Table Of ContentPrecambrian Rocks and Mineralization,
Southern Wyoming Province
Hartville Uplift to Copper Mountain Area, Wyoming
July t9-25, t 989
Field Trip Guidebook T332
Leaders:
George L. Snyder W Dan Hausel Terry L. Klein
Robert S. Houston Paul}. GraH
American Geophysical Union, Washington, D.C.
Copyright 1989 American Geophysical Union
2000 Florida Ave., N.W., Washington, D.C. 20009
ISBN: 0-87590-613-3
Printed in the United States of America
COVER Precambrian peridotite exposure in canyon wall on north side of North
Fork Cherry Creek and on Tony Ridge, Bull Camp Peak 1 1/2-minute quadrangle,
Wyoming.
Leaders:
George L. Snyder
U.S. Geological Survey
MS 913, Federal Center
Denver, CO 80225
w.
Dan Hausel
Deputy Directory
Theological Survey of Wyoming
Box 3008, University Station
Laramie, WY 82071
Terry L. Klein
U.S. Geological Survey
National Center, MS 954
12201 Sunrise Valley Drive
Reston, VA 22092
Robert S. Houston
Research Professor
Department of Geology and Geophysics
The University of Wyoming
Laramie, WY 82071
Paul J. Graff
Research Associates of Wyoming
2220 East 17th St.
Casper, WY 82601
IGCFIELDTRIPT332
PRECAMBRIANROCKSAND MINERALIZATION,
SOUTHERNWYOMING PROVINCE
by
1 2 3 4
George L. Snyder ,W. DanHausel ,TerryL. Klein ,Robert S. Houston ,
andPaulJ. Grafts
CONTENTS
Page
Chronologicalsummaryoffield trip (referto fig. 1,p. 2, for route) 3·
Acknowledgments 3
Illustrations 2-44
Tables 11,14,15,31
Overallgeologicsummary 3
Hartvilleupliftgeologicsummary(Snyder) 4
Hartvilleuplift stop descriptions (Snyder) 8
Laramie Mountainsgeologicsummary(Snyder) 12
Laramie Mountains stop descriptions (Snyder, Graff, and Hausel) 20
Medicine BowMountains geologicsummary(Houston) 25
Medicine BowMountains stop descriptions (Houstonand Graff) 25
Seminoe Mountainsgeologicsummary(Klein) 26
Seminoe Mountains stop descriptions (Kleinand Hausel) 33
SoutheastWind RiverRange geologicsummary(Hausel) 34
SoutheastWind RiverRange stop descriptions (Hausel) 39
CopperMountainareageologicsummary(Hausel and Graff) 41
Copper Mountainarea stop descriptions (Hausel and Graff) 44
References cited 44-48
1U.S.GeologicalSurvey, Denver, Colorado.
~e
GeologicalSurveyofWyoming, Laramie,Wyoming.
4U.S. GeologicalSurvey, Reston, Virginia.
The UniversityofWyoming, Laramie, Wyoming.
5ResearchAssociates ofWyoming, Casper, Wyoming.
T332: 1
43- 42- 41-
'
gg
I'0MILESI,I9,,,90KILOMETERSI !§~HH"'''l~',t-~~~DOUGLAS i~270j/""....IJ..,::,............",'"4.1A.; '-..I::tl'1+-,.~,.......IJ Q:'I~I::""""'GUERNSEY'\tNI '1-25 \'WHEATLAND\-.Jw"e••• CHEYENNEo 7"I1050 ereappropriate)forfieldtripvisitinocksdarklinedpatternonWyominInrocksdarklinedpatternonU.S.map.
o ~L'- "V"7 swhzoicrozoic
.!.::~~.... •"::.': 60 numberProteroPhaner
PER"~ •'10 routeattern;oicand
~~ hpz
~ ~'~~rpg~SPER.. CA a~dots,witlIghtdottedmap;Protero
en
, (hksiming
- 007 uterocyo
1 onW
, ra
en
. pho
..\~~ LYSITE:: <.....-.-....... showingtrioming.Arcnpatterned
) pWyu
a s
m k
nc
ro
xer
ehc
oS ndutoi
0 ioz
1 gicofsero
eoloocksPhan
Grg
nn
1ai
Erier
bv
Rmo
Uac
Gcp;
FIPrema
-
9
0
1
~wWf\J f\J
CHRONOLOGICAL SUMMARY OF FIELD Colorado. Lunches have been arranged by Steve
TRIP Schilling, U.S. Geological Survey, Denver,
Colorado.
Wednesday, July 19, 1989: Field trip participants We thank the following ranchers orlocal officials
assemble at Casper, Wyoming, airport by8:00 P.M. for theircooperationand land-accesspermission:
(United Airlines flight leaves Dulles International Hartville uplift: Faith Fanke ofDouglas'Holiday
Airport 2:15 P.M. and arrives Casper airport 7:50 Inn, Carl, Harry, Loretta, and Paul Soderberg, Mr.
P.M.) Group transported by field trip vehicles to and Mrs. J. E. Hoy, Mr. and Mrs. Albert Martin,
HolidayInnatDouglas, Wyoming (307-358 9790). Mr. and Mrs. Peter Martinez, Harold Anderson of
Thursday, July 20, 1989 (Snyder): Vehicle cara the Peter Kiewit Company, Darrell and Marian
van proceeds through geology stops in Archean Offe of the Bunkhouse Motel, and Leonard and
metasedimentary rocks with unusually well-pre SandyWolfe ofCrazyTony's restaurant.
served primary structures in Hartville uplift to Central Laramie Mountains: Mr. and Mrs.
Bunkhouse Motel, Guernsey, Wyoming (307-836 Springer Jones, the Eugene and Craig Kennedy
2356). Cultural opportunity to visit traces of families, Joseph and Ruth O'Brien, Warren and
OregonTrail stage coach route bywhich migrating Edie Riff, Tom and Valerie Christnick, Mr. and
settlerspopulatedwesternU.S. inlate 19thcentury. Mrs.JackRadichal, and KathleenandTomMoore.
Friday, July21, 1989 (Snyder, Graff, and Hausel): Medicine Bow Mountains: C.E. Pitcher of
Field trip Visits central Laramie Mountains with Arlington.
geology stops in Archean basement, metasedimen Bradley Peak area: John France of the Miller
tary and ultramafic meta-intrusive rocks, plus Estate, andDave Radar ofBelAirInn.
Proterozoic intrusives of the Laramie Anorthosite Southeast Wind River Ran~e: Jim Ni~emyer
Complex, and one Devonian kimberlite Elug. and Bob Klinger of Umversal EqUIpment
Evening at Chutes Inn, Laramie, Wyoming (307 Company, Bart Rea and Bruce Ward, owners of
7426611). the Duncan Mine, Michelle Vinich of Club EI
Saturday, July 22, 1989 (Houston and Graff) Toro, andSueHomecofSvilars restaurant.
Field trip route crosses the Cheyenne Belt, a shear Copper Mountain area: Mr. and Mrs. John
zone at the southeast margin of the North Herbst,Jr., andfamily.
American continental core, and visits various
Proterozoic greenstone belt rocks and potential
thoriumore horizons, endingup at the Bel AirInn, OVERALLGEOLOGICSUM~Y
Rawlins, Wyoming (307-324 2737).
Sunday, July 23, 1989 (Klein and Hausel): Field The United States of America contains surface
trippers visit spinifex-textured komatiites, banded exposures of two extensive Archean terranes, the
iron-formations, and various uranium and ~old Wyoming Province and the Superior Province (fig.
prospects inthe Bradley Peak area ofthe Selllinoe 1), which are separated under cover by the north
Mountains. Caravan continues on to the Holiday south trending Trans-Hudson orogen. Sm-Nd iso
Lodge, Lander, Wyoming (307-3322511). topic work indicates that these two Archean ter
Monday, July 24, 1989 (Hausel): Participants ranes may have been brought to their present rela
visit metasedimentary and metavolcanic rocks of tive positions by extensive north-south motion
the South Pass Greenstone belt of the Wind River along the Trans-Hudson orogen (Peterman and
Range, including iron-formation formerly quarried Futa, 1987). The southeastmargin ofthe Wyoming
at the Atlantic City mine. Return to Holiday Province will be visited during the first half of this
Lodge, Lander, for evenin~. field trip. It consists offragments ofboth Archean
Tuesday, July 25, 1989 (Hausel and Graff): Trip and Proterozoic metamorphosed sequences oflava
participants visit Copper Mountain supracrustal and sediments sitting atop and intruded by a remo
beltofOwl Creek Mountains, and returnto Casper bilized ~ranitic basement with extensive swarms of
airport by 4:00 P.M., completing a 1500km circuit mafic Intrusives. Throughout the Wyoming
ofthe accessible exposed Precambrian rocks ofthe Province and adjacent areas some mafic dikes are
southern Wyoming Province. (United Airlines veined by the enclosing granite that they originally
flight leavesCasperfor Dullesat4:50P.M.) intruded, suggesting remobilization of the granite
mass (Houston, 1971; Houston, and others, 1968, p.
143; Snyder, and others, 1988a, fig. 27). In the
Acknowledgments Hartville uplift and central Laramie Mountains the
southeast margin of the Archean craton is repre
Geochronological expertise has beenprovidedby sentedbyEarlyor Middle Proterozoicintrusives; in
Zell E. Peterman and Kenneth R. Ludwig of the the Medicine Bow Mountains and Sierra Madre
U.S. Geological Survey, Denver, Colorado. Trans the margin is represented bya sheared zone oftec
portation has been arranged by Paul Graff, tonic convergence, the Cheyenne Belt (fig. 1;
Research Associates of Wyoming, Casper, Houston and others, 1979; Duebendorfer and
Wyoming. Lodginglogistics have been arranged by Houston, 1987a and b). Similar Archean granitic
George Snyder, U.S. Geological Survey, Denver, gneisses and greenstone belt rocks near the center
T332: 3
CHRONOLOGICAL SUMMARY OF FIELD Colorado. Lunches have been arranged by Steve
TRIP Schilling, U.S. Geological Survey, Denver,
Colorado.
Wednesday, July 19, 1989: Field trip participants We thank the following ranchers orlocal officials
assemble at Casper, Wyoming, airport by8:00 P.M. for theircooperationand land-accesspermission:
(United Airlines flight leaves Dulles International Hartville uplift: Faith Fanke ofDouglas'Holiday
Airport 2:15 P.M. and arrives Casper airport 7:50 Inn, Carl, Harry, Loretta, and Paul Soderberg, Mr.
P.M.) Group transported by field trip vehicles to and Mrs. J. E. Hoy, Mr. and Mrs. Albert Martin,
HolidayInnatDouglas, Wyoming (307-358 9790). Mr. and Mrs. Peter Martinez, Harold Anderson of
Thursday, July 20, 1989 (Snyder): Vehicle cara the Peter Kiewit Company, Darrell and Marian
van proceeds through geology stops in Archean Offe of the Bunkhouse Motel, and Leonard and
metasedimentary rocks with unusually well-pre SandyWolfe ofCrazyTony's restaurant.
served primary structures in Hartville uplift to Central Laramie Mountains: Mr. and Mrs.
Bunkhouse Motel, Guernsey, Wyoming (307-836 Springer Jones, the Eugene and Craig Kennedy
2356). Cultural opportunity to visit traces of families, Joseph and Ruth O'Brien, Warren and
OregonTrail stage coach route bywhich migrating Edie Riff, Tom and Valerie Christnick, Mr. and
settlerspopulatedwesternU.S. inlate 19thcentury. Mrs.JackRadichal, and KathleenandTomMoore.
Friday, July21, 1989 (Snyder, Graff, and Hausel): Medicine Bow Mountains: C.E. Pitcher of
Field trip Visits central Laramie Mountains with Arlington.
geology stops in Archean basement, metasedimen Bradley Peak area: John France of the Miller
tary and ultramafic meta-intrusive rocks, plus Estate, andDave Radar ofBelAirInn.
Proterozoic intrusives of the Laramie Anorthosite Southeast Wind River Ran~e: Jim Ni~emyer
Complex, and one Devonian kimberlite Elug. and Bob Klinger of Umversal EqUIpment
Evening at Chutes Inn, Laramie, Wyoming (307 Company, Bart Rea and Bruce Ward, owners of
7426611). the Duncan Mine, Michelle Vinich of Club EI
Saturday, July 22, 1989 (Houston and Graff) Toro, andSueHomecofSvilars restaurant.
Field trip route crosses the Cheyenne Belt, a shear Copper Mountain area: Mr. and Mrs. John
zone at the southeast margin of the North Herbst,Jr., andfamily.
American continental core, and visits various
Proterozoic greenstone belt rocks and potential
thoriumore horizons, endingup at the Bel AirInn, OVERALLGEOLOGICSUM~Y
Rawlins, Wyoming (307-324 2737).
Sunday, July 23, 1989 (Klein and Hausel): Field The United States of America contains surface
trippers visit spinifex-textured komatiites, banded exposures of two extensive Archean terranes, the
iron-formations, and various uranium and ~old Wyoming Province and the Superior Province (fig.
prospects inthe Bradley Peak area ofthe Selllinoe 1), which are separated under cover by the north
Mountains. Caravan continues on to the Holiday south trending Trans-Hudson orogen. Sm-Nd iso
Lodge, Lander, Wyoming (307-3322511). topic work indicates that these two Archean ter
Monday, July 24, 1989 (Hausel): Participants ranes may have been brought to their present rela
visit metasedimentary and metavolcanic rocks of tive positions by extensive north-south motion
the South Pass Greenstone belt of the Wind River along the Trans-Hudson orogen (Peterman and
Range, including iron-formation formerly quarried Futa, 1987). The southeastmargin ofthe Wyoming
at the Atlantic City mine. Return to Holiday Province will be visited during the first half of this
Lodge, Lander, for evenin~. field trip. It consists offragments ofboth Archean
Tuesday, July 25, 1989 (Hausel and Graff): Trip and Proterozoic metamorphosed sequences oflava
participants visit Copper Mountain supracrustal and sediments sitting atop and intruded by a remo
beltofOwl Creek Mountains, and returnto Casper bilized ~ranitic basement with extensive swarms of
airport by 4:00 P.M., completing a 1500km circuit mafic Intrusives. Throughout the Wyoming
ofthe accessible exposed Precambrian rocks ofthe Province and adjacent areas some mafic dikes are
southern Wyoming Province. (United Airlines veined by the enclosing granite that they originally
flight leavesCasperfor Dullesat4:50P.M.) intruded, suggesting remobilization of the granite
mass (Houston, 1971; Houston, and others, 1968, p.
143; Snyder, and others, 1988a, fig. 27). In the
Acknowledgments Hartville uplift and central Laramie Mountains the
southeast margin of the Archean craton is repre
Geochronological expertise has beenprovidedby sentedbyEarlyor Middle Proterozoicintrusives; in
Zell E. Peterman and Kenneth R. Ludwig of the the Medicine Bow Mountains and Sierra Madre
U.S. Geological Survey, Denver, Colorado. Trans the margin is represented bya sheared zone oftec
portation has been arranged by Paul Graff, tonic convergence, the Cheyenne Belt (fig. 1;
Research Associates of Wyoming, Casper, Houston and others, 1979; Duebendorfer and
Wyoming. Lodginglogistics have been arranged by Houston, 1987a and b). Similar Archean granitic
George Snyder, U.S. Geological Survey, Denver, gneisses and greenstone belt rocks near the center
T332: 3
CHRONOLOGICAL SUMMARY OF FIELD Colorado. Lunches have been arranged by Steve
TRIP Schilling, U.S. Geological Survey, Denver,
Colorado.
Wednesday, July 19, 1989: Field trip participants We thank the following ranchers orlocal officials
assemble at Casper, Wyoming, airport by8:00 P.M. for theircooperationand land-accesspermission:
(United Airlines flight leaves Dulles International Hartville uplift: Faith Fanke ofDouglas'Holiday
Airport 2:15 P.M. and arrives Casper airport 7:50 Inn, Carl, Harry, Loretta, and Paul Soderberg, Mr.
P.M.) Group transported by field trip vehicles to and Mrs. J. E. Hoy, Mr. and Mrs. Albert Martin,
HolidayInnatDouglas, Wyoming (307-358 9790). Mr. and Mrs. Peter Martinez, Harold Anderson of
Thursday, July 20, 1989 (Snyder): Vehicle cara the Peter Kiewit Company, Darrell and Marian
van proceeds through geology stops in Archean Offe of the Bunkhouse Motel, and Leonard and
metasedimentary rocks with unusually well-pre SandyWolfe ofCrazyTony's restaurant.
served primary structures in Hartville uplift to Central Laramie Mountains: Mr. and Mrs.
Bunkhouse Motel, Guernsey, Wyoming (307-836 Springer Jones, the Eugene and Craig Kennedy
2356). Cultural opportunity to visit traces of families, Joseph and Ruth O'Brien, Warren and
OregonTrail stage coach route bywhich migrating Edie Riff, Tom and Valerie Christnick, Mr. and
settlerspopulatedwesternU.S. inlate 19thcentury. Mrs.JackRadichal, and KathleenandTomMoore.
Friday, July21, 1989 (Snyder, Graff, and Hausel): Medicine Bow Mountains: C.E. Pitcher of
Field trip Visits central Laramie Mountains with Arlington.
geology stops in Archean basement, metasedimen Bradley Peak area: John France of the Miller
tary and ultramafic meta-intrusive rocks, plus Estate, andDave Radar ofBelAirInn.
Proterozoic intrusives of the Laramie Anorthosite Southeast Wind River Ran~e: Jim Ni~emyer
Complex, and one Devonian kimberlite Elug. and Bob Klinger of Umversal EqUIpment
Evening at Chutes Inn, Laramie, Wyoming (307 Company, Bart Rea and Bruce Ward, owners of
7426611). the Duncan Mine, Michelle Vinich of Club EI
Saturday, July 22, 1989 (Houston and Graff) Toro, andSueHomecofSvilars restaurant.
Field trip route crosses the Cheyenne Belt, a shear Copper Mountain area: Mr. and Mrs. John
zone at the southeast margin of the North Herbst,Jr., andfamily.
American continental core, and visits various
Proterozoic greenstone belt rocks and potential
thoriumore horizons, endingup at the Bel AirInn, OVERALLGEOLOGICSUM~Y
Rawlins, Wyoming (307-324 2737).
Sunday, July 23, 1989 (Klein and Hausel): Field The United States of America contains surface
trippers visit spinifex-textured komatiites, banded exposures of two extensive Archean terranes, the
iron-formations, and various uranium and ~old Wyoming Province and the Superior Province (fig.
prospects inthe Bradley Peak area ofthe Selllinoe 1), which are separated under cover by the north
Mountains. Caravan continues on to the Holiday south trending Trans-Hudson orogen. Sm-Nd iso
Lodge, Lander, Wyoming (307-3322511). topic work indicates that these two Archean ter
Monday, July 24, 1989 (Hausel): Participants ranes may have been brought to their present rela
visit metasedimentary and metavolcanic rocks of tive positions by extensive north-south motion
the South Pass Greenstone belt of the Wind River along the Trans-Hudson orogen (Peterman and
Range, including iron-formation formerly quarried Futa, 1987). The southeastmargin ofthe Wyoming
at the Atlantic City mine. Return to Holiday Province will be visited during the first half of this
Lodge, Lander, for evenin~. field trip. It consists offragments ofboth Archean
Tuesday, July 25, 1989 (Hausel and Graff): Trip and Proterozoic metamorphosed sequences oflava
participants visit Copper Mountain supracrustal and sediments sitting atop and intruded by a remo
beltofOwl Creek Mountains, and returnto Casper bilized ~ranitic basement with extensive swarms of
airport by 4:00 P.M., completing a 1500km circuit mafic Intrusives. Throughout the Wyoming
ofthe accessible exposed Precambrian rocks ofthe Province and adjacent areas some mafic dikes are
southern Wyoming Province. (United Airlines veined by the enclosing granite that they originally
flight leavesCasperfor Dullesat4:50P.M.) intruded, suggesting remobilization of the granite
mass (Houston, 1971; Houston, and others, 1968, p.
143; Snyder, and others, 1988a, fig. 27). In the
Acknowledgments Hartville uplift and central Laramie Mountains the
southeast margin of the Archean craton is repre
Geochronological expertise has beenprovidedby sentedbyEarlyor Middle Proterozoicintrusives; in
Zell E. Peterman and Kenneth R. Ludwig of the the Medicine Bow Mountains and Sierra Madre
U.S. Geological Survey, Denver, Colorado. Trans the margin is represented bya sheared zone oftec
portation has been arranged by Paul Graff, tonic convergence, the Cheyenne Belt (fig. 1;
Research Associates of Wyoming, Casper, Houston and others, 1979; Duebendorfer and
Wyoming. Lodginglogistics have been arranged by Houston, 1987a and b). Similar Archean granitic
George Snyder, U.S. Geological Survey, Denver, gneisses and greenstone belt rocks near the center
T332: 3
ofthe Wyoming Provincewill bevisited on the last
halfofthis field trip; some rocks in the central and
northern Wyoming Province have recently been
reported to be among the oldest on the continent
(3.8-3.9 Ga) (Aleinikoffand others, 1987; Wooden
and Mueller, 1987). All surface exposures of the
Archean continent occur today in north- to north
west-trending Laramide anticlines, with locally
faulted borders, that are expressed topo~aphically
as erosion-resistant mountains or low hIlls (Reed,
1987). A Phanerozoic rock cover fills structural
depressionsbetweenthe Laramide anticlines; these
rockswillbe crossedwith minimal emphasis onthis
field trip. The trip will emphasize the complex
interrelationships of the remobilized granitic
basement, multiple-metamorphosed Archean
supracrustal greenstone belt rocks with some
remarkably well-preserved primary structures,
marginal Proterozoic intrusives and their high
temperature low-pressure cooked contact rocks,
andseveral types ofiron, gold, oruranium deposits
thatoccurin-this Precambrianterrane.
~ CASSA
ANTICLINE
HARlVILLEUPLIFTGEOLOGIC SUMMARY
(Snyder, adaptedfrom Houstonand others, 1988)
The Precambrian rocks of the Hartville uplift
consist of medium- to high-grade metasedimentary
rocks cut by felsic plutonic rocks of three ages and
mafic dike rocks of two ages (fig. 2; Snyder and
Peterman, 1982). Earlywork inthe Hartvilleuplift
recognized the major lithologies and some broad
age ~roupings ofrocks; the latestwork developed a
detaIled stratigraphyand time sequence ofgeologic
events (Snyder and Peterman, 1982). The Precam
brian rocks of the Hartville uplift have provided
small ore deposits ofbase metals and uranium and
SCALE
large reserves of hematitic iron ore and crushed 1...-......1:::::=10==----1'5 KILOMETERS
rock.
EXPLANATION
The stratified rocks of the Archean Whalen
Group of Smith (1903) are 70 to 80 percent clastic ~
~
or biochemical sediments and 20 to 30 percent Graniteof Graniteof Contact
mafic extrusives or volcanic-derived sediments. Ha-~ystackRange RaDwh.id'.e·.B.uttes
They are currently ~rouped into four formations , ,
that together comprIse more than 3700 m of sec TDwioinriteHilolsf FWoirlmdcaatitoHnilolsf Fault
tion (fig. 3). These layered rocks of the Whalen ~~~~
~"'~","
Group, which contain rare granitic rebbles, were
Graniteof Schistof Foldaxis
probably deposited on a basement 0 3.Q-Ga sialic FlattopButte SilverSprings
rocks that was later reactivated to intrude the lay [3l] •5
ered rocks, as inferred from isotopic model ages Metabasaltof Field trip stop
MotherFeatherlegs
(Peterman, 1982; Snyder and Peterman, 1982). U
Geopetal information from six types of primary
i Formationof
structures in the stratified rocks, together with the ~ L MuskratCanyon
geologic mapping constraints, have permitted
recognition of open to isoclinal north-northeast
trendingfolds tightlyrefolded alongeast-westaxes. FIGURE 2 Geologic summary map for the surface
The lowest rock unit of the Whalen Group, the and near-surface Precambrian rocks of the
formation of Muskrat Canyon, is predominantly Hartville uplift. Modified from Houston and
carbonate rock that includes nearly pure tremolite others (1988, fig. 2.14).
dolomite in the southern part of the uplift and
siliceous ortremolite dolomitewith interlayers of
T332: 4
