·. 

Deposition of Uranium 

in Salt-Pan Basins 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 354-G 

Prepared on behalf of the United States 

Atomic Energy Commission and published 

with permission of the Commi.rsion 
") 

y' 

Deposition of U rani urn 

in Salt-Pan Basins 

By KENNETH G. BELL 

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

GEOLOGICAL SURV.EY. PROF .. ESSIONAL PAPER 354-G 

Prepared on behalf of the· Uni"ted States 

Atomic Energy Commission and published 

with permission of the Commission 

UNITED STATES GOVERN;tv.I.ENT. PRINTING OFFICE, WASHINGTON : 1960 
,.f 

UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary 

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington 25, D.C. :- Price 20 cents '(paper cover) 

< 

_... 
CONTENTS 

Page. 

Abstract------------------------------------------------------------------------------------------------------ 161 

Introduction----------------------------------------------------~--------------------------------------------- 161 Uranium in evaporite minerals and deposits ______________________________________ ·_________________________________ 162 

SummarY----------------------------------------------------------------------------------------------------- 169 

Literature cited------------------------------------------------------------------------------------------------ 169 

TABLES 

Page 

TABLE 1. Uranium content of typical deposits of anhydrite and gypsum______________________________________________ 164 

2. Chemical and mineralogic determinations on samples from a drill core of an evaporite deposit__________________ 166 

3. Uranium contents of euxenic dark shales and enclosing dolomi~es and anhydrite for the Paradox basin__________ 168 

m 
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

DEPOSITiON OF URANIUM IN SALT-PAN BASINS 

By KENNETH. G. BELL 

ABSTRACT 

Drainage :waters carry minute quantities of uranium l.nto 

oceans, inland seas, and lakes, and when bodies of water evaporate completely in desiccating salt-pan basins, the uranium must 

be deposited together with all other dissolved materials. The 

ratio of uranium to total evaporite sediments is approximately 

1: 2 .x 101. The distribution of uranium in salt-pan basin sediments is not completely known. Some organic-rich muds, and 

phosphatic sediments deposited in desiccating basins may contain uranium in amounts as large as O.OX percent. Uranium 

may be adsorbed on clays that are deposited with some evaporite sediments. These muds, phosphatic sediments, and clays 

may remove nearly all of the dissolved uranium from the water 

of some basins. Anhydrite, gypsum, halite, and potassiumbearing. evaporite minerals probably are the least uraniferous 

of all rocks in the earth's crust; their uranium contents generally are less than 0.00001 percent. Within salt-pan basins 

where oxidizing conditions tend to prevail, and no slgp.lflcant 

.amounts of organic-rich muds, clays, and phosphatic !l!ediments 

are deposited, highly soluble uranium salts ~erilaln hi solution 

and are deposl.ted only as the basin finally is completely desic-

·cated. These final highly soluble evaporite sediments are not 

likely to be preserved because they are subject to rell,loval.by 

wind erosion and leaching. 

INTRODUCTION 

Waters draining lands commonly ··carry · minute 

·a.mounts of dissolved uranium. Unles·s 'drainage waters have traversed highly uranifero~s terranes, their 

'contents of uraniU:ql generally are fractions of ~.part 

per billion (Fix, 1956; Judson and Osmond, 1955·; 

Adams, 1954; Ro;na· and Urry, 1952). · This uranium 

is carried into .lakes, inland seas, and the oceans. 

Ocean water cqntains traces of uranium; the amounts 

'vary slightly, depending upon tot~l salinity, depth., 

and positi<:>:t;l.with respect to shore line .. Uraniul!l contents ranging from 0.36 to 3.5 parts per billion (ppb), 

oil 0.36 to 3.5 · X 10-9, for ocean water from different 

localities. have be.en reported by various authors (Hern:egger and Karlik, 1935; '.f4"oyn and · others, 1939; 

l{oczy, 1950; Nakanishi, 195.~; Rona and U rry, 1952; 

Stewart and. _Bentley, 1954; Rona and others, 195~). 

~~ere are fe~ pu~lished .da.ta on the uranium contentS 

of waters from saline lakes and inland seas. Stewart .. . .. . . . 

552507-60 

and Bentley {1954) have reported uranium contents 

of 4.7 to 5.3 micrograms per liter' ( 4.7 to 5.3 ppb) in 

water samples from· Great s·alt Lake, Utah. Some 

samples from the Salton Sea, Cali£., that were analyzed in the U.S. Geological Survey laboratories contained about 10 · ppb of· uranium .(Butler, A. P., Jr., 

written communication, 1947). Tourtelot ( 1955) has 

stated that highly ·alkaline water from lakes in western Nebraska contains 12 tq 100 ppb of uranium. The 

concentration of ·uranium in ocean water is about a 

10-fold .increase over that· in drainage waters, and the 

concentration in some saline lake' waters is greater. 

The amount of uranium that can be. deposited .within 

a salt-pan basin normally is very small. I£ the figure 

of 0.1 ·ppb, l.ndicated by Fix {1956) to be approximately the average uranium .. content for wa.ter of major .streams in the United States, is· consi'dered to 

represent. drainage waters in general,. then 10 billion 

tons,'or 7.4 million acre-feet,.o£ water.must evaporate 

for each ton of uranium deposited during complete 

desiccation. An approximate comparison between the 

amount of uranium and the tota1 amount of evaporite·sediments that can be deposited from a given vol-

.ume of wa'ter can be obtained by considering the :com:-

position' of -the .. ocean. I£ the quantity of 35 grams per 

kilogram {35,000,000 ppb ). for the total salinity of 

ocean water (Sverdrup and others; 1942,. p •. 176-:177 

and. 219) and. a uranium content of 1.5 ppb are used, 

and desiccation is assumed· to be complete,,. a simple 

calculation shows that for .. every ·ton of uranium de-

·posited. about 23 million tons of .. evaporite s~diment~ 

·are. deposited. I£ the uranium is assumed to be un~­

formly distributed in the evaporite sediments the· eontent would J:>e less than 0.00001 percent:· 

If an undrained basin that _initially- held a lake.,. an 

inland sea, or a detached body of o'cean water becomes 

completely desiccated, .all the d1.~solved ·niaterial is de-

.posited, mostly in the form ·of_ saline or evaporite sedi:. 

·ments; a· minute p~r~ion·.of the dis_solved matter may 

be adsO'rped on· clast~-~.·~~.~ ~f.~·~.~!~~~e~i~e~ts. U~i'-

161 
162 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

form, uninterrupted desiccation would cause progressive deposition of the most abundant minerals in the 

general sequence: calcium carbonate (as calcite or 

limestone) and calcium phosphate (as forms of apatite or dispersed in other minerals), calcium sulfate 

(as gypsum and anhydrite), sodium chloride (as halite) , potassi urn chloride (as sy I vite) , and magnesi urn 

chlorides and sulfates; other less abUndant minerals 

may be deposited. This idealized sequence rarely is 

obtained because desiccation generally is neither uniform nor uninterrupted; cyclic repetition of parts of 

the sequence may occur many times, mainly because · 

of influxes of water into the basin. An important 

result of influxes· of ~ater is the increasi.ngly high 

concentration of very soluble salts in the residual liquid as .desiccation reduces the volume and causes precipitation of slightly and moderately soluble salts 

(evaporite minerals) ; the influxes also may bring substantial amounts of detrital and organic sediments 

into the . basin. Complete desiccation can be expected 

to result in deposition of a fuial, uppermost thin layer 

containing the most· soluble ·evaporite minerals. 

Some minerals and compounds in an evaporite sequen~e may be intermixed to a considerable degree. 

Calcium phosphate is likely to be dispersed in calcite 

(or limestone). Calcite and gypsum or anhydrite. may 

be intimately mixed or occur in alternating, thin, relatively pure layers. Sylvite commonly is mixed wltlt 

halite. After desiccation has ceased, redistribution' of 

material may result in the formation of secondary 

minerals that may be intermixed with the. primary 

minerals; poly halite, carnallite, and other 'minerals 

that are double salts may be formed in this manner. 

Redistri.bution of material may tend to co11centrate 

some elements. 1n thin zones. The _physical chemistry 

of the formation of evaporite minerals,. both during 

and after desiccation, is nqt fully known. ' 

There is no analytical evidence that conclusively indicates that uranium minerals ~re depo~ited from saline water simultaneously with anhydrite, gy_psum, 

·halite, sylvite, and other minerals of similar. solubility. As desiccation proceed~ and minerals of. increasing solubility are depos1ted, the concentration of 

uranium in the water should_ increase,· and uraniu:t;n 

minerals should be deposited. with. the final,_ most solu-

,ble evaporite .minerals. Clays, shales, and organic 

sediments that are interbedded with some evaporite 

sediments commonly contain slightly greater amounts 

of uranium, probably held by adsorption or chemica1ly combined with ~rganic matter, than the evaporite minerals themselves. Any calcium phosphate min-

.erals that are deposited can be expected to 'co'ntain 

small amounts of uranium held in isomorphous substitution for calcium. 

Most of the uranium that enters lakes, inland seas, 

and oceans with drainage waters probably is carried 

as highly '·soluble uranyl ions or in complex ions containing a uranyl radical. Inasmuch as uranium salts 

that might be present in lake or ocean waters are 

highly soluble, a tremendous concentration of such 

·ions must occur before any evaporite uranium minerals are_ deposited. The hydrous forms of urany~ 

chloride (U02Cl2·3H20) and uranyl sulfate (2U02 

S04•7H20) are soluble to the extent of several parts 

of the salt to one part of water; sodium and potassium chlorides are soluble to the extent of about 0.35 

parts of the salt. to one part of water at 20° C ( Chemical Rubber Publishing Co., 1956, p. 622-623, 596-597, 

570-571). The deposition of halite, sylvite, and other 

saline minerals of similar solubility begins long before saturation points of hydrous urany I salts are 

reached. · 

A desiccating· body of water, particularly if it is 

shallow, generally is well aerated and therefore maintains an oxidizin,g environment. This condition is indicated by the common presence of ferric oxides as 

impurities in evaporite sediments. The oxidizing environment maintains . the dissolved uranium in the 

highly soluble uranyl form. A reducing environment, 

caused by stagnation of part of the. body of water ·or 

by. an influx of putrefying organic matter, is either. a 

local or a temporary condition. Where a reducing 

environment exists some uranium may be reduced to 

the tetravalent state and be deposited with organic-rich 

muds, or some urap.ium in the uranyl state may be 

sorbe~. by organic matter and subsequently become reduced to tlw tetravalent state. ·Many evaporite dEk· 

posits include no sediments that co~ld have been de:-

posited only under reducing conditions. Reduction or 

sorption of uranyl uranium and its incorporation in 

nonsaline ·reduzates is . strictly the result of a local 

condition that exists temporarily during desiccation 

of. some salt-pan basins. It is probable that in most 

basins only a small part of the uranium in the water 

is removed by this mechanism. 

Shortly after the desiccation of ·a salt-pan basin begins, the water becomes permanently saturated with 

the· carbonate ion. in equilibrium with. calcium except 

for short intervals o_ccurring immediately .. after large 

influxes of water. The carbol).ate ion is an effective 

agent for holding the uranyl ion in solution. Whether 

or not it plays a significant role :in maintaining the 

solubility of uranium in. desiccating basins is a moot 

question. It is probable that the · ·concentration ·of. 

'-t"' 

~-
DEPOSITION OF URANIUM IN SALT-PAN BASINS 163 

~arbona~e ion ~onsiderably exceeds that of the urany I phosphate mineral containing between 0.0000003 and 

10n until possibly such time as desiccation is almost 0.000.1 milligrams of uranium, whereas the available 

complete. The excess of carbonate ion enhances the uraniU . I 

1 

b' . m averages approximate y 0.002 milligrams per 

s~ u Ility of the uranyl ion, but in an oxidizing en- kilogram of ocean water). Phosphatic sediment that 

VIronment the urany 1 ion is so soluble that the pres"' rest~ upqn the bottom for a long period of time 

en.ce of carbonate may not be significant. Also, little: c?ntlnues to ta~e up uranium, and rewor.ked marine apaseems to be known concerning the effect of the car~ tlte may contain as much as 0.1 percent of this element 

bonate ion on the adsorption of uranium by clays and (Alt sc h u I er an d o th ers, 1 95 8 . ) Under · some conditions 

other substances. · · · th e p h osphatic . sedilnents n1ay remove esse1itially 

URANIUM IN EVAPORITE MINERALS AND DEPOSITS 

Thin beds. of limestone or marlstone. may be deposited during the initial stage of desiccation in a 

salt-pan basin. The uranium content of such limestone and marlstone generally is in the order of 0.0001 

percent, or less, except where· the rock is appreciably 

phosphatic. · 

Ocean water contains phosphorus in amounts ranging from 0.001 to 0.1 mg per kg, or 1 . to 100 ppb 

( ~~er~rup and .others, 1942, p. 176). Complete precipitatiOn of tlus phosphorus in the form of marine 

apatite produces about 0.005 to 0.5 milligrams of the 

phosphate mineral. The waters of some lakes and 

inland seas contain more phosphorus than the ocean 

wate:rs. ~t has been established that marine phosphatiC sediments generally contain small. and variable · 

amounts of uranium, and some phosphatic sediments 

deposited.from saline lake waters are also uraniferous. 

I~ryestigations by Altschuler ·and others (1958) ha~e 

sh~wn that sedimentary marine apatite typically contains between 0.005 and 0.02 percent uranium that is 

considered to be in the· apatite structure in . isomorphous substitution for calcium. Deposition of phosphatic sediments from saline waters therefore provides 

a mechanism for removal of uranium. . 

Pure phosphate minerals are not characteristic cons~i~utents of evaporite deposits because the small quant~ties of phosphates present generally are dispersed .in 

other evaporite minerals, but all the dissolved phosp~ate must be deposited in any basin that becomes 

completely 'desiccated. The relatively low solubility 

of the phosphate minerals causes them to be deposited 

simultaneously with the carbonate minerals, arid· consequently in an evaporite sequence a large portion of 

the phosphatic constituents are deposited early and 

are found in thin beds of slightly phosphatic marlstone or limestone. By use of the values given by 

Sverdrup and others {1942, p. 176) for the phosphorus content of ocean water and the data of Altschuler and others (1958) for the uranium content of 

marine phosphatic sediments it can be seen that the 

phosphatic constituent removes a variable portion of 

the available uranium ( 0.005 to 0.5 milligra~s of 

all of the uraiuum from the saline water· under· 

other conditions only a small fraction of th~ available uranium . may be r~moved. Evaporite minerals· 

that are deposited after the bulk of the.carbonate min~' 

erals generally contain mere traces of phosphates· 

such m~nute q_uantities of uranium as are in gypsum: 

anhydrite; hahte, and sylvite could be associated with 

phosphatic impurities. 

Large amounts of calcium sulfate minerals are deposited during the early stages of desiccation of saltpan basins t~at initially are filled with ocean water. 

Gypsum is deposited during desicc'ation of lakes and 

inland seas that are characterized by sulfate-rich waters. ~any thick deposits of anhydrite and gypsum 

occur In nearly pure form, that is,. they contain less 

than 20 percent of o~her materials. If organic matter 

~nd clays are not the major impurities, these deposits 

are ess~ntiaJly_ devoid of uranium. · As indicated .below, the sulfate· minerals hold only minute· traces of 

ur~n~um, and the uranium conten~ of impure anhydrite and gypsum rocks is contained in the .clay or- . ' ganic matter, and other substances, and not in the 

sulfate minerals. · · · 

Many deposits of anhydrite become partly or wholly 

converted· to gypsum by the· hydrating action of 

ground and surface waters, therefore, a question arises 

concerning_ the possibility that uranium might be 

leached during the hydration. This action undoubt~ 

edly can occur, but it is probable that the anhydrite 

held nq significant amount of uranium. Gamma-ray 

logs_ of test well.s drilled through evaporite sequences 

indicate that anhydrite and halite strata· show, in general,. the lowest levels of radioactivity of all sedimentary rocks. Exaln:ples of this low radioactivity are 

found in gamma-ray logs of many wells drilled 

through evaporite-mineral deposits in the Paradox 

basin of southwest~rn Colorado and southeastern Utah 

and in the Del a ware basin of southeastern New Mexico. 

On the west slope of the Humboldt Range, Pershing County, Nev., there are large outcrops o:f gypsum,' 

one of which has an area of about a square mile. The 

principal impuri~ies in this gypsum are carbonate. min-. 

erals. The outcrops ar~.covered.by a layer of weath-. 
164 SHORTER CONTRIBUTIONS TO GENERAL·. GEOLOGY 

ered gypsum a few inches thick mixed with. a small 

amount .of wind-deposited sediment .derived mostly 

from dust and .salt. flats of the adjacent Humboldt 

Sink. Radioactivity measurements made on the outcrops with a scintillation counter gave readings of approximately 0.003 milliroentgens per hour when the 

instrument was held aboJ.It 2 feet above the weathered 

gypsum surface. The readings were almost nil where 

taj,{en inside some prospect tunnels. . The small amount. 

of. energy measured on the outc:rop probably was. pre~: 

dominately cosmic radiation. A similar condition exists in White Sands National Monument, N. Mex., 

where dunes of gypsum sand cover large areas. A 

scintillation counter gave no measurable reading du~:­

ing a traverse of some of these dunes (A. P. Pierce 

and J. W. Mytton, U.S. Geological Survey, oral communication, 1957). 

Secondary uranium min~rals have been found in a 

few bedded· gypsum deposits, for example in the Paradox member of the Hermosa formation in Gypsum 

Valley, San Miguel County;· Colo., and in the Brule 

formation, Dawes County, Nebr. These uranium minerals are epigenetic and have been introduced by 

ground and surface ·waters. The Brule formation isnonmarine, and its gypsiferous member was deposited 

from a lake of sulfate-rich water in which the salinity 

apparently did not reach the point where minerals 

more soluble than gypsum were deposited. A .. field 

examination in sec. 3, T. 34 N., R. 47 W. showed that 

anomalous radioactivity, and· ura~ium minerals,. occur 

at scattered points along the gypsum outcrop where 

there are intermittent ground-water seeps. The flow 

of water is insufficient to make surface streams, except during unusually wet periods, but does cause small. 

landslides· and collapse of steep slopes. The -1;1ranium 

minerals ·are · carnotit~, autunite,. and sabugalite 

[Hal(U02)4(P04)~ ·16 H20] (Dunham, 1955). They·,-

ar~ concentrated on the surfaces of the outcrops and in. 

the thin soil mantle . where the ground water evapo-· 

Fates. Where. there is no evidence of ground-water 

seepage, neither anomalous radioactivity nor uranium~ 

minerals can be found. .. . , 

Two ·samples of the bedded gypsum from the Brule 

formation contaiiled 0.0008 and 0.0001 percent;of uranium (Nos. 260461, and 260462, table .1). Sample no. 

260461 was light brown, had a str~mg fetid odor, and 

CQntainecl a small amount of organic ma~ter that probably had._sorbed the apparently anomalous amount of 

uranium; ,sample 260462 w.as ·white and odorless. The_ 

samples contained ~bout 5. percent of aciq-insoluble 

matter. The waters that formed the Brule lake drained 

a terrane characterized by s~dim~:rit~ry d'eposits c·on~ 

taining ·an abundance of volcanic·: ash· :and- therefore· 

probably contained greater-than-average quantities of 

uranium.· This condition is reflected in the abnormally high uranium content of the gypsum. It is 

unlikely that the minute, although anomalous, amount 

of uranium in this gypsum accounts for the secondary 

uranium minerals on the surfaces of the outcrops and 

in the topsoil. It is more likely that the uranium in 

the secondary minerals is leached from tuffaceous clays 

in the vicinity and is deposited on the outcrops and in. 

the topsoil where the water evaporates. 

Anhydrite is anomalously radioactive within or in 

the vicinity of some petroleum and natural gas fields, 

for example, in the Permian formations of the Panhandle field of Texas. Investigations have shown that 

the radioacti:Vity originates in uraniferous organic 

substances that have been epigenetically emplaced in 

secondary. anhydrite; the primary anhydrite, which 

was deposited as an evaporite sediment, is no more. 

uraniferous than primary anhydrite found elsewhere 

(A. P. Pierce, U.S. Geological Survey, oral communication, 1957). 

The uranium contents of some typical deposits of 

anhydrite and .gypsum are presented in table 1. Three 

samples (Nos. 252251, 252252, and 260461) contained 

small amom:its of organic matter. These three samples cont~ined anomalous quantities of uranium, which 

possibly were sorbed by the organic matter. 

Saline .minerals, such as halite, sylvite, carnallite, 

R'nd others of siJTlilar solubility contain so little uranium that the amount cannot be determined with preTABLE 1.-Uranium content of typical deposits of anhydrite and · gypsum 

(Analysts: D.~- Ferguson, H. H. Lip~ W. J. Mountjoy, 0. G. Angelo, J.P. Schuch, · ·· · · · and ~. J. Fenelly.] 

SamPle 

No.· 

Material 

., \ 

. Acid· 

insoluble SOc Uranium matter percent percent 

percent 

-252250 ·Anhydrite ________________________ ------------------------ 0.0001 252251 ..... do ____ ....................... __ .. ·.: ...... _............ .0004 252254 -~---do ______ ; ................. .: .................... ·....... .0002 260459 Gypsum .......... ______ .__________ 10.2 35. 5 • 0001 

260460 Anhydrite __ ...................... . 5 39. 9 . 0001 · 260461 Gypsum__________________________ 5. 0 40. 1 • 0008 260462 _____ do ___ .......................... 5.9 41.8 .0001 

. ··NoTE.-Sources·of samples: · · 252250. Sample of core chips, Shell Oil Co.'s Desert Creek 

No. l.well, SW%SE~~NW% sec. 2, T. 42 S., R. 23 

E., San Juan County, Uta.h, depth 5,122~~ ft. 

252251. Same as source of sample 252250; depth 5,124~ ft. 

252254. Sample of core chips, Reynolds Metal Co.'s Hatch 

No. 1, sec. 4, T. 39 S., R. 24 E., San Juan , Countv, Utah, depth 5,797-5,799 ft. 

260459 .. Sample from prospect~ tunnel, W~ sec. 27, T. 

26 N., R. 32 E., Pershing County, Nev. 

260460. Sample .from· abandoned ·Regan mine, approxi- .. mately 12 miles so.uth of Yerington, Nev. · 260461. Sample from outcrop of gypsiferous member of 

Brule· formation; W~ sec. 3, T. 34 N., R. 47 W., 

Dawes County, Nebr. . · 260462 ..... sample from same locality as sample 260461. 

'"{ 
DEPOSITION OF URANIUM IN SALT-PAN BASINS 165 

cision by standard methods of chemical analysis. There 

are but few published data on. this subject. Kemeny 

(1941) has reported that the uranium contents of rock 

salt, sylvite, and carnallite from Germany and Austria, determined by radiometric methods, average 

0.0006 percent ( 6 X 10-10 g/ g). Gentner and others 

(1954) have reported a uranium content of 0.00001 

percent (1 X 10-10 g/g) for sylvite from Buggingen, 

Germany; the determination was made by a method of 

counting alpha tracks on an emulsified plate. A few 

samples of potash ores, consisting mainly of halite, 

sylvite, and polyhalite, from the Carlsbad district, 

New Mexico, have been tested for uranium in the 

Geological Survey laboratories. The uranium contents of the samples were les$ than 0.0001 percent, so 

no attempt was made to determine them precisely. All 

uranium determinations by the Geological Survey labpratories were made by fluorometric methods. 

These meager data do not indicate enrichment of 

uranium in evaporite sediments. They do not warrant any conclusions regarding the proportionate rate 

at which uranium is deposited during stages of desiccation represented by halite and sylvite. 

The clays and the iron and aluminum oxides that 

are deposited with saline minerals probably as a rule 

are considerably more uraniferous than the saline 

minerals themselves. Some information about the distribution of uranium between water-soluble evaporite 

minerals and water-insoluble matter was obtained by 

analyzing several samples taken from a drill core recovered from potassium-bearing beds in the Salado 

formation of Permian age, Dei a ware basin, N. Mex. 

The samples were cut from a 19-foot length of core 

from a stratiO'raphic section that includes two thin b • 

zones having large contents of clays. The clays evidently were deposited when ~arge influxes of s~diment-bearing water entered the basin. The analytical 

data are presented in table 2. 

The sections of core were split lengthwise, and one 

part was crushed and mixed to provide material for 

analysis. Uranium in the total sample was determined by a fluorometric method. The samples were 

then separated into water-soluble saline minerals, 

water-insoluble but acid-soluble saline minerals, and 

water- and acid-insoluble matter by the following procedure: The samples were leached by ·weighing 1 

gram of the substance into a tared sintered glass crucible of medium porosity, 10 ml of water were added, 

the slurry was stirred briefly, and the. resulting solution was drawn by vacuum into a volumetric flask; 

this procedure was repeated ten times for a total of 

100 ml of water; the water-soluble-· evaporite 'rriirierals, 

such as halite and sylvite, and a small portion of the 

slightly water-soluble minerals, such as polyhalite and 

. anhydrite, were dissolved in the water leachate; the 

crucible and contents were then dried under a vacuum 

of less than 1 em of mercury in a desiccator containing 

anhydrous calcium sulfate, were weighed, and the 

leaching procedure repeated with 1 :1 hydrochloric 

acid; the acid leachate contained most of the poly halite 

and the calcium sulfate minerals, as well as phosphate 

and carbonate minerals; the water- and acid-insoluble 

matter remaining in the crucible consisted of clay 

minerals and other clastic sediments, which were then 

dried and weighed. 

An attempt was made to determine the uranium 

contents of the water-soluble leachates by the fluorometric method, but the quantities of uranium present 

were below the threshold of the procedure used, or 

less than 0.00002 perc~nt. Uranium in the acid leachates was determined, but there is no assurance that 

the values obtained are indicative of the uranium contents of the water-insoluble but acid-soluble minerals; 

some of this uranium may have been adsorbed on clays 

and was removed· by the acid. Uranium in the waterand acid-insoluble matter was obtained by difference, 

and again there is no assurance that the yalues indicate the true quantiti~s of uranium because some uranium may have been removed by the acid. 

The data presented in table 2 indicate that most of 

the uranium is concentrated in the water-insoluble but 

acid-soluble matter and the water- and acid-insoluble 

matter. The water-soluble matter contains extremely 

small amounts of uranium, the amount being less than 

0.00002 percent of the total sample for all samples 

analyzed. The uranitun contents of the water-insoluble but acid-soluble matter are very small and show a 

positive correlation with the total uranium contents 

of the samples; the latter feature may be an indication of extraction of uranium from the water- and 

acid-insoluble matter by the acid. 

One sample (No. 254465, table 2) is of especial in· 

terest because it represents a clay-rich zone about 6 

inches thick. Unfortunately about three-quarters of 

the ma:terial from this zone was lost during drilling; 

that which was recovered was completely consumed in 

the various chemical analyses. The megascopically 

visible constituents of the sample were coarse crystalline halite, sylvite; and polyhalite, and galls and 

stringers of greenish-gray clay consisting of montmorillonite, illite, and kaolinite and (or) chlorite. The 

analytical data (table 2) indicate the presence of a 

surprisingly large amount of uranium; two splits of 

the core ·contained 0.0078. and 0.038 percent uranium, 
.). 

TABLE 2.-Chemical and mineralogic determinations on samples from a drill core·of an evaporite deposit Potash Company of America drill:..hole-151, Sec. 12, T. 20 S., R 

33 E., Lea County, N.Mex. 

[Analysts: W. T. Mountjoy, H; H. Lipp, and C. G~ Angelo, U.S. Geological Survey. ·Clay minerals indentifled by A. J. Gude, U.S. Geological Survey.) 

Acid-soluble but 

Uranium (as percent of total sample) Chemical composition (as percent of total sample) 

Sample Water- Water- water-insol- In Acid Sample interval Principal minerals soluble and acid- ublesaline insoluble Water leachate 

No.· leachate of water-insoluble matter 2 (depth) saline insoluble minerals In water In acid 

minerals matter (by Total leachate leachate matter CO a so' 1

ct- (mini" · difference) 1 mum by Ca++ Mg++ Na++ K+ Ca++ Na+ K+ S04 

difference) --- -------------------- 254463 2,258 ft 0 in to Halite ••••• ____ _. ________ 99.85 0.10 0.05 0.00008 <0.00002 <0.00001 0.00005 ------ 0. 56 0.29 35.75 3.93 2.85 52.28 0.06 <0.02 0.02 <0.02 

2,262 ft 4 in. 

254464 ~,262ft4in. to Polyhalit_e~ ____ --------- 67.2 .65 32.15 . 00012 <.00002 .ooog2 .00008 ------ 9.18 2.80 1.12 10.00 43.50 l. 78 3. 78 .02 2. 78 17.50 .. 2,263 ft 8 in. 

1254465 2,263ft 8 in Halite, •ylvite, niont- } to 2,264 ft morillonite, Illite, { .038 ·<:a~oooo2 ---------- ---------- 2. 61 1.60 3.06 9.14 9.17 7.60 27.85 1. 70 <.02 .07 1. 06 

2 in. kaolinite and (or) 71.6 19.4 9.00 ~·-~~~~- ---3~_04·-- · chlorite, carbonate 

minerals. 

254466 2,264 ft 2 in Halite------------------- 99.49 . 47 .04 .00006 <.00002 <.00001 . 00003 ------ .47 .29 35.75 4.90 2.05 56.45 .04 <.02 <.02 .05 to 2,264 ft 

10 in. 

2544.67 2,264 ft 10 in Halito, sylvite.--------- 99.05 .88 .07 . 00004 <.00002 <.00001 .00001 -----· .12 .62 22.25 22.60 2.12 52.10 .04 <.02 <.02 .02 

254468 to 2,268 ft. 2,268 ft to Halite, sylvite, clay 94.3 3.9 1. 80 .00065 <.00002 . 00007 .00056 ------ .24 .47 26.25 14.00 1. 38 52.00 . 78 .15 .02 . 75 

2,273 ft 6 minerals. in. 254469 2,273 ft 6 in Halite, sylvite, mont- 61.9 32.7 5.40 .00011 <.0002 <.00001 . 00008 ------ .56 2.07 13.46 4.42 3.30 28.90 .24 <.02 .08 .29 to 2,274 ft morilloni te, Illite, 

6 in. kaolinite and (or) 

chlorite. 

254470 2,274 ft 6 in Halite ..• ---------------- 98.3 .89 .81 .00004 <.00002 <.00001 .00001 ------ . 71 .34 36.75 1. 62 3.30 55.95 .17 .02 .02 .38 to 2,277 ft. 

~~- --------- - ----- -- -- -- -- ------- - ---- ----~-~~------------- -- -- -

I Acid-soluble but water-insoluble saline minerals include carbonate and phosphate minerals, and part of 

any polyhalite, gypsum, and anhydrite in the sample. t Mg++ and C1-, were present, are in amounts ofless than 0.01 percent in all samples. 

' Partial analyses were made of three portions of the sample. 

j.. ~ 4 

PO; 

---

<0.0005 

.007 

--------

3.041 

<.0005 

.001 

.009 

.004 

<.0005 

-

Approxi-

· mate 

summation 

---

101:8 

91.3 

83.2 

100.5 

101.0 

99.9 

90.2 

100.2 

A 

~ 

0') 

0') 

~ 0 

~ 

~ ~ 

a 

0 

z 

1-3 

~ 1-1 

tll 

§ 

0 

z 

Ul 

1-3 

0 

0 

1::".1 

z 

1::".1 

~ 

~ 

0 

1::".1 

0 

t"l 

0 

0 

~ 
~-

DEPOSITION OF URANIUM IN SALT-PAN BASINS 167 

or 78 and 380 (ppm); the acid-soluble matter of a 

third split, obtained after removing water-soluble matter, contained an amount of uranium corresponding to 

0.040 percent ( 400 ppm) of the sample. The range 

of values is attributed to the coarse heterogeneous 

character of the material and the improbability of 

making three identical splits of the core. This sample contained about 19 percent water- and acid-insoluble matter, about 2.6 percent carbonate as COa=, and 

about 0.041 percent phosphate as P04 =. · Above average quantities of uranium and phosphate were found in the second thin clay-rich zone 

represented by samples 254468 and 254469 (table 2) . 

The amount of uranium in sample 254468 was 0.00065 

percent ( 6.5 ppm) and of phosphate as P04 = was 

0.009 percent ( 90 ppm)-. 

These clay-rich samples contained no visible uranium minerals and no fluorescent substance. Some 

uranium undoubtedly was combined with the phosphate constituent, but the amounts of uranium found 

seem to be con~iderably in excess of what reasonably 

could be accounted for by this combination. Some of 

the uranium could have been adsorbed on clays, and ·a 

finely dispersed uranium mineral could have been 

present. 

The clay-rich zones undoubtedly represent interruptions in the desiccation of the basin caused by large 

influxes of water carrying dissolved matter and much 

fine-grained sediment. Such influxes could have resulted from occasional floods that washed the adjacent terrain. "When the floods subsided, desiccation 

immediately was resumed; fine-grained suspended clastic sediments settled to the bottom and became mixe'd 

with the initial evaporite layer which contained some 

phosphatic and carbonate constituents. This action 

provided at least two mechanisms for removal ·of uranium from the basin water, adsorption on clays, and 

combination with phosphatic constituents. It seems 

probable that most of the uranium thus removed was 

already in the basin prior to the influx that brought 

in the clays. · 

Stagnant, anaerobic conditions may exist tempo;. 

rarily within the water of parts of some desiccating 

salt-pan basins. If there is an influx of fine-gra~ned 

clastic sediments and organic matter during such periods, organic-rich dark muds or limy muds may be 

deposited and ultimately become shales. So~e of sue~ 

shales that are slightly phosphatic may be anomalously radioactive and contain uranium· in the range 

of O.OOX to O.OX percent. On the other hand, organicrich muds can be deposited in· oxidizing environments; 

and subsequently. a zone in 'w~ch redu~ing condi~io~s 

exist may form in them although the uppermost layer 

of mud and the water above it remain in an oxidizing 

condition; under these circumstances the reducing zone 

is insulated from the main body 9f water, and the only 

uranium that can be sorbed is that in the connate water, consequently the muds do not pecome significantly 

enriched in uranium. Uranium-rich muds generally 

are deposited in reducing environments, and if the 

bottom surface remains in a reducing condition, sorption of uranium in a particular layer may continue 

for as long as water can move freely past or through it. 

In the Paradox basin of southwestern Colorado and 

southeastern Utah some thin beds of euxenic darkgray and black shale are 'interspersed among the carbonate and saline deposits of the Paradox member of 

the Hermosa formation. They are good marker beds 

for stratigraphic correlation because they show anomalously high radioactivity on gamma-ray logs. The 

characteristics and possible origin- of these dark -shale 

beds have been discussed by Wengerd and Strickland 

(1954). The uranium contents of a few samples of 

some of these dark-shale beds and of the dolomites and 

anhydrite that enclose them have been determined. 

These data are presented in table 3. The samples were 

chipped from drill cores and represent the only material that was available at the time of this investigation. The most uraniferous sample, No. 252252, contained 0.0057 percent uranium. In general, the uranium contents of these shale beds are about an order 

of magnitmle higher than those of the enclosing dolomites and anhydrite. Probably some uranium is 

sorbed by organic. matter and phospha.tic sediments 

and thereby is removed from the saline during the 

deposition of sediments such. as those that formed the 

~hales· in the Paradox member. This mechanism operates only temporarily in a few basins and probably 

removes only ·a small part of the dissolved uran1 urn 

from the water. 

TABLE 3.-Uranium contents of euxenic dark shales and enclosing 

dolomites and anhydrite from the Paradox basin. 

[Analysts; G. G. Angelo, J.P. Schuch, ~dE. J. Fennelly] 

Description 

!

Uranium 

percent 

Shell Oil Co.'s North Boundary Butte No. 1 Well, C SWM NE~ sec. 33, T. 42 S., 

R. 22 E., San Juari County, Utah 

252220 

252221 

252222 

252223 

252224 

252225 

252226 

252227 

252228 .. 252229. 

4, 212 Limy gray shale------------------------"------ 4, 615 -- ___ do ____________________________ • ____ • ____ • __ 

!: 4, ~~~~ 620~ =====~g========================~================ Shale and dolomite, anhydrlte----------------- 4, 621~~ Dolomite _____________________ ----------------- 4, 622 _____ do. ____ -·- ___________ --- ___________________ _ 4, 623 _____ do ___ ·- _____ :_· ____________ ~ ______________ • __ 

4,625 Dolomite, anhydrite--------------------------- . ·4, 628 _Limy gray shale.--.---,"-------~----·----------

0.0009 

.0007 

.0009 

.0013 

.0005. 

.0004. 

.0011 

.0003 .. 0003 

.00~ 
168 SHORTER CONTRIBUTIONS TO .GENERAL GEOLOGY 

TABLE 3.-Uranium contents of.euxenic dark shales·and enclosing 

dolomites and anhydrite from the Paradox basin-Continued 

Sample I Depth No. (feet) Description 

!

Uranium 

percent 

Superior Oil Co.'s No.1-28 Navajo Well, C NW~ NW~ sec. 28, T. 41 S., R. 26 E., 

San Juan County, Utah 

252230 

' 252231 

252232 

252233 

252284 

252235 

252236 

252237 

252238 

252239 

252240 

252241 

252242 

252243 

252244 

252245 

252246 

252247 

252248 

6, 048-6,049 Shaly dolomite __ ~ __ -------------~•-----"'----- 6, 053-6, 054 _____ do.-----------------------------------------

6,055-6,056 Gray shale-------------------------------------

6, 056-6, 057 _____ do.----~-----------------------------------

6, 057-6, 058 _____ do ___ -------------------------------------- 6, 058-6, 059 _____ do.-----------------------------------------

6,058-6,060 Black shale----------------------------"-'------ 6, 061-6, 062 _____ do ________________________ -----------------

6,062-6,063 _____ do.---------------------------------'-------

6, 063-6,064 -----d0-----------------------------------------

6, 064-6,065 _____ d0----------------------"-----------·-------

6, 065-6, 066 _____ do.----------------------------------------

6,067-6,068 _____ do.----------------------------------------

6, 068-6,069 _____ d0--------------------------------_,---------

6, 069-6,070 _____ d0-----------------------------------------

6, 070-6, 071 _____ do.----------------------------------------

6, 071-6, 072 _____ do.-------------------------------·--------- 6, 072-6,073 Shaly dolomite _______________________________ _ 

6, 073-6,074 Dolomite--------------------------------------

o:ooo8 

.0006 

.0007 

.0007 

.0008 

.0006 

.0006 

.0010 

.0010 

.0010 

.0012 

.0007 

.0006 

.0007 

.0011 

.0032 

. 0013 

.0007 

.0002 

Shell Oil Co.'s Desert Creek No. 1 Well, SW~ SE~ NW~' sec. 2, T. 42 S., R. 23 E, 

252249 

252250 

252251 

252252 

252253 

· · San Juan County, Utah · 

5, 122H Anhydrite ______________ ----------------------- 5, 124Y.I __ ---do._-----_--- __ ---------------------------- 5, 126 Gray shale. _____ ------------------------------ 5,127 Black shale------------------------------------ 5, 128H Dolomite _____________________________________ _ 

o. 0001 

.0001 

.0004 

.0057 

.0001 

Reynolds Metal Co.'s Hatch No.1 Well, sec. 4, T. 39 S., R. 24 E., San Juan County, 

Utah 

2522541 5, 797-5,7991 Anhydrite •• -----------------------------------1 o. 0002 252255 5, 799-5, 799~ Rlack shale ______ _,~"--------------------------- . 0017 252256 5, 799~-5,800 Shaly dolomite.------------------------------- .0005 

The data presented above -indicate that the distribution of uranium in sediments deposited in desiccating salt-pan basins is not uniform and is not completely known. In attempting to determine the distribution, a major difficulty arises from the fact that 

the amounts of uranium and its. co~pounds involved 

are very small in comparison to the total bulk of sediments. It is known that in some salt-pan~basin deposits uranium is not uniformly distributed among 

the various sedimentary materials but is relatively enriched in clays, in phosphatic sediments, and in some 

beds of organic-rich, d_a~k shale that were deposited 

in reducing environments. It is possible. that in some 

basins essentially all of .the dissolved uranium can be 

removed from solution by inclusion in clays and phosphatic and organic sediments. Within basins wh~re 

such sediments are not deposited, or are deposited in 

very small amounts, it seems most likely that a substantial part of the· uranium must remain in· solution 

until the bittern finally evaporates. 

The probability that the concentration of uranium 

increases continuouslt in: ·the water .of some salt-pan 

b~sins even though slibst~ntial amounts o~ Clays, phosphatic sediments,~ and-· carbonate and evaporite minerals ·are --deposited .. 'is .. indicated· by .. thlf ·com{>"aratively· 

high concentrations of _uranium in the waters of the 

Salton Sea, Calif., and Gre~t Salt Lake, Utah. J\1uch 

of the water entering Great Salt Lake drains terran~s 

to the east and northeast that are composed in part of 

highly phosphatic formations (Phosphoria and Park 

(Jity formations). Rather extensive deposits of calcareous oolites that contain small amoun~s· of phosphatic' material ~re found along parts of the- shore, 

and the oolites still are being ·:formed ; black, organic.:. 

rich clays are being deposited-along other parts of the 

shore (Eardley, 1938). The uranium contents of the 

oolites and black clays are unknown. ·Even though 

these sediments are types that commonly are enriched 

in ur~nium from solution, the lake water has about 

twice the concentration of uranium as does ocean water. The concentration of uranium in the Salton Sea 

(10 ppb) is about four times that of ocean. water. 

It already has been pointed out that within desiccating salt-pan basins oxidizing cond1 tions tend to 

prevail and reducing conditions tend to be localized 

and often are of brief duration. As a consequence~ 

most of the dissolved uranium is maintained in th~ 

highly soluble uranyl state. The uranyl salts are so 

highly soluble that it is reasonable to assume that the 

water in a basin must evaporate completely to cause 

deposition of uranium that is not sorbed by clays, organic matter, and phosphatic sediments. If the water never evaporates completely it is unlikely that any 

uranium salts will be deposited. If a basin becomes 

completely desiccated, a small but appreciable amount 

of uranium minerals should be deposited in a final 

layer of highly soluble evaporite minerals. Such uraniferous deposits apparently are unknown; the re~­

son is that they are readily susceptible to removal. 

The surface of a dried-up basin, or even a partly 

dried-up basin, is subject to wind erosion that can 

remove considerable amounts of sediment. Anyone 

who has been in the vicinity of the Bonneville salt 

flats of Utah, or the smaller salt flats in the Carson 

and Humboldt Sinks o.f Nevada, in the Mohav~ and 

Death Valley areas of California, or the bolsons of 

west Texas on windy days can _attest to the fact that 

wind moves large amounts of evaporite minerals. An. 

indication of the amount of evaporite material that 

can be so moved is given by Eardley and others (1957, 

p. 1151) in discussing wind erosion in the Bonn~ville 

basin of Utah. They stated: "The writers postulate· 

that the wind removes about 3,000,000 tons of salt a:r;tnually from the Great Salt Lake desert. This is .. carried by the wind out of the drainage basin." . It is 

reasonable to assume that -an exposed lay~r of ~raniferous evaporite minerals. could be remove<l._.bY. -~iii~ 

~!thin a very short period .. ' . . . ... ... ' . 
. .,. 

DEPOSITION OF URANIUM IN SALT-PAN BASINS 169 

Uraniferous evaporite minerals would have to be 

covered by some other kind of sediment immediately 

after they were deposited in order to be preserved 

from wind erosion. Even then, these very soluble 

minerals would be leached by the first passage of water through the sediments. This water would remove 

the highly soluble salts, including uranium salts, from 

the places of initial deposition and transport them 

laterally or downward, thereby dispersing them 

through much larger volumes of rock and sediment, 

or it would bring them to the surface to form deposits of efflorescent minerals that subsequently would 

become dispersed. 

There is little possibility that a final deposit o£ uranium-rich evaporite sediments can be preserved in a 

salt-pan basin. 

SUMMARY 

In summary, it can be stated that evaporite sediments deposited in salt-pan basins are probably the 

least uraniferous of all rocks. Their uranimn contents average less than 0.00001 percent. This condition results from (1) the paucity of uranium in ocean 

and surface waters, (2) the oxidizing environments 

that generally exist within the evaporating bodies o£ 

water, (3) the great solubility of uranyl chlorides and 

sulfates and urany 1 carbonate complexes, and ( 4) the 

likelihood that any uraniferous evaporite sediments 

that might be deposited are removed by wind erosion 

or by leaching. Analytical work that would indicate 

whether uranium is deposited at a fairly uniform rate 

throughout the desiccation of a salt-pan basin or tends 

to remain in solution until the basin finally dries out 

has not been done. Theoretical considerations indicate that in some basins most of the uranium can be 

removed from solution through sorption by clays, 

phosphatic sediments and organic-rich muds; in other. 

basins the bulk of the uranium should remain in solution until such time as desiccation is almost complete. 

'LITERATURE CITED 

Adams, J. A. S., 1954, Uranium contents of Wisconsin rivers 

and their use in geochemical prospecting [abs.]: Geol. Soc. 

America Bull., v. 65, p. 1225. 

Altschuler, Z. S., Clarke, R. S., Jr., and Young, E. S., 1958, 

Geochemistry of uranium in apatite and phosphorite: U.S. 

Geol. Survey Prof. Paper 314-D, 50 p. 

Chemical Rubber Pub. Co., 1956, Handbook of chemistry and 

physics : 38th ed. Cleveland. 3206 p. 

0 

Dunham, R. J., 1955, Uranium minerals in Oligocene gypsum 

near Chadron, Dawes County, Nebr.: U.S. Geol. Survey 

TEI-525, 31 p., issued by U.S. Atomic Energy Comm. Tech. 

Inf. Service Ext., Oak Ridge, Tenn. 

Eardley, A. J., 1938, Sediments of Great Salt Lake, Utah: Am. 

Assoc. Petroleum Geologists Bull., v. 22, p. 1305-1411. 

Eardley, A. J., Gvosdetsky, Vasyl, and Marsell, R. E., 1957, 

Hydrology of Lake Bonneville and sediments and soils of 

its basin: Geol. Soc. America Bull., v. 68, p. 1141-1201. 

Fix, P. F., 1956, Hydrogeochemical exploration for uranium, in 

Contributions to the geology of uranium and thorium by 

the United States Geological Survey and Atomic Energy 

Commission for the United Nations International Conference on peaceful uses of atomic energy, Geneva, Switzerland 1955: U.S. Geol. Survey Prof. Paper 300, p. 667-671. 

Foyn, E., Karlik, B., Petterson, H., and Rona, E., 1939, Radioactivity of sea water: Nature, v. 143, p. 275-276. 

Gentner, W., Goebel, K., and Priig, R., 1954, Argonbestlmmungen 

an Kallum-Mineralien. III. Vergleichende Messungen nach 

der Kalium-Argon- und Uran-Helium Methode: Geochim. 

et Cosmochim. Acta, v. 5, p. 124-133. 

Hernegger, Friedrich, and Karlik, Berta, 1935, Die quantitative 

Bestimmung sehr kleiner Uranmengen un der Urangehalt 

des Meerwassers: Sitzungsberichte Academie der Wissenschafter in Wien, Math.-naturw. Kl. Abt. IIa, v. 144, p. 217-

225. 

Judson, Sheldon, and Osmond, J. K., 1955, Radioactivity in 

ground and surface water: Am. Jour. Sci., v. 253, p. 104-

116. 

Kemeny, Etel, 1941, Uran- und Radiumgehalt von Stelnsalz und 

Sylvin: Sitzungsberichte Akademie der Wissenschafter in 

Wien, Math.-naturw. Kl., Abt. IIa, v. 150, p. 193-207. 

Koczy, Gerta, 1950, Weitere Uranbestlmmungen an Meerwasserproben: Sitzungsberichte Akademie der Wissenschafter 

ln Wien, Math.-naturw. Kl., Abt. IIa, v. 158, p. 113-121. 

Nakanishi, Masaki, 1952, Fluorometric microdetermination of 

uranium. V. The uranium content of sea water: Chem. 

Soc. Japan, Bull., v. 24, p. 36-38. 

Rona, Elizabeth, Gilpatrick, L. 0., and Jeffrey, L. M., 1956, 

Uranium determination in sea water: Am. Geophysical 

Union, Trans., v. 37, p. 697-701. 

Rona, Elizabeth, and Urry, W. D., 1952, Radioactivity of ocean 

sediments. VIII. Radium and uranium content of ocean 

and river waters: Am. Jour. Sci., v. 250, p. 241-262. 

Stewart, D. C., and Bentley, W. C., 1954, Analysis of uranium 

in sea water: Science, v. 120, p. 50-51. 

Sverdrup, H. V., Johnson, M. W., and Fleming, R. H., 1942, The 

oceans. Their physics, chemistry and general biology : 

New York, Prentice-Hall, Inc., 1087 p. 

Tourtelot, H. A., 1955, Uranium content of water in the Great 

Plains region of Nebraska and in adjacent states [abs.]: 

Geol. Soc. America Bull., v. 66, p. 1627-1628. 

Wengerd, S. A., and Strickland, J. W., 1954, Pennsylvania 

stratigraphy of Paradox salt basin, Four Corners region, 

Colorado and Utah : Am. Assoc. Petroleum Geologists Bull., 

v. 38, p. 2157-2199.