GEOLOGICAL SURVEY CIRCULAR 837 

Biogeochemical Evidence for 

Subsurface Hydrocarbon Occurrence, 

Recluse Oil Field, Wyoming: 

Preliminary Results 

Biogeochemical Evidence for 

Subsurface Hydrocarbon Occurrence, 

Recluse Oil Field, Wyoming: 

Preliminary Results 

By Mary C. Dalziel and Terrence J. Donovan 

GEOLOGICAL SURVEY CIRCULAR 837 

1980 
United States Department of the Interior 

CECIL D. ANDRUS, Secretary 

Geological Survey 

H. William Menard, Director 

Free on application to Branch of Distribution, U.S. Geological Survey, 604 South Pickett Street, Alexandria, VA 22304 
Contents 

Abstract ••••.••••.•.••••••.•••.•••••••...••••.••• • • • • • • • • • • • • • • • • • • · 

Introduction •••••••••••••••••••••••••••••••••••••••••••••••••••••••• 

Manganese and iron anomalies in pine needles and sage leaves •••••••• 

Methods •••••••••••••••••••••••••••••••••••••••••••••••••••••••• 

Mn/Fe ratios in plantS••••••••••••••••••••••••••••••••••••••••• 

Petroleum microseepage at the Recluse oil field, Wyoming •••••••••••• 

The chemistry of manganese and iron in microseepage 

environments ••• .••••••••••..••••••••••.••••••.•••••••••••.••••••••• 

Manganese and iron behavior in soils ••••••••••••••••••••••••••• 

Uptake of elements by plantS••••••••••••••••••••••••••••••••••• 

Summary • ••••••••••••••• • •••• • • • •• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 

References . ....••.••....•.••••••.....••..•••••... • ......• • • • • •. • • • • • 

Figure 1. 

2. 

3. 

4. 

s. 

7. 

8. 

Illustrations 

Map of Wyoming showing the outline of the Recluse 

oil field, Campbell County, Wyoming ~lack area), as 

well as the Powder River Basin (shaded area) ••••••••••• 

Isopach map of the producing Muddy Sandstone, 

Recluse oil field, Wyoming••••••••••••••••••••••••••••• 

Isopleth map of the ratio of manganese to 

iron in pine needles (Pinus ponde~osa) collected 

over the Recluse oil field, Wyoming•••••••••••••••••••• 

Isopleth map of the ratio of manganese to iron 

in sage leaves (A~temisia ~identata) collected 

over the Recluse ~il field, Wyoming •••••••••••••••••••• 

Isopleth map of ~c 1 values in carbonate cements 

from sandstone outcrops, Recluse oil field, 

Wyoming • •••••••••••• • • • •• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 

Isopleth map of ~0 18 values in carbonate 

cements from sandstone outcrops, Recluse oil 

field, Wyoming •••••••••••••••••••••••••••••••••••• • • • • • 

Isopleth map of the ratio of manganese to iron 

in carbonate cements of sandstone outcrops, 

Recluse oil field, Wyoming ••••••••••••••••••••••••••••• 

Isopleth map of the ratio of manganese to iron 

in soils, Recluse oil field, Wyoming ••••••••••••••••••• 

III 

Page 

1 

1 

1 

1 

2 

2 

8 

8 

8 

9 

10 

Page 

2 

2 

3 

4 

5 

6 

7 

9 

Biogeochemical Evidence for Subsurface 

Hydrocarbon Occurrence, 

Recluse Oil Field, Wyoming: Preliminary Results 

By Mary C. Dalziel and Terrence J. Donovan 

ABSTRACT 

Anomalously high manganese-to-iron ratios 

occurring in pine needles and sage leaves over 

the Recluse oil field, Wyoming, suggest effects 

of petroleum microseepage on the plants. This 

conclusion is supported by iron and manganese 

concentrations in soils and carbon and oxygen 

isotope ratios in rock samples. Seeping 

hydrocarbons provided reducing conditions 

sufficient to enable divalent iron and manganese 

to be organically complexed or adsorbed on 

solids in the soils. These bound or adsorped 

elements in the divalent state are essential to 

plants, and the plants readily assimilate 

them. The magnitude of the plant anomalies, 

combined with the supportive isotopic and 

chemical evidence confirming petroleum leakage, 

makes a strong case for the use of plants as a 

biogeochemical prospecting tool. 

INTRODUCTION 

Classical surface geochemical and 

biogeochemical exploration methods have been 

used extensively in the worldwide search for 

metals and in the search for petroleum in the 

USSR, but in general they have not received 

widespread attention from North American 

petroleum explorationists (Hawkes, 1957; Kartsev 

and others, 1959; Boyle and Garrett, 1970; and 

Brooks, 1972). Geochemical and biogeochemical 

petroleum exploration techniques have been 

directed primarily toward the detection of trace 

amounts of hydrocarbons in soils or soil gases 

and the metabolic byproducts of microbial attack 

on hydrocarbons at or near the surface 

(Laubmeyer, 1933; Horvitz, 1939; Pirson, 1940; 

Rosaire, 1940; Kartsev and others, 1959; Davis, 

1967; and Debnam, 1969). !-fore recently, 

diagenetic or epigenetic indicators of 

subsurface petroleum deposits have received 

attention (McCulloh, 1969; Donovan, 1974; 

1 

Donovan and others, 1974; Donovan and Dalziel, 

1977). This report presents preliminary data on 

pronounced systematic elemental variations in 

pine needles and sage leaves that closely correspond with several kinds of epigenetic anomalies 

in rocks and soils overlying the Recluse oil 

field, a large stratigraphic trap in Wyoming. 

The Recluse oil field is in T. 56 and 57 

N., R. 74 and 75 w., Campbell County, Wyo., 

along the northeastern flank of the Powder River 

Basin (fig. 1). The field was discovered in 

1967 and has been interpreted to be a Cretaceous 

Muddy Sandstone barrier island (Woncik, 1969). 

The productive part of the northwest-trending 

bar is about 13 km long and ranges from 1 to 5 

km wide. Maximum drilled thickness of the 

reservoir is 14 m. The regional dip is 

southwest, and oil and some gas are trapped 

along the updip edge of the sandstone body. The 

average drilled depth is about 2,330 m (fig. 

2). Produced oil has an API gravity of 32 

degrees. 

The Fort Union Formation of Tertiary age 

crops out over the Recluse oil field and 

includes sandstone, shale, and coal of the 

Tongue River Member, a 400- to 500-m-thick 

nonmarine sequence. Sandstone is normally fine 

to medium grained, friable, and yellowish 

gray. Shale is medium gray and waxy. Coal 

lenses and widespread coal seams as much as 5 m 

thick occur in the area; clinker is also common 

{Olive, 1957). 

MANGANESE AND IRON ANOMALIES 

IN PINE NEEDLES AND SAGE LEAVES 

Methods 

Samples of pine needles (Pinus pondePosa) 

and sage leaves (APtemisia tpidentata) were 

collected over the Recluse oil field and 

surrounding area. The samples were washed in an 

ultrasonic bath using an aqueous, phosphate-free 

detergent solution followed by two successive 
0 100 MILES 

0 100 KILOMETERS 

Figure 1.--Map of Wyoming showing the outline of 

the Recluse oil field, Campbell County, 

Wyoming (black area), as well as the Powder 

River Basin (shaded area). 

10~ ~2 30" 

44°52'3 0" 

E X PLANATION 

0 2 MILES 

0 2 KILOMETERS 

Iso pach •nter va l = 10 fee t 

R. 75 w. R. 74 w. 

T. 

"" N. 

T. e1 

N . 

T. 

e1 

N. 

T. 

56 

N . 

T. 

N . 

T . 

55 

N 

Figure 2.--Isopach map of the producing Muddy 

Sandstone, Recluse oil field, Wyoming, 

Modified from Woncik, 1969. 

rinses with distilled water (Mitchell, 1960; 

Mason, 1953). After air drying, the samples 

2 

were ground in a coffee grinder and 4 g were 

ashed at 450°C for 6 hours. 

Samples of 100 mg ·of ash were digested in 4 

mL of 3 N hydrochloric acid and gently heated 

without stirring for 15 minutes. The supernatant was diluted to 100 mL with distilled 

water and analyzed for iron and manganese by 

atomic absorption spectrophotometry (Ward, and 

others, 1969). The data from these analyses are 

tabulated in a u.s. Geological Survey open-file 

report (Dalziel and Donovan, 1980). 

Mn/Fe Ratios in Plants 

Figure 3 shows the distribution of Mn/Fe 

ratios in pine needles collected over the 

Recluse oil field. Because of the large range 

(about three orders of magnitude; Dalziel and 

Donovan, 1980) of the ratio, log values were 

used to construct the isopleth map. Distinctly 

high ratio values occur along the trend of the 

productive part of the field. A complex doublelobed area of high values occurs over the 

northwestern end of the field. 

A similar double-lobed area of high values 

in the sage data also occurs over the northwestern part of the field (fig. 4). The mapped 

pattern of the Mn/Fe ratios in sage leaves 

appears more convoluted and complex than that of 

pine; this may be partly attributed to the 

sampling density being greater for sage than fqr 

pine. Another factor contributing to the 

differences in the ratio patterns is the overall 

higher concentration of manganese in the pine 

needles (Dalziel and Donovan, 1980). This is 

reflected in a broader and areally larger 

anomaly pattern for pine •. 

Both figures 3 and 4 clearly suggest a 

correlation between anomalously high !1n/Fe 

values in plants and the distribution of 

subsurface petroleum. This apparent correlation 

can be made for the Recluse field and for 

smaller producing oil fields in the immediate 

region as well (Petroleum Information 

Corporation, 1979). 

PETROLEUM MICROSEEPAGE AT THE 

RECLUSE OIL FIELD, WYOMING 

Hydrocarbons can escape their subsurface 

reservoirs by one or any combination of the 

following three mechanisms: (1 p effusion of 

gases and liquids, (2) dissolution and 

subsequent migration of low-molecular-weight 

hydrocarbons in water, and (3) diffusion of 

gases through an aqueous phase (Donovan and 

Dalziel, 1977). 

Seeping hydrocarbons are microbially 

attacked in porous rock in the near-surface 

oxidizing zone. Increasing amounts of the 

resulting carbon dioxide go into solution and 

precipitate as isotopically distinctive, porefilling carbonate cements that ai~ 

characteristically depleted in C and either 
44° 57'30" 

44° 52'30" 

105°52'30" 105°45' 

EXPLANATION 

0 2 MILES 

t----,r-''--T"""-

0 2 KILOMETERS 

Sample locality 

-

Oil field 

Isopleth interval = 0.2 log units of the ratio Mn/Fe X 100 

R. 75 w. R. 74 w. R. 74 W. R . 73 W. 

Figure 3.--Isopleth map of the ratio of manganese to· iron in pine needles 

(Pi nus ponde~osa) collected over the Recluse oil field, Wyoming. 

T. 

58 

N. 

T. 

57 

N. 

T . 

57 

N. 

T. 

56 

N. 

T. 

56 

N. 

T. 

55 

N.-

enriched or impoverished in o18 ; the direction 

of oxygen isotopic fractionation provides 

important clues as to which of the three. 

mi croseepage mechanisms has dominated (Donovan 

and Dalziel, 1977). 

Data demonstrating the anomalous character 

of the overlying rock and soil at Recluse have 

been presented previously (Donovan, in press; 

Dalzil~ and Donovan, 1980). Figure 5 is a map 

of oC values in carbonate cements in sandstone 

3 
105°52'30" 

44°57'30" 

44° 55' 

44° 52'30" 

• 

• 

EXPLANATION 

0 2 MILES 

b 2 K

1

1LOMETERS 

• Sample locality 6!f!J) Oil field 

Isopleth interval 0.2 log units of the ratio Mn/Fe X 100 

R. 75 W. R. 74 w. R. 74 w. R. 73 w . 

Figure 4.--Isopleth map of the ratio of manganese to iron in sage leaves 

(APtemisia tPidentata) collected over the Recluse oil field, Wyoming. 

4 

T. 

58 

N. 

T . 

57 

N. 

T. 

57 

N . 

T . 

56 

N. 

T . 

56 

N . 

T. 

55 

N. 
105°52'30" 

52'30" 

45' 

R. 75 W. R. 74 W. R. 74 W. R. 73 W. 

105°37'30" 

EXPLANATION 

0 2 MILES 

0 2 KILOMETERS 

• Sample locality 

......-~5_..... Isopleth interval 5 units 

Oil f ield 

T. 

57 

N . 

T. 

57 

N. 

T. 

56 

N. 

T. 

56 

N. 

T. 

55 

N. 

Figure 5.--Isopleth map of 6C 13 values in carbonate cements from sandstone 

outcrops, Recluse oil field, Wyoming. 

cropping out over the Recluse oil field. Thinsection examination of samples reveals that the 

primary cement is calcite, with secondary 

ferroan dolomite and minor hr~tite. The 

systematic pattern of the oC . isopleths 

corresponds strikingly with the mapped 

occurrence of petroleum and gas in the Muddy 

5 

reservoir. The oo 18 pattern of variation (fig. 

6) appears slightly more variable, probably 

owing to some admixing in the ground waters 

between seeping waters and homogenizing meteoric 

w!§ers; however, the general distribution of 

0 ~depleted carbonate cements immediately 

overlying and along the trend of the subsurface 
44' 

EXPLANATION 

0 2 MILES 

0 2 KILOMETERS 

~, _., Isopleth interYal 1 unit 

+15 

c:!) Oil field 

• Sample locality 

R. 75 W . R . 74 W . R. 74 W . R . 73 W . 

Figure 6.--Isopleth map of ~ol8 values in carbonate cements from sandstone 

outcrops, Recluse oil field, Wyoming. 

6 

T. 

57 

N . 

T. 

57 

N. 

T. 

56 

N. 

T. 

56 

N . 

T. 

55 

N. 
44° 57'30" -

105°45' 105'37'30" 

• EXPLANATION 

• 

• 

R. 75 w. R. 74 w. R. 74 W. R. 73 W. 

0 2 MILES 

0 2 KILOMETERS 

Sample locality 

cJJ1jfjJfJ) Oilfield outline 

Isopleth interval = 5 units of the ratio 

Mn/Fe x 100 in carbonate cements 

of outcropping sandstones. 

0 

• 

Figure 7.--Isopleth map of the ratio of manganese to iron in carbonate cements 

of sandstone outcrops, Recluse oil field, Wyoming. 

7 

T. 

57 

N. 

T. 

56 

N. 

T. 

56 

N. 

T. 

55 

N . 
reservoir suggests micropore filtration of 

upward-moving waters carrying dissolved 

hydrocarbons (Donovan and Dalziel, 1977). 

THE CHEMISTRY OF MANGANESE AND IRON 

IN MICROSEEPAGE ENVIRONMENTS 

The near-surface chemically reducing 

environment created by the presence of seeping 

hydrocarbons contributes to reduction, 

dissolution, and mobilization of iron and 

manganese from their solid mineral phases. In 

shallow superincumbent rocks, manganese is 

precipitated in the presence of dissolved 

carbonate to take up residence in pore-filling 

carbonate-cement lattices. Depending upon the 

pH and redox potential of the environment and 

the rapidity with which they are subject to 

change, mobilized manganese and iron may either 

be transported together or be effectively 

separated (Krauskopf, 1957). Although 

systematic variations in manganese and iron 

concentrations occur in both rocks and soils in 

the Recluse oil field, manganese appears to 

display a greater variability. Mn/Fe ratio maps 

were constructed to illustrate the anomalous 

nature of their distribution pattern, because it 

has been shown that the manganese-to-iron ratio 

in carbonate cements is a striking indicator of 

microseepage (Donovan and Dalziel, 1977; Donovan 

and others, 1975). A particularly strong 

correlation is suggested between the Mn/Fe ratio 

in the carbonate cements and the subsurface 

accumulation of oil in the Recluse oil field 

(fig. 7). Of special interest also are the 

Mn/Fe ratios in soils overlying the Recluse 

field area (Dalziel and Donovan, 1980; fig. 8); 

the soil data suggest relatively depleted Mn/Fe 

ratios over and along the producing trend in the 

Recluse oil field. 

Manganese and Iron Behavior in Soils 

The most likely forms that manganese takes 

in soils are (1) absorbed Mn2+ in strongly 

reduced soil; (2) manganese in aqueous 

solutions, most likely present as complexes 

ra~her than as a simple ion; and (3) absorbed 

Mn +, which may persist in considerable amounts 

in oxidizing soils, but much of which should 

occur as highly insoluble oxide minerals 

(Krauskopf, 1972). Further, the low solubility 

of Fe(OH) 3 and the observation that iron-rich 

soils commonly develop over iron-rich rocks 

indicate that soils largely reflect the iron 

composition of their parent rock (Krauskop~+ 

19~~)· Under reducing conditions, both Fe and 

Mn increase in solubility sufficiently to 

become adsorbed or exchangeable ions (Mandai, 

1961), and as much as 90 percent of the 

manganese in soil solution may actually be 

organically bound (Geering and ot~ers, 1961~· 

Adsorption reactions involving Fe + and Mn may 

represent intermediate phases between the true 

solution and precipitation of insoluble oxides 

8 

and hydroxide (Ellis and Knezek, 1972), but such 

intermediate phases could be expected to persist 

indefinitely if the amount of organic material 

in the soil and the chemical environment there 

remain relatively fixed. Viets (1962) stressed 

that divalent iron and manganese would also be 

subject to strong adsorption on negatively 

charged clay particles as well as on humus. 

Additionally, these metals may enter into other 

adsorption reactions, such as bonding to 

specific functional groups on the clay 

surfaces. Chelation also appears to be an 

important bonding mechanism (Ellis and Knezek, 

1972). 

Uptake of Elements by Plants 

The total uptake of nutrient elements by 

plants has been resolved into two components: 

metabolic and nonmetabolic (Jacobson and others, 

1958). The metabolic component involves rootabsorption phenomena, whereas the nonmetabolic 

component refers to diffusion and mass flow of 

ions in external solution in free water and 

Donnan microregions surrounding the root. Upon 

chelation (or ion-pair formation), both the 

concentration and the concentration gradient of 

the chelated ion in solution can be 

significantly greater than that of the 

unchelated ion, thus markedly increasing 

transfer by diffusion (Wilkinson, 1972). The 

contact-exchange mechanism defined by Jenny and 

Overstreet (1939) includes the hypothesis that 

an ion passes directly from the adsorbed state 

on solids to the root through the exchange of 

adsorbed H+ or other ions, bypassing direct 

solution. When chelated ions contact the root 

surface, the plant can similarly liberate the 

ion from the chelating agent and absorb it 

(Hodgson, 1968; Chaney and others, 1972). Thus, 

plants may assimilate elements from soils even 

though no measurable water-soluble pool of ions 

is available in true solution. 

We speculate that the reducing conditions 

provided by seeping hydrocarbons from the 

subsurface in the Recluse oi1 2field ha~e 

facilitated the release of Mn + and Fe + from 

their solid mineral phases and resulted in 

immediate complexation, chelation, and 

adsorption by the soils. In these organically 

bound and adsorbed states, their uptake by pine 

and sage roots has been accelerated, resulting 

in anomalous concentrations in needle and leaf 

tissue. This accelerated direct uptake by the 

plants has further resulted in these elements 

bypassing the soil-formation process wherein 

they would have ultimately precipitated as 

insoluble oxides or hydroxides. This phenomenon 

is interpreted to be the cause of the Mn/Fe 

ratio in the plants more closely resembling the 

ratio in the parent rocks rather than that in 

their overlying soils. This in turn suggests 

that plants can assimilate these micronutrient 

elements in direct proportion to their 

availability, which may be enhanced in a 

microseepage environment. 
44° 45" 

EXPLANATION 

0 2 MILES 

0 2 KILOMETERS 

• Sample local ity 

__ 1 .

0 _...... Isopleth 1nterv al 0 .2 un 1ts 

of the ratio Mn/Fe x 100 

T 

57 

N 

T 

57 

N 

T . 

56 

N . 

T 

56 

N . 

T 

55 

N. 

R. 7 5 W R. 74 W R. 74 W . R. 73 W . 

Figure 8.--Isopleth map of the ratio of manganese to iron in soils, Recluse 

oil field, Wyoming. 

SUMMARY 

Systematic anomalously high Mn/Fe ratio 

values in pore-filling carbonate cements in 

bedrock over the Recluse oil field are the 

direct consequence of petroleum microseep1~e, an 

interpretation confirmed by diagnostic ~ and 

9 

18 distribution patterns. Continued seepage 

of hydrocarbons produced a near-surface reducing 

environment over the field sufficient to release 

Mn 2+ and Fe2+ from their solid mineral phases, 

enabling them to be organically bound or 

adsorbed on solids in soils. In these forms, 

manganese and iron are readily assimilated by 
pine and sage, resulting in high Mn/Fe ratios in 

the needles and leaves and lower ratios in the 

soil. The data suggest that biogeochemical 

analysis may be a promising petroleum 

prospecting tool. 

References 

Boyle, R. w., and Garrett, R. G., 1970, 

Geochemical prospecting--A review of its 

status and future: Earth-Science Review, 

v. 6, P• 51-75. 

Brooks, R. R., 1972, Geobotany and 

biogeochemistry in mineral exploration: 

New York, Harper and Row Publishers, Inc., 

290 P• 

Chaney, R. L., Brown, J. c., and Tiffin, L. o., 

1972, Obligatory reduction of ferric 

chelates in iron uptake by soybeans: Plant 

Physiology, v. 50, p. 208-213. 

Dalziel, M. c., and Donovan, T. J., 1980, 

Chemical and isotopic data for some plants, 

soils, and carbonate cements in sandstone 

outcrops, Recluse oil field, Wyoming: u.s. 

Geological Survey Open-File Report 80-783, 

21 p. 

Davis, J. B., 1967, Petroleum microbiology: 

Amsterdam, Elsevier, 604 P• 

Debnam, A. H., 1969, Geochemical prospecting for 

petroleum and natural gas in Canada: 

Geological Survey of Canada Bulletin 177, 

26 P• 

Donovan, T. J., 1974, Petroleum microseepage at 

Cement, Oklahoma--Evidence and mechanism: 

American Association of Petroleum 

Geologists Bulletin, v. 58, p. 429-446. 

Donovan, T. J., in press, Geochemical 

prospecting for oil and gas from orbital 

and suborbital altitudes, in Symposium II, 

Unconventional Methods of Oil and Gas 

Prospecting, Dallas, Texas, 1979: Southern 

Methodist University, Proceedings. 

Donovan, T. J., and Dalziel, M. c., 1977, Late 

diagenetic indicators of buried oil and 

gas: u.s. Geological Survey Open-File 

Report 77-817, 44 p. 

Donovan, T. J., Friedman, Irving, and Gleason, 

J. D., 1974, Recognition of petroleumbearing traps by unusual isotopic 

compositions of carbonate-cemented surface 

rocks: Geology, v. 2, p. 351-354. 

Donovan, T. J., Noble, R. L., Friedman, Irving, 

and Gleason, J. D., 1975, A possible 

petroleum-related geochemical anomaly in 

surface rocks, Boulder and Weld Counties, 

Colorado: u.s. Geological Survey Open-File 

Report 75-47, 11 P• 

Ellis, B. G., and Knezek, B. D., 1972, 

Adsorption reactions of micronutrients in 

soils, in Mortvedt, J. J., Giordano, P. M., 

and Lindsay, w. L., eds., Micronutrients in 

agriculture: Madison, Wisconsin, Soil 

Science Society of America, Inc., p. 59-78. 

Geering, H. R., Hodgson, J. F., and Sdano, 

Caroline, 1969, Micronutrient cation 

10 

complexes in soil solution--The chemical 

state of manganese in soil solution: Soil 

Science Society of America Proceedings, 

v. 33, P• 81-85. 

Hawkes, B. E., 1957, Principles of geochemical 

prospecting: u.s. Geological Survey 

Bulletin 1000-F, p. 225-355. 

Hodgson, J. F., 1968, Theoretical approach for 

the contribution of chelates to the 

movement of iron to roots: International 

Congress on Soil Science Transactions, 9th 

(Adelaide, Australia), v. 2, P• 229-241. 

Horvitz, L., 1939, On geochemical prospecting: 

Geophysics, v. 4, p. 210-228. 

Jacobson, Louis, Hannapel, R. J., and MOore, D. 

P., 1958, Nonmetabolic uptake of ions by 

barley roots: Plant Physiology, v. 33, 

P• 278-282. 

Jenny, Hans, and Overstreet, Roy, 1939, Cation 

exchange between roots and soil colloids: 

Soil Science, v. 47, p. 257-272. 

Kartsev, A. A., Tabasaranskii, z. A., Subbota, 

M. J., and Mogelevskii, G. A., 1959, 

Geochemical methods of prospecting and 

exploration for petroleum and natural gas, 

English translation edited by Witherspoon, 

P. A., and Romey, w. D.: Berkeley and Los 

Angeles, University of California Press, 

349 P• 

Krauskopf, K. B., 1957, Separation of manganese 

from iron in sedimentary processes: 

Geochemica et Cosmochemica Acta, v. 12, 

P• 61-68. 

______ 1972, Geochemistry of micronutrients, in 

Mortvedt, J. J., Giordano, P.M., and 

Lindsay, w. L., eds., Micronutrients in 

agriculture: Madison, Wisconsin, Soil 

Science Society of America, Inc., p. 7-40. 

Laubmeyer, G., 1933, Eine nueve geophysikalesche 

Schurfmethode insbesondere fur 

Kohlenwasserstoff Lagerstatten [in 

German]: Petroleum, v. 29, no. 18, P• 1-4. 

Manda!, L. N., 1961, Transformation of iron and 

manganese in waterlogged rice soils: Soil 

Science, v. 91, p. 121-126. 

Mason, A. c., 1953, The cleaning of leaves prior 

to analysis: Maidstone, England, East 

Mailing Research Station, v. 40, 

P· 104-107. 

McCulloh, Thane, 1969, Oil fields, gravity 

anomalies, and surface chemical 

manifestations--Correlations, causes, and 

exploration significance [abs.]: Society 

of Exploration Geophysicists Program, 

Pacific Section Annual Meeting, 44th, Los 

Angeles, California, 1969, p. 17-18. 

Mitchell, R. L., 1960, Contamination problems in 

soil and plant analysis: Journal of 

Science Food Agriculture, v. 11, 

P• 553-560. 

Olive, w. w., 1957, The Spotted Horse coalfield, 

Sheridan and Campbell Counties, Wyoming: 

u.s. Geological Survey Bulletin 1050, 83 p. 

Petroleum Information Corporation, 1979, Wyoming 

4 regional map: scale 1:40,000, 1 sheet. 
Pirson, s. J., 1940, Critical survey of recent 

developments in geochemical prospecting: 

American Association of Petroleum 

Geologists Bulletin, v. 24, p. 1464-1474. 

Rosaire, E. E., 1940, Geochemical prospecting 

for petroleum: American Association of 

Petroleum Geologists Bulletin, v. 24, 

P• 1400-1433. 

Viets, F. G., Jr., 1962, Chemistry and 

availability of micro-nutrients in soils: 

Journal of Agriculture and Food Chemistry, 

v. 10, no. 3, P• 174-178. 

Ward, F. N., Nakagawa, H. M., Harms, T. F., and 

11 

Van Sickle, G. H., 1969, Atomic-absorption 

methods of analysis useful in geochemical 

exploration: u.s. Geological Survey 

Bulletin 1289, 45 P• 

Wilkinson, H. F., 1972, Movement of micronutrients to plant roots, in Mortvedt, J. 

J., Giordano, P. M., and Lindsay, w. L., 

eds., Micronutrients in agriculture: 

Madison, Wisconsin, Soil Science Society of 

America, Inc., p. 139-166. 

Woncik, John, 1969, Recluse field, Campbell 

County, Wyoming: The MOuntain Geologist, 

v. 6, no. 4, p. 221-226. 

-t< U.S. GOVERNMENT PRINTING OFFICE' 1980----677-129/13