front uranium deposits

(Crowe Butte cluster, p1. 1) in the Chadron Formation,

White River Group, are in the Crawford Basin. The

RMIBUP boundary that excludes the Crow Butte and related

deposits is drawn on the north edge of the Black Hills

domain in the Trans-Hudson orogeny in contact with the

Central Plains orogeny in the Precambrian basement (Sims

and others, 1991, fig. 2). The clusters in Weld County,

Colo., are in the Upper Cretaceous Fox Hills Formation in
8 URANIUM PROVINCES OF NORTH AMERICA

the Denver Basin. Uranium deposits occur east of the

RMIBUP farther to the south in Colorado and New Mexico;

all these deposits east of the RMIBUP are in the High Plains

physiographic province. The southern tip of the RMIBUP is

in contact with the Basin and Range Uranium Province. The

southernmost part of the RMIBUP includes the Tertiary volcanic rocks and their uranium clusters in the Rio Grande rift,

which might more properly belong in the Basin and Range

Uranium Province, but for convenience they are included in

the RMIBUP.

The predominant type of uranium deposit is the

roll-front sandstone deposit in Tertiary continental fluvial

basins developed between uplifts. These ore deposits were

formed by oxidizing uranium-bearing ground waters that

entered the host sandstone from the edges of the basins. Two

possible sources of the uranium were (1) uraniferous Precambrian granite that provided sediment for the host sandstone and (2) overlying Oligocene volcanic ash sediments.

Several major uranium deposits occur as veins in Precambrian metamorphic and lower Paleozoic sedimentary rocks

outside the Tertiary basins in the central part of the province.

These vein deposits also formed during Tertiary time but had

a uranium source related to Proterozoic volcanic rocks

deposited in a back-arc basin.

THE MODEL

Brief Description. Boundary coincides with Laramide

tectonic province in the southern and middle Rocky Mountains, Wyoming basins, and Black Hills regions; major uranium deposits occur in vein structures in Proterozoic igneous

and metamorphic and Paleozoic sedimentary rocks and as

sandstone deposits in Cretaceous and Tertiary basinal sediments.

Key Deposit Clusters, Districts. Powder River Basin,

Gas Hills, Shirley Basin, Crooks Gap, and Hulett Creek districts, Wyoming; Tallahassee Creek district, Colorado;

Schwartzwalder, Pitch, and Los Ochos clusters, Colorado;

Hagan Basin, New Mexico (pl. 2).

Types of Deposits. Roll-front sandstone in continental

fluvial sandstone; veins in metamorphic, igneous, and sedimentary rocks.

Cluster Size and Grade Ranges. Sandstone:

500–20,000 tons U3O8, 0.04–0.23 percent U3O8; vein:

500–5,000 tons U3O8, 0.15–0.48 percent U3O8.

Total Resource Magnitude. 3.5 × 105 tons U3O8.

Tectonostratigraphic Setting. Predominant roll-front

uranium ores formed in arkosic and tuffaceous fluvial sandstone formations deposited in small basins developed by

Laramide uplifts. Protoliths of the metamorphic hosts for

uranium ores deposited in a volcanic back-arc basin environment prior to 1,730 Ma.

Host Rocks. Continental fluvial sandstone; metavolcanic and metasedimentary metamorphic rocks; dolomite.

Principal Ages of Host Rocks. Early Proterozoic

(≈1,700 Ma), Mississippian-Pennsylvanian, Early Cretaceous (144–97 Ma), Eocene (52–36 Ma), Oligocene (36–24

Ma).

Epochs of Mineralization. 70 Ma, 35–26 Ma, 3 Ma.

Ore Mineralogy. Uraninite, pitchblende, coffinite, carnotite.

Associated Ore Elements. V.

Alteration. Roll-front sandstone ore: oxidation of iron

minerals updip from front and reduction of iron minerals

downdip along advancing redox interface. Vein ore in metamorphic hosts: carbonate-sericite and hematite-adularia

alteration.

Probable Sources of Uranium. Sandstone deposits:

Oligocene volcanic ash and (or) Precambrian granite

(2,900–2,600 Ma); vein deposits: Proterozoic volcanogenic

metamorphic rocks, Oligocene(?) welded tuft.

Mineralizing Solutions. Sandstone: oxygen-bearing

ground water; vein: hydrothermal (100°–200°C) fluids.

Plate Tectonic Relations. Uranium mineralization

began with inception of Laramide uplift (≈70 Ma) and

peaked in Oligocene as evidenced by apparent relation of

uranium ore to a pervasive Oligocene surface stretching

from New Mexico to Montana and Dakotas and associated

volcanism related to plate tectonic activity to the west in the

Basin and Range province.

Principal References. Chenoweth, 1991; Dickinson,

1981; Epis and others, 1976; Harshman, 1972; Harshman

and Adams, 1980; Hausel and others, 1990; Nash, 1988;

Olson, 1988; Robinson and Goode, 1957; Wallace and

Whelan, 1986.

GULF COAST URANIUM PROVINCE, UNITED 

STATES AND MEXICO

DEFINITION

The Gulf Coast Uranium Province lies along the northwest sector of the Gulf of Mexico in south Texas and adjacent Mexico. The landward extent of Eocene host

formations form the western boundary of the province.

Potential Tertiary host uranium formations do not extend to

present-day shoreline except in Mexico where they strike

into the water. For practical reasons, the shoreline of Texas

and Mexico is the eastern boundary of the province. The

north boundary is based on the farthest northward extent of

volcanic ash facies in Eocene and younger rocks. The

Eocene, Oligocene, Miocene, and Pliocene host units were

formed by megachannel fluvial systems that prograded

gulfward into near-shore and eventually true marine sediments. The host units are stacked but rarely are they
DEFINITIONS AND MODELS OF NORTH AMERICAN URANIUM PROVINCES 9

mineralized with uranium so that orebodies overlie one

another (Adams and Smith, 1981). A major source of volcanic ash was derived from an Oligocene volcanic arc,

probably in the Big Bend country of West Texas (Clark and

others, 1982).

All the deposits in the province are marginal marine

roll-front sandstone deposits (fig. 3). Carbonaceous plant

material needed for reduction is sparse in the host formations. Contemporaneous down-to-coast growth faults are

most likely the source of the H2S gas reductant for most

of the uranium deposits (Reynolds and Goldhaber, 1983).

THE MODEL

Brief Description. Broad flat coastal plain in southeast

Texas and adjacent Mexico on the northwest flank of the

Gulf of Mexico; uranium deposits in Eocene Whitsett,

Figure 3. Details of the Gulf Coast Uranium Province, United States and Mexico.
10 URANIUM PROVINCES OF NORTH AMERICA

Oligocene Frio, Oligocene and Miocene Catahoula, Miocene

Oakville, and Pliocene Goliad Formations; bounded updip

by older Tertiary rocks and downdip by limit of marine

equivalent facies.

Key Deposit Clusters. Panna Marie, Clay West, Holiday–El Mesquite, Lamprecht-Felder, Kingsville Dome, Alta

Mesa, and Trevino, Texas; El Chapote–Diana, La Comma,

and Buenavista, Nuevo Leon Province, Mexico (fig. 3).

Types of Deposits. Roll-front sandstone of marine

sub-type. 

Cluster Size and Grade Ranges. 500–10,000 tons

U3O8; 0.04–0.30 percent U3O8.

Total Resource Magnitude. 1 ×105 tons U3O8.

Tectonostratigraphic Setting. Superimposed and

stacked Eocene to Pliocene megachannel fluvial systems

(also includes modern rivers) that prograded into subsiding

gulf; fluvial sequences of each host unit pass into marine

facies in short distances gulfward so that rarely do two favorable host units overlie; contemporaneous down-to-coast

growth faults, especially those close to most uranium deposits, provided H2S reductant.

Host Rocks. Mixed fluvial-beach facies, quartzose to

arkosic permeable unconsolidated sandstones, most organic

poor.

Principal Ages of Host Rocks. Eocene, Oligocene,

Miocene, Pliocene.

Epochs of Mineralization. Late Oligocene (30–24

Ma), Pliocene (5 Ma).

Ore Mineralogy. Uraninite, coffinite, ilsemannite.

Associated Ore Elements. Mo.

Alteration. Roll-front sandstone ore: oxidation of iron

minerals updip from front and reduction of iron minerals

downdip along advancing redox interface.

Probable Sources of Uranium. Volcaniclastic sediments, particularly thick volcaniclastic siltstone and shale in

the Oligocene and Miocene Catahoula in juxtaposition with

older units and updip from younger units.

Mineralizing Solutions. Oxidizing uraniferous ground

water passed basinward through permeable sandstone. 

Plate Tectonic Relations. Major episodes of plate subduction and spreading in Paleozoic-Mesozoic time created

basic homoclinal dip of Gulf Coastal area and uplands for

Tertiary fluvial systems; “Andean” volcanic arc inland from

the subduction zone at west edge of continent progressed

eastward by 40 Ma and regressed westward by 18 Ma, coinciding with maximum Oligocene-Miocene volcaniclastic

sedimentation, particularly in the Catahoula, which was

probably derived from the Oligocene volcanic rocks to the

west in the Big Bend region.

Principal References. Adams and Smith, 1981; Clark

and others, 1982; Eargle and others, 1975; Galloway and others, 1979; Goodell, 1981, 1985; Reynolds and Goldhaber,

1983; Salas and Nieto, 1991; Worrall and Snelson, 1989.

BASIN AND RANGE URANIUM PROVINCE, 

UNITED STATES AND MEXICO

DEFINITION

The Basin and Range Uranium Province is defined

by numerous widely distributed volcanic uranium deposits

(for example in Arizona, Wenrich and others, 1990) in

late Tertiary volcanic rocks related to back-arc extensional

and regional transtensional tectonics that produced the

basin-and-range physiography (Zoback and Thompson,

1978). The province has a sharp boundary with the Colorado Plateau Uranium Province, and extending southward

the eastern boundary touches the Rocky Mountain front

that narrowly divides the Great Plains and the Basin and

Range. The northern part of the Rio Grande trough is arbitrarily placed in the Rocky Mountain and Intermontane

Basins Uranium Province. In Mexico, the eastern boundary is with the Gulf Coastal Plains. The southern part surrounds the Sierra Madre Occidental (Drewes, 1978; Raisz,

1964; de Cserna, 1989). In the United States, the western

boundary is along the east side of the Sierra Nevada

batholith and to the north it abuts the Neogene volcanic arc

rocks (Bayer, 1983). The northern boundary is with Quaternary volcanic rocks of the Snake River Plain that mark

the northern extent of basin-and-range structures shown by

Bayer (1983). 

Although the Basin and Range Uranium Province is

the largest one in area in North America, only four of the

numerous uranium clusters in the province are large, but

they span the length of the province (pl. 2). Most of the

deposits belong to the volcanic class, and only a few are of

other types in older rocks. However, sandstone type

deposits are commonly found in the volcanic environment.

THE MODEL

Brief Description. Coincides with the Basin and Range

physiographic province, characterized by extensional tectonics and late Eocene–early Miocene ignimbrite volcanism,

bounded on the northeast by fold-and-thrust belt and on the

west by Mesozoic granite and accreted terranes; major uranium deposits occur in Tertiary volcanic and related sedimentary lacustrine rocks associated with calderas.

Key Deposit Clusters, Districts. McDermitt, Nev.;

Marysvale, Utah; Date Creek Basin, Ariz.; Peña Blanca,

Chihuahua, Mexico (pl. 2).

Types of Deposits. Volcanic, composite of hydrothermal vein and tabular lacustrine sandstone deposits.

Cluster Size and Grade Ranges. 500–20,000 tons

U3O8; 0.05–0.10 percent U3O8.
DEFINITIONS AND MODELS OF NORTH AMERICAN URANIUM PROVINCES 11

Total Resource Magnitude. 4×104 tons U3O8.

Tectonostratigraphic Setting. McDermitt caldera:

eruption of ash-flow tuffs and domes, many peralkaline, at

the end of the extensional Northern Nevada rift; Marysvale:

early Miocene quartz monzonite intrusion followed by

hypabyssal granite and uranium mineralization with

emplacement of glassy rhyolite dikes; Date Creek Basin:

felsic middle Miocene volcanism including rhyolitic flows

and ignimbrites, and airfall debris adjacent to the basin contributed to the lacustrine and paludal facies of the host

Chapin Wash Formation; Peña Blanca: Eocene rhyolitic ash

flow volcanism produced volcaniclastic and ignimbrite hosts

from unidentified calderas and Miocene(?) uplift initiated

geothermal mineralizing activity.

Host Rocks. McDermitt: andesitic to rhyolitic flows

and tuffaceous moat sediments; Marysvale: granite, quartz

monzonite; Date Creek Basin: carbonaceous tuffaceous

mudstone; Peña Blanca: rhyolitic ignimbrite.

Principal Ages of Host Rocks. McDermitt: Miocene,

18.5–13.5 Ma; Marysvale: early Miocene, 23–18 Ma; Date

Creek Basin: early to late Miocene; Peña Blanca: Eocene,

44–37 Ma (pl. 2).

Epochs of Mineralization. McDermitt: ≈12 Ma;

Marysvale: 19–18 Ma; Date Creek Basin: early to middle

Miocene; Peña Blanca: Miocene(?).

Ore Mineralogy. Uraninite, coffinite, metatyuyamunite, carnotite, uranophane, jordisite, fluorite, molybdenite,

cinnabar.

Associated Ore Elements. Mo, V, F, Hg. 

Alteration. Predominant minerals are silica, kaolinite,

montmorillonite, and alunite.

Probable Sources of Uranium. Volcanic ash and glass,

magmatic system.

Mineralizing Solutions. McDermitt: hydrothermal fluids and hot spring and meteoric waters; Marysvale: hydrothermal magmatic fluids (≈200°C); Date Creek Basin:

diagenetic alkaline carbonate lacustrine pore water; Peña

Blanca: geothermal convective ground water.

Plate Tectonic Relations. Basin and Range characterized by Tertiary back-arc extensional tectonics and ignimbrite volcanism beginning in Eocene-Oligocene time in the

south that changed to a transtensional setting as the Mendocino triple junction migrated northward up the west coast of

North America that produced Miocene felsic igneous intrusive and extrusive host rocks and attendant volcaniclastic

lacustrine host rocks related to calderas.

Principal References. Bagby, 1986; Càrdenas-Flores,

1985; Cunningham and others, 1982; Dayvault and others,

1985; Goodell, 1981, 1985; Luedke and Smith, 1978a,

1978b, 1981; Otton and others, 1990; Salas and Nieto,

1991; Sherborne and others, 1979; Zoback and Thompson,

1978.

FLORIDA PHOSPHORITE URANIUM 

PROVINCE, UNITED STATES

By Warren I. Finch and James B. 

Cathcart

DEFINITION

The Florida Phosphorite Uranium Province occupies

most of the State of Florida and extends barely into Georgia

(Cathcart and others, 1984); the boundary is well defined

by wide-spaced drilling. Uranium occurs in carbonate fluorapatite and is recovered as a byproduct in the manufacture

of phosphoric acid fertilizer. The resources in this province

are the largest of any in North America (fig. 4 ). The phosphate beds were deposited during turbulent upwelling and

mixing of cool and warm waters in a long period of relative

stability of the eastern margin of the North American plate.

THE MODEL

Brief Description. Defined by the Floridan Plateau and

the coastal plains of Florida and southernmost Georgia. Uranium occurs evenly distributed in phosphate rock in the

Miocene and Pliocene Bone Valley Formation of the Hawthorn Group and other Hawthorn Group units and is enriched

in weathered zones. Uranium is produced as a byproduct of

the production of phosphoric acid fertilizer in the Central

Florida District .

Key Deposit Clusters, Districts. Central Florida

land-pebble District, Polk, Hillsborough, Hardee, and Manatee Counties; North Florida–South Georgia District,

Hamilton and Columbia Counties; Northeast Florida, Duval

County; East Florida District, Brevard County; South Florida District (pl. 1).

Types of Deposits. Phosphorite.

Cluster Size and Grade Ranges. 90,000–270,000 tons

U3O8; 0.0070–0.0125 percent U3O8 (average 0.0090 percent).

Total Resource Magnitude. 1×106 tons U3O8.

Tectonostratigraphic Setting. Relatively stable Floridan Plateau, phosphate deposited in basins adjacent to rising

positive areas that caused turbulent mixing of cool, nutrient

laden water with warmer surface water. Phosphate and uranium precipitated from ocean water, later reworking, enrichment, and concentration.

Host Rocks. Phosphate pellets in dolomite, clay, and

siliciclastic sediments.

Principal Ages of Host Rocks. Miocene, some

reworked phosphate in Pliocene and Pleistocene sediments.
12 URANIUM PROVINCES OF NORTH AMERICA

Epochs of Mineralization. Miocene, reworking and

acid weathering in Pliocene, Pleistocene, and Holocene.

Mobilization of phosphate and uranium at base of weathered

zones caused enrichment to 40 percent P2O5 and 0.050 percent U3O8.

Ore Mineralogy. Francolite (carbonate fluorapatite).

Crandallite, millisite, wavellite, and vivianite in weathered

zone. 

Associated Ore Element. P. 

Probable Sources of Uranium. Sea water.

Mineralizing Solutions. Sea water; later supergene

enrichment by acid ground water.

Plate Tectonic Relations. Coastal plains, uplift began

in late Oligocene and continued through Pliocene, several

transgressions and regressions related to passive plate margin, relatively stable during long time of deposition: related

to upwelling adjacent to the Gulf Stream. Floridan Plateau

was relatively stable from Miocene to present.

Principal References. Cathcart, 1978; Cathcart and

others, 1984; Pool, 1992; Van Kauwanbergh and others,

1990.

DISTRIBUTION OF URANIUM IN 

NORTH AMERICA

The identification of uranium concentrated into geologic uranium deposits and the grouping of them into clusters to define uranium provinces illustrates the geographic

and geologic distribution of uranium in North America (pls.

1 and 2; figs. 1–3). In order to obtain a sense of the intensity of this distribution, the magnitude of the total size of

uranium resources was determined for each province as

well as for those uranium resources located outside of the

defined provinces. The production and the initial reserves

or remaining reserves for each cluster (including small ones

not shown in this report), and in some instances for larger

areas, were totaled and rounded to obtain an order of magnitude of resources. These are plotted on the graph in figure 4.

The total magnitude of uranium resources for North

America is 3×106 tons U3O8 (table 1). The Florida Phosphorite Uranium Province is about 33 percent of this total

(fig. 4). The availability of this uranium resource, however,

is tied to its recovery as a byproduct (grade 0.009 percent

U3O8) of the manufacture of phosphoric acid. The option

to recover uranium is dependent on market conditions, and

one not commonly taken because the profit margin is generally small. In 1992, production of uranium from phosphorite amounted to 40 percent of U.S. output (Pool, 1993), but

recovery of uranium from one operation was discontinued

in 1992 and contribution of phosphorite to uranium output

was cut in half. The Colorado Plateau share of uranium

resources is about 19 percent. About two-thirds of these

resources have been produced, and most of the reserves are

deeply buried and low-grade sandstone ores (0.02–0.60

percent U3O8), so that its future production capability is

limited. On the other hand, the 18 percent in the Athabasca

Basin is largely reserves, and it has a bright future, especially because of the high-grade of its ores (>1.0 percent

U3O8). About 11 percent is in the Rocky Mountain and

Intermontane Basins Uranium Province. The ores in this

province are roll-front sandstone deposits and about

one-half of them have been mined. The Blind River–Elliot

Lake Uranium Province is nearly 10 percent of the total.

The grades of the quartz-pebble conglomerate ores in this

province are generally below 0.10 percent U3O8 and are

costly to produce. Only 3 percent is in the Gulf Coast

Province (fig. 4). About three-quarters of this has been

produced so that its future is limited. The largest province

in area but smallest in resources is the Basin and Range

with only 0.1 percent, but considering the large number of

unexplored calderas and the potential of the Date Creek

Basin and nearby basins in western Arizona (Otton and others, 1990), the magnitude of resources in the province is

expected to increase markedly in the future. The deposits

outside the defined provinces (NPCAN, NPMEX, NPUSA)

contain about 5 percent. Several deposits in these

non-province areas could be in the future be redefined as a

province. 

Figure 4. Distribution of uranium (short tons) in North America.

ABUP, Athabasca Basin Uranium Province; BRELUP, Blind River–Elliot Lake Uranium Province; CPUP, Colorado Plateau Uranium Province; RMIBUP, Rocky Mountain and Intermontane Basins

Uranium Province; GCUP, Gulf Coast Uranium Province; BRUP,

Basin and Range Uranium Province; FPUP, Florida Phosphorite

Uranium Province; NPCAN, Non-Province Canada; NPUSA,

Non-Province United States; NPMEX, Non-Province Mexico.
TECTONOSTRATIGRAPHIC AND PLATE TECTONIC PERSPECTIVE OF THE DISTRIBUTION OF NORTH AMER- 13

TECTONOSTRATIGRAPHIC AND 

PLATE TECTONIC PERSPECTIVE OF 

THE DISTRIBUTION OF NORTH 

AMERICAN URANIUM PROVINCES

Evidence presented in the models points to a unified

theme of the development of uranium provinces and the evolution of the North American continent. The early uranium

provinces BRELUP and ABUP developed near the edge of

the continent before the breakup of “Precambrian Pangea”

described by Bally and others (1989) at ≈600 Ma. These

provinces are at the south and west edges, respectively, of

the Precambrian Shield. The quartz-pebble conglomerate

deposits in the BRELUP formed as paleoplacers under oxygen-deficient conditions in Early Proterozoic, 2,500–2,250

Ma, in an intracratonic rift basin near volcanic centers at the

passive continental margin. Deposition of the basal Huronian host fluvial Matinenda Formation and associated felsic

and mafic volcanic rocks began at ≈2,490 Ma (Roscoe and

Card, 1992). The position of the uranium-bearing conglomerate of the Matinenda Formation on the Archean basement

floor was apparently controlled by volcanic activity (Roscoe,

1969).

The Middle Proterozoic Athabasca Group, ≈1,450 Ma,

host of the unconformity-related uranium deposits in the

ABUP, formed as marine transgressive sequences and thick

fluvial fans in a depression that were deposited on the thick

regolith previously formed on metamorphic and granitic

rocks of the Aphebian basement, ≈1,750 Ma. The

unconformity developed on rocks of the Hudsonian orogeny

(1,850–1,550 Ma) in the Churchill Province as part of a

worldwide orogenic event (1,800–1,300 Ma). Sedimentation took place in three northeast-trending subbasins within

the Athabasca Basin. Furthermore, similar sedimentation

took place in the nearby, northeast-aligned Thelon and Border Basins. The ABUP uranium deposits were most likely

formed initially by hot saline hydrothermal water related to

diagenesis (≈1,330–1,308 Ma) and later reconcentrated by

hydrothermal events (≈1,280– ≈1,000, ≈575, and ≈225 Ma)

(Cumming and Krstic, 1992). The source of uranium for the

deposits was most likely heavy minerals in the Athabasca

sandstone and the underlying Aphebian graphitic pelitic

gneiss in the vicinity of the deposits. Volcanic sources for

sediment in the marine black shale, progenitor of the pelitic

gneiss, may have been the initial source of the uranium (Sibbald and others, 1991).

From Late Proterozoic through the end of the Mississippian, North America was mostly submerged, and deposition of marine limestone, dolomite, and shale formations

dominated. Most Devonian marine black shales deposited

in shallow epicontinental seas in the Central States are

uraniferous, and the Upper Devonian and Lower Mississippian Chattanooga Shale contains large noneconomic uranium resources (Swanson, 1961). The immediate source of

the uranium was sea water (≈3 ppb U), but volcanic activity

in surrounding mountain ranges contributed significant uranium and other metals to the shale. Limited continental

Devonian sandstone sediments were shed from Ordovician

granite into the Catskill delta to form hosts of minor uranium deposits (Finch, 1967). Continental sedimentation

became dominant in Pennsylvanian time, and host rocks for

PERSPECTIVES OF THE DISTRIBUTION OF URANIUM PROVINCES

Table 1. Distribution of uranium in North America.

[NA, not applicable]

Uranium province name Total resource Area Cluster size range Cluster grade range

magnitude (mi2) (tons U3O8) (percent U3O8)

(tons U3O8)

Athabasca Basin1 5.5×105 100,000 650–195,000 0.30–16.5

Blind River–Elliot Lake1 3×105 25,000 3,000–240,000 .04–.125

Colorado Plateau 6×105 200,000 500–200,000 .05–.60

Rocky Mountain and Intermontane 3.5×105 320,000 500–20,000 .04–.48

Basins

Gulf Coast 1×105 50,000 500–10,000 .04–.30

Basin and Range 4×104 675,000 500–20,000 .05–.10

Florida Phosphorite 1×106 30,000 90,000–270,000 .007–.0125

Non-province Canada1 9×104 NA 500–25,000 .07–.60

Non-province U.S.A. 6×104 NA 800–22,000 .09–.75

Non-province Mexico 2×103 NA 800–1,200 .03–.08

Total 3×106

1Includes some data modified from Volker Thoste, Bundesanstalt fur Geowissenschaften und Rohstoffe, Hanover, Germany

(written commun., 1991).
14 URANIUM PROVINCES OF NORTH AMERICA

large uranium deposits were deposited in Permian and

younger periods after continental collision in Permian time

(255 Ma).

The CPUP has been a stable craton since late Paleozoic.

The Permian, Triassic, and Jurassic host-facies sedimentation was essentially limited to intracratonic basins in the

CPUP block; extensions of these stratigraphic units outside

the plateau are fine-grained facies unfavorable for uranium

deposition. The sources of uranium for deposits in Permian

through Jurassic hosts are thought to have been various volcanic arcs to the west and south at the edge of the North

American plate (Busby-Spera, 1988; Dickinson, 1981;

Granger and Finch, 1988). Three main epochs of mineralization occurred during Late Triassic–Early Jurassic

(≈210–200 Ma) for Permian and Triassic host rocks, Late

Jurassic (≈155–150 Ma) for Middle Jurassic host rocks, and

Early Cretaceous (≈135 Ma) for Late Jurassic host rocks

(modified from Finch, 1991). Redistribution of the primary

uranium ores took place after the beginning of the Laramide

orogeny (≈70 Ma) (Finch, 1991).

The Laramide orogeny continued well into the Tertiary,

during which time numerous intermontane basins were

formed in which Eocene and Miocene host formations were

deposited in the Rocky Mountains and Intermontane Basins

Uranium Province. In the intervening Oligocene time, a

widespread thick blanket of tuffaceous sediments covered

the Eocene basinal arkosic sandstone and older rocks below

a late Eocene surface of low relief developed on Precambrian

and younger rocks. This surface formed during a period of

about 10 million years of tectonic and magmatic quiescence

described by Epis and others (1976) for central Colorado,

which most likely extended into the northern part of the uranium province. Evidence supports the conclusion that the

tuffaceous rocks of the White River Formation were the

most likely source for the uranium deposits in the Eocene

basins (Zielinski, 1983). However, Stuckless (1979) presented evidence that Precambrian granite was a source of

uranium adjacent to some of the Wyoming basins. As far

south as the Pitch cluster (pl. 2) hosted by Mississippian

Leadville Limestone in south-central Colorado, the most

likely source for the uranium (Olson, 1988) was Oligocene(?) siliceous ash-flow tuff and waterlaid tuff. Volcanism to the west in the Basin and Range region provided

silicic ash for many Tertiary host sediments. 

To the south in the Gulf Coast Uranium Province of the

United States and Mexico, major sea-floor spreading in late

Mesozoic and later Tertiary extension created the basic

homoclinal dip of the Gulf Coastal area and uplands for Tertiary fluvial sedimentation (Worrall and Snelson, 1989). At

the west edge of North America, by 40 Ma a volcanic arc

system related to subduction progressed eastward and

regressed westward by 18 Ma coinciding with the maximum

Oligocene-Miocene volcaniclastic sedimentation (Clark and

others, 1982). The Catahoula Formation probably derived

its volcaniclastic component from the Oligocene volcanics

in the Big Bend region of West Texas. These Catahoula volcaniclastic sediments in juxtaposition with major Eocene

host rocks and updip from major Miocene and Pliocene hosts

were probable sources for most of the uranium deposits in

provinces.

To the west and north in North America, the Basin and

Range Uranium Province stretches from the Oregon-Nevada

border southward into northern Mexico, where sparse but

economically important volcanic-type uranium deposits

occur in upper Tertiary volcanic hosts related to back-arc

extensional tectonics. The tectonostratigraphic settings

range in the north from middle Miocene ash-flow tuffs and

domes along the Northern Nevada rift, particularly at the

McDermitt caldera (Zoback and Thompson, 1978); southward to early Miocene intrusions in the Marysvale district,

Utah; farther south to early and late Miocene volcanism that

produced rhyolitic flows, ignimbrites, and airfall ash hosting

uranium deposits in the Date Creek Basin; and at the south,

in Mexico, Eocene rhyolitic ash-flow volcanism that produced volcaniclastic and finally ignimbrite hosts for the Peña

Blanca uranium deposits. All these occurrences of volcanic

uranium deposits are related to calderas.

Finally, the Florida uraniferous phosphorite beds were

deposited over a long period of time in Miocene basins on

the coastal plain on the relatively stable Floridan Plateau

adjacent to rising positive areas. It should be noted that Florida did not become a part of the North American plate until

Late Permian (255 Ma) (Bally and others, 1989). Uplift of

the coastal plains began in late Oligocene and continued

through Pliocene, with several transgressions and regressions related to the passive plate; the Miocene transgression

produced the uraniferous phosphorite beds. Reworking and

acid weathering during Pliocene, Pleistocene, and Holocene

times resulted in enrichment of the phosphate and uranium.

In conclusion, uranium provinces in North America are

generally associated with volcanic activity related to the

development of the western margin of North America. The

south and west margin of the Canadian Shield formed the

leading edge of uranium source development and mineralization from the Proterozoic to the present. The development of favorable hosts and sources for uranium are related

to various tectonic elements developed over time. Periods of

major uranium mineralization were Early Proterozoic, Late

Triassic–Early Jurassic, Early Cretaceous, Oligocene, and

Miocene. Tertiary mineralization was the most widespread

covering most of Western North America and the southeastern coastal region.
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Manuscript approved for publication June 19, 1995

Published in the Central Region, Denver, Colorado

Photocomposition by Norma J. Maes

Graphics by Norma J. Maes and Springfield & Springfield