Advances in Soil Gas Geochemical Exploration for Natural Resources

8/10/2019 Advances in Soil Gas Geochemical Exploration for Natural Resources

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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 91, NO. B12, PAGES 12,327-12,338,NOVEMBER 10, 1986

Advances in Soil Gas Geochemical Exploration for Natural Resources'

Some Current Examples and Practices

J. HOWARD MCCARTHY, JR., AND G. MICHAEL REIMER

U.S. GeologicalSurvey, Denver, Colorado

Field studieshave demonstrated that gas anomalies are found over buried mineral deposits.Abnor-

mally high concentrations of sulfur gases and carbon dioxide and abnormally low concentrations of

oxygenare commonly ound over sulfide ore deposits.Helium anomaliesare commonly associatedwith

uranium depositsand geothermal areas. Helium and hydrocarbon gas anomalies have been detected over

oil and gas deposits.Gases are sampledby extracting them from the pore spaceof soil, by degassing oil

or rock, or by adsorbing them on artificial collectors.The two most widely used techniques or gas

analysisare gas chromatographyand mass spectrometry.The detection of gas anomaliesat or near the

surfacemay be an effectivemethod to locate buried mineral deposits.

INTRODUCTION

Further, we search or the veins by observing he hoar-frosts,

which whiten all herbage except that growing over the veins,

because he veins emit a warm and dry exhalation which hinders

the freezing of the moisture...

"De Re Metallica"--Georgius Agricola, 1556

It is generally accepted hat new deposits of metals, oil and

gas, and other resourcesmust continually be found to ensure

future economic and social progress.Despite this need, the

rate of discoveryof new mineral depositsand oil and gas fields

has declined n the last few years, argely becausemost of the

deposits that are exposed at the surface have already been

found. Most of the ore depositsmined in the past and being

mined today were discoveredbecause hey cropped out at the

surface. Similarly, many oil and gas deposits were discovered

by oil or gas seeps t the surface Mclver, 1984]. Increasingly,

geologists ealize that our search for new deposits must now

concentrate on those concealed beneath the surface and that

prospecting or them will require new exploration techniques.

One such technique is to measure gases that emanate from

buried mineral depositsand escape o the surface.

There are two reasons or the increasing nterest in the use

of gases or geochemicalexploration: (1) In addition to an-

cient observations noting the occurrenceof gasesaround ore

deposits [Agricola, 1556], recent field and laboratory studies

indicate that gasesoccur at or near the surfaceabove virtually

all mineral deposits,either as primary components or as reac-

tion products [Lovell et al., 1979; Lovell and Hale, 1983;

Hinkle and Kantor, 1978; Hale and Moon, 1982; McCarthy,

1972; Tanner, 1964, 1978; Taylor et al., 1982; Jones and

Drozd, 1983; Mclver, 1984; Philp and Crisp, 1982]. (2) The

development of new and sensitiveanalytical instruments, such

as the gas chromatograph and the mass spectrometer, has

enabled us to measure both high and extremely low con-

centrations of gases ound in nature. Studies on the diffusion

and transport of gaseshave been carried out by a number of

scientists Tanner, 1964, 1978; Stahl et al., 1981; Leythaeuser

et al., 1982, 1983; Kvenvolden nd Claypool, 1980; Kristiansson

and Malmquist, 1980; Roberts, 1981; Reimer and Orton, 1976;

Reimer et al., 1979]. In this paper the generation and migra-

This paper is not subject to U.S. copyright. Published in 1986 by

the American GeophysicalUnion.

Paper number 5B5883.

tion of gases,current practices and techniquesused in gas

geochemistry, nd examplesof the use of gases n exploration

are described.

GENERATION OF GAS ANOMALIES

Gas anomalies are generated by both primary (hypogene)

and secondary (supergene)processes.Examples of primary

processes re outgassing rom the mantle and deep crust, mag-

matic differentiation leading to active venting of volatiles

through volcanoesor seafloorspreading enters, nd emplace-

ment of hydrothermal ore deposits.Secondaryprocesses en-

erate gas anomalies through the interaction of the hydro-

sphere,biosphere,and atmospherewith crustal rocks and min-

eral deposits.Examples include the generation of sulfur gases

and carbon dioxide during oxidation of sulfide ore bodies and

hydrocarbon gases rom natural gas and petroleum deposits.

Helium and radon are generatedby radioactive decay and are

transported and accumulatedby supergene nd hypogenepro-

cesses.

Primary Gases

Primary gasesare emitted from the mantle and deep crust

through volcanoes,spreading centers,and deep-seated aults

(Figure 1). One of the earliest studies of volcanic emanations

was conducted by Zies [1938] in the Valley of Ten Thousand

Smokes in Alaska. He found that fumarole gases contained

about 99.5% water; other componentshe identifiedwere CO2,

GO, 02, CH4, H2S H2, N2, Ar, HC1, and HF. Zies proposed

that these gases accumulated as late-stage differentiates of a

deep-seatedrhyolitic magma. Many of the same gases were

found at Kilauea volcano in Hawaii [Shepherd, 1938; Green-

land et al., 1985], as well as SO2, S2, and SO3. n addition, F,

C1, Br, and I have been reported in gases rom volcanoes n

Japan [Shitiura et al., 1964]. Organic halides have been re-

ported in gases rom Mauna Loa and Kilauea in Hawaii and

from Mount St. Helens in the United States [Howard et al.,

1980]. Evidence for deep outgassing s found in differences n

the composition of gasesand their isotopic makeup. Dymond

and Hogan [1973] measured the noble gases in midocean

ridge basalts and found that the abundance patterns of the

noble gases resembled those of the sun rather than those of

the earth's atmosphere. They concluded that the basalts con-

tained primordial noble gases.Similarly, 3He is enriched n

tectonic settingswhere mantle-derivedmaterial is being inject-

ed into the crust. Lupron and Craig [1975, 1981] and Craig et

al. [1975] found 3He enrichment t submarine olcanicvents

12,327


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12,328 MCCARTHY AND REIMER:SOIL GASES N GEOCHEMICAL XPLORATION

He3,H2S,H2,cO

Ne,Ar,Kr,Xe

Spreading

Centers

H20,CO 2,cO,N 2,He

CH4,SO2,F,GI,Br,I

He3,H2%

Volcanoes

ust

\-antle

Deep Faults

Fig. 1.

PRIMARY GAS EXHALATIONS

Some gases hat have bccn identified in primary gaseous

and vapor emanations.

along the East Pacific Rise. Craig and Lupton [1976] mea-

sured Ne, He, and H isotope ratios in oceanic basalts and

concluded hat thesegaseswere probably mantle derived.

Some emanations of CO2 appear to be mantle derived

based on carbon isotope measurements. O2 gas collected

from phreaticmaars n Alaskawere ound o havea 63C

value of -6.36%0, suggestinga deep source [Barnes and

McCoy, 1979].

Carbon monoxide is also found in volcanic emanations at

Kilauea, Hawaii [Shepherd, 938], at Erta 'Ale, Ethiopia [Gi7-

7enbachnd LeGuern,1976], and at Nyiragongo ava lake in

Africa [Gerlach, 1980a]. Wherever CO is detected n gases

from fumarolesand volcanoes, educing conditionsare indi-

cated by low partial pressures f 02 and by the presence f

other reducedgases, uchas H2, H2S, and CH,, and a deep-

seatedsource s suggested.

Methane and other light hydrocarbons ound in volcanic

gases and tholeiitic basalts from the Mid-Atlantic Ridge

[Pineau et al., 1976] and the East Pacific Rise [Welhan and

Craig7, 979] are enriched n 3C, suggesting thermogenic

and probably deep source.Gold [1979] has proposed hat

somemethane s primordial.

Sulfur gasesdetected n volcanicemanations re SO2 (the

most abundant and most often reported), H2S, 8 2, and COS.

Isotope measurements y $akai et al. [1982] of SO2 from

Kilauea volcano indicated a deep-seated source. Similarly,

sulfur sotopestudiesby Arnoldand $heppard 1981] of sulfide

minerals from the East Pacific Rise indicate that the sulfides

"... are only compatiblewith a dominantlymagmaticsource."

All the halogenshave been found in volcanicgases Ger-

lach, 1980b; Shi7iura t al., 1964; White and Warin7,1963]

and in fluid inclusions Roedder, 1972] with C1 being the most

abundant in both. Evidence that halogen complexesmay be

important in the transport of metals n hydrothermalsolu-

tions [Krauskopf,1979], coupledwith their volatility, suggests

that they may serveas exploration guides f they are released

during weathering.

Primary gasesdetectedat the surfacemay only indicate

mantleoutgassing,ommonlyalong deep-seatedaults; f min-

eral depositsoccur along these aults, he primary gasesmay

be useful n exploration.

SecondaryGases

Secondarygasesare those generatedby the interaction of

rocks and ores with the hydrosphere, atmosphere, or bio-

sphere. Examples of major secondary gas production are

found in the large natural gas fields of the world. Hydro-

carbongases re producedrom complex rganicmatterby

thermal maturation or "cracking" [Waples, 1981]. The re-

quired temperatures (80-200C) are attained when the

organic material is deeply buried by sediments.Petroleum,

formed by the samecatagenicprocess, lso containsgases.

Secondary gasesare also produced by inorganic reactions.

For example, CO2 results from the reaction of acid ground-

waters with calcareousminerals. Acid groundwatersare found

around oxidizing sulfide bodies, and not only is CO2 formed

in such settings,but 02 is consumed Lot)ell et al., 1979, 1983;

Lovell and Hale, 1983; Hale and Moon, 1982] Sulfur gas

speciesare also produced [Hinkle and Kantor, 1978; Hinkle,

1984; Hinkle and Dilbert, 1984; Kesler, 1984]. COS and CS2

are the most abundant sulfur gasesdetected,but H2S and SO2

have also been found (Figure 2).

Hydrogen gas is often detected n field studies.Several n-

vestigatorshave proposed hat a natural electrochemicalpo-

tential exists around an oxidizing sulfide body producing hy-

drogen ions [Bolviken and Lotn, 1975; Govett, 1976; Govett

and Chork, 1977]. McGee et al. [1984] and Sato et al. [1984]

detectedH 2 in areas of seismicand geothermalactivity and

suggestedhat it is generatedby the reaction of ferrous ron

mineralswith water. If H 2 is available, volatile hydridessuch

as AsH3 and SbH 3 may be formed. The widespread oc-

currence of As and Sb minerals in epithermal gold deposits

suggests hat these volatile compounds may be detected over

suchdeposits.

Mercury vapor has also been successfully sed as a geo-

chemical indicator of buried ore deposits [Rose et al., 1979].

Mercury is commonlyenriched n ore minerals [Jonasson nd

Boyle, 1972], particularly sulfides, nd is volatile; hence t may

be a useful pathfinder for such ores [McCarthy, 1972].

Helium is found in high concentrations associated with

various types of energyresources,ncluding uranium deposits,

oil and gas deposits,and hot water geothermal occurrences.

Helium is continuouslyproduced n the earth's crust from the

alpha particles that are emitted by the natural radioactive

decay of uranium and thorium. Where uranium-containing

minerals are concentrated in a deposit, higher helium con-

centrations n the vicinity may be an indicator of the deposit.

Oil and gas are naturally found in some ypes of reservoirsor

traps, and helium is trapped along with other gasesand has

been used as a geochemical ndicator for both oil and gas

[Potorskiand Quirt, 1981; Roberts, 1981].

Migration of Gases

Two processeswhereby gases migrate are diffusion and

mass ransport. Diffusion takes place in any medium, and the

rate is determined by the character of the medium, the size

and molecular weight of the diffusing species, nd the temper-

ature of the gas. Although diffusion is the probable mecha-

nism for slow transport of gasesover short distances, articu-

Fig. 2.

CO2,H2S,SO 2,CS 2

COS

I I.,..? I I i,O2 Consumed

Sulf

SECONDARY GAS EXHALATIONS

Somegases roducedor consumed)roundoxidizing ul-

fide bodies.


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MCCARTHY AND REIMER' SOIL GASES N GEOCHEMICAL XPLORATION 12,329

larly below the water table [Rose et al., 1979], mass ransport

is the only mechanism hat can account for rapid migration

over considerabledistances.Gasesdissolved n a fluid (gas or

liquid) can move through interconnectingspaces n rock or

soil. Faults or fracturesprovide channelways or mass trans-

port of fluid and contained gases. Fault zones have been

mapped by measuring gasesemanating from them [Kasimov

et al., 1978].

Helium is a very light, diffusivegas and can move through

the overlyingrock faster than heaviergases.Because f these

characteristicsnd its inertness,t has beensuccessfulysed n

exploration for energy resources.Hot geothermalwaters fre-

quently contain high concentrations f helium, because hey

are formedat depthwhere he partial pressure f He is greater

and helium is more soluble in hot water than in cold water. As

these waters convectively irculate and cool, the gas is re-

leased.

The detectionof rapid changesn the concentration f gases

and vapors at the surface or in drill holes is compelling evi-

dence for mass transport. McCarthy et al. [1970] measured

mercury vapor at the ground surface over a mercury deposit

in the western United States and found a 20-fold increase in

Hg within 4 hours (Figure 3). The highest concentration of

mercury coincided with the maximum rate of fall of baro-

metric pressure.These nvestigators oncluded hat changes n

barometric pressure exerted a pumping action, much like a

piston, that resulted n rapid releaseof Hg vapor to the atmo-

sphere. Only mass transport of Hg through permeable over-

burden could account for these results.

Tanner [1959] measured radon in drill holes that intersec-

ted a uranium ore deposit in the southwestern United States.

He found an inverse relation between radon in the drill hole

and barometric pressureon a daily basis, and concluded that

changes n barometric pressureexerted a pumping action that

caused an increase or decrease of Rn in the drill hole. He also

stated that "Experimental evidence and theoretical treatment

of the migration of radon have led to the conclusion that

diffusion is not the mechanism whereby large amounts of

radon migrated from uraniferous rock into drill holes"

[Tanner, 1959]. He observed that the ore and enclosing rock

had appreciable permeability and porosity and that, under the

influence of changing barometric pressure, air would move

along paths of greatest permeability and carry the radon with

it.

(.nO


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12,330 MCCARTHYAND REIMER.' OILGASESN GEOCHEMICALXPLORATION

Another means of sampling gases s to degas rock or soil

samples,usuallyby heating n closedcontainers. he desorbed

gases n the head space of the container are then analyzed.

Soils are good natural collectors f gas because lay and

organic constituents f soils stronglyadsorbgases Hinkle,

1984; Hinkle and Dilbert, 1984].

Artificial collectors have also been used to collect gases

rising from below the surface.The collectors re placed n

invertedcupsunder the surfaceof the soil and left for several

days or weeksbefore thay are retrievedand the gas s ana-

lyzed.Hinkle and Kantor [1978] usedartificialzeolites s gas

collectors. R. W. Klusman and K. J. Voorhees [Bisque, 1983]

have developedanother type of gas collector: a thin wire

coated with activated charcoal is buried in a cup 6-12 in

below the surface. After 1-2 weeks the collector is taken to the

laboratory for analysisby massspectrometry. n older, simi-

lar sampling echnique,he track-etch echnique sed o mea-

sure radon, has been successfully pplied to exploration for

uranium and thorium [Gingrich,1984]. In all the gas-sampling

techniqueshat use collectors, he gasesare adsorbedover a

periodof time, hus argelyeliminating iurnalvariationshat

can strongly influence direct gas sampling. Higher con-

centrationsof gasesare commonly found when degassing

rock, soil, or artificial collectors han are found in soil pore

space; hus ess ensitive nalyticalmethodsmightbe used or

the desorbed gas.

Samplingof gases rom aircraft has shownenrichment f

SO2 n air oversulfidedepositsRouse ndStevens, 971] and

of Hg in air over mercuryand porphyry-copper epositsMc-

Carthyet al., 1969].Theseexperimental urveys re suggestive

but provideno adequate asis or assessinghe effectivenessf

airborne sampling.

Norman [1983] analyzedgases n fluid inclusions rom 10

Ag-Au epithermaldeposits nd found that the principal n-

clusiongaseswere nitrated hydrocarbons, 2S, N2, and CO2.

Gases found in inclusions from gold-rich areas contained

> 1% H2S and were rich in CnHnNn,while epithermalde-

posits n volcanic ockswith no Au, Ag, or sulfideminerals

contained no organics or H2S.

Gases found in fluid inclusions from a Mississippi Valley-

type deposit n New Mexico includedCO2, C-C6 hydro-

carbons, nd N 2 [Norman et al., 1985]. Inclusions elated o

sulfide mineralization were rich in H2S.

Hedenquist nd Henley [1985] compared luid inclusionsn

active geothermalsystemswith inclusions n base and pre-

ciousmetal ore deposits. hey concluded hat "epithermalore

depositsorm from hydrothermal ystems nalogouso those

we see active today," and further that, "in any systemwhere

eithersalinityor gascontent s high, a baseor preciousmetal

ore depositmay be formed."

The three above-mentioned studies contribute to an under-

standing f ore-forming rocessesnd fluidsand at least mply

that gasesound n fluid inclusionsmay be useful n explora-

tion. Inclusionswith high gas contentsare more likely to be

associatedwith ore, and measurementof specificgases, uchas

H2S and CO2, and hydrocarbonsan ndicate avorable reas

[Norman, 1983].

ANALYSIS

The gas chromatograph is the most commonly used nstru-

ment for gas analysis. n the past few years, remarkable ad-

vances n instrumentation and gas separation have made pos-

sible extremely sensitive and rapid gas analysis. Another in-

strument commonly used for gas analysis is a mass spec-

trometer. Recent analytical advancesallow us to measure the

trace concentrationsof gases hat emanate from mineral de-

posits; or example,concentrations f H2S and COS over sul-

fide depositsare in the parts per billion range [Hinkle and

Kantor, 1978; Hinkle and Dilbert, 1984].

The average concentration of helium in the atmosphere s

5.240 ppm [Gluckauf, 1946; Oliver et al., 1984], and variations

of less han 1% of this value have been found to be significant

as indicators of energy resources Roberts et al., 1975; G. E.

Goldak, unpublished report, 1974]. Laboratory-based mass

spectrometricanalyseshave the sensitivity o detect such small

variations, but are expensiveand time consuming o perform.

However, small, portable mass spectrometersof the type typi-

cally used for leak detection in vacuum systems,and specifi-

cally designed o detect helium, have been found to provide

adequate sensitivity to analyze low, energy-related con-

centrations [Reimer, 1976; Dyck and Pelchat, 1977; G. E.

Goldak, unpublished report, 1974]. Systems based on the

small mass spectrometerhave been designed o operate in the

field, analyzing a sample within several minutes, with a sensi-

tivity of 20 ppb helium.

The gas analyzer used in many of the studiesreported here

is a quadrupole mass spectrometer nterfaced with a program-

mable calculator (Figure 5). In a quadrupole mass spec-

trometer, ionized gas moleculesare acceleratedalong the axis

between four cylindrical rods. A combined electrostatic and

radiofrequency field imposed by the rods allows only those

ions with a specificmass-to-charge atio to pass through. By

varying the voltages on the rods at a constant rate, ions of

various masses are sequentially scanned and measured. The

analyzer can detect atomic or molecular species anging in

mass from 2 to 300 atomic mass units (amu); however, the

range used n this study was for gas speciesrom 2 to 100 amu.

This range s scanned n about 40 s.

.... . ..-- . ....-:.... ,.,.,...

...... ..... ................... ['3 .....

': .. '.' '.

Fig. 5. Truck-mounted gas analyzer (quadrupole mass mass spec-

tromete0 and programmable calculator. The quadrupole mass spec-

trometer is manuhctured by UTI Corporation of Sunnyvale, Califor-

nia; a model 100 C is interfaced with a Tectronic 31 calculator. The

complete assembly as hbdcated and installed in a field vehicle by

Pernicka Corporation of Fort Collins, Colorado. (Use of brand

names and manuhcturers' nameshere is for descriptivepurposesonly

and doesnot imply endorsementby the U.S. Geological Survey.)


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MCCARTHY NDREIMER: OILGASESN GEOCHEMICALXPLORATION 12,331

The gas analyzer is mounted in a four-wheel drive vehicle,

and power is provided for the instrument by a 160-amp alter-

nator, two 12-V batteries, and a dc-ac converter. About 1100

W of power is neededwhen the instrument is operating. Con-

stant power is provided by running the vehicleengineat about

1200 rpm.

The limit of detection of the mass spectrometer s about 15

ppm for CH4, 0.01% for CO2, and < 1% for 02. Calibration

curves were prepared for CO2 and CH4 using varied con-

centrations of standard gases.A calibration curve was pre-

pared for 02 by successive ilutions of air with N 2. Instru-

ment response s linear, and the reproducibility is + 5%. Ioni-

zation energy is 70 V. A permanent record of relative con-

centration is printed out on paper tape besideeach mass unit.

It takes about 7 min at each site to collect and analyze the soil

gas sample.

Lovell and Hale [1983] used separate nstruments to ana-

lyze soil air for CO2 and 02. These instruments are portable

and provide gas analyses n the field. Lovell and Hale demon-

strated that these two gasesare good indicators of oxidizing

sulfide bodies' hence for detection of this type of deposit the

measurement of other gases s unnecessary.However, other

gasessuch as COS and H2S are also useful guides to sulfide

deposits [Hinkle and Kantor, 1978' Hinkle, 1984' Hinkle and

Dilbert, 1984], and volatile hydrocarbon gases are detected

above oil and gas deposits [Jones and Drozd, 1983]. Thus a

gas analysis acility that is capable of analyzing many gasesat

once (suchas a massspectrometer)s advantageous.

FIELD STUDIES

The use of soil gases n geochemical xploration is indicated

when searching or buried mineral deposits,particularly when

the suspected epositsare coveredby exotic overburdensuch

as glacial till, alluvial sediments, r desert sand. Sampling of

surface soils in these types of transported overburden (and

analysis or ore-related race elements)may not reflect un-

derlyingdeposits.n the examplecited below, a soil sampling

survey and analysis of the soils for several metals did not

reveal the deposit n bedrock (H. Alminas, unpublisheddata,

1984]. However, soil gases an reflect suchdeposits.

An example showing the use of soil gasesover a massive

sulfide deposit in glaciated terrain is illustrated in Figures 6

and 7. The massivesulfide deposit s near the town of Cran-

don in northern Wisconsin [May and Schmidt, 1982-l, in an

area where severalepisodesof glaciation have left as much as

65 m of glacial drift covering he bedrock.The depositoccurs

in metamorphicrocks, s a near-vertical abular body, striking

N85W, and consists of a stratabound massive sulfide zone

and an underlying stringer zone at the suboutcrop contact

with the overlyingglacial deposits.We sampledsoil gas along

several raversesnormal to the strike of the elongate deposit

and well beyond the subcroparea of the deposit.Figure 6a is

a plot of percent CO2 in soil gas on one of these traverses

(G-G'). Sample intervals were 15 m (50 ft) except for a 53-m

gap in the center, where no samples were obtained. Total

length of the traverse s about 360 m (1200 ft). The high CO2

anomaly occurs over and to the north of the deposit. The

highest CO2 concentration s 4% by volume compared with

0.035% in air. The 02 concentration along the same traverse

is shown in Figure 6b. In general, where the CO2 is anoma-

lously high, the 02 is anomalously ow. The lowest 02 con-

centration in the soil gas is only slightly more than half of its

concentration in air. The oxidation of sulfide minerals by

groundwater forms sulfuric acid, which attacks calcareous and

SOUTH

4.0

2.0

G

I i i i i i i i i i i

NORTH

,

i i i i i I I i i i I

Z14

i i i i i i i i i i i

B

i i i i i i i i i i i i

Fig. 6. CO 2 and 0 2 in soil gas along traverseG-G' over the

Crandon massivesulfide deposit, Wisconsin.Tick marks on horizon-

tal axis show samplesites;sampling nterval is 15 m (50 ft), except or

a 53-m (175-ft) gap in the middle, where no sampleswere collected.

Data points on the curvescorrespondwith sample sites tick marks).

Total traverse length is about 360 m (1200 ft). Shaded blocks in

Figure 6a show ocation of ore, and the solid dot indicatesan isolated

lens of sulfide minerals.

other minerals (e.g., CaCO3) and thereby releasesCO2. We

believe that both these anomalies are a result of active oxida-

tion of sulfide minerals where CO2 is being produced and 02

is being consumed.

Carbon dioxide is also produced by decay of organic matter

in the soil, but measurement of gases n similar soils away

from the sulfide deposit shows a background level averaging

less than 0.2% CO2. Because the surface environments are

similar, there is no evidence o suggest hat biological pro-

duction of CO2 would be any different n soils whether over

the deposit or beyond t. The fact that the CO2 concentrations

in soil gas over the deposit are an order of magnitudehigher

than background argues against biological processesas the

mechanism producing the CO2 anomalies.

Another traverse hat crosses he deposit showssimilar pat-

terns for CO2 and 02. A plot of CO2 in soil gas along this


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12,332 MCCARTHY NDREIMER.'OILGASESN GEOCHEMICALXPLORATION

SOUTH

NORTH

1.0

w

.I

.O5

ee

A

200'-' ,''

. I O0

c

traverse (D-D') is shown in Figure 7a. The sample interval is

15 m (50 ft) except for the last five sites, which are separated

by 30-m (100-ft) intervals. The total length of the traverse is

about 450 m (1500 ft). High CO2 anomalies occur over the ore

deposit and over an area to the north where no drill data are

available. A plot of 02 along the same traverse is shown in

Figure 7b. The low 02 anomalies coincide with high CO2

anomalies.One matched pair of low 02, high CO2 anomalies

occursover the ore deposit,and another is over some solated

sulfide enses. igures7a and 7b also illustrate he repro-

ducibility of soil gas measurements n different days. The re-

producibility is reasonably good; although the absolute con-

centrations of gasesare not the same, the pattern is. Other

investigatorshave found similar antithetical CO2 and 02 pat-

terns n soil gases vermineraldepositsLovellet al., 1980,

1983; Lovell and Hale, 1983; Glebovskaya nd Glebovskii,

1960].

Soil gas surveysat this and other deposits have revealed

volatile hydrocarbon gases; hose that have been recognized

are methane, ethane, propane, and butane (and evidence or

others exists). Other investigators [Carter and Cazalet, 1984]

have found hydrocarbon gases in rocks and used them as

pathfinders n mineral exploration.Figure 7c showsplots for

methane (CH4) along the same traverse shown in Figures 7a

and 7b. Although the background-to-anomaly atio is only

about 1:2, one of the anomalies occurs over the ore deposit

and another is to the north, coinciding with the CO2 and 02

anomalies.The relationshipof hydrocarbon gasesand mineral

depositswill be discussedurther.

Plots for CO2 in soil gas are shown in Figure 8 along a

traversecrossingover three roll-front uranium deposits n the

Powder River Basin, Wyoming. The sample nterval was 75 m

(250 ft), and the length of the traverse is 1.6 km (1 mi). High

CO2 anomaliesoccur over the depositsand extend to the

north. The sandstones hat host the depositsdip gently to the

north, and groundwater flow is also to the north. The ground-

water may have been responsible or the northerly displace-

ment of the CO2 soil gas anomalies. The traverse was run

1.6

SOUTH NORTH

Fig. 7. CO2, 02, and CH in soil gas along traverseD-D' over the

Crandon massivesulfide deposit, Wisconsin.Tick marks on horizon-

tal axis showsamplesites;samplingnterval s 15 m (50 ft) exceptat

the far right, where it is 30 m (100 ft). Data points on the curves

correspondwith sample sites (tick marks). Total traverse ength is

about 450 m (1500 ft). Shadedblocks n Figure 7a show ocation of

ore, and solid dots indicate isolated lenses of sulfide minerals. Solid

and dashed ines representsampling and analysison two separate

days.

Fig. 8. CO 2 in soil gas along a traversecrossing hree roll-front

uranium depositsn the Powder River Basin,Wyoming.Tick marks

on horizontal axis show samplesites;sampling nterval is 75 m (250

ft), and total traverse ength s 1.6 km (1 mi). Solid dots show ocation

of depositsalong the traverse,and numbers n parenthesesndicate

depth to deposits n feet. Solid line shows esultsof sampling rom

south to north in the morning; dashed ine reflectssampling rom

north to south in the afternoon. The consistent offset between the two

measurementss due to an analytical law (see ext).


7/12

MCCARTHY AND REIMER'SOIL GASESN GEOCHEMICAL XPLORATION 12,333

43 37 30"

43o30

10407 30"

DEWEY

3.54 TERRACE

10400'

s

JPs

JPs

Cheyenne

QKs

I

JPs

103 52 30" EXPLANATION

.i"'l edimentarcksf uatern

o Early Cretaceous age

InyanKaraGroupf Early

Cretaceous age

j-- Sedimentaryocks f Jurassico

..' Permian age

Contact

Fault u-Upthrown side

d d-Downthrownide

Dashed where projected

// Isogramhowingissolved elium

z/% contentfgroundwater.Contour

nterval is lx10 -b cm He/cm H?O

(In vicinity of LongMountain

structural one, onto_unterval

s25x10-6 m He/cm H20)

lsogram dashed where infered

X Uranium deposit -Includes some

( undevelopedrospects

Location of sample and dissolved

lm.8 helium ontent

10345,

? 43 30'

4322 30"

QKs x 6

13

Approximate Mean

Declination 1974

o

I I I i I KM

Fig. 9.

QKs

QKs

4315'

103o45

Dissolved eliumdistribution n groundwater f the nyan Kara Group of the southernBlackHills.

toward the north in the morning (solid line) and toward the

south in the afternoon (dashed ine). The nearly perfect offset

of the plots from each other led us to suspecta flaw in the

analytical procedure. We discovered hat we had a "memory

effect" from the previous sample; some of the gas from the

previous sampleremained n the inlet systemof the gas ana-

lyzer and contributed to the next measurement.We have since

corrected this source of error by thoroughly flushing the inlet

systemwith air between each sample.

RADON AND HELIUM

Helium and radon are members of the radioactive disinte-

gration seriesof uranium and thorium. They are inert gaseous

molecules' radon is the immediate progeny of radium, and is

itself radioactive. Radon-222, with a half-life of 3.8 days is

derived from the U-238 series and is the isotope most com-

monly used in exploration or uranium. Helium is formed

from the alpha particlesemitted during the decaysequences.

Both helium and radon have been used to explore for oil,

naturalgas,and geothermal nergy nd have beenused n

experimentso predict volcaniceruptionsand earthquakeac-

tivity.

Informativeeviews nd casehistories f radonusehave

been publishedairly recently, s the technique ained e-

newed interest from the energy-related esearchof the 1970's

[Tanner,1978;Rubin, 978;Soonawaland Telford, 980;

Kraner et al., 1964]. The use of helium in exploration is a

recentdevelopment,and casehistoriesare few but informative

[Reimer et al., 1970; Dyck, 1976; Butt and Gole, 1984].


8/12

12,334 MCCARTHY AND REIMER' SOIL GASES N GEOCHEMICAL XPLORATION

43 7' 0"040730"

DEWEY

TERRACE

4330

cheterme

" I

QKs

I

10400'

JPs

10352' 30"

...-

...

EXPLANATION

Sedimentaryocks f Quaternary

to Early Cretaceous age

Inyan ara roupf Early

Cretaceous age

j Sedimentaryocks f Jurassico

Permian age

Contact

Fault u-Upthrown side

d d-Downthrownide

Dashed where projected

Line showing dissolved radon

content of ground water. Dashed

where inferred

Hachures indicate closed low

value Contour interval = 10,50p

curies/liter H20

X Uranium deposit -Includes some

undevelopedrospects

Location of sample and dissolved

1%8 Radonontent

10345 ,

43o30

...

43 22' 30"

13

Approximate Mean

Declination 1974

5 KM

I

4315'1

104 00'

QKs

QKs

QKs

4315

10345'

,

Fig. 10. Dissolved adon distribution n groundwaterof the Inyan Kara group of the southernBlack Hills.

The migrationand measurementf heliumand radonhave mationon the flow rate andmixingof water rom he recharge

been the subject of much debate. The magnitude of external areas.

effects uchas hydrologycontrollingplacement nd meteorol- Formations roppingout o,ermost of the studyareaare, n

ogy controlling oncentration radientss quitevariable.Also, ascending rder, the Skull Creek Shaleand Mowry Shaleof

structuresuchas fractures,oints, and faultsplay a major part Early Cretaceousage and the Belle Fourche Shale of Late

in determining he local concentration f radon. Cretaceous ge.The formations ange n thicknessrom 45 to

Although many studiesdiscusshe useof helium and radon 75, 40 to 53, and 56 to 130 m, respectively. he Inyan Kara

separately, greater interpretative capabilities are achieved Group, which contains he uranium depositsof the Edgemont

when combinedwith other techniques. n exampleof the con- district, ies immediatelybelow the Skull Creek Shale Figure

juctive use of Rn and He is provided by the following field 9).

study.Radon and helium analyseswere performedon ground- Within the buried sedimeltary ection, he PahasapaLime-

water samples ollected n the EdgemontUranium District in stone of Mississippian ge and the Minnelusa Formation of

the Black Hills of Wyoming and South Dakota [Bowleset al., Permian and Pennsylvanian gehave a significant ut indirect

1980]. Previous studies had yielded information on the role in the formation of the uranium deposits Bowles and

groundwater chemistry, and tritium data provided infor- Braddock, 1963; Bowles, 1968]. Breccia pipes that bottom


9/12

MCCARTHYNDREIMER:OILGASESN GEOCHEMICALXPLORATION 12,335

within the upper anhydritic part of the Minnelusa Formation

are major conduits for artesian recharge of the Inyan Kara

Group at the margin of the Black Hills.

Uranium deposits n the Edgemont Uranium District are

presentboth above and below the water table (Figure 9). De-

posits lie above the water table at the outcrop of the Inyan

Kara Group on the hogback east of the study area.

Drilling has reportedly encountered economic deposits of

reduced uranium lying below the water table within the study

area southeastof Dewey (Figure 9).

Uranium is introduced into the Inyan Kara Group rocks

with the artesian recharge of calcium-magnesium sulfate

water, but during the middle to late Tertiary, significant

amounts of uranium probably were also introduced by down-

ward percolating meteoroic waters that leached overlying tuf-

faceous sandstones and mudstones of Oligocene age. As

groundwater migrates downdip within the Inyan Kara, it is

modified by ion exchange and sulfate reduction to either a

sodium sulfate or a sodium bicarbonate type water, and redox

potentials decrease correspondingly. Reduction of sulfate in

the groundwater has been a major factor in creating a favor-

able environment for the precipitation of uranium. The deple-

tion of dissolveduranium from the reducing groundwater has

prevented the detection of uranium depositsby an analysis of

uranium in solution. However, helium and radon generatedby

uranium depositscan be readily detected n reducing ground-

waters.

Water sampleswere collected,and the gas in the headspace

was analyzed for radon and helium. Dissolved helium in the

groundwater samples rom the Inyan Kara ranges from 0.22

x 10 6 to >130 x 10 6 cm3 He/cm3 H20. Low con-

centrationsof dissolvedhelium ( 130 x 10 6 cm3 He/cm3

H20 ) occurred n the Long Mountain structural zone.

Dissolved radon in the groundwater from the Inyan Kara

Group ranges from 1 to 167 pCi/L (Figure 10). The general

distribution pattern for dissolved adon (Figure 10) is the op-

posite of that for dissolvedhelium. For the most part, dis-

solved radon decreases owndip, ranging from as much as 53

pCi/L near the Inyan Kara outcrop to as little at 1 pCi/L west

of the CheyenneRiver. The largestconcentrationsof dissolved

radon (167 and 151 pCi/L)occur in the Dewey structural

zone.

Helium generated n rocks of pre-Cretaceousage is appar-

ently introduced nto the Inyan Kara Group within the artes-

ian water from the Minnelusa Formation. Control samplesof

ascendingMinnelusa waters collected outside the study area

yielded dissolved helium and dissolved radon in con-

centrationsranging from 0.09 x 10 6 to 200 x 10 6 cm3

He/cm3 H20 and from 16 to 23 pCi/L, respectively. he high-

est dissolved helium was found in the water from Evans

Plunge, where 4.0% helium has been detected n the free gases.

A high rate of groundwater low in the Burdock area appar-

ently is responsible for the absence of anomalous con-

centrations of dissolved helium, which would be expected

downflow from a uranium deposit reported to be of commer-

cial size and grade. A strong artesian recharge occurs near the

Inyan Kara outcrop, and then the groundwater flows ex-

tremely rapidly downdip toward the confluence of the

Cheyenne River and Beaver Creek, where much of the water

apparently leaks upward and discharges into the surface

drainage. The westward flow rate was calculated from the

tritium data to be as much as 1 mi/yr. (14.4 m/d) [Gott et al.,

1974]. Low dissolvedhelium concentrations n the ground-

water extend far downdip within the area outlined by the

tongue of tritiated water. It is concluded that the high flow

rate allows the groundwater only a very short residence ime

within the mineralized ock; that is, this time span s not long

enough for the generation and accumulation of anomalous

concentrations of dissolved helium before the groundwater

flows out of the mineralized ground. Farther downdip within

and near the Long Mountain structural zone, anomalous con-

centrationsof dissolvedhelium (130 x 10 6 and 85 x 10 6

cm3 He/cm3 H20 ) providea favorable eochemicalarget or

uranium exploration. The absenceof high dissolved adon in

the anomalous helium samples ndicates hat the postulated

uranium depositsare not penetratedby the wells that yield the

anomalous concentrations of helium, but the site of helium

generation must lie updip toward the area of artesian re-

charge.

In summary, the dissolvedhelium detection technique may

be more difficult to apply to uranium exploration in areas of

very rapid groundwater flow, because nsufficient time exists

for the accumulation of anomalous concentrations of dis-

solved helium as the groundwater pases through a uranium

deposit.

However, the analysis of dissolved radon and helium in

groundwater complements other hydrochemical exploration

techniques used in the search for uranium. Anomalous con-

centrations of helium in reducing groundwaters in the study

area provided an exploration target, whereas analysesof dis-

solved uranium during earlier investigationsyielded no indica-

tion of a uranium deposit.

HYDROCARBONS ASSOCIATED WITH MINERAL DEPOSITS

As shown in Figure 7c, methane was found in soil gas over

the Crandon massive sulfide deposit. We have also found

methane and other light hydrocarbons in soil gas over

porphyry copper deposits, disseminated gold deposits, and

other types of deposits.Methane is the most abundant hydro-

carbon in all these cases. Its occurrence can be accounted for

by bacteriogenic production under anoxic conditions, as in

bogs or swamps.Enhalt 1-1974]has estimated that 80% of the

methane in the atmosphere s of recent biologic origin based

on measurement f 'C. However, the higher hydrocarbons

(C2 +) are not ordinarily produced by bacteria. At least some

of the light hydrocarbons ound around mineral depositsmay

be produced by catagenesis,he same processwhereby oil and

gas are produced from kerogen. It is generally agreed [Hunt,

1979] that oil and gas are produced by thermal maturation of

complex organic matter (kerogen). The temperatures required

are about 80 to 200C; petroleum geologists refer to this

temperature range as the "oil window" [Waples, 1981]; that

is, the optimum temperature range for the production of oil.

At higher temperatures he oil degrades,and methane gas is

the dominant product. In many cases, he temperatures at-

tained by hydrothermal systemsemplacing mineral deposits

are more than sufficient to "crack" organic matter in sur-

rounding rocks, producing methane and other light hydro-

carbons.

An example that illustrates this concept is found in the

work of Simoneitet al. [1979] in the Guaymas basin, Gulf of


10/12

12,336 MCCARTHY AND REIMER: SOIL GASES N GEOCHEMICAL XPLORATION

California. Core samplesof organic-rich sedimentswere found

to have a strong petroliferousodor and when analyzed were

found to contain high concentrations f gasoline-range ydro-

carbons (C2-C8). These investigatorsconcluded hat the high

geothermal gradient in the basin resulted in thermal matura-

tion of organic matter in the sediment.At another nearby site,

gasoline-rangehydrocarbons were formed by thermal stress

from sills and/or dikes that intruded the sediments Simoneit

et al., 1979]. Rashid and McAlary [1977] also reported that

organic matter in Cretaceous sediments on the Scotian Shelf

thermally matured as a result of heat from a shallow salt

dome, producing gaseoushydrocarbons.

OIL AND GAS EXPLORATION

Measurement of hydrocarbon gases s increasingly being

used in the search for oil and natural gas fields. Two recent

reviews llustrate the useof gases n exploration or oil and gas

and give casehistories [Jones and Drozd, 1983; Horvitz, 1985].

Development of sensitivegas chromatographswith flame ioni-

zation detectors that rapidly measure hydrocarbons in the

parts per billion range has made geochemicalexploration sur-

veys for oil and gas routine [Mclver, 1984; Philp and Crisp,

1982]. By measuring gas compositions and ratios of light

hydrocarbons--methane, ethane, propane, and butane--one

can predict whether oil or gas is more likely to be discovered

in the subsurface Jonesand Drozd, 1983]. The higher paraffin

homologs that are thermogenically produced are associated

with petroleum reservoirs,whereas a predominance of meth-

ane may indicate a natural gas reservoir.

Methane alone can be misleading,as it is produced by bac-

teria in the near-surfaceenvironment. However, ratios of C

/C2 + C3 can be used to distinguish thermogenic from bac-

teriogenic gas. Carbon isotopes are also used to elucidate the

origin of gases, s biogenicmethane s highlydeplectedn 3C.

The origin of a gas can be establishdby plotting the ratio

C1/C 2 -[- C 3 againstx3C Waples,1981].

In addition to representingseepageof hydrocarbon gases

from buried reservoirs, ight hydrocarbonsmay form zoning

patterns around and over petroleum and mineral deposits

[Herbert, 1984]. When light hydrocarbons diffuse from a

source, the l ightest (methane) will diffuse farther and more

rapidly than the higher homologs and will form haloes. Thus

careful measurementof these hydrocarbonsmay indicate the

direction of the source. These haloes can be comparedwith

trace element zoning patterns found around mineral deposits

[Rose et al., 1979].) Hydrocarbon gasesextracted rom rocks

have been found to correlate with mineral deposits n Ireland

[Carter and Cazalet, 1984]. These nvestigators ound that the

ratio of methane to heavier hydrocarbons s unusually high

around mineral deposits and that methane haloes extend for

many kilometers.

DISCUSSION AND CONCLUSIONS

Gases measured at or near the surface can delineate buried

mineral deposits,even through thick overburden.Sulfur gases,

CO2, and O2 can indicate oxidizing sulfide deposits.Hydro-

carbon gasesand helium have been successfully sed in the

search for petroleum and natural gas. Radon and helium gas

anomalies have led to the discoveryof uranium and thorium

deposits. Laboratory studies are revealing which gases are

given off by minerals n simulatedweatheringconditions.Both

field and laboratory studies are increasing our knowledge of

gaseousemanations and our confidence n their use for ex-

ploration. Gases can indicate buried depositswhere other geo-

chemical sampling media fail, and this is particularly true for

those depositscovered by exotic overburden.As with any ex-

ploration technique, analysis of gaseswill be most useful when

used in conjunction with other tecnhiques. For example,

where geophysical methods indicate a buried electrical con-

ductor that may or may not be a mineral deposit, gas

measurementsmay resolve he question.

The use of soil gases n exploration, however, is not without

pitfalls. As Peachey et al. [1985, p. 201] points out, "...al-

though orebodies could sometimes be detected clearly, in

some nstances he data were more equivocaland in others he

techniques failed." These investigators found that gases are

occluded n wet ground or in areas of impeded drainage. Ball

et al. [1985, p. 181] concluded rom their studies hat "soil gas

methods are least successfulor deeply buried orebodies or

where the concentationof sulphideminerals in the deposit s

similar to that in the host rock."

Gas measurementsseem to pose greater problems in wet

environments.Some ndicator gases hat are highly soluble n

water (H2S SO2, CO2) dissolve to form nonvolatile ionic or

molecular species.And as Rose et al. [1979, p. 499] note, only

a small fraction of these gases"would be likely to escape n

the vapor phase from an environment containing abundant

water." Despite this, CO2 anomalies in soil gas have been

found over a massivesulfidedeposit n wet terrain [McCarthy

et al., 1986].

Meteorological variations affect the migration and con-

centration of soil gases, particularly in the near surface.

Reimer [1979] found that the concentration of helium in soil

gas was affectedby wind speed,precipitation, and atmospheric

pumping, but at sampling depths below 1 m, theseeffectswere

minimal. The concentration of mercury vapor measuredat the

ground surfacewas found to change markedly throughout the

day as a result of changes n barometric pressure [McCarthy

et al., 1970]. McCarthy et al. [1986] also concluded that

meteorological changeshave little effect when soil gas is sam-

pled at depths of 0.5 m or greater.

Gaseshave applicationsother than helping to locate energy

resources.Gas distribution is frequently controlled by geologic

structure such as faults or joints. Variations in the gas flux

from deep faults may prove to be reliable precursors or the

prediction of earthquakes or volcanic eruptions [Reimer,

1981; Friedman and Reimer, 1986].

Increasingly sensitive and rapid analytical instruments

allow us to measuremany hitherto untestedgases hat may be

significant n geochemical xploration for many different types

of mineral deposits. We believe that gas geochemistrywill

contribute to the discovery of mineral deposits in the vast

covered areas of the earth.

REFERENCES

Agricola,G., De Re Metallica, Froben, Basel,1556. Translated rom

Latin by H. C. Hooverand L. H. Hoover,Dover, New York, 1950).

Arias, J., J. Lovell, and M. Hale, Development nd applicationof

vapour geochemistry echniques o minerals exploration in over-

burdencovered reasof northernChile, Rev. Geol.Chile,16, 23-80,

1982.

Arnold, M., and S. M. F. Sheppard,East Pacific Rise at latitude

21N: Isotopic compositionand origin of the hydrothermal sul-

phur, Earth Planet. Sci. Lett., 56, 148-156, 1981.

Ball, T. K., R. A. Nicholson, nd D. Peachey,Gas geochemistrys an

aid to detection of buried mineral deposits, Trans. Inst. Min.

Metall. Sect. B, 94, 181-188, 1985.

Barnes,., and G. A. McCoy, Possibleole of mantle-derived O2 in

causing wo "phreatic"explosionsn Alaska, Geology,7, 434-435,

1979.

Bisque,R. E., New geochemical echniqueused n the Denver Basin,

West. Oil Rep., 40, 23-26, 1983.

Bolviken, B., and O. Logn, An electrochemicalmodel for element


11/12

MCCARTHYNDREIMER:OIL ASESN GEOCHEMICALXPLORATION 12,337

distribution around sulphide bodies, in GeochemicalExploration

1974, edited by I. L. Elliott and W. K. Fletcher, pp. 631-648, Else-

vier, New York, 1975.

Bowles, C. G., Theory of uranium deposition from artesian water in

the Edgemont District, southern Black Hills, Black Hills Area,

South Dakota, Montana, Wyoming, Guideb. Wyo. Geol. Assoc.

Annu. Field Conf.,20, 125-130, 1968.

Bowles, C. G., and W. A. Braddock, Solution breccias of the Minnel-

usa Formation in the Black Hills, South Dakota and Wyoming,

Short Papers in Geology and Hydrology, U.S. Geol. Surv. Prof.

Pap. 475-C, C91-C95, 1963.

Bowles, C. G., G. M. Reimer, J. M. Been, and D. G. Murrey, Helium

investigations n the Edgemont uranium district, southern Black

Hills, South Dakota and Wyoming, U.S. Geol. Surv. Open File Rep.

80-1077, 27 pp., 1980.

Butt, C. R. M., and M. J. Gole, Helium determination in mineral

exploration, Rep. NERDDP/EG/84/271, 351 pp., Dep. of Resourc.

and Energy, Canberra, Australia, 1984.

Carter, J. S., and P. C. D. Cazalet, Hydrocarbon gases n rocks as

pathfinders or mineral exploration, Prospecting n Areas of Glaci-

ated Terrain 1984, Trans. Inst. Min. Metall. Sect. B, 93, 11-20,

1984.

Craig, H., and J. E. Lupton, Primordial neon, helium, and hydrogen

in oceanic basalts, Earth Planet. Sci. Lett., 31, 369-385, 1976.

Craig, H., W. B. Clarke,and M. A. Beg,Excess He in deepwater on

the East Pacific Rise, Earth Planet. Sci. Lett., 26, 125-132, 1975.

Dyck, W., The use of helium in mineral exploration, J. Geochem.

Explor., 5, 3-20, 1976.

Dyck, W., and J. C. Pelchat, A semi-portablehelium analysis acility,

Report of Activities, Part C, Geol. Surv. Can. Pap. 77-1C, 85-87,

1977.

Dymond, J., and L. Hogan, Noble gas abundancepatterns in deep-

sea basalts--Primordial gases rom the mantle, Earth Planet. Sci.

Lett., 20, 131-139, 1973.

Enhalt, D. H., The atmospheric cycle of methane, Tellus, 26, 58-70,

1974.

Friedman, I., and G. M. Reimer, Helium at Kilauea, U.S. Geol. Surv.

Prof. Pap. 1350, in press,1986.

Gerlach, T. M., Chemical characteristicsof the volcanic gases from

Nyiragongo lava lake and the generation of CH,-rich fluid in-

clusions in alkaline rocks, J. Volcanol. Geotherm. Res., 8, 177-189,

1980a.

Gerlach, T. M., Evaluation of volcanic gas analyses rom Kilauea

Volcano, J. Volcanol. Geotherm.Res., 7, 295-317, 1980b.

Giggenbach, W. F., and F. LeGuern, The chemistry of magmatic

gases from Erta'Ale, Ethiopia, Geochim. Cosmochim. Acta, 40,

25-30, 1976.

Gingrich, J. E., Radon as a geochemical xploration tool, J. Geochem.

Explor., 21, 19-39, 1984.

Glebovskaya, V. S., and S.S. Glebovskii, The possibility of appli-

cation of gas surveys n prospecting for sulfide deposits, Transl.

603, Geol. Surv. of Can., Ottawa, 1960.

Gluckauf, E., A microanalysisof the helium and neon contents of air,

Proc. R. Soc. London, 185, 89-98, 1946.

Gold, T., Terrestrial sourcesof carbon and earthquake outgassing,J.

Pet. Geol., (3), 3-19, 1979.

Gott, G. B., D. E. Wollcott, and C. G. Bowles, Stratigraphy of the

Inyan Kara Group and localization of uranium deposits,southern

Black Hills, South Dakota and Wyoming, U.S. Geol. Surv. Prof.

Pap. 763, 1974.

Govett, G. J. S., Detection of deeply buried and blind sulfide deposits

by measurementf H and conductivity f closely paced urface

soil samples, . Geochem. xplor., 6(3), 359-382, 1976.

Govett, G. J. S., and C. Y. Chork, Detectionof deeplyburied sulphide

depositsby measurement f organiccarbon, hydrogen on, and

conductancen surfacesoils, Prospectingn Areas of Glaciated

Terrain 1977, Trans. Inst. Min. Metall., 49-55, 1977.

Greenland, L. P., W. I. Rose, and J. B. Stokes, An estimate of gas

emissions amd magmatic gas content from Kilauea volcano, Ge-

ochim. Cosmochim.Acta, 49, 125-129, 1985.

Hale, M., and C. J. Moon, Geochemical expressionsat surface of

mineralization concealedbeneath glacial till at Keel, Eire, in Pro-

specting n Areas of Glaciated Terrain 1982, edited by P. H. Daven-

port, pp. 228-239, Canadian Institute of Mining and Metallurgy,

Montreal, 1982.

Hedenquist, J. W., and R. W. Henley, The importance of CO2 on

freezing point measurementsof fluid inclusions: Evidence from

active geothermalsystems nd implications or epithermal ore dep-

osition, Econ. Geol., 80, 1379-1406, 1985.

Herbert, S., Irish ideas improve mineral reconnaissance,Min. Mag.,

150, 50-54, 1984.

Hinkle, M. E., Volatile constituents of soils and soil gases over the

sulfide deposits at Johnson Camp, Arizona, U.S.A., paper presented

at the 1984 International Chemical Congress of Pacific Basin So-

cieties, Honolulu, Hawaii, Dec. 16-21, 1984.

Hinkle, M. E., and G. A. Dilbert, Gases and trace elements in soils at

the North Silver Bell deposit, Pima County, Arizona, J. Geochem.

Explor., 20, 323-336, 1984.

Hinkle, M. E., and J. A. Kantor, Collectionand analysisof soil gases

emanating rom buried sulfidemineralization,JohnsonCamp area,

CochiseCounty, Arizona, J. Geochem. xplor., 9, 209-216, 1978.

Horvitz, L., Geochemical exploration for petroleum, Science, 229,

821-827, 1985.

Howard, B., A. Mesereau, and P. Mariani, Analysis of gas samples

from Mount St. Helens, Am. Lab., 117-118, 1980.

Hunt, J. M., Petroleum Geochemistry nd Geology,W. H. Freeman,

San Francisco, Calif., 1979.

Jonasson, . R., and R. W. Boyle, Geochemistry of mercury and ori-

gins of natural contamination of the environment, Can. Min.

Metall. Bull., 65, 32-39, 1972.

Jones,V. T., and R. J. Drozd, Predictions of oil or gas potential by

near-surfacegeochemistry,Bull. Am. Assoc.Pet. Geol., 67, 932-952,

1983.

Kasimov, N. S., M. I. Kovin, Y. V. Proskuryakov, and N. A.

Shmel'kova,Geochemistryof the soilsof fault zones exemplifiedby

Kazakhstan), Soy. Soil Sci., 11, 397-406, 1978.

Kesler, S. E., Soil and fluid inclusiongas analysis n mineral explora-

tion, paper presentedat the 1984 International Chemical Congress

of Pacific Basin Societies,Honolulu, Hawaii, Dec. 16-21, 1984.

Kraner, H. W., G. L. Schroeder, R. D. Evans, Measurements of the

effects of atmospheric variables on Radon-222 flux and soil gas

concentrations,n The Natural RadiationEnvironment, dited by J.

A. S. Adams and W. M. Lowder, p. 191, University of Chicago

Press,Chicago, ll., 1964.

Krauskopf, K. B., Introduction to Geochemistry,McGraw Hill, New

York, 1979.

Kristiansson, K., and L. Malmquist, A new model mechanism or the

transportation of radon through the ground, paper presented at

50th Annual International Meeting, Soc. of Explor. Geophys.,Hou-

ston, Tex., Nov. 16-20, 1980.

Kvenvolden, K. A., and G. E. Claypool, Origin of gasoline-range

hydrocarbons and their migration by solution in carbon dioxide in

Norton Basin, Alaska, Bull. Am. Assoc.Pet. Geol.,64(7), 1078-1086,

1980.

Leythaeuser, D., R. G. Schaefer, and A. Yuk er, Role of diffusion in

primary migration of hydrocarbons, Bull. Am. Assoc.Pet. Geol., 66,

408-429, 1982.

Leythaeuser, D., R. G. Schaefer,and H. Pooch, Diffusion of light

hydrocarbons in subsurfacesedimentary rocks, Bull. Am. Assoc.

Pet. Geol., 67, 889-895, 1983.

Lovell, J. S, and M. Hale, Application of soil-air carbon dioxide and

oxygen measurements to mineral exploration, Trans. Inst. Min.

Metall. Sect. B, 92, 28-32, 1983.

Lovell, J. S., M. Hale, and J. S. Webb, Soil air disequilibriaas a guide

to concealedmineralization at Keel, Eire, Prospecting n Areas of

Glaciated Terrain 1979, Trans. Inst. Min. Metall. Sect. B, 45-50,

1979.

Lovell, J. S., M. Hale, and J. S. Webb, Vapour geochemistry n min-

eral exploration, Min. Mag., 143, 229-239, 1980.

Lovell, J. S., M. Hale, and J. S. Webb, Soil air carbon dioxide and

oxygen measurementsas a guide to concealed mineralization in

semi-arid and arid regions,J. Geochem. xplor., 19, 305-317, 1983.

Lupton, J. E., and H. Craig, ExcessHe 3 in oceanicbasalts--Evidence

for terrestrial primordial helium, Earth Planet. Sci. Lett., 26, 133-

139, 1975.

Lupton, J. E., and H. Craig, A major helium-3 source at 15Son the

East Pacific Rise, Science,214, 13-18, 1981.

May, E. R., and P. G. Schmidt, The discovery,geology, and mineral-

ogy of the Crandon Precambrian massive sulfide deposit, Wiscon-

sin, Precambrian Sulfide Deposits, H. S. Robinson Mem. Vol., Spec.

Pap. Geol. Assoc.Can., 25, 446-480, 1982.

McCarthy, J. H., Jr., Mercury vapor and other volatile components n

the air as guides to ore deposits,J. Geochem.Explor., 1, 143-162,

1972.

McCarthy, J. H., Jr., W. W. Vaughn, R. E. Learned, and J. L.

Meuschke, Mercury in soil gas and air--A potential tool in mineral

exploration, U.S. Geol. Surv. Circ. 609, 1-16, 1969.

McCarthy, J. H., Jr., J. L. Meuschke, W. H. Ficklin, and R. E.


12/12

12,338 MCCARTHY AND REIMER:SOIL GASESN GEOCHEMICAL XPLORATION

Learned, Mercury in the atmosphere, Mercury in the Environment,

U.S. Geol. Surv. Profi Pap., 713, 37-39, 1970.

McCarthy, J. H., Jr., R. N. Lambe, and J. A. Dietrich, A casestudy of

soil gases as an exploration guide in glaciated terrain--Crandon

massivesulfidedeposit,Wisconsin,Econ. Geol.,81, 408-420, 1986.

McGee, K. A., A. J. Sutton, and M. Sato, Observationsof hydrogen

gas eventsprior to volcanic seismicity,paper presentedat the 1984

International Chemical Congressof Pacific Basin Societies,Hono-

lulu, Hawaii, Dec. 16-21, 1984.

McIver, R. D., Near-surface hydrocarbon surveys n oil and gas ex-

ploration, Oil Gas d., 82, 115-117, 1984.

Norman, D. I., Gases n epithermal Ag-Au ore fluids (abstract), GSA

Abstr. Programs, 15, 654, 1983.

Norman, D. I., T. Wupoa, B. R. Putnam III, and R. W. Smith, Missis-

sippi Valley-type deposit, New Mexico: Insight from composition

of gases n fluid inclusions,Can. Mineral., 23, 353-368, 1985.

Oliver, B. M., J. G. Bradley, and H. Farrar IV, Helium concentration

in the earth's lower atmosphere, Geochim. Cosmochim.Acta, 48,

1759-1768, 1984.

Peachey, D., R. A. Nicholson, and T. K. Ball, Discussion on use of

carbon dioxide and oxygen n soil gases o detect hidden orebodies,

Trans. Inst. Min. Metall. Sect. B, 94, 201-203, 1985.

Philp, R. P., and P. T. Crisp, Surfacegeochemicalmethodsused for

oil and gas prospecting--A review, d. Geochem.Explor., 17, 1-34,

1982.

Pineau, F., M. Javoy,and Y. Bottinga,C3/C2 ratios of rocks and

inclusions n popping rocks of the mid-Atlantic ridge and their

bearing on the problem of isotopic composition of deep-seated

carbon, Earth Planet. Sci. Lett., 29, 413-421, 1976.

Pogorski,L. A., and G. S. Quirt, Helium emanometry n exploring or

hydrocarbons,1, in UnconventionalMethods in Exploration or Pe-

troleum and Natural Gas, edited by B. M. Gottleib, pp. 124-135,

SMU Press, Dallas, Tex., 1981.

Rashid, M. A., and J. D. McAlary, Early maturation of organic

matter and genesis of hydrocarbons as a result of heat from a

shallow piercement salt dome, d. Geochem.Explor., 8, 549-570,

1977.

Reimer, G. M., Design and assemblyof a portable helium detector for

evaluation as a uranium exploration instrument, U.S. Geol. Surv.

Open File Rep. 76-398, 18, 1976.

Reimer, G. M., The use of soil gas helium concentrations or earth-

quake prediction: Studies of factors causingdiurnal variation, U.S.

Geol. Surv. OpenFile Rep. 79-1623, 68, 1979.

Reimer, G. M., Helium soil-gasvariations associatedwith recent cen-

tral California earthquakes: Precursor or coincidence?,Geophys.

Res. Lett., 8, 433-435, 1981.

Reimer, G. M., and C. G. Bowles, Soil gas helium concentrations n

the vicinity of a uranium deposit,Red Desert, Wyoming, U.S. Geol.

Surv. Open File Rep. 79-975, 1979.

Reimer, G. M., and J. K. Otton, Helium in soil gas and well water in

the vicinity of a uranium deposit, Weld County, Colorado, U.S.

Geol. Surv. Open File Rep. 76-699, 1976.

Reimer, G. M., E. H. Denton, I. Friedman, and J. K. Otton, Recent

developments n uranium exploration using the U.S. Geological

Survey's mobile helium detector, d. Geochem.Explor., 11, 1-12,

1979.

Roberts, A. A., Helium emanometry n exploring or hydrocarbons, ,

in UnconventionalMethods in Exploration or Petroleumand Natu-

ral Gas, edited by B. M. Gottleib, pp. 136-149, SMU Press,Dallas,

Tex., 1981.

Roberts, A. A., I. Friedman, T. J. Donovan, and E. H. Denton,

Helium survey, A possible echnique or locating geothermal reser-

voirs, Geophys.Res. Lett., 2, 209-210, 1975.

Roedder, E., Composition of fluid inclusions, U.S. Geol. Surv. Profi

Pap. 440-rid, 1972.

Rose, A. W., H. E. Hawkes, and J. S. Webb, Geochemistry n Mineral

Exploration, 657 pp., Academic, New York, 1979.

Rouse, G. E., and D. N. Stevens, The use of sulfur dioxide gas geo-

chemistry n the detection of sulfide deposits abstract), Min. Eng.,

22, 65, 1971.

Rubin, R. M., Literature survey on radon distributions in soil and air,

Rep. GJBX-110-80, 63 pp., U.S. Dep. of Energy, Grand Junction,

Colo., 1978.

Sakai, H., T. J. Casadevall, and J. G. Moore, Chemistry and isotope

ratios of sulfur in basalts and volcanic gasesat Kilauea Volcano,

Hawaii, Geochim.Cosmochim.Acta, 46, 729-738, 1982.

Sato, M., K. A. McGee, and A. J. Sutton, Anomalous hydrogen emis-

sionsalong seismogenicaults in California, paper presentedat The

1984 International Chemical Congress of Pacific Basin Societies,

Honolulu, Hawaii, Dec. 16-21, 1984.

Shepherd, E. S., The gases n rocks and some related problems, Am. d.

Sci., 35-A, 311-351, 1938.

Shigiura, T., Y. Mizutani, and S. Dana, Fluorine, chlorine, bromine,

and iodine in volcanic gases,d. Earth Sci. Nagoya Univ., 11(2),

272-278, 1964.

Simoneit, B. R., M. A. Mazurek, S. Brenner, P. T. Crisp, and I. R.

Kaplan, Organic geochemistryof recent sediments rom Guaymas

Basin,Gulf of California, Deep Sea Res.,26A, 879-891, 1979.

Soonawala, N.M., and W. M. Telford, Movement of radon in over-

burden, Geophysics, 5, 1297, 1980.

Stahl, W., E. Faber, B. D. Carey, and D. L. Kirksey, Near-surface

evidence of migration of natural gas from deep reservoirs and

source ocks, Bull. Am. Assoc.Pet. Geol.,65(9), 1543-1550, 1981.

Tanner, A. B., Meteorological influence on radon concentration in

drill holes, Min. Eng., 11, 706-708, 1959.

Tanner, A. B, Radon migration in the ground: A review, in The

Natural Radiation Environment, edited by J. A. S. Adams and W.

M. Lowder, pp. 161-190, University of Chicago Press,Chicago, I1.,

1964.

Tanner, A. B., Radon migration in the ground: A supplementary

review, U.S Geol. Surv. Open File Rep. 78-1050, 1978.

Taylor, C. H., S. E. Kesler, and P. L. Cloke, Sulfur gasesproduced by

the decompositionof sulfide minerals: Application to geochemical

exploration, d. Geochem. xplor., 17, 165-186, 1982.

Waples, D., Organic Geochemistryor Exploration Geologists,Burgess

Publishers,Minneapolis, Minn., 1981.

Welhan, J. A., and H. Craig, Methane and hydrogen in East Pacific

Rise hydrothermal fluids, Geophys.Res. Lett., 6(11), 829-831, 1979.

White, D. E., and G. A. Waring, Volcanic emanations, U.S. Geol.

Surv. Prof. Pap. 440-K, 1963.

Zies, E.G., The concentration of the less familiar elements through

igneous and related activity, Am. d. Sci., 35A, 385-404, 1938.

J. H. McCarthy, Jr., and G. M. Reimer, U.S. Geological Survey,

Box 25046, MX/912, Denver Federal Center, Denver, CO 80225.

(ReceivedNovember 27, 1985;

revised May 12, 1986;

acceptedMay 28, 1986.)

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Advances in Soil Gas Geochemical Exploration for Natural Resources

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