3H1 SIONIT1I ISVe 

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Cover. Leached ilmenite grain approximately 60 microns in diameter surrounded by 

quartz overgrowth in Lower Pennsylvanian sandstone in Indiana. Quartz overgrowths 

occlude much of the pore space in these rocks. Sample collected by Paula Hansley, U.S. 

Geological Survey.
Fluid Inclusions and Biomarkers in the 

Upper Mississippi Valley Zinc-Lead 

District Implications for the Fluid-Flow and 

Thermal History of the Illinois Basin

By E.L. Rowan and M.B. Goldhaber

EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN 

Jennie L. Ridgley, Project Coordinator

U.S. GEOLOGICAL SURVEY BULLETIN 2094-F

A multidis tip Unary approach to research studies of 

sedimentary rocks and their constituents and the 

evolution of sedimentary basins, both ancient and modern

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1996
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

For sale by U.S. Geological Survey, Information Services

Box 25286, Federal Center

Denver, CO 80225

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

does not imply endorsement by the U.S. Government

Library of Congress Cataloging-in-Publication Data

Rowan, E. Lanier.

Fluid inclusions and biomarkers in the Upper Mississippi Valley zinc-lead district: 

implications for the fluid-flow and thermal history of the Illinois Basin / by E. L. Rowan 

and M. B. Goldhaber. F) (U.S. Geological Survey bulletin ; 2094)

Includes bibliographical references.

Supt. of Docs, no.: I 19.3:2094-F

1. Hydrothermal deposits Illinois Basin. 2. Fluid inclusions Illinois Basin. 

3. Biochemical markers Illinois Basin. I. Goldhaber, Martin B. II. Series. 

III. Series: U.S. Geological Survey bulletin ; 2094. 

QE75.B9 no. 2094-F 

[QE390.5] 

557.3 s-<ic20

[551.1'4] 95-49007

CIP
CONTENTS

Abstract........................................................................................................................... Fl

Introduction.................................................................................................................... 2

Geologic Setting............................................................................................................. 4

Fluid Inclusions.............................................................................................................. 7

Sulfur Isotope Geothermometry..................................................................................... 9

Biomarkers...................................................................................................................... 12

Fluid- and Heat-Flow and Thermal Maturity Calculations............................................ 18

Boundary Conditions and Grid............................................................................... 18

Depth of Burial....................................................................................................... 23

Permeability, Porosity, Fracture Zone Width, and Fluid Flux ............................... 23

Thermal Properties................................................................................................. 25

Results............................................................................................................................ 25

Calculated Duration of Hydrothermal Flow........................................................... 25

Sources of Error...................................................................................................... 25

Discussion....................................................................................................................... 28

Implications for Regional Fluid Flow .................................................................... 29

Sources of Salt........................................................................................................ 32

Conclusions .................................................................................................................... 32

References Cited............................................................................................................. 32

FIGURES

1. Map showing location of Upper Mississippi Valley district and area of outlying mineralization......................... F3

2. Diagram showing timing of major structural, tectonic, and mineralization events related to

Upper Mississippi Valley and Southern Illinois fluorite districts.......................................................................... 5

3. Stratigraphic section of Upper Mississippi Valley zinc-lead district..................................................................... 6

4. Map showing outline of principal mineralized area, Upper Mississippi Valley district........................................ 7

5. Chart showing stratigraphy of lower Paleozoic rocks, Upper Mississippi Valley district..................................... 8

6. Schematic represention of spatial and time relationships between sphalerite zones A, B, and C in

hypothetical vein.................................................................................................................................................... 9

7. Graph showing fluid inclusion temperatures in sphalerite and calcite.................................................................. 10

8. Histograms of fluid inclusion homogenization temperature by sphalerite zone ................................................... 11

9. Graph showing temperatures calculated from sphalerite sulfur isotope measurements........................................ 12

10-12. Diagrams showing:

10. Numbering system for carbon atoms in steranes and triterpanes (hopanes) ............................................... 13

11. Isomerization reactions in sterane and triterpane ........................................................................................ 14

12. Maximum thermal maturity of hopane and sterane compared with stages of oil generation and with

vitrinite reflectance....................................................................................................................................... 15

13. Graph showing biomarker isomaturity curves for time-temperature combinations that give calculated

maturities equal to average of hopane and steranes ratios measured in Upper Mississippi Valley district........... 16

14. Map showing sample sites in Thompson and Temperly orebodies and biomarker and Tmax measurements........ 17

15. Schematic cross section showing configuration of flow model............................................................................. 19

16. Map showing sample sites projected onto a line drawn normal to approximate trend of fractures that

controlled emplacement of Thompson and Temperly orebodies........................................................................... 20

17. Graph showing grid used in numerical calculations.............................................................................................. 21

III
IV CONTENTS

18, 19. Graphs showing contours of calculated thermal maturity ratios for sterane and hopane over grid, assuming 

best-fit temperature path and specified temperature basal boundary at:

18. St. Peter Sandstone....................................................................................................................................... 22

19. Mount Simon Sandstone.............................................................................................................................. 24

20-22. Graphs showing:

20. Maturities of hopane and sterane plotted versus distance from Thompson orebody at Quimbys Mill

horizon......................................................................................................................................................... 26

21. Calculated hopane and sterane maturities shown as function of temperature and time............................... 27

22. Comparison of fluid inclusion temperatures and temperatures predicted for Upper Mississippi Valley

district using two gravity-driven flow models.............................................................................................. 30

23. Map showing anomalous fluorine concentrations in the Illinois Basin................................................................. 31

TABLES

1. Recently published ages for the Upper Mississippi Valley and Southern Illinois fluorite districts....................... F4

2. Sterane and hopane biomarker maturity ratios in the barren drift between the Thompson and Temperly

orebodies............................................................................................................................................................... 15

3. Kinetic constants for sterane and hopane isomerization reactions........................................................................ 16

4. Comparison of the durations calculated for the average biomarker maturities of Hatch and others (1986)

assuming a temperature of 130°C and using several selected kinetic constants from the literature..................... 28
Fluid Inclusions and Biomarkers in the 

Upper Mississippi Valley Zinc-Lead DistrictImplications for the Fluid-flow and 

Thermal History of the Illinois Basin

By E.L. Rowan 1 and M.B. Goldhaber2

ABSTRACT

The Upper Mississippi Valley zinc-lead district is 

hosted by Ordovician carbonate rocks at the northern margin 

of the Illinois Basin. Fluid inclusion temperature measurements on Early Permian sphalerite ore from the district are 

predominantly between 90°C and 150°C. These temperatures are greater than can be explained by their reconstructed 

burial depth, which was a maximum of approximately 1 km 

at the time of mineralization. In contrast to the temperatures 

of mineral formation derived from fluid inclusions, biomarker maturities in the Upper Mississippi Valley district give 

an estimate of total thermal exposure integrated over time. 

Temperatures from fluid inclusions trapped during ore genesis with biomarker maturities were combined to construct 

an estimate of the district's overall thermal history and, by 

inference, the late Paleozoic thermal and hydrologic history 

of the Illinois Basin.

Circulation of groundwater through regional aquifers, 

given sufficient flow rates, can redistribute heat from deep in 

a sedimentary basin to its shallower margins. Evidence for 

regional-scale circulation of fluids is provided by paleomagnetic studies, regionally correlated zoned dolomite, fluid 

inclusions, and thermal maturity of organic matter. Evidence 

for igneous activity contemporaneous with mineralization in 

the vicinity of the Upper Mississippi Valley district is absent.

Regional fluid and heat circulation is the most likely 

explanation for the elevated fluid inclusion temperatures 

(relative to maximum estimated burial depth) in the Upper 

Mississippi Valley district. One plausible driving mechanism and flow path for the ore-forming fluids is groundwater

^.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025.

2U.S. Geological Survey, P.O. Box 25046, Denver, Colorado 80225.

recharge in the late Paleozoic Appalachian-Ouachita mountain belt and northward flow through the Reelfoot rift and the 

proto-Illinois Basin to the Upper Mississippi Valley district. 

Warm fluid flowing laterally through Cambrian and Ordovician aquifers would then move vertically upward through 

the fractures that control sphalerite mineralization in the 

Upper Mississippi Valley district.

Biomarker reactant-product measurements on rock 

extracts from the Upper Mississippi Valley district define a 

relatively low level of thermal maturity for the district, 0.353 

for sterane and 0.577 for hopane. Recently published kinetic 

constants permit a time-temperature relationship to be determined from these biomarker maturities. Numerical calculations were made to simulate fluid heat flow through the 

fracture-controlled ore zones of the Thompson-Temperly 

mine and heat transfer to the adjacent rocks where biomarker 

samples were collected. Calculations that combine the fluid 

inclusion temperatures and the biomarker constraints on 

thermal maturity indicate that the time interval during which 

mineralizing fluids circulated through the Upper Mississippi 

Valley district is on the order of 200,000 years.

Fluid inclusion measurements and thermal maturities 

from biomarkers in the district reflect the duration of peak 

temperatures resulting from regional fluid circulation. On 

the basis of thermal considerations, the timing of fluorite 

mineralization in southern Illinois, and the northward-decreasing pattern of fluorine enrichment in sediments, we hypothesize that the principal flow direction was 

northward through the Cambrian and Ordovician aquifers of 

the Illinois Basin. A basin-scale flow system would result in 

mass transport (hydrocarbon migration, transport of metals 

in solution) and energy (heat) transport, which would in turn 

drive chemical reactions (for example, maturation of organic 

matter, mineralization, diagenetic reactions) within the Illinois Basin and at its margins.

Fl
F2 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

INTRODUCTION

This study expands on ideas presented in Rowan and 

Goldhaber (1995) and discusses the methods and assumptions. A combination of data and calculations from the traditionally separate disciplines of hydrology, petroleum 

geology, and economic geology provides insight into the 

thermal and hydrologic history of the Illinois Basin and adjacent areas (fig. 1). Fluid flow in this basin, as in many others, 

is intimately linked to heat transfer and thus to generation 

and migration of petroleum and to the maturation of coal. An 

understanding of the Upper Mississippi Valley zinc-lead district, just north of the Illinois Basin (fig. 1), provides unique 

information on the thermal regime and hydrology of the 

basin. The Upper Mississippi Valley district represents a 

local area in which fluids discharged upward from the underlying aquifers. The temperature of fluids trapped in inclusions in sphalerite places a lower limit on fluid temperature 

as the fluids moved upward into fractures from these aquifers. Biomarker measurements provide a time-temperature 

relationship that, in conjunction with temperatures determined independently by fluid inclusions, can be used to calculate the duration of sphalerite mineralization. This 

duration represents the time interval over which warm fluids 

circulated through the basal aquifers in the Illinois Basin.

Migration of brine during the late Paleozoic is increasingly recognized as a widespread phenomena affecting the 

sedimentary rocks of the Midcontinent region of the United 

States. In the Ozark region of Missouri, Arkansas, Kansas, 

and Oklahoma, several lines of evidence document this 

regional-scale migration of fluids (see, for example, Leach 

and Rowan, 1986; Bethke and Marshak, 1990). Evidence for 

this migration includes paleomagnetic studies on both carbonate-hosted Mississippi Valley-type ore districts and the 

unmineralized carbonate rocks between these districts, all of 

which were remagnetized in the late Paleozoic by migrating 

fluids (Pan and others, 1990; Symons and Sangster, 1991). 

Paleozoic carbonate rocks in the Ozark region were exposed 

to warm, saline, dolomitizing hydrothermal fluids. Cathodoluminescence microscopy studies show a microstratigraphy 

within dolomitic cements that is correlatable over several 

hundred kilometers and is indicative of a very large regional 

flow system (Gregg and Shelton, 1985; Rowan, 1986; Fair, 

1989). These correlatable dolomite cements are present as 

part of the ore paragenesis in the Southeast Missouri Mississippi Valley-type district (Viburnum trend) and link the 

dolomitizing fluids to mineralization (Voss and Hagni, 

1985).

Fluid inclusion temperatures both within and between 

the Ozark ore districts are anomalously high relative to temperatures calculated from a maximum estimated burial depth 

and a geothermal gradient controlled by basement heat flow 

(Leach and others, 1975; Leach and Rowan, 1986; Rowan 

and Leach, 1989). This anomalous thermal regime requires a

mechanism such as gravity flow to redistribute heat from 

nearby deeper (and hotter) sedimentary basins to shallower 

platform areas that host ores and hydrothermal dolomite 

cements. Fluid inclusion temperatures for the shallower 

rocks on the Ozark platform are consistent with gravity flow 

and advective heat transport by fluids originating in the deep 

Arkoma Basin. In a gravity-driven flow system fluids moved 

continentward (northward) driven by meteoric water 

recharge in the highlands of the Ouachita foldbelt that 

formed during the Late Pennsylvanian and Early Permian 

Appalachian-Ouachita orogeny (Bethke and others, 1988; 

Bethke and Marshak, 1990; Garven and others, 1993).

The Illinois Basin region, which is the focus of this 

study (fig. 1), has also experienced extensive regional fluid 

flow during its history. Our working hypothesis is that northward regional fluid flow also occurred in the Illinois Basin, 

driven by tectonic-hydrologic processes directly analogous 

to those operating to the west in the Ozarks. Evidence both 

for basinwide fluid flow and for a south to north flow direction includes development of a systematic zonation in carbon 

and oxygen isotopes of authigenic dolomite cements (Pitman 

and Spottl, in press), the near simultaneous formation of 

major base-metal- and fluorite-bearing ore districts (table 1), 

and long-distance migration of hydrocarbon fluids (Bethke 

and others, 1991).

Figure 2 and table 1 summarize what is known about 

the tectonic history of the Illinois Basin and the mineralization history of the Upper Mississippi Valley and Southern 

Illinois fluorite districts. Fluid inclusions in sphalerite dated 

as 270+4 Ma record the presence of brines of probable deep 

basin origin in the Upper Mississippi Valley district. Rock 

alteration and lead loss from the upper basement and illitization of bentonite in the northern Illinois Basin indicate fluid 

circulation through the basal aquifers at approximately the 

same time, 260±35 Ma (Doe and others, 1983). In southern 

Illinois, the Early Permian was a period of intense igneous 

activity during which Hicks dome formed, related igneous 

rocks were emplaced, and the Southern Illinois fluorite district developed. Hydrocarbon generation and migration 

broadly coincide in time with these events (Cluff and 

Byrnes, 1991). Development or reactivation of many of the 

major structural features of the Illinois Basin area may have 

preceded the events noted above (Kolata and Nelson, 1991). 

These Permian ages contrast with Devonian ages for authigenic potassium feldspars in Cambrian-Ordovician strata; 

the Devonian ages may be related to the Acadian orogeny 

(Hay and others, 1988).

Fluid inclusion temperatures in ore and gangue minerals in the Upper Mississippi Valley district provide a record 

of the region's thermal history. The Upper Mississippi Valley district was at maximum burial depth at about the time 

that it formed in the Permian, but even then it was not buried 

to more than approximately 1 km. A geothermal gradient of 

25°C/km, typical of continental regions, should have
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT

94° 92° 90° 88° 86°

F3

84°

44°

42°

40°

38°

36°

34'

. . UPP.ER MISSISSIPPI . 

. . VALLEY DISTRICT .

...... _ . . . .

:>w:::«W FQREST CITY

OLD LEADV 

BELT \

*iv/.* TRI-STATE

MARGIN OF MISSISSIPPI 

EMBAYMENT OF THE GULF COAST

- MARGINOFAPPALACHIANOUACHITAOROGENIC BELT

200 KILOMETERS

Figure 1. Location of the Upper Mississippi Valley district and area of outlying mineralization, central United States. Crosshatching 

indicates areas of Pennsylvanian rock outcrop, the youngest Paleozoic basin fill not removed by erosion. Asterisk (*) indicates location 

of mining district. Modified from Bethke (1986) and Buschbach and Kolata (1991).
Table 1. Recently published ages for the Upper Mississippi Valley and Southern Illinois fluorite districts and the Hicks dome.

Location

Upper Mississippi Valley district

Upper Mississippi Valley district

Upper Mississippi Valley district, southeastern

margin, northern Illinois Basin

Southern Illinois fluorite district

Southern Illinois fluorite districtHicks dome

Grants intrusive brecciaGrants intrusive brecciaHamp Mine intrusive breccia

Grants intrusive breccia and Downeys Bluff sillDowneys Bluff sill

Mineral or rock 

type dated

SphaleriteSphalerite

Basement granite

Fluorite

Fluorite

Hornblende

Biotite

Biotite

Limestone, brecciaBiotite

Age

269±6 Ma

270±4 Ma

260±35 Ma

272+17 Ma

Late Jurassic

271.7±0.7Ma

272.7±0.7 Ma269.4±0.4 MaEarly Permian

275±24 Ma

Method

Rb-Sr

Rb-Sr

U-Th-Pb

Sm-Nd

Paleomagnetism

Ar-Ar

Ar-ArAr-Ar

PaleomagnetismRb-Sr

Reference

Brannon and others (1992).

Brannon and others (1992).

Doe and others (1983).Chesley and others (1994).

Symons(1994).Snee and Hayes ( 1992).Snee and Hayes ( 1992).

L.W. Snee (oral commun.).

Reynolds and others (1992).

Zartman and others (1967). 1

'Recalculated by Reynolds and others (1992).

M 

O

r

H

on

S

productive south-central part of theUppr flley district, southwest ofSchullsburg, inLa

I 

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Illinois Basinand itheUpper Mississippi consists oflower Paleozoic sandstone and<i Valley di:carbonate r

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Figure 2. Timing of major structural, tectonic, and mineralization events related to the Upper Mississippi Valley and Southern Illinois fluorite distric

from Kolata and Nelson (1991).
F6 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

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Platteville Formation

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Description

Dolomite, buff, cherty; Pentamerus oblongus common

Dolomite, buff, cherty

Dolomite, gray, argillaceous

Disconformiiy 

Shale, blue, dolomitic; phosphatic depauperate fauna at bas

Dolomite, vellowish-buff, thin-bedded, shalv 

Dolomite, yellowish-buff; thick-bedded; Receptaculites in 

middle

Dolomite, drab to buff, thick-bedded; Receptaculites at 

base

/Dolomite, limestone, and shale, green and brown; phosph

nodules and bentonite near base

Limestone and dolomite, brown and grayish; green, sandy 

shale and ohosohatic nodules at base

Sandstone, quartz, coarse, rounded

Dolomite, light-buff, cherty; sandy near base and in upper 

part; shaly in upper part

Sandstone, siltstone, and dolomite

Sandstone and siltstone, glauconitic

Sandstone

Siltstone and sandstone

Sandstone

Average 

thickness 

(meters)

58+

14-15

3-35

91+

; 33-73

12 

24

32

itic 1 1-

69

12

17-23

12+

0-73 85-98

37-48

34-43

18-43

21- 

101

134- 

238

213- 

320

Figure 3. Stratigraphy of the Upper Mississippi Valley zinc-lead district. Modified from Heyl (1968).

Wisconsin (fig. 4). The Thompson and Temperly orebodies, 

like many others in the Upper Mississippi Valley district, are 

in Ordovician carbonate rocks, primarily the Quimbys Mill 

Member of the Platteville Formation, the Decorah Formation, and the lower part of the Galena Dolomite (fig. 5) (Heyl 

and others, 1959; Hatch and others, 1986). Sphalerite and 

galena ore was localized primarily by high-angle fractures. 

In some mines these fractures intersect permeable horizons
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F7

92° 91° 90°

43'

42'

\-^____]Boundary of 

\ driftless area

\

Upper Mississippi Valley district

Figure 4. Principal mineralized area in the Upper Mississippi Valley district. Modified from Heyl and others (1959).

and bedding-plane fractures that may also localize ore deposition. A detailed description of the district geology is given 

in Heyl and others (1959) and Heyl (1968).

FLUID INCLUSIONS

Of several fluid inclusion studies conducted in the 

Upper Mississippi Valley district (Newhouse, 1933; Bailey 

and Cameron, 1951; Erickson, 1965; McLimans, 1977) the 

most complete was carried out by McLimans (1977), who 

measured homogenization temperatures of sphalerite-hosted 

fluid inclusions from three mines in the district, the West 

Hayden, South Hayden, and Edgerton. There is almost complete overlap in the data from each mine, and no trends could 

be defined on the basis of geographic location within the 

region studied. McLimans related the position of each fluid 

inclusion to a well-defined color-banding "stratigraphy" that 

he correlated among sphalerite samples from mines throughout the Upper Mississippi Valley district (McLimans, 1977; 

McLimans and others, 1980). The Thompson-Temperly

mine is approximately 5 km from the mines in which fluid 

inclusion measurements were made, at the margin of the 

region across which there is a detailed correlation of the 

sphalerite stratigraphy (Mullens, 1960, plate 25; McLimans, 

1977, fig. 8). Correlation of this stratigraphy districtwide 

provides evidence for hydrologic continuity and for similar 

physical and chemical conditions throughout the Upper Mississippi Valley district (McLimans and others, 1980). We 

assume that the temperature range reported by McLimans 

(1977) prevailed also in the Thompson-Temperly mine for 

which there are no fluid inclusion data.

The complex sphalerite stratigraphy can be summarized as three zones: A (oldest), B, and C (youngest) (fig. 6). 

Figure 7 shows the homogenization temperature data of 

McLimans plotted as a function of relative age or position in 

the sphalerite paragenesis. This figure shows the evolution 

of temperature, as a function of relative time, during precipitation of the sphalerite. On the basis of almost uniform 

thickness of the sphalerite stratigraphy across the district, 

McLimans and others (1980) assumed approximately constant rates of sphalerite precipitation districtwide. We
Formation

Galena 

Dolomite

Decorah 

Formation

Platteville 

Formation

St. Peter 

Sandstone

Member and 

subdivision

Prosser Cherty 

Member unjt

Ion Dolomite 

Member

Guttenberg 

Limestone Member

Spechts Ferry 

\

Shale Member

Quimbys Mill 

Member 

/

McGregor 

Limestone 

Member

Petronica Polomite 

Member

X X

Glenwood Shale \ 

Member ^

/ / 

/

A/A/

/ / 

/

/ / 

/

/-/ 

/

/ /-/

/ / 

/

/-/ 

/

\ \ \ \ l-l I I- I I

1 l-l i I i i i i i 

O O O CX" ^\^~^\ 1 --'I 1 1 1 1 /-/-/

1 1 1 / / 

/ 1 I 1 1 / / 

/ 1 1 1 1 l'l

1 1 ' ' 1 1 1 / / 

/ / / 

/ / / 

/ / / 

/ / / 

/

Description

Dolomite, drab to buff, thick- to thin-bedded, cherty; Receptaculites abundant

' Dolomite and limestone, light-gray, argillaceous; grayish-green dolomitic shale

y^ Limestone, brown, fine-grained, thin-bedded, nodular, conchoidal; dark- ' brown shale

/ Shale, green, fossiliferous; greenish-buff fine-grained limestone

Dolomite and limestone, dark-brown, fine-grained, sugary, medium-bedded, 

conchoidal; dark-brown shale, especially at base

\

Limestone and dolomite, light-gray, fine-grained

v Limestone, light-gray, fine-grained, thin-bedded, nodular, conchoidal

Dolomite, brown, medium-grained, sugary, thick-bedded, blue-gray where weathered

Shale, green, sandy

Sandstone, quartz, medium- to coarse-grained, poorly cemented, crossbedded

Thickness of 

unaltered rock 

(meters)

11

6

4-5

0-2

0-5

4-5

4-5

6-7

0-1

10-1317-23

12+

w o

o zo fl

C/3

w o

m2;H

CO> 

23

^

IF 

r

1

on 03

Figure 5. Stratigraphy of lower Paleozoic rocks in the Upper Mississippi Valley district. Modified from Heyl and others (1959).
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F9

VeinFigure 6. Spatial and time relationships between sphalerite 

zones A, B, and C in a hypothetical vein. Fluid inclusion measurements show decreasing temperature with time.

assume as well that zones A, B, and C represent equal intervals of time.

Four distinct post-sphalerite stages of calcite (Heyl and 

others, 1959) formed as long as 111 m.y. after the sphalerite 

(Brannon and others, 1993). In contrast to fluids in the 

main-stage sphalerite, these calcite phases contain low-salinity inclusion fluids that have a distinct deuterium-oxygen 

isotopic signature (McLimans, 1977, fig. 21). The fluid 

inclusions are interpreted to represent conditions that prevailed a substantial time after decay of the fluid flow system 

responsible for sphalerite mineralization.

To define temperature at the ore horizon for the fluid 

heat flow model, we chose high- and low-temperature paths 

and a best-fit path through the sphalerite fluid-inclusion data 

(fig. 7). A polynomial curve was fit to the homogenization 

temperature data, and within each zone, A, B, and C, the 

approximate average value on this curve was taken as 

best-fit temperature. Values for the high and low time-temperature histories were chosen by inspection, as representative of the high or low end of the range of homogenization 

temperatures.

Figure 7 shows significant scatter in the homogenization temperature measurements for primary fluid inclusions 

from the same, or correlative, sphalerite growth zones. 

Although the mineralizing fluid undoubtedly underwent 

some temperature fluctuation, a significant proportion of the 

variability is most likely due to "necking-down," a process 

whereby an inclusion having a high aspect ratio evolves by 

dissolution and reprecipitation into two (or more) more 

equant inclusions. If necking-down occurs after a vapor bubble has nucleated, the liquid-vapor ratios, and thus the 

homogenization temperatures, in the new, necked inclusions 

will be erroneous and, in some cases, will differ greatly from 

those of an undisrupted inclusion. The necking-down phenomenon is discussed in more detail by Roedder (1984).

Fluid inclusions that are present at the same horizon in 

a specific growth zone are generally considered to be contemporaneous and to have formed from a fluid that has a single temperature and composition. Consequently, they should 

have the same homogenization temperature; if they do not, 

then a process such as necking-down may have disrupted the 

inclusion after its entrapment. Furthermore, some homogenization temperatures in Upper Mississippi Valley sphalerites are unreasonably high, given the thermal maturity of the 

biomarkers and organic matter in the surrounding rocks. If 

the rocks adjacent to the sphalerite are accepted as thermally 

immature with respect to hydrocarbon generation (Hatch and 

others, 1986), they cannot have experienced temperatures as 

high as 218°C, for example (fig. 7; see discussion in section 

on "Biomarkers" following). We interpret the extreme upper 

end of the homogenization temperature distribution 

(>160°C) as the result of necking-down. Inclusions in the 

process of necking-down are easily recognized and avoided; 

however, if the process is complete, it may be impossible to 

detect by any direct means.

Necking-down produces both erroneously high and low 

homogenization temperature values, but the magnitude of 

the change is unpredictable. To approximate an average 

homogenization temperature undisrupted by necking-down 

for each of the three zones, we chose values on a polynomial 

best-fit curve through the data, as described earlier (fig. 7). 

For comparison, we fitted a normal probability function to 

the homogenization temperatures (fig. 8). The means of 

these distributions coincide closely with values taken from 

the polynomial best-fit curve.

A pressure correction would increase the homogenization temperatures by approximately 10°C for a burial depth 

of 1 km, assuming that NaCl is the predominant salt species 

in solution; however, dissolved gases such as CH4 or CC»2 

would decrease the pressure correction from the pure 

water-salt system value (see, for example, Hanor, 1980). 

Given the relatively small value of the maximum pressure 

correction, and the likelihood of at least small quantities of 

dissolved CC»2 and CFL; in the inclusion fluid, we chose to 

neglect the pressure correction in this study.

The time-temperature histories that we examined consist of a single, distinct temperature for each zone, A, B, and 

C. The times spanned in each individual zone were assumed 

to be equal, but the total time is unknown. In the calculations 

described following, we varied total time for each time-temperature path until the calculated biomarker maturity 

approximately matched the values measured by Hatch and 

others (1986).

SULFUR ISOTOPE 

GEOTHERMOMETRY

Under certain conditions, sulfur isotope ratios may indicate the temperature of sulfide precipitation. Sulfur isotope 

ratios were measured in sphalerites and galenas from 11 ore-
O

220200

180

160140120

100

806040

20 ___ n __ga_i_5o_°c_ _ E n n "-biss'c

B

Sphalerite 

(270 ±4 Ma)

Temperature-time paths

High : 150 °C, 145 °C, 115 °C 

Mid: 135 °C, 130 °C, 105°C 

Low: 120'C, 115 °C, 95 °C

Calcite 

(159 Ma)

-Relative paragenetic position-

| i i i > | i i i i | i i i i | i i I i | riii | i i i i |

1 2 3

NORMALIZED DISTANCE FROM VEIN WALL, IN CENTIMETERS

220200

180

160

140120100

80

6040

20

W 

Or c

H 

O

00

I

W Z

H

03

O on 03

Figure 7. Fluid inclusion temperatures for three sphalerite zones, A, B, and C (McLimans, 1977), and for three generations, II, III, and IV, of late, postmineralization calcite 

(Erickson, 1965) in the Upper Mississippi Valley district. The solid lines are polynomial best fits to the data (see text for discussion). Radiometric ages of sphalerite (27Qt4 

Ma) and calcite (159 Ma) mineralization were determined by Brannon and others (1992, 1993).
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT Fll

180 200

200

_ Zone A (oldest)

20 40 60 80 100 A A 140 A 16° 

HOMOGENIZATION TEMPERATURE, IN °C

180 200

Figure 8. Histograms of fluid inclusion homogenization temperature by sphalerite zone. The solid curves show a normal distribution fitted to the data set. Triangles indicate the values used to define the high-, low-, and "best-estimate" temperatures for 

each zone. Data from McLimans (1977).

bodies in the Upper Mississippi Valley district (Pinckney 

and Rafter, 1972; McLimans, 1977); however, the 

isotope-derived temperatures are significantly higher than 

the fluid inclusion temperatures (figs. 7, 9). If sphalerite and 

galena are assumed to have formed at chemical and isotopic 

equilibrium, the difference in the isotopic ratios between the 

two phases is a function of their formation temperature. This 

equilibrium temperature was recalculated for the two data 

sets using the fractionation-temperature curve of Ohmoto 

and Rye (1979). Figure 9 shows the resulting equilibrium 

isotopic temperatures plotted versus relative position in the 

sphalerite stratigraphy of McLimans and others (1980). 

Although there is considerable scatter, particularly in the 

measurements of Pinckney and Rafter (1972), there is rough

agreement between the two sulfur isotope data sets. Both 

indicate a pattern of higher temperature early in the 

paragenesis and declining temperature in the later stages, 

similar to the fluid inclusion data.

The isotope-fractionation-derived temperatures are systematically higher than those of the fluid inclusion data 

through approximately the first two-thirds of the paragenesis 

(figs. 7, 9). This relationship is not unexpected and usually 

occurs when the concentration of sulfur in the form of F^S 

in the mineralizing fluid does not significantly exceed the 

concentration of total metals (Ohmoto, 1986). If the concentration of tbS is low, precipitation of the least soluble phase 

(galena) will modify the isotopic composition of the 

remaining H2S in solution by preferentially removing the
F12 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

250

225

200

175

150

cc

UJ 125 

£L

D 

D

D ! D

o

UJ

100

75

50

25

01234 

NORMALIZED DISTANCE FROM VEIN WALL, IN CENTIMETERS

Figure 9. Temperatures calculated from the sphalerite sulfur isotope measurements of Pinkney and Rafter (1972) (solid squares) and 

McLimans (1977) (open squares). The solid line is a polynomial fit to the data. Distances were normalized to the scale of the sphalerite 

stratigraphy defined by McLimans (1977).

light isotope. This case occurs because galena is enriched in 

the light isotope of sulfur as compared to aqueous sulfide. 

Subsequent precipitation of sphalerite will thus occur from 

an thS reservoir enriched in the heavy isotope. This process 

increases the isotopic difference between ZnS and PbS and 

leads to calculation of apparent temperatures of formation 

above the true value.

BIOMARKERS

Biomarkers were originally used primarily as an indicator of provenance or depositional environment, hence their 

name. The two categories of biomarkers that we discuss here, 

steranes and triterpanes (of which hopanes comprise one category), are sometimes referred to as "chemical fossils" 

because their basic structure is similar to a known contemporary natural product. Steranes and triterpanes are not found 

in living organic matter, but closely related compounds (for 

example, triterpenoids and steroids) are present in many 

organisms. During diagenesis, some of these precursor molecules are converted through a complex series of reactions 

into more stable, saturated-hydrocarbon biomarkers that are 

preserved in geological samples (see, for example, references in Waples and Machihara, 1991). In the last decade, the 

rates at which several of the biomarker compounds undergo 

isomerization reactions as a function of temperature have 

been well established (Mackenzie, 1984; references in 

Lewis, 1993). Progressive changes in the ratio of biomarker 

reactant to product ratio are a measure of thermal stress, or 

temperature integrated over time. The biomarker data of 

Hatch and others (1986) provide an important constraint on 

the thermal history of the Thompson-Temperly mine.

Among the best characterized of these biomarker transformations are the isomerization reactions at C-20 in 

5a(H),14a(H),17a(H)-steranes, and at C-22 in 

17a(H),21(3(H)-hopanes (fig. 10) (Mackenzie, 1984; Marzi 

and Rullkotter, 1992, p. 19). Hatch and others (1986) measured the extent of these reactions in C29 24-ethyl-sterane 

and in C3i-homohopane. In the sterane isomerization reaction, a precursor of biological origin that has 20R configuration is transformed to the 20S epimer (fig. 11), a reaction that 

occurs naturally only in the geosphere (Marzi and Rullkotter, 

1992, p. 22). R and S refer to rectus and sinister, mirror 

image orientations of an epimer (Waples and Machihara, 

1991, p. 4). The initial concentration of the product (20S) in 

the organic-bearing sediments is assumed to be zero and
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F13

STERANES

27

TRITER PANES

34

24

B

Figure 10. Numbering system for carbon atoms in (A) steranes and (fi) triterpanes (includes hopanes). The steranes are 

identified by the orientation of the hydrogens located at carbon atoms C-5, C-14, and C-17 and the hopanes by the orientation 

of the hydrogens located at carbon atoms at C-17 and C-21. Isomerization reactions take place at C-20 and C-22 in steranes 

and hopanes, respectively. Modified from Waples and Machihara (1991).

proceeds to an equilibrium ratio of 20S/20S+20R=0.55. 

Similarly, the isomerization reaction for hopane progressively transforms the original, purely biogenic precursor that 

has 22R configuration into a mixture of precursor (22R) and 

product (22S) whose maximum ratio is 0.60 (Peters and 

Moldowan, 1993; also see references in Marzi and 

Rullkotter, 1992, p. 22-23).

Laboratory experiments carried out on initially mature 

rocks have in several instances resulted in a reversal in the 

trend toward increasing sterane maturity ratios 

(20S/20S+20R) with further thermal stress. Lewan and others (1986) noted such a reversal in the sterane isomerization 

trend during hydrous pyrolysis experiments on the Phosphoria Retort Shale. The sterane epimer ratio for the
F14 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

STERANE

20R 20S

REACTANT PRODUCT

HOPANE

22R 22S

8

REACTANT PRODUCT

Figure 11. Isomerization reactions for the specific sterane and triterpane whose maturity ratios are used in this study, (#) 5a(H), 

14<x(H),17cc(H) 24-ethylcholestane and (fi) C31-17<x(H),21(3(H) homohopane. See figure 10 for the numbering system for the carbon atoms. Open circles and open wedges denote bonds oriented in alpha configuration (pointing down), and solid circles and 

hatchured wedges denote bonds in beta configuration (pointing up). Modified from Waples and Machihara (1991).

starting material was 0.42. Marzi and Rullkotter (1992) 

noted a similar reversal in the sterane ratio during laboratory hydrous pyrolysis experiments. The maturity ratios in 

their samples reached a maximum near 0.54 and then 

declined to lower values (Marzi and Rullkotter, 1992, figs. 

2.1, 2.2); however, hopane maturity ratios did not show a 

reversal. Abbott and others (1990) and Marzi and Rullkotter 

(1992) attributed the reversals to the preferential destruction 

of the 20S sterane epimer in samples that are at or near their 

maximum maturity ratios.

Individual biomarkers are sensitive as measures of 

maturity over different ranges of thermal stress. Both the 

hopanes and the steranes used in this study record conditions 

of relatively low thermal maturity. The hopanes record conditions to the beginning of early oil generation (vitrinite 

reflectance, RQ, approximately 0.6 percent), and the steranes

record conditions up to the beginning of peak oil generation 

(approximately 0.8 percent R0) (fig. 12) (Mackenzie, 1984, 

fig. 26; Peters and Moldowan, 1993, fig. 3.46).

The samples collected from the Upper Mississippi Valley district are at an early stage of maturity and oil generation 

is still "incipient." The Guttenberg Limestone Member of 

the Decorah Formation (fig. 5), for example, which overlies 

the Platteville Formation from which the biomarker samples 

were collected, is referred to locally as "oil rock" because of 

the small amounts of oil staining associated with the dark, 

organic-rich, shaly horizons (Heyl and others, 1959). The 

average sterane ratio measured by Hatch and others (1986) 

is 0.35 (table 2), corresponding to immature and early stages 

of oil generation (fig. 12). The hopane ratio, which is not 

known to undergo reversals, averages 0.58 and also corresponds to immature oil. Because the maturity with respect to
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F15

Table 2. Sterane and hopane biomarker maturity ratios in the barren drift between the Thompson and Temperly orebodies.

[From Hatch and others (1986). Distance is position of the sample relative to a point within main orebody of Thompson mine (see text for discussion).

R, reactant or precursor compound; P, product]

Sample No.

Distance 

(meters)

Sterane 

P/R

Sterane 

P/(P+R)

Hopane 

P/R

Hopane 

P/ (P+R)

Limestone

TT64-2A

TT64-3A

TT64-5A

TT64-7A

TT64-13A

Average limestone

5.72

9.53

32.39

44.45

161.93

50.80

0.48

0.52

0.53

0.60

0.55

0.54

0.32

0.34

0.35

0.38

0.35

0.35

1.25

1.24

1.32

1.53

1.34

1.34

0.56

0.55

0.57

0.60

0.57

0.57

Shale

TT64-3

TT64^

TT64-5

TT64-7

TT64-8

TT64-13

Average shale

Average (limestone and shale) 

Theoretical maximum

9.53

24.77

32.39

44.45

51.44

161.93

54.09

52.59

0.48

0.50

0.65

0.52

0.57

0.61

0.56

0.55

0.32

0.33

0.39

0.34

0.36

0.38

0.36

0.35 

0.55

1.26

1.43

1.33

1.33

1.51

1.45

1.39

1.36

0.56

0.59

0.57

0.57

0.60

0.59

0.58

0.58 

0.60

t

ID

o

22S/(22S+22R)=0.60 Hopane

I 20R/ (20S+20R)=0.55 Sterane

o 0.4 0.5 0.6 0.7 0.8 1.0 1.4

| | Immature oil

STAGES OF OIL GENERATION

Peak 3 Late fTl Condensate/wet gas

Figure 12. Maximum thermal maturity of hopane and sterane compared with stages of oil generation and with vitrinite reflectance 

(R0, in percent). Modified from Peters and Moldowan (1993).
F16 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

12.0

11.0

10.0

9.0

CO

5 8.0 in

>

Z 7.0

uf

p= 6.0

O

g 5.0

4.0 

3.0 

2.0 

1.0

0.0

"s* Hopane = 0.577

Sterane = 0.353 

20 40 60 80 100 120 140

TEMPERATURE, IN °C

160 180 200 220

Figure 13. Biomarker isomaturity curves for time-temperature combinations that give calculated maturities equal 

to the average of hopane and steranes ratios measured in the Upper Mississippi Valley district. Data from Hatch 

and others (1986).

Table 3. Kinetic constants for sterane and hopane isomerization reactions.

[From Marzi and Rullkotter (1993). A sample calculation shows biomarker maturity ratios [P/ (P+R)] based on the following relationships:

k=A0 e(~Ea/RTK); P/ (P+R)=l-e~kt . R, reactant or precursor compound; P, product; temperature 130°C; duration 200,000 years]

Sterane 

Hopane

Pre-exponential factor

A0 (S-')

4.86x1 0+8 

8.10xlO+8

Activation energy 

Ea (kJ/mol)

169 

168

Rate constant k

(s- 1 )

-6.17X10" 14 

-1.39X10- 13

Sample calculation 

P/ (P+R)

0.32 

0.58

oil generation is low, we are confident that the sterane ratios 

reflect conditions of overall low thermal maturity and were 

not achieved by a reversal from earlier, higher values. Good 

agreement between the sterane and hopane maturities is further evidence that progressive isomerization has not been 

disrupted in the sterane by a possible reversal (fig. 13).

The biomarker transformation reactions are non-linear 

and are treated as first-order reactions,

dC/dt=-kC,

where C is the mass of reactant in the system, k is a rate constant, and t is time. The equation can be integrated to give the 

ratio of reactant remaining (C) to the initial concentration of 

reactant (C0) in the system (see Barker, 1989)

C/C0=e _~-kt

The rate constant, k, is given by the Arrhenius equation

where A0 and Ea are empirical kinetic parameters, R is the 

gas constant, and TK is temperature (Kelvin). In the numerical calculations described in the next section, temperature is 

held constant for each of three stages of mineralization at 

values determined from the fluid inclusion data. We used 

values from Marzi and Rullkotter (1992) for the pre-exponential factor, A0, and activation energy, Ea (table 3). Their 

approach combines results of both laboratory hydrous 

pyrolysis experiments performed at short durations and 

field-derived information that represents much longer 

durations. Waples and Machihara (1991) favored this 

approach because it incorporates information representing a 

large range in time.
EXPLANATION FOR PLAN VIEW 

Approximate extent of mineralized rock

Approximate extent of alteration aureoleSolid line indicates mapped boundary

Outline of mine workings 

Sample location and number

Temperly 

orebody

/

t; 0.6- 

<

^°

< 

*£

<H 0.4^ 

So

^5

£8 0.3-J

DC DC

< 0.

00 0.2-

0.0-

-----Hopane avg. ---- -----------J---. --------

O+QK o no o\ ir\ ^fe

Tmax av9- +

 nP

c»°

-^^s3

05

h-425*

O

-400

100 200 300 400 500

DISTANCE, IN METERS

Thompso

orebody

EXPLANAT

 Hopane (li

n Hopane (s

O Sterane (li

O Sterane (s

+ Tmax (lim

X Tmax(sha

Figure 14. Sample sites in the Thompson and Temperly orebodies and alteration halo and along the barren drift between the two mines. S

from the Quimbys Mill Member of the Ordovician Platteville Formation, from a thin, continuous shale layer, and from the adjacent, overly

marker measurements (left axis) and Tmax values (right axis) for individual sites are shown in the graph. Data from Hatch and others (19

from Heyl (1968) and Hatch and others (1986).
F18 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

Hatch and others (1986) measured sterane and hopane 

biomarker ratios in samples collected at the Thompson-Temperly mine, both within the Thompson orebody and along a 

barren drift at sites extending approximately halfway to the 

Temperly orebody (fig. 14). Samples were collected both 

from the shaly basal part of the Quimbys Mill Member of the 

Platteville Formation and from the overlying limestone. It is 

significant that the biomarker ratios show no clear, systematic trend in thermal maturity with distance from the Thompson orebody (fig. 14) (Hatch and others, 1986). The 

analytical error of the measurements maturity ratio measurements is ±0.005 (D. King, personal commun.). Scatter in the 

measurements reflects the overall error due to factors such as 

inhomogeneity among individual samples, but significantly, 

there are no systematic differences between samples from 

the limestone versus the shale (see the section on "Sources 

of Error," following).

Tmax, another common measure of thermal maturity, 

also was examined both at the Thompson and Temperly orebodies and at a number of sample sites along the drift 

between them (fig. 14). Tmax records the temperature of 

maximum hydrocarbon generation during pyrolysis and provides a reliable indicator of relative thermal maturity (Tissot 

and Welte, 1984). Tmax values of less than 435°C generally 

indicate thermally immature samples. Because the Tmax values exhibit only a small degree of variation, and no systematic trend between the mines, we are confident that thermal 

conditions adjacent to the Temperly orebody are similar to 

those reflected in biomarker measurements made in and 

adjacent to the Thompson orebody.

Using the product to reactant ratios measured by Hatch 

and others (1986) and the kinetic constants of Marzi and 

Rullkotter (1992), we were able to define the range of time 

and temperature that would give biomarker ratios equal to 

the average measured hopane and sterane values (fig. 13). 

The temperature range shown in figure 13 is equal to the 

range of fluid inclusion homogenization temperatures measured by McLimans (1977). Although the diagram assumes 

a single, constant temperature, it nevertheless provides useful constraints, At 50°C, for example, it would take approximately 53 billion years to obtain the observed biomarker 

maturities, but at 220°C these maturities would be attained in 

approximately 20 years.

FLUID- AND HEAT-FLOW AND

THERMAL MATURITY

CALCULATIONS

The Thompson and Temperly orebodies are in permeable, fractured zones in otherwise low-permeability rock. In 

our conceptual model, mineralizing fluid circulates upward 

through fracture zones, and heat moves out into unmineralized rock. Heat transport is primarily by advection within

fracture zones and primarily by conduction in adjacent 

unmineralized rock. Elevated heat flow due to the presence 

of hot fluids in the fracture zones and in underlying aquifers 

plays an important role in thermal maturation of the biomarkers.

The immediate source of the warm, mineralizing fluid 

is an underlying aquifer; the highly permeable Mount Simon 

and St. Peter Sandstones have been suggested as likely possibilities (see, for example, Heyl, 1968). The ultimate source 

of the fluid is not addressed by the calculations but is discussed in the next section. Fluid inclusions provide a temperature constraint for the orebodies, and the biomarkers give a 

measure of thermal maturity (a function of both time and 

temperature) both in the orebodies and in the adjacent 

unmineralized rock. Our approach to combining these two 

constraints was to find durations that, given a specific temperature history for the orebodies, gave biomarker maturities 

consistent with the measurements of Hatch and others 

(1986). We made an initial estimate using an average temperature and the time read from the curves in figure 13. Then, 

using a fluid-inclusion derived temperature history, we 

adjusted time until we achieved the best possible match, for 

both hopane and sterane, between the measured and calculated biomarker maturities.

Coupled, numerical fluid- and heat-flow calculations 

were carried out using a finite difference program, HYDROTHERM (Hayba and Ingebritsen, 1994), to determine the 

time interval needed to produce the observed biomarker 

maturities. The program calculates the density of water as a 

function of temperature but does not account for salinity. 

Incremental and cumulative thermal maturities are calculated for each time step, at each cell in the grid, using a subroutine written to work in conjunction with the flow 

program.

BOUNDARY CONDITIONS AND GRID

Figure 15 shows a schematic cross section through the 

Thompson-Temperly mine and the configuration of the flow 

model. The horizontal dimension of the grid is 380 m, determined by projecting the sample sites of Hatch and others 

(1986) onto a line drawn orthogonal to the trend of the Temperly orebody and intersecting the Thompson orebody (fig. 

16). Two vertical dimensions of the grid were utilized, representing two possible depths for the upper surface of an 

aquifer system underlying the Platteville Formation. The 

vertical dimension of 1,485 m assumes a lower grid boundary at the top of the Mount Simon Sandstone and that of 

1,150 m a boundary at the top of the St. Peter Sandstone. 

Fluid circulates upward from the aquifer through near-vertical fractures to the mineralized horizon.

The symmetry of the cross section, as conceptualized 

here, implies a fluid- and heat-flow divide midway between 

the two orebodies at which the temperature and pressure 

gradients are zero. Calculations are therefore carried out in
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F19

SPECIFIED TEMPERATURE AND PRESSURE BOUNDARY

BOUNDARY OW 

0

Z

9.5

t

t

m '

^ 360 m 

Fracture Unmineralized rock Fracture

zone zone

Permeability Thermal conductivity 

Fracture zone: 10-11 (m2) 2.5 (W-m'1-K' 1 ) 

Country rock: 10-16 (m2) Porosity H20 

Heat capacity Fracture zone: 25% 

1.05x1o3(J.kg-1.K-1) Country rock: 1%

Thompson 

Temperly orebody ^

orebody

Quimbys Mill Member (biomarker sample sites) )

r?"-° ...- ... ,.- ...- ,. .. " ..- ./ ..- " .- ' ...- ..-' ,.- //,- ./ .. .. / ,.- " ,-- / .,.' .,.- ..- x ..- ,.- .. ..' y .- .- .. ,- / ,.- .- .' 

9.

>^

^

*

 -

m

5 m

t

t

Upper surface of Mount Simon or St. Peter Sandstone

SPECIFIED TEMPERATURE AND PRESSURE BOUNDARY

Figure 15. Schematic cross section showing configuration of flow model. Fluid inclusion measurements 

for the district constrain temperature at the mineralized horizon. Thermal maturities were measured in samples from the Quimbys Mill Member of the Ordovician Platteville Formation. A fixed-temperature basal 

boundary was tested at two positions corresponding to the Mount Simon and the St. Peter Sandstone Sandstones. Heavy arrows indicate fluid circulation upward from the underlying aquifer(s) through the fracture 

zones. See text for discussion.

the half-space that extends from one fracture zone to the central symmetry plane, or no-flow boundary. The fracture zone 

itself has a symmetry plane at its center and is also modeled 

as a half-space. The half-space cross section was divided into 

434 cells, using 14 columns and 31 rows. Intersecting lines 

show the positions of the nodes at the center of each cell in 

the grid (fig. 17). The spacing of rows and columns is variable; cells are smaller near the fracture zone and near the 

Quimbys Mill horizon where more detail is desirable. The 

top boundary, representing the ground surface, is one of 

specified temperature and pressure, except for four cells at 

the top of the fracture zone for which fluid flux is specified. 

Two types of thermal boundary condition were tested at the 

base of the grid: (1) specified temperature, representing the 

top of the Mount Simon or St. Peter Sandstone, and (2) specified heat flux from the basement. Pressure was fixed at the 

bottom boundary.

The variations in fluid temperature with time that we 

specify at the bottom boundary were constrained by fluid 

inclusion temperatures measured in the district (see preceding discussion ). The three stages of temperature evolution, 

corresponding to zones A, B, and C in the sphalerite stratigraphy of McLimans (1977), represent an extreme simplification of the true temperature history, which, for example, 

would have changed as a smooth function of time rather than 

in stairstep fashion. Furthermore, our temperature information applies, strictly speaking, only to the ore horizon in the 

Upper Mississippi Valley district, and we have no temperature information for the fluids in the underlying aquifers. If, 

however, we specify the aquifer temperatures as the values 

observed in the ore, advective heat transport by fluid flow in 

the fracture zone causes rapid thermal equilibration so that 

the calculated temperatures at the mineralized horizon match 

the observations. Temperature within the aquifer is assumed 

to be constant on a horizontal scale of several hundred 

meters; that is, on the scale of the cross section between the 

two mines.

The fixed-temperature boundary of the base of the grid 

represents the upper surface of the aquifer. Two positions 

were tested for this basal boundary, the top of the St. Peter 

Sandstone and the top of the Mount Simon Sandstone, 

approximately 15 m and 350 m, respectively, below the 

Quimbys Mill Member of the Platteville Formation. Both the 

Mount Simon and the St. Peter Sandstones have been pro-
EXPLANATION 

["_ ^ Approximate extent of mineralization

Approximate extent of alteration aureole 

Solid line indicates mapped boundary

Outline of mine workings 

Sample location

Temperly 

orebody

Thompso

orebody

Figure 16. Sample sites projected onto a line drawn normal to the trend of the fractures that controlled emplacement of the Thompson and 

ies. The distance between the two orebodies was taken as the horizontal dimension of the grid. Map modified from Heyl (1968) and Hatch 
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F21

>^

F

\ 

rac

zo

ture

ne

/

St. Peter San<

 Q

th

4

/r 

jstone (top)

uimbys Mill Member 

e Platteville Formatic

/

/

/

Mount Simon Sar

*

of 

>n

dstone (top)

- 0

- 100

- 200

- 300

- 400

- 500

- 600

O

h 700 Tj 

I

- 800 "-

- 900 |

-1000 3 

en

-1100

-1200

-1300

-1400

-1500

20 40 60

\ 

80 100 120 

DISTANCE, IN METERS

140 160 180

Figure 17. Grid used in numerical calculations; intersections of grid lines show the positions of the nodes at the center of each cell. 

Because the system is symmetrical, only half of the distance between the two orebodies (fracture zones) is represented here. Three scenarios were assumed: (1) a specified temperature basal boundary at the St. Peter Sandstone, (2) a specified temperature basal boundary 

at the Mount Simon Sandstone, and (3) constant heat flux from the basement, with temperature fixed in the fracture zone immediately 

below the Quimbys Mill Member of the Platteville Formation. Four additional rows, used to extend the grid into the basement for the 

constant heat flux calculation, are not shown here. See figure 15 for conceptual model and boundary conditions.

posed as likely aquifers and a source for the mineralizing fluids (see, for example, Heyl, 1968).

The surface temperature was fixed at 22°C, appropriate 

for this region during the Permian (Cluff and Byrnes, 1991), 

and the bottom boundary was set to fixed values; for example, 130°C-125°C-105°C, for the best-fit temperature path, 

based on the fluid inclusion data (fig. 7). The time intervals 

were equal for each temperature stage, as discussed previously. Calculated biomarker maturities in the Quimbys Mill 

differ only to a small degree as a function of position of the 

basal boundary, Mount Simon versus St. Peter Sandstone. If 

the top of the St. Peter Sandstone is taken to be the upper surface of the principal aquifer, thermal equilibration occurred 

very rapidly within the Quimbys Mill, and the calculated 

biomarker maturities vary very little across the grid between 

the two mines (fig. 18). If this boundary is moved down to 

the top of the Mount Simon Sandstone, thermal equilibration 

took slightly longer time, but the results are similar (fig. 19). 

Initial differences in temperature between the fracture zones 

and sample sites in unmineralized rock are preserved as

cumulative differences in the thermal maturity of the biomarkers; however, these differences are insignificantly small 

(<0.006) even if the Mount Simon is taken as the bottom 

boundary, and they are within the uncertainty of the measurements made by Hatch and others (1986) (fig. 20).

We tested a third boundary condition, a fixed basal heat 

flux of 62.5 mW/m2 , with temperature specified only within 

the fracture zone at the ore horizon. This configuration produces a much larger difference in the thermal maturity ratios 

(0.1), decreasing away from the fracture zone. This result is 

inconsistent with the data of Hatch and others (1986), which 

show no systematic trend with distance either for the biomarkers or Tmax (fig. 14). We conclude that physical conditions approximating a fixed-temperature lower boundary are 

necessary to explain the absence of a gradient of decreasing 

maturity away from the ore. This conclusion is significant 

because a fixed-temperature lower boundary requires 

regional flow through aquifers below the ore horizon. Heat 

is conducted upward from the aquifer, producing 

near-uniform temperatures at the horizontal scale of the
F22 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

100-

200- 

300- 

400- 

500- 

600- 

700- 

800- 

900- 

1000- 

1100-

0.001 _

-^0.330^

Mineralized horizon

0 20 40 60 80 100 120 140 160 180

0-

100- 

200- 

300- 

400- 

500- 

600- 

700- 

800- 

900-

1000

1100H

0.001 _

-0.594^ Mineralized horizon

B

i i i i i i i i I i i i i i i 1 i i i i i i i i i i i i i i i 

20 40 60 80 100 120 140 160 180

0

1 DO200- 

300 

400 

500- 

600- 

700- 

800 

900- 

1000- 

1100-

,40.0

-60.0

-80.0

-100.0

TEMPERATURE

>x. Fracture 

zone

-105.0°C-

?105.0°C_ Mineralized horizon

n i i i i i i i i i i i i i i i i i i i i i i i i i | i i i | i i i | i r 

0 20 40 60 80 100 120 140 160 180

DISTANCE, IN METERS
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F23

Figure 18 (facing page). Contours of calculated thermal maturity 

ratios for sterane (A) and hopane (fi) over the grid, assuming a best 

fit-temperature path and a specified temperature basal boundary at 

the St. Peter Sandstone. Temperatures at the end of the fluid flow 

event are shown in (Q.

mines and biomarker maturities that record the absence of a 

horizontal thermal gradient.

DEPTH OF BURIAL

In a purely conductive thermal regime, depth of burial 

determines temperature. Previous estimates of maximum 

burial depth at the time of mineralization range from 600 to 

800 m (Bailey and Cameron, 1951; Haas, 1961); Cluff and 

Byrnes (1991, fig. 25-6) estimated approximately 900 m of 

erosion in the northern Illinois Basin since the Permian, giving a burial depth on the order of 1 km during mineralization. 

These depths correspond to temperatures of 37°C-47°C, 

assuming a 25°C/km geothermal gradient and a 22°C surface 

temperature, appropriate for the Midcontinent in the Permian 

(Cluff and Byrnes, 1991). The elevated fluid inclusion temperatures in the orebodies clearly require an additional 

source of heat.

Fluid inclusions in the post-ore calcite have an average 

temperature of approximately 50°C (Erickson, 1965) and 

may represent reestablishment of a conductive thermal 

regime long after decay of the mineralizing system. Brannon 

and others (1993) determined a Rb-Sr age of 159 Ma for 

stage II of the four post-ore generations of calcite; thus, 

stages II-IV are at least 110 m.y. younger than the ore and 

have fluid inclusion salinities and oxygen isotope values distinct from those of the ore fluids (McLimans, 1977). We 

hypothesize that fluid flow rates in a regional, gravity-driven 

system gradually declined due to factors such as erosion of 

the elevated recharge area and possibly faulting or diagenetic 

changes in the rocks along the flow path. Warm, highly 

saline brines of deep basin origin were gradually replaced by 

cooler, low-salinity, meteoric water.

We reason that the calcite most likely formed in a conductive thermal regime controlled by basement heat flow 

with little contribution from the thermal effects of 

regional-scale fluid flow. Given a paleogeothermal gradient 

of 25°C/km, and a surface temperature of 22°C, the 50°C 

isotherm would have been at a depth of 1,120 m. We have 

assumed that 1,120 m represents the burial depth during formation of the calcite and take this to be the burial depth of 

the ore and of the Quimbys Mill horizon in the numerical 

model. Our somewhat deeper estimate of maximum burial is 

conservative in the sense that it permits a greater component 

of the heat to be explained by simple burial and by the geothermal gradient. It is important to note, however, that heat 

derived from the underlying aquifer, the fixed-temperature

lower boundary, is the predominant factor influencing the 

biomarker maturity and that burial depth plays a secondary 

role in determining the thermal history at the Quimbys Mill 

horizon.

PERMEABILITY, POROSITY, FRACTURE 

ZONE WIDTH, AND FLUID FLUX

Unmineralized limestone has been assumed to have a 

permeability of 10~12 cm2 (10~16 m2) at the low end of the 

normal range for limestone (Freeze and Cherry, 1979), and 

the fracture zone was treated as an equivalent porous 

medium having a permeability of 10~5 cm2 (10~9 m2) over a 

half-thickness of 9.5 m. These values were chosen to reflect 

a large permeability contrast between the fracture zone and 

the country rock, which is a sublithographic limestone.

The fluid flux that we have specified entering the base 

of the fracture, 1 g/s, is not tightly constrained but is of the 

same order as flux values used in other studies (see, for 

example, Garven, 1985; Hayba, 1993). Accordingly, we 

tested the effects of varying fluid flux on the thermal history 

of the Quimbys Mill Member. With the fixed-temperature 

boundary condition at the bottom of the grid that is, the top 

of the Mount Simon Sandstone or the St. Peter Sandstone 

aquifers variations in fluid flux have little effect on the 

thermal history of the Quimbys Mill Member. Both the 

Mount Simon and the St. Peter were sufficiently close to the 

Quimbys Mill that thermal equilibration took place rapidly 

in response to changes in the fluid temperature within the 

aquifer.

We tested the sensitivity of biomarker maturities to several other factors including the width of the fracture zone and 

the porosity and permeability of the unmineralized country 

rock. Doubling or halving the width of the fracture zone, for 

example, while maintaining a constant flux had little effect 

on the thermal maturity of the Quimbys Mill Member 

because of its proximity to the underlying aquifer and the 

fixed-temperature boundary; however, high in the fracture, 

near the ground surface, the fluid temperature changed significantly due to the corresponding changes in the thermal 

inertia of the fracture system. The thermal maturity of rocks 

near the surface is therefore sensitive to the width of the fracture zone, but small errors in measuring the width of the ore 

zone had no significant effect on the biomarker ratios in the 

Quimbys Mill Member, deep in the sedimentary section.

Preliminary calculations included heat conduction 

only, but we chose to include fluid flow to give a more realistic transient vertical thermal profile in the fracture zone 

and to allow a small amount of advective heat transport by 

fluid circulation outside of the fracture zone. In our calculations fluid flow from the fractures into the surrounding rock 

is minor due to their low permeability, and heat transfer 

from the fracture to the surrounding rocks is primarily by 

conduction. Increasing the permeability of the unmineral-
F24 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

0

100-

200-

300-

400-

500-

600-

700-

800-

900-

1000

1100-

1200-

1300-

1400-

1500-

0.001 

STERANE

Mineralized horizon

-0.334-

0 20 40 60 80 100 120 140 160 180

o100- 

200- 

300-

co 40°- 

gj 500- 

600- 

700- 

800- 

H 900- 

5] 1000-,

Q 1100:

1200

1300

tH

1500-

-0.001-

0.010-

"0.58

Fracture 

'zone HOPANE

Mineralized horizon

-0.599-

20

I 

40

I 

60

i 

80 100 120 140 160 180

0 

100:

200: 

300: 

400:

500- 

600

700:

800:

900:

iooo:

1100-

1200

1300: 

1400:

1500-

TEMPERATURE

Mineralized horizon

_105°C_

0 20 40 60 80 100 120 140

DISTANCE, IN METERS

160 180
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F25

Figure 19 (facing page). Contours of calculated biomarker maturity ratios for sterane (A) and hopane (fi) over the grid, assuming a 

best-fit temperature path and a specified temperature basal boundary at the Mount Simon Sandstone. Temperatures at the end of the 

fluid flow event are shown in (Q.

ized country rock by an order of magnitude resulted in a 

slight decrease in the time required for thermal equilibration 

due to increased fluid circulation outside of the fracture 

zones; however, the effect is minor at the Quimbys Mill 

horizon.

THERMAL PROPERTIES

Heat capacity and thermal conductivity values of the 

rock help to determine the rate at which the system reaches 

thermal equilibrium. We chose values typical of sedimentary 

rocks such as carbonate and sandstone, 2.5xl05 ergs/cm-s-K 

(2.5 W/m-K) for conductivity, and 1.05xl07 ergs/g-K 

(2.6xl06 J/m3 -K) for heat capacity (Roy and others, 1981).

Porosity plays a role in the thermal regime of the system 

by determining the bulk thermal properties of the rock-water 

system. These properties also help to determine the time 

required for the system to reach thermal equilibrium. The 

porosity of the fracture zone was chosen as 25 percent, and 

most of the void space was assumed to be in the form of fractures. We assumed a porosity of 1 percent for the Quimbys 

Mill, a sublithographic limestone, as well as for the remaining unmineralized rock. Thermal equilibrium was attained 

rapidly at the stratigraphic level of the Quimbys Mill, again, 

due to proximity to the underlying aquifer, and biomarker 

maturity at this horizon was attained predominantly under 

near steady state thermal conditions. Several trials confirmed 

that calculated biomarker thermal maturity in the Quimbys 

Mill is not sensitive to changes in fracture zone porosity.

RESULTS

CALCULATED DURATION OF 

HYDROTHERMAL FLOW

We tested three temperature histories (fig. 7), each consistent with the fluid inclusion measurements: high- and 

low-temperature paths and a best-fit through the fluid inclusion data. The time calculated to give the observed thermal 

maturities assuming the high-temperature path, 

1500C-135°C-115°C, is 37,500 years. If the low-temperature path is assumed, 115°C-1050C-95°C, the time is 3.3 

m.y. (fig. 21). The high- and low-temperature paths bracket 

the range of likely durations for a thermal episode, as constrained by biomarker and fluid inclusion data. We, however, consider the best-fit path, 130°C-125°C-110°C, to be 

the best representation of the fluid inclusion data. The

best-fit path corresponds to 212,000 years; thus, a time 

period on the order of 200,000 represents a best estimate for 

the duration of the heating event responsible for mineralization in the Upper Mississippi Valley district. Figure 21 summarizes these results, showing the time-temperature paths 

and the resulting hopane and sterane biomarker maturities.

A conservative estimate of the thermal maturity due to 

burial alone was made by assuming that the Quimbys Mill 

was at its maximum burial depth, 1,120 m, for 475 m.y., the 

approximate age of the rocks. This depth corresponds to a 

temperature of 50°C for a geothermal gradient of 25°C/km 

and a surface temperature of 22°C. The contribution of burial 

under these conditions to biomarker product-reactant ratios 

(thermal maturities) is calculated to be less than 0.01. This 

calculation oversimplifies the complexity of low-temperature reactions but serves to illustrate that the contribution of 

burial to overall thermal maturity can safely be neglected in 

the Upper Mississippi Valley district.

Five of the fluid inclusion temperature measurements 

reported for sphalerite in the Upper Mississippi Valley district are in the range 160°C-218°C (fig. 7), significantly 

above the rest of the data (McLimans, 1977). The question 

of whether these high values represent a fluid temperature or 

are a product of necking-down is important due to the implications for the duration of the hydrothermal event, as well as 

metal solubility and maturation of hydrocarbons. At 218°C 

it would take only 26 years to obtain the observed hopane 

and sterane ratios (fig. 13). This is not sufficient time to form 

an orebody at any plausible concentration of zinc in solution 

nor is such an extremely short duration of heating geologically reasonable. At 160°C the biomarker maturities would 

be attained in approximately 6,500 years. A pulse of hot fluid 

cannot be ruled out by the data or the calculations; however, 

even for a geologically very brief time interval, temperatures 

of 160°C or more would make a major contribution to the 

biomarkers' thermal maturity, placing severe constraints on 

the total duration of the mineralization. We suggest that fluid 

inclusion homogenization temperatures of 160°C-218°C are 

more likely to have resulted from necking-down after entrapment of the inclusions (see preceding section on fluid inclusions), and therefore are not representative of fluid trapping 

temperatures.

SOURCES OF ERROR

We investigated the error resulting from several 

sources: (1) coarseness of the time-temperature discretization, (2) error inherent in the biomarker calculations, and (3) 

uncertainty in the fluid inclusion temperatures. The first two 

sources gave relatively small errors and are insignificant 

compared with the third source, uncertainty in the fluid 

inclusion temperatures.

In our original calculations we divided time into three 

stages, A, B, and C, each of equal duration (Rowan and
F26 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

0.610-J

0.600-

0.590-^

:

0.580 -_

0.570 -_

0.560H

I

0.550 -j

0.540 7

0.530 -j

-

n son 

^A 

2(7

" .1

t

 0

1

1 ft _____

ft Mount Simnn Sanrlstnnfi Aquifer

f «t Refer Sanrlstnne Aquifer A

1(7

Average of hop_ane measurements

t 

^^^

Biomarker error ±0.024

o=0.018

CO

A

0.400- 

0.39Q-

~

0.380-

0.370 -:

0.360^

0.350 -,

0.340 -.

0.330-

0.320-

I

0.310-

n -ann 

Biomarker error ± 0.018

/ 

/ 

^

Average of sterane measurements

1a

-" ~ Mount Rjmnn fianrlstnne Aquifer.,.,.,..,, )

~ St. Peter Sandstone Aquifer 

 2

1(7=0.023

f

C7

> f

20 40 60 80 100 120

DISTANCE, IN METERS

140 160 180

Figure 20. Maturities of hopane (A) and sterane (fi) plotted versus distance from the Thompson orebody at the Quimbys Mill horizon. Symbols represent measurements made by Hatch and others (1986), and dashed lines show the means 

of these measurements. Solid lines show maturities calculated assuming best-fit temperature path and two basal boundary conditions specified temperature at Mount Simon Sandstone and at St. Peter Sandstone. Assumed fluid flow duration of 212,000 years achieves a compromise between hopane and sterane maturity ratios calculated for both 

boundary conditions. Biomarker error bars represent the overall uncertainty both in measurements and calculations reflected by separation of sterane and hopane curves shown in figure 13. See text for discussion.

Figure 21 (facing page). Calculated hopane and sterane maturities (heavy solid lines) shown as a function of temperature (light solid lines) 

and time. The ratios are the average of calculated values across the grid at the Quimbys Mill horizon. Dashed lines show average sterane and 

hopane ratios measured by Hatch and others (1986). Three time-temperature histories were evaluated: (4) high-temperature, (B) "best-estimate," and (Q low-temperature paths through the fluid inclusion data. Time periods A, B, and C represent three stages of sphalerite growth 

whose durations are assumed equal but are unknown in absolute terms. Time is treated as a variable and was adjusted until calculated biomarker maturities approximately matched average measured values. Calculations in this figure assume a specified temperature basal boundary 

at the St. Peter Sandstone.
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F27

0.60 J

0.50 T

0.40^

0.30^

0.20-

0.00

Average ofhopane measurements (0.576)

Average ofsterane 

measurements (0.353)

0.60 T A verage of hopane measuremt nts (0.576)

Average ofsterane 

measurements (0.353)

o

150,000 200,000

0.60 -__Average_of hopane measurements (OJ576_l

0.50 -_

0.40 J

Hopane

0.00-5 

0

Average ofsterane 

measurements (0.353)

-160

-140

1.0x106 2.0x106 

TIME (YEARS)

3.0x106
F28 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

Goldhaber, 1995). This coarse discretization resulted in a 

calculated duration for a hydrothermal event of 212,000 

years. To test the effects of a finer time discretization, we 

divided each stage into three parts for a total of nine equal 

subdivisions. Temperatures for each division were taken 

from the polynomial best-fit curve to the fluid inclusion data 

(fig. 7). When we matched the calculated with the measured 

thermal maturities, the total calculated duration of the hydrothermal event was reduced to 200,000 years, indicating an 

error of 5.7 percent due to the coarseness of our time-temperature discretization.

The combined error inherent in the biomarker measurements of Hatch and others (1986) and in the kinetic constants 

of Marzi and Rullkotter (1992) is summarized in figure 13. 

These two curves show the combinations of time and temperature that give the average biomarker maturity ratios 

measured by Hatch and others (1986). Because the hopane 

and sterane ratios were measured on the same samples, having identical time-temperature histories, they should, ideally, 

give identical curves. The small separation between them 

(1.05°C for 200,000 years) reflects the combined effects of 

natural variation in the samples and analytical error, both in 

the measurements of Hatch and others (1986) and in the laboratory determinations of the kinetic constants (Marzi and 

Rullkotter, 1992). When we recalculated duration using the 

analytical solution, and adding or subtracting this temperature difference, we obtained an error of ±0.0175 for sterane 

and ±0.024 for hopane. These errors are virtually identical to 

one standard deviation of the biomarker measurements (fig. 

20). This inherent error is useful in comparing calculated and 

measured values of the thermal maturity. These errors in the 

thermal maturity, assuming the best-fit temperature path, 

correspond to an error in duration of ±7,000 years, or ±3.3 

percent.

In table 4 we compare results of calculations made with 

the kinetic constants (A0 and Ea) of Marzi and Rullkotter 

(1992) and calculations made using the constants of several 

other authors. Our comparison included only kinetic constants that gave a rate constant (k) differing by less than a 

factor of five from the value calculated from the kinetic constants of Marzi and Rullkotter (1992). We did not compare 

our calculations with those based on published kinetic constants that gave dramatically different rate constants (see, for 

example, kinetic constants reported in Lewis, 1993). The 

calculated time necessary for sterane and hopane maturities 

to reach the values measured by Hatch and others (1986), 

assuming a temperature of 130°C, varies by a factor of 

approximately two (table 4) The kinetic constants of Marzi 

and Rullkotter (1992) are considered to be the most reliable 

(see discussion of biomarkers above); however, error in the 

determination of kinetic constants, and thus the rate constant, 

contributes to the overall uncertainty of the calculations. 

Hopane and sterane biomarker product-reactant ratios 

are extremely sensitive to temperature. A 20°C increase in 

temperature decreases the amount of time needed to reach a 

given thermal maturity by approximately an order of magnitude (fig. 13). It is not surprising, therefore, that by far the 

greatest source of error is in determining a temperature history based on the fluid inclusion data. Although these highand low-temperature paths were chosen subjectively, by 

inspection of the data, we believe that they adequately represent the extremes in the likely range of fluid inclusion temperatures. Given the sensitivity of the calculations to 

temperature, error in the estimation of the time-temperature 

history is dominant over all other sources of error.

DISCUSSION

Despite the elevated temperatures indicated by the 

fluid-inclusion data, the measured product to reactant ratios 

for hopane and sterane are indicative of organic matter that 

is immature or in the earliest stages of oil generation (Hatch 

and others, 1986). The immaturity of the organic matter is 

confirmed by Tmax measurements in the Thompson-Temperly mine (Hatch and others, 1986) and by an organic 

geochemical study of the Schullsburg mine (Gize and 

Barnes, 1987), also within the region studied in detail by 

McLimans (1977) (fig. 4). Sangster and others (1994) 

reported lower thermal maturities in conodonts; however, 

the discrepancy may be explained by the presence of water

Table 4. Comparison of the durations calculated for the average biomarker maturities of Hatch and others (1986) assuming a 

temperature of 130°C and using several selected kinetic constants from the literature. 

[A0 and Ea kinetic constants; R, reactant; P, product; k, rate constant. See text for discussion]

Aots' 1 ) Ea (kJ/mol) Ms' 1 ) P/R PI (P+R) Time (years) Reference

Sterane

4.86xl08

7.83X109

6.60xl03

169

175.59

84

-6.17E-14

-1.39E-13

-8.63E-14

0.546

0.546

0.546

0.353

0.353

0.353

224,326

99,445

160,319

Marzi and Rullkotter (1992).

Lewan and others (1986)

Alexander and others (1986), Strachan, Alexander, van

Bronswijk, and Kagi (1989), and Strachan, Alexander,

Subroto, and Kagi (1989).

Hopane

S.lOxlO8

3.50xl02

168

87.8

-1.39E-13

-1.47E-13

1.363

1.363

0.577

0.577

196,993

185,263

Marzi and Rullkotter (1992).

Sajgo and Lefler ( 1986).
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F29

(±methane) during conodont alteration, which has been 

shown to retard the alteration process (Rejebian and others, 

1987). Our calculations are in general agreement with the 

results of Lavery and Barnes (1971), who calculated 250,000 

years for the formation of an orebody in the Upper Mississippi Valley district, assuming a metal concentration of 35 

ppm zinc in the mineralizing fluid.

The assumptions built into our numerical calculations 

make our 200,000-year time estimate for sphalerite deposition a maximum. We have assumed instantaneous temperature changes in the underlying aquifers that supply heat and 

fluid to the ore zone. This simplification was chosen due to 

the absence of any information with which to constrain the 

true temperature path during the onset of regional fluid circulation but prior to sphalerite precipitation. If this onset 

were more gradual, then biomarker maturity might have 

increased significantly even prior to sphalerite deposition, 

thus decreasing the time interval during which sphalerite 

could form without exceeding the constraint of the observed 

biomarker ratios.

IMPLICATIONS FOR REGIONAL FLUID 

FLOW

Our calculation of the duration of the hydrothermal 

event in the Upper Mississippi Valley district was made 

independently of any assumptions regarding the ultimate 

fluid source or flow direction through underlying aquifers. In 

the discussion that follows, we do assume, however, that 

regional flow at a velocity on the order of meters per year a 

velocity capable of advective heat transport is required to 

explain the thermal history of the Upper Mississippi Valley 

district. Previous studies have examined gravity flow from 

several directions, westward from the Appalachian Basin 

(Garven and others, 1993) and northward through the Illinois 

and Arkoma Basins (Bethke, 1986; Garven and others, 

1993). Of the numerous possible flow paths, northward flow 

through the Reelfoot rift and Illinois Basin meets the thermal 

requirements of the Upper Mississippi Valley fluid inclusion 

temperatures, whereas it appears that other flow paths do 

not. Additional geochemical evidence, discussed following, 

combines to make a strong case for northward flow within 

the Illinois Basin.

Both the relatively short duration and the elevated temperatures of the mineralizing event place important constraints on the nature of processes operating in the Illinois 

Basin during the late Paleozoic. Calculations for steady-state 

heat transport through the Illinois Basin by advecting fluids 

predict temperatures in the Upper Mississippi Valley district 

of only 95°C, even allowing for focusing of fluids into the 

district by regional structural trends and vertical discharge of 

fluids along faults zones in the Upper Mississippi Valley district (Bethke, 1986) (fig. 22, curve C). The origin of the temperatures exceeding 100°C in the Upper Mississippi Valley

district is difficult to explain without invoking either high 

basement heat flow or fluid-flow paths passing through 

deeper parts of the basin than have been modeled to date. 

Bethke (1986), for example, modeled elevated heat flow 

(three times normal or 179 mW/m2 ) in the southern third of 

the Illinois Basin (fig. 22, curve E). Garven and others (1993, 

fig. 30) assumed a burial depth of 2 km for the Upper Mississippi Valley district and an initial temperature of 110°C, 

on the basis of higher basement heat flow and a steeper geothermal gradient than we assumed in this study. If, however, 

the temperature scale of Garven and others is shifted downward to an initial temperature of 50°C, as we assumed in this 

study, the peak transient temperature is just less than 100°C 

and steady-state temperatures are near 90°C (fig. 22). These 

temperatures are still significantly lower than the majority of 

temperatures indicated by the fluid inclusion data. The additional thickness of Pennsylvanian and Permian sediments as 

assumed by Garven and others (1993) contributes to elevated 

temperatures but is not by itself sufficient to account for the 

fluid inclusion temperatures under a normal geothermal gradient. In the southern Illinois Basin and northern Reelfoot 

rift, there is geographically widespread evidence of Permian 

igneous activity. The Hicks dome, Omaha dome, and temporally related dikes and sills, as well as numerous igneous 

intrusions to the south in the Reelfoot rift, represent a potentially significant heat source (Bethke, 1986). Dikes, breccias, 

and intrusive rocks associated with the Hicks dome have 

been shown by radiometric dating to be contemporaneous, 

within uncertainty, to the Upper Mississippi Valley district 

(table 1). The coincidence in time of the igneous activity and 

Upper Mississippi Valley mineralization permits input of 

igneous heat into northward-moving fluids in the Illinois 

Basin.

Bethke (1986) tested a hypothetical south to north flow 

path, with fluid recharge on the Pascola arch, a structural 

high of Mesozoic(?) age (Kolata and Nelson, 1991); however, the Early Permian age for the Upper Mississippi Valley 

district recently determined by Brannon and others (1992) 

precludes the Pascola arch as a possible recharge zone. If the 

flow path of Bethke (1986) is revised to place the recharge 

zone farther to the south in the Appalachian-Ouachita foldbelt and northward flow through the Reelfoot rift prior to 

Pascola arch uplift is considered, then burial depths along the 

flow path are several kilometers deeper than in the Illinois 

Basin proper (Buschbach and Kolata, 1991). Emplacement 

of igneous rocks along the flow path would further elevate 

fluid temperatures.

In addition to explaining, at least in part, the elevated 

temperatures in the Upper Mississippi Valley district, igneous processes are also consistent with the limited duration of 

the heating event relative to the time scale of basin evolution 

or of the mountain building-erosion cycle in the Appalachian-Ouachita foldbelt that would have provided the hydrologic head for a gravity-driven flow system. The 

200,000-year duration that we calculate for circulation of
F30 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

o

140"

130-

120-

100- 

90-

//y

,^m^m^^ Fluid inclusion temperatures (zone A sphalerite) ////

//////////////////////////

Steady-state ternperature (depth= 1,100 m)

-150

m

200

O

110

400 600

TIME, IN THOUSANDS OF YEARS

800 1000

Figure 22. Comparison of fluid inclusion temperatures and temperatures predicted for the Upper Mississippi Valley district 

using two gravity-driven flow models. The crosshatched band indicates the range of values spanned by the high and low fluid 

inclusion temperatures in zone A, the earliest stage of sphalerite (see fig. 7). Curves C and E are the steady-state temperatures 

predicted by Bethke (1986) for a depth of 1,100 m. Curve C assumes that flow is focused by structural arches at the northern 

end of the basin and that highly permeable fracture zones focus flow upward in the vicinity of the Upper Mississippi Valley 

district. Curve E further assumes an elevated heat flow (179 mW/m2) over the southern third of the basin. Transient temperatures, as presented in Garven and others (1993), are read from the temperature scale on the right; these temperatures assume 

a burial depth of 2 km for the Upper Mississippi Valley district and an initial temperature of 110°C. The temperature scale 

on the left effectively shifts the transient temperature curve from the initial temperature of 110°C to 50°C, which we assume 

for the Upper Mississippi Valley district in this study, allowing us to compare the magnitude of the transient heat pulse to 

steady-state calculations and fluid inclusion temperatures.

anomalously warm fluids through the Upper Mississippi 

Valley district and through aquifers at the northern margin of 

the Illinois Basin is short relative to the duration of the evolution and eventual decay of such a system. It may represent 

the period of emplacement and cooling of igneous rocks 

associated with the Hicks dome igneous event, a time interval of exceptionally high heat flow in the southern Illinois 

Basin. A relatively brief, but intense injection of heat into 

fluids circulating through the basin could explain fluid inclusion temperatures of more than 100°C in the Upper Mississippi Valley district. A contribution of igneous heat to a 

regional flow system, and ultimately to the Upper Mississippi Valley district, would require a northerly flow direction.

Lewchuk and Symons (1995) recently estimated that 

magnetite formed over a time interval lasting from 1 to 8 

m.y. in four Mississippi Valley-type districts in the Ozark 

region to the west of the Illinois Basin. They interpreted this

interval as representing the duration of lead-zinc mineralization and pointed out a general agreement with the time frame 

of orogenesis and gravity-driven fluid circulation through a 

sedimentary basin. Because we believe that similar processes of regional gravity flow were also operating in the Illinois Basin, it is important to reconcile the estimate of 

Lewchuk and Symons (1995) with our estimated duration, 

which is an order of magnitude shorter. Our time estimate 

represents the duration of a hydrothermal event; that is, the 

presence of fluids at the northern end of the Illinois Basin at 

anomalously high temperatures given their burial depth. In 

the Upper Mississippi Valley district, the main stage of 

sphalerite precipitation records the hydrothermal event; 

however, fluid circulation at lower temperatures may have 

been much longer lived. Magnetite is a minor phase in Midcontinent Mississippi Valley-type districts and may have 

formed substantially below peak mineralization temperatures; it may also have formed as an alteration of pyrite. The
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F31

biomarker maturity curves of figure 21 are almost flat in the 

third time stage (zone C) because of the lower fluid temperatures and the first-order kinetics of the isomerization 

reaction. Fluid flow and magnetite precipitation could have 

occurred for many millions of years at temperatures of less 

than 100°C without exceeding observed biomarker maturities in the Upper Mississippi Valley district.

Geochemical data provide an independent line of evidence for northward flow in the Illinois Basin during the Permian. A data base of 15,000 analyses of element 

concentrations in drill core from the Illinois Basin was used

to define a threshold between background and anomalous 

values for fluorine. Values in the southern Illinois Basin are 

strongly anomalous and decrease northward (fig. 23) 

(Goldhaber and others, 1994; M.B. Goldhaber, unpublished 

data). Hicks dome and the spatially and genetically associated Southern Illinois fluorite district (Goldhaber and others, 

1992) are the only sources of fluorine presently recognized 

in the region. Igneous dikes related to the Hicks dome and to 

the fluorite itself have been dated as contemporaneous, 

within uncertainty, with the Upper Mississippi Valley district (table 1). The pattern of decreasing fluorine enrichment

90° 88° 86°

42°

40°

38°

36°

Figure 23. Anomalous fluorine concentrations in drill core (circles) from the St. Peter Sandstone through the 

Maquoketa Formation in units of AMF/100 ft. Background levels of fluorine computed for the entire region have 

been subtracted. Units of AMF (anomalous metal feet) are defined as the element concentration (above background) over an interval of drill core times the length of the interval, then divided by the threshold concentration 

defining anomalous values.
F32 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

in the drill core to the north is best explained by northward 

fluid flow.

SOURCES OF SALT

Fluid inclusions in the Upper Mississippi Valley district 

contain highly saline brines, predominantly in the range 

18-23 weight percent NaCl equivalent (McLimans, 1977). 

The source of the salinity is enigmatic because the Illinois 

Basin is poor in evaporites and shales. The Michigan Basin 

to the north contains major evaporites, but thermal considerations alone, as well as brine chemistry, probably eliminate 

them as a source of salinity. In a study of Cl-Br-Na systematics of present-day Illinois Basin pore fluids, Walter and 

others (1990) concluded that the high salinities resulted predominantly from subaerial, evaporative concentration of 

seawater just less than halite saturation, with a relatively 

small contribution from halite dissolution in the Mississippian and Pennsylvanian strata above the New Albany Shale. 

Viets (1995) reported that Cl/Br ratios measured in fluids 

extracted from inclusions in sphalerite from the Upper Mississippi Valley district are also similar to the ratios for seawater. Like the modern pore fluids, the fluid inclusion ratios 

are consistent with an evaporitically concentrated seawater 

fluid source that did not reach the point of halite precipitation; they are not consistent with evaporite dissolution as a 

principal source of salt. The brines trapped in these fluid 

inclusions may have formed in the evaporative environment 

of the Reelfoot rift to the south of the Illinois Basin.

CONCLUSIONS

Biomarker and fluid inclusion data for the Upper Mississippi Valley district provide a constraint on the duration of 

the thermal event that is independent of the mechanism of 

heating. The best estimate for the duration of the heating 

event is on the order of 200,000 years. The majority of the 

fluid inclusion temperatures in the Upper Mississippi Valley 

district exceed 100°C and, given estimates of burial depth, 

are difficult to explain by topographically driven flow 

through the Illinois Basin. Deeper fluid flow paths and (or) 

elevated basement heat flow are required to account for temperatures in the district. Sources of heat such as the Hicks 

dome and related igneous rocks are likely to have contributed significantly to the temperature of fluids deep in the Illinois Basin; their temperature would have decayed on the 

order of several hundred thousand years, approximately the 

same time scale as the hydrothermal event in the Upper Mississippi Valley district.

We postulate that gravity flow drove fluids from south 

to north in the Illinois Basin during the Early Permian. A 

pulse of heat related to igneous processes was superimposed 

on this system in the southern Illinois Basin, and advective 

heat transport by northward fluid flow resulted in elevated 

fluid inclusion temperatures in the Upper Mississippi Valley

district. Advection of heat through the Illinois Basin as a 

consequence of regional fluid flow would have contributed 

significantly to its thermal history.

REFERENCES CITED

Abbott, G.D., Wang, G.Y., Eglinton, T.I., Home, A.K., and Fetch, 

G.S., 1990, The kinetics of biological marker release from vitrinite kerogen during the hydrous pyrolysis of vitrinite kerogen: Geochimica et Cosmochimica Acta, v. 54, p. 2451-2461.

Alexander, R., Strachan, M.G., Kagi, R.I., and van Bronswijk, W., 

1986, Heating rate effects in aromatic maturity indicators,//? 

Leythaeuser, D., and Rullkotter, J., eds., Advances in organic 

geochemistry 1985: Oxford, Pergamon Press, p. 997-1003.

Bailey, S.W., and Cameron, E.N., 1951, Temperatures of mineral 

formation in bottom-run lead-zinc deposits of the upper Mississippi Valley, as indicated by liquid inclusions: Economic Geology, v. 48, p. 626-651.

Barker, C.E., 1989, Temperature and time in the thermal maturation 

of sedimentary organic matter, in Naeser, N.D., and McCulloh, 

T.H., eds., Thermal history of sedimentary basins, methods and 

case histories: New York, Springer-Verlag, p. 73-98.

Bethke, C.M., 1986, Hydrologic constraints on the genesis of the 

Upper Mississippi Valley mineral district from Illinois basin 

brines: Economic Geology, v. 81, p. 233-249.

Bethke, C.M., Harrison, W.J., Upson, C., and Altaner, S.P., 1988, 

Supercomputer analysis of sedimentary basins: Science, v. 

239, p. 261-267.

Bethke, C.M., and Marshak, S., 1990, Brine migrations across 

North America The plate tectonics of groundwater: Annual 

Review of Earth and Planetary Sciences, v. 18, p. 287-315.

Bethke, C.M., Reed, J.D., and Oltz, D.F., 1991, Long range petroleum migration in the Illinois basin, in Leighton, M.W., Kolata, 

D.R., Oltz, D.F., and Eidel, J.J., eds., Interior cratonic basins: 

American Association of Petroleum Geologists Memoir 51, p. 

455-472.

Brannon, J.C., Podosek, F.A., and McLimans, R.K., 1992, Alleghenian age of the Upper Mississippi Valley zinc-lead deposit 

determined by Rb-Sr dating of sphalerites: Nature, v. 356, p. 

509-511.

 1993, Isotopic constraints for the formation of the Upper 

Mississippi Valley (UMV) district, southwest Wisconsin, 

USA: MVT Workshop, Campus Jussieu-Societe Geologique 

de France, February 15-18, Proceedings, p. 33-34.

Buschbach, T.C., and Kolata, D.R., 1991, The regional setting of 

the Illinois basin, in Leighton, M.W., Kolata, D.R., Oltz, D.F., 

and Eidel, J.J., eds., Interior cratonic basins: American Association of Petroleum Geologists Memoir 51, p. 29-55.

Chesley, J.T., Halliday, A.N., Kyser, T.K., and Spry, P.G., 1994, 

Direct dating of Mississippi Valley-type mineralization Use 

of Sm-Nd in fluorite: Economic Geology, v. 89, p. 1192-1199.

Cluff, R.M., and Byrnes, A.P., 1991, Lopatin analysis of maturation 

and petroleum generation in the Illinois Basin, in Leighton, 

M.W., Kolata, D.R., Oltz, D.F., and Eidel, J.J., eds., Interior 

cratonic basins: American Association of Petroleum Geologists Memoir 51, p. 425-437.

Doe, B.R., Stuckless, J.S., and Delevaux, M.H., 1983, The possible 

bearing of the granite of the UPH drill holes, northern Illinois,
FLUID INCLUSIONS AND BIOMARKERS, UPPER MISSISSIPPI VALLEY ZINC-LEAD DISTRICT F33

on the origin of Mississippi Valley ore deposits: Journal of 

Geophysical Research, v. 88, p. 7335-7345.

Erickson, A.J., Jr., 1965, Temperatures of calcite deposition in the 

Upper Mississippi Valley lead-zinc deposits: Economic Geology, v. 60, p. 506-528.

Fair, M.R., 1989, Compositional zoning characteristics of late 

dolomite cement in the Cambrian Bonneterre Formation, 

Missouri Implications for parent fluid migration pathways: 

Carbonates and Evaporites, v. 4, p. 177-194.

Freeze, R.A., and Cherry, J.A., 1979, Groundwater: Englewood 

Cliffs, N.J., Prentice-Hall, 604 p.

Garven, G., 1985, The role of regional fluid flow in the genesis of 

the Pine Point deposit, Western Canada sedimentary basin: 

Economic Geology, v. 80, p. 307-324.

Garven, G., Ge, S., Person, M.A., and Sverjensky, D.A., 1993, Genesis of stratabound ore deposits in the midcontinent basins of 

North America I, The role of regional groundwater flow: 

American Journal of Science, v. 293, p. 497-568.

Gize, A.P., and Barnes, H.L., 1987; The organic geochemistry of 

two Mississippi Valley-type lead-zinc deposits: Economic 

Geology, v. 82, p. 457-470.

Goldhaber, M.B., Plumlee, G.S., Hayes, T.S., Potter, C.J., Rowan, 

E.L., and Taylor, C.D., 1992, The Illinois-Kentucky fluorspar 

district Rift-related fluorite mineralization superimposed on 

a basinal brine flow system: Geological Society of America 

Annual Meeting Abstracts with Programs, v. 24, p. A21-A22.

Goldhaber, M.B., Rowan, E.L, Hatch, J., Zartman, R., Pitman, J., 

and Reynolds, R., 1994, The Illinois basin as a flow path for 

low temperature hydrothermal fluids, in Basin-wide diagenetic 

patterns Integrated petrologic, geochemical, and hydrologic 

considerations: SEPM Research Conference, Lake Ozark, Missouri, Program Abstracts and Field Guide, p. 29-30.

Gregg, J.M., and Shelton, K.L., 1985, Regional epigenetic dolomitization in the Bonneterre Dolomite (Cambrian), southeastern Missouri: Geology, v. 13, p. 503-506.

Haas, J.L., 1961, Partial vapor pressures and Mississippi Valley-type ore deposits: State College, Pennsylvannia State University, Seniors' thesis.

Hanor, J.S., 1980, Dissolved methane in sedimentary 

brines Potential effect on the PVT properties of fluid inclusions: Economic Geology, v. 75, p. 603-617.

Hatch, J.R., Heyl, A.V., and King, D., 1986, Organic geochemistry 

of hydrothermal alteration, basal shale and limestone beds, 

Middle Ordovician Quimbys Mill Member, Platteville Formation, Thompson-Temperly zinc-lead mine, Lafayette County, 

Wisconsin, in Dean, W.E., ed., Organics and ore deposits: Denver Regional Exploration Geologists Society, Proceedings, p. 

93-104.

Hay, R.L., Lee, M., Kolata, D.R., Matthews, J.C., and Morton, J.P., 

1988, Episodic potassic diagenesis of Ordovician tuffs in the 

Mississippi Valley area: Geology, v. 16, p. 743-747.

Hayba, D.O., 1993, Numerical hydrologic modeling of the Creede 

epithermal ore-forming system, Colorado: Champaign, University of Illinois, Ph.D. dissertation, 186 p.

Hayba, D.O., and Ingebritsen, S.E., 1994, The computer model 

HYDROTHERM, a three-dimensional finite-difference model 

to simulate ground-water flow and heat transport in the temperature range of 0 to 1200°C: U.S. Geological Survey Water 

Resources Investigations Report 94-4045, 85 p.

Heyl, A.V., 1968 The Upper Mississippi Valley base-metal district, 

in Ridge, J.D., ed., Ore deposits of the United States: New 

York, American Institute of Mining, Metallurgy, and Petroleum Engineering, p. 431-459.

Heyl, A.V., Agnew, A.F., Lyons, E.J,, and Behre, C.H., 1959, The 

geology of the Upper Mississippi Valley zinc-lead district: 

U.S. Geological Survey Professional Paper 309, 310 p.

Kolata, D.R., and Nelson, W.J., 1991, Tectonic history of the Illinois basin, in Leighton, M.W., Kolata, D.R., Oltz, D.F., and 

Eidel, J.J., eds., Interior cratonic basins: American Association 

of Petroleum Geologists Memoir 51, p. 263-286.

Lavery, N.G., and Barnes, H.L., 1971, Zinc dispersion in the Wisconsin zinc-lead district: Economic Geology, v. 66, p. 

226-242.

Leach, D.L., Nelson, R.C., and Williams, D., 1975, Fluid inclusion 

studies in the northern Arkansas zinc district: Economic Geology, v. 70, p. 1084-1091.

Leach, D.L., and Rowan, E.L., 1986, Genetic link between Ouachita foldbelt tectonism and the Mississippi Valley-type lead-zinc 

deposits of the Ozarks: Geology, v. 14, p. 931-935.

Lewan, M.D., Bjoroy, M., Dolcater, D.L., 1986, Effects of thermal 

maturation on steroid hydrocarbons as determined by hydrous 

pyrolysis of Phosphoria Retort Shale: Geochimica et Cosmochimica Acta, v. 50, p. 1977-1987.

Lewchuk, M.T., and Symons, D.T.A., 1995, Age and duration of 

Mississippi Valley-type ore-mineralizing events: Geology, v. 

23, p. 233-236.

Lewis, C.A., 1993, The kinetics of biomarker reactions Implications for the assessment of the thermal maturity of organic matter in sedimentary basins, in Engel, M.H., and Macko, S.A., 

eds.. Organic geochemistry, principles and applications: New 

York, Plenum Press, p. 491-510.

Mackenzie, A.S., 1984, Applications of biological markers in petroleum geochemistry, in Brooks, J., and Welte, D., eds., Advances in petroleum geochemistry, v. 1: New York, Academic 

Press, p. 115-214.

Marzi, R., and Rullkotter, J,, 1992, Qualitative and quantitative evolution and kinetics of biological marker transformations Laboratory experiments and application to the Michigan basin, in 

Moldowan, J.M., Albrecht, P., and Philp, R.P., eds., Biological 

markers in sediments and petroleum: Englewood Cliffs, N.J., 

Prentice Hall, p. 18-41.

McLimans, R.K., 1977, Geochemical, fluid inclusion, and stable 

isotope studies of the Upper Mississippi Valley zinc-lead district, southwest Wisconsin: State College, Pennsylvania State 

University, Ph.D. dissertation, 175 p.

McLimans, R.K., Barnes, H.L., and Ohmoto, H., 1980, Sphalerite 

stratigraphy of the Upper Mississippi Valley zinc-lead district, 

southwest Wisconsin: Economic Geology, v. 75, p. 351-361.

Mullens, T.E., 1960, Geology of the Cuba City, New Diggings, and 

Shullsburg quadrangles, Wisconsin and Illinois, in Geology of 

parts of the Upper Mississippi Valley zinc-lead district: U.S. 

Geological Survey Bulletin 1123-H, p. 437-532.

Newhouse, W.H., 1933, The temperature of formation of the Mississippi Valley lead-zinc deposits: Economic Geology, v. 28, p. 

744-750.

Ohmoto, H., 1986, Stable isotope geochemistry of ore deposits, in 

Valley, J.E., Taylor, H.P., Jr., and O'Neil, J.R., eds., Stable isotopes in high temperature geological processes: Mineralogical
F34 EVOLUTION OF SEDIMENTARY BASINS ILLINOIS BASIN

Association of America Reviews in Mineralogy, v. 16, p. 

491-560.

Ohmoto, H., and Rye, R.O., 1979, Isotopes of sulfur and carbon, in 

Barnes, H.L., ed., Geochemistry of hydrothermal ore deposits: 

New York, John Wiley, p. 509-567.

Pan, H., Symons, D.T.A., and Sangster, D.F., 1990, Paleomagnetism of the Mississippi Valley-type ore and host rocks in the 

northern Arkansas and Tri-State districts: Canadian Journal of 

Earth Sciences, v. 27, p. 923-931.

Peters, K.E., and Moldowan, J.M., 1993, The biomarker guide, 

interpreting molecular fossils in petroleum and ancient sediments: Englewood Cliffs, N.J., Prentice Hall, 363 p.

Pinckney, D.M., and Rafter, T.A., 1972, Fractionation of sulfur isotopes during ore deposition in the Upper Mississippi Valley 

zinc-lead district: Economic Geology, v. 67, p. 315-328.

Pitman, J.K., and Spottl, C., in press, Origin and timing of carbonate 

cements in the St. Peter Sandstone, Illinois basin Evidence 

for a genetic link to Mississippi Valley-type mineralization, in 

Louks, R., Totten, M., and Crossey, L., eds., Siliclastic diagenesis and fluid flow Concepts and Applications: SEPM Special Publication.

Rejebian, V.A., Harris, A.G., and Huebner, J.S., 1987, Conodont 

color and textural alteration An index to regional metamorphism, contact metamorphism, and hydrothermal alteration: 

American Association of Petroleum Geologists Bulletin, v. 99, 

p. 471-479.

Reynolds, R.L., Goldhaber, M.B., and Snee, L.W., 1992, Paleomagnetic study of the Grants Breccia and the Downeys Bluff 

Sill Implications for the influence of Permian igneous activity on Mississippi-Valley type (MVT) mineralization in southern Illinois, in Goldhaber, M.B., and Eidel, J.J., eds., Mineral 

resources in the Illinois basin in the context of basin evolution: 

U.S. Geological Survey Open-File Report 92-1, p. 51-52.

Roedder, E., 1984, Fluid inclusions: Mineralogical Association of 

America Reviews in Mineralogy, v. 12, 644 p.

Rowan, E.L., 1986, Cathodoluminescent zonation in hydrothermal 

dolomite cements Relationship to Mississippi Valley-type 

Pb-Zn mineralization in southern Missouri and northern 

Arkansas, in Hagni, R.D., ed.. Process mineralogy VI: American Institute of Mining Engineers, Symposium Proceedings, p. 

69-87.

Rowan, E.L., and Goldhaber, M.B., 1995, Duration of mineralization and fluid flow history of the Upper Mississippi Valley 

zinc-lead district: Geology, v. 23, p. 609-612.

Rowan, E.L., and Leach, D.L., 1989, Fluid inclusion constraints on 

sulfide precipitation mechanisms and ore fluid migration in the 

Viburnum Trend lead-zinc district, southeast Missouri: Economic Geology, v. 84, p. 1948-1965.

Roy, R.F., Beck, A.E., and Touloukian, Y.S., 1981, Thermophysical properties of rocks, in Touloukian, Y.S., and Ho, C.Y., eds., 

McGraw-Hill/Cindas data series on material properties, volume II-2 Physical properties of rocks and minerals: New 

York, McGraw-Hill/Cindas, p. 409-502.

Sajgo, Cs., and Lefler, J., 1986, A reaction kinetic approach to the 

temperature-time history of sedimentary basins, in Buntebarth, 

G., and Stegena, L., eds., Paleogeothermics, Lecture notes in 

earth sciences, v. 5: Berlin, Springer-Verlag, p. 119-151.

Sangster, D.F., Nowlan, G.S., and McCracken, A.D., 1994, Thermal comparison of Mississippi Valley-type lead-zinc deposits 

and their host rocks using fluid inclusion and conodont color 

alteration index data: Economic Geology, v. 89, p. 493-514.

Snee, L.W., and Hayes, T.S., 1992, 40Ar/39Ar geochronology of 

intrusive rocks and Mississippi Valley-type mineralization and 

alteration from the Illinois-Kentucky fluorspar district, in 

Goldhaber, M.B., and Eidel, J.J., eds., Mineral resources in the 

Illinois basin in the context of basin evolution: U.S. Geological 

Survey Open-File Report 92-1, p. 59-61.

Strachan, M.G., Alexander, R., Subroto, E.A., and Kagi, R.I., 1989, 

Constraints upon the use of 24-ethylcholestane diastereomer 

ratios as indicators of the maturity of petroleum: Organic 

Geochemistry, v. 14, p. 423-432.

Strachan, M.G., Alexander, R., van Bronswijk, W., and Kagi, R.I., 

1989, Source and heating rate effects upon heating rate parameters based on ratios of 24-ethylcholestane diastereomers: Journal of Geochemical Exploration, v. 31, p. 285-294.

Symons, D.T.A., 1994, Paleomagnetism and the late Jurassic genesis of the Illinois-Kentucky fluorspar deposits: Economic Geology, v. 89, p. 438^49.

Symons, D.T.A., and Sangster, D.F., 1991, Paleomagnetic age of 

the Central Missouri barite deposits and its genetic implications: Economic Geology, v. 86, p. 1-12.

Tissot, B.P., and Welte, D.H., 1984, Petroleum formation and 

occurrence: New York, Springer-Verlag, 538 p.

Viets, J.G., A comparative study of the composition of MVT ore 

fluids Solute compositions of inclusion fluids in North American and European MVT deposits: Society of Economic Geologists International Field Conference on Carbonate-Hosted 

Lead-Zinc Deposits, St. Louis, June 3-6, 1995, Abstracts, p. 

328-330.

Voss, R.L., and Hagni, R.D., 1985, The application of cathodoluminescent microscopy to the study of sparry dolomite from the 

Vibrnum trend, southeastern Missouri, in Hausen, D.M., and 

Kopp, O.C., eds., Mineralogy-applications to the minerals 

industry: Society of Mining Engineers, American Institute of 

Mining Engineers, Paul Kerr Memorial Symposium, New 

York, Proceedings, p. 51-68.

Walter, L.M., and Stueber, A.M., and Huston, T.J., 1990, Br-Cl-Na 

systematics in Illinois basin fluids Constraints on fluid origin 

and evolution: Geology, v. 18, p. 315-318.

Waples, D.W., and Machihara, T., 1991, Biomarkers for geologists A practical guide to the application of steranes and triterpanes in petroleum geology: American Association of 

Petroleum Geologists Methods in Exploration 9.

Zartman, R.E., Brock, M.R., Heyl, A.V., and Thomas, H.H., 1967, 

K-Ar and Rb-Sr ages of some alkalic intrusive rocks from central and eastern United States: American Journal of Science, v. 

265, p. 848-870.

Published in the Central Region, Denver, Colorado 

Manuscript approved for publication August 31, 1995 

Edited by Judith Stoeser 

Graphics by the authors 

Photocomposition by Joan G. Nadeau