Pegmatite
Brown Derby Mine
Gunnison
Parlin
K/Ar
Lepidolite
53
1460 ± 58
Aldrich and others (1956)
Location approximate.  Some microlite in sample.
1400 ± 56
Location approximate.
1380 ± 55
1420 ± 57
Granite
Henry Mountain pluton
Granite A
U-Pb
Zircon
140
1540 ± 140
Henry Mountain Granite of DeWitt and others (2002); 207Pb/206Pb date.  Apparently same site as B-81-70 of Bickford, Shuster, and Boardman (1989).
Granite B
Doyleville
Biotite
K-feldspar
39
1040 ± 42
60
1700 ± 60
207Pb/206Pb age.  Location approximate.
Gneiss
Quartz Creek Granite
Quartz Creek
Saguache
Houston Gulch
1280
Aldrich and others (1958)
Age recalculated by Shaw and others (2005).
Pikes Peak pluton
Top of Pikes Peak
Pikes Peak
Not report
980
Pikes Peak granite.  Biotite partially chloritized.
Syenite
McClure Mountain alkaline complex
MMhb-1
Canon City
Iron Mountain
Hornblende
2.5
519.5
Alexander and others (1978)
Granodiotite
Kroenke Granodiorite;
BF 176
Mount Harvard
Sphene
5
1,665
Fridrich and others (1998)
Map gives age as 1,665 but Reed and others (1987) give it as 1404 Ma. Likely that the 1,665 Ma date is for zircons and Table 1 of the map incorrectly lists the mineral analyzed as sphene.
Quartz syenite
Alkaline complex of Democrat Creek
Curley Peak
Rb-Sr
Whole-rock
8
511
Armbrustmacher and Hedge (1982)
Isochron age.  Sample locations not given; coordinates mark approximate center of mapped complex for plotting purposes.
535
Isochron. Samples include nepheline syenite and hornblende-biotite syenite.  Locations not given; coordinates mark approximate center of mapped complex for plotting purposes.
4
524.2
Baadsgaard and others (1988)
3.3
514.5
Baksi and others (1996)
Vein material
Sweet Home Mine
SH-2
Leadville
Alma
40Ar/39Ar
Sericite
0.1
25.5
Barbá and others (2005)
Plateau age.  Location approximate; estimated from description.
SH-3
26.1
SH-4/#1
0.2
25.1
Weighted average of lowest Cl/K fractions.  Integrated [=K-Ar] age is 108.0 ± 0.8.  Location approximate; estimated from description.
SH-4/#2
0.4
25
Weighted average of lowest Cl/K fractions.  Integrated [=K-Ar] age is 82.5 ± 1.3.  Location approximate; estimated from description.
SH-4/#3
0.6
26.3
Weighted average of lowest Cl/K fractions.  Integrated [=K-Ar] age is 68.9 ± 0.5.  Location approximate; estimated from description.
Granodiorite
Kroenke Granodiorite
BF-176a
100
1700
Barker and others (1974)
Isochron based on 6 samples.  (Sample 1 of 6)  Recalculated date in DeWitt and others (2002).
BF-301
Winfield
Isochron based on 6 samples.  (Sample 2 of 6)  Recalculated date in DeWitt and others (2002).  Location approximate.
BF-302
Mount Yale
Isochron based on 6 samples.  (Sample 3 of 6)  Recalculated date in DeWitt and others (2002).  Location approximate.
BF-303
Isochron based on 6 samples.  (Sample 4 of 6)  Recalculated date in DeWitt and others (2002).  Location approximate.
BF-304
Isochron based on 6 samples.  (Sample 5 of 6)  Recalculated date in DeWitt and others (2002).  Location approximate.
BF-305
Isochron based on 6 samples.  (Sample 6 of 6)  Recalculated date in DeWitt and others (2002).  Location approximate.
Trondhjemite
Palisade Mountain plug
50
Estes Park
Drake
15
Barovich (1986)
This unpublished age is a common reference in published papers.  Date of Palisade Mountain plug puts maximum age on latest stages of Early Proterozoic deformation.
Pando Porphyry
C-12
Leadville North
FT
6.3
61.1
Beaty and others (1987)
T-1
7.7
67.7
Apatite
24
72.7
Granodiorite porphyry
Lincoln Porphyry
T-2
11.1
56.4
T-3
38.7
6.8
42.1
T-38
Pando
7.1
34.9
4.3
Porphyry
Sacramento porphyry
T-39
19
45.2
6
53.6
T-4
26
48.6
6.2
53.2
T-40
3.6
39.9
7.5
40.7
Spene
6.6
43.7
Eagle River Porphyry
T-41
4.8
52.9
17
54.5
T-42
7.6
42
4.2
43.3
49.3
Syenodiorite
unamed stock near Buckeye Lake
T-43
13
44.2
4.9
48.4
18
64.7
T-44
48.3
8.2
73.6
T-5
39.5
T-6
60.6
T-7
5.6
55.5
Granite of Williams Creek (and Bear Creek)
BC-1
Blanca Peak
Bear Creek
36
1486
Bickford, Cullers, and others (1989)
Concordia, upper intercept.  Probably considerable inherited zircons.  Location approximate.
Monzogranite
Garell Peak batholith
CO-15
Echo
22
1666
Concordia, upper intercept.  Location given in Reed and others (1987), Supplemental Data 8731.
McCoy Gulch stock
CO-7
7
1474
Concordia, upper intercept.  Location approximate.
CO-9
Cotopaxi
21
1460
San Isabel pluton
LDS-105
Beulah
34
1345
Isochron based on nine samples.  (Sample seven of nine.)  Location approximate.
LDS-36
Saint Charles Peak
Isochron based on nine samples.  (Sample three of nine.)  Location approximate.
LDS-45
Isochron based on nine samples.  (Sample five of nine.).   Location approximate.
LDS-67
Isochron based on nine samples.  (Sample four of nine.)  Location approximate.
LDS-94
Isochron based on nine samples.  (Sample six of nine.)  Location approximate.
Leucogranite
MM-B
Arkansas Mountain
1663
Charnockite
Mount Tyndall Charnockite
MT-2
Mount Tyndall
10
1694
Estimated age based on 207Pb/206Pb ages of four nearly concordant fractions.  Could be time of either intrusion or metamorpism. Location approximate.
Granite of Bear Basin
MT-3
11
1359
Concordia, upper intercept; lower intercept forced through 99 Ma.  Location approximate.
Tonalite
Foliated tonalite of Mount Tyndall area
MT-8
1653
Concordia, upper intercept.  May be metamorphic age.  Location given in Reed and others (1987).
Tonalitic gneiss of Mount Tyndall area
MT-9A
1622
Concordia, upper intercept; lower intercept forced through 99 Ma.  May be metamorphic age.  Location given in Reed and others (1987).
Megacrystic granite
Foliated megacrystic granite of Mount Tyndall area
MT-9B
3
1615
Concordia, upper intercept; lower intercept forced through 99Ma.  Location given in Reed and others (1987).
Granitic sill in paragneiss
NOB-1
Wetmore
82
1441
Crampton Mountain pluton
RG-25
McIntyre Hills
1705
Twin Mountain pluton
RG-4
Rice Mountain [?]
1706
Oak Creek stock
RG-6
1439
RV-1C
Rockvale
1442
Concordia, upper intercept; lower intercept forced through 99 Ma. Location approximate.
SC-2
1362
Concordia, upper intercept. Reported in Thomas and others (1984) as 1,362 ± 3 Ma.  Location approximate.
SD-2
14
1371
Concordia, upper intercept; lower intercept forced through 99 Ma.  Reported in Thomas and others (1984) as 1,356 ± 2 Ma.  Location approximate.
TG-1
Isochron based on nine samples.  (Sample one of nine.)  Location approximate.
TG-17
Isochron based on nine samples.  (Sample two of nine.)  Location approximate.
TG-70
San Isabel
Isochron based on nine samples.  (Sample eight of nine.)  Location approximate.
TG-91
Isochron based on nine samples.  (Sample nine of nine.) Location approximate.
VS-3
536
Concordia, upper intercept; lower intercept forced through 0 Ma.  Location approximate.
Phantom Canyon batholith
VS-6
Phantom Canyon
1665
VS-75
1703
Granite of Cripple Creek, Elevenmile Canyon batholith
VS-8
Wrights Reservoir
28
1423
VS-9
Elevenmile Canyon
1459
Metarhyolite
Rhyolite of Iris Formation (of Afifi)
B-81-13
Iris
1740
Bickford, Shuster, and Boardman (1989)
Concordia, upper intercept.  Location reported in Reed and others (1987), Supplemental Data 8731.
Pluton of Gold Basin
B-81-24
1713
Granite of South Beaver Creek
B-81-40
Iris NW
1721
Unamed granite
B-81-42
B-81-43
1730
Granite of Tolvar Peak
B-81-59
Montrose
Powderhorn
1757
Concordia, upper intercept.  Location reported in Reed and others (1989), Supplemental Data 8731.
Rhyolite of Dubois
B-81-60
1766
B-81-61
1781
Concordia, upper intercept.  Location approximate; estimated from Montrose 1:250,000 scale geologic map (Tweto and others, 1976).
Granite of Cochetopa Canyon
B-81-68
Sawtooth Mountain
1676
Concordia, upper intercept.  Location approximate and reported in Reed and others (1987), Supplemental Data 8731.
Granite of Wood Gulch
B-81-70
1701
Concordia, upper intercept.  Location reported in Reed and others (1987); coordinates estimated from page-size location map.
Powderhorn Granite
B-81-71
1751
Concordia, upper intercept.  Location reported in Reed and others (1989), Supplemental Data 8731, where it is also identified as B-71 and AA-85-43.
B-81-82
1759
B-81-85
Gateview
B-82-2
1770
B-83-1
1733
Ohio City volcanic succesion
B-85-1
16
1745
Near Ohio City
QCF
Pitkin
Concordia, upper intercept.
South of Salida
RC-HO-1
Wellsville
1668
RC-HO-2
SAB 79-12
1742
SAL-1
Cameron Mountain
1672
Concordia, upper intercept.  Location given in Supplemental Data to Reed and others (1987); longitude corrected from 106° to the apparently correct 105°.
Unamed rhyolite (in Dubois basalt)
SOC-1
1728
Rhyolite of Dubois (?)
SOC-2
1765
Quartz diorite
Mafic pre-Beaver Creek pluton
T-81-10
Metadacite
Salida metavolcanics
Z-3
Salida East
Concordia, upper intercept.  Location given in Supplemental Data to Reed and others (1987).
Buckskin Gulch granodiorite
Climax
55.9
Bookstrom (1989)
1.9
62.4
Granodiorite stock
1.2
Biotite rhyolite-B porphyry
Stock southeast of Camp Hale
1323-AB-82-1
3.2
35.5
Bookstrom and others (1987)
43.5
Sanidine
2
40.2
Sericitized granite-B porphyry
Stock of Silver Mountain (Montezuma)
AB-77G-12A
Denver West
Montezuma
Small intrusion interpreted to be cupola of underlying stock.
Rhyolite-A porphyry
Montezuma east area
AB-77-G-27A
Rhyolite-A porphyry dike
Near Kite Lake
B-5289
2.3
63.6
Rough and Tumbling stock
B-5853
Jones Hill
2.1
BU-77-H-100
Rhyolite-B porphyry dike
Buckskin Gulch porphyritic dike
BU-77-H-98
26.7
Average of 3 grains.
35.4
Average of 7 grains.
43.9
Average of 4 grains.
Climax, seriate granite stock
Climax 78-1
24.4 ± 4.9
Otter Mountain plug
DF-1496
Georgetown
Funnel-shaped neck.
Sericitized rhyolite-B porphyry
Paines Mountain plug
DF-1497
Central plug of a cluster of plugs and dikes.
Rhyolite-B porphyry
Plug at Webster Pass
DF-1498
3.7
Biotite dacite porphyry
Montezuma, late phase
DF-1499
Granite-B porphyry
Montezuma stock
DF-1500
Montezuma stock, southeast margin
DF-1528
Mad Creek stock, which cuts Empire stock
DF-2692
Empire
Explosion breccia
Surrounds Mad Creek stock
DF-2693
6.5
Northwest-trending dike
DF-2695
Biotite rhyolite-B porphyry dike
Northeast-trending dike in Montezuma-Silver Plume swarm
DF-2697
Grays Peak
Britannic Mine stock (Montezuma east)
DF-2698
Hornblende-biotite dacite porphyry dike
Northwest-trending dike south of Montezuma stock
DF-2699
Radial dike swarm around Red Mountain
DF-2700
Berthoud Pass
Granite-A porphyry
Urad stock, Henderson Mine
DF-4829
3.1
7550 level.
DF-4830
8100 level.
Granite-A
DF-4831
7500 level.
Kersantite
Dike, Henderson  Mine
KA-82-585
Buckskin biotite granodiorite dike
KL-1-2134
27.6
Leucorhyolite porphyry
Near contact of Urad stock
70-164
Bookstrom and others (1988)
2700 m altitude in Henderson mine.
Leucogranite porphyry
Henderson stock
77-133
2150 m altitude in Henderson mine.
Composite kersantite-rhyolite dike north of Henderson mine
82-287
2275 m altitude in Henderson mine.
Interior of Urad stock
CX122-4820
2000 m altitude in Henderson mine.
Vasque Porphyry
CX127-3980
2100 m altitude in Henderson mine.
CX165-3265
Post-ore Dailey stock
H-480-1046
2050 m altitude in Henderson mine.
Rhyolite porphyry
Mount Cumulus stock, central part
Mount Richthofen
0.7
Braddock and Cole (1990); Gamble (1979)
Mount Cumulus stock, outer part
1.5
Gabbro
Iron Dike
30-1-9
Fall River Pass
Braddock and Peterman (1989)
19 point isochron.
Granophyre
Plagioclase
Tuff
San Luis Valley
Amer 1760-70
Mount Pleasant School
0.16
27.7
Brister and McIntosh (2004)
Laser-fusion weighted-mean age.  Sample from well-cuttings; probably includes detrital grains.
32.68
Amer 1820-30
0.09
27.79
0.19
32.32
Amer 1930
0.11
27.76
0.32
32.58
Amer 2180-2200
32.17
Amer 2460-70
0.15
28.03
Amer 2860-70
0.28
0.3
32.24
Treasure Mountain Tuff (?)
Brister 90-6
Alamosa
Trinchera Ranch
0.12
29.95
Plateau age.
ES 2500-30
Alamosa East
23.21
Laser-fustion weighted-mean age.  Sample from well-cuttings; probably includes detrital grains.  Location approximate; probably good to within 1 km.
Unit correlates with Carpenter Ridge Tuff
ES 2560-90
27.22
Laser-fusion weighted-mean age.  Sample from well-cuttings.  Location approximate; probably good to within 1 km.
Probably correlates with Chiquito Peak Tuff
ES 3040-70
0.21
28.91
Laser-fusion weighted-mean age.  Sample from well-cuttings; may include detrital grains.  Location approximate; probably good to within 1 km.
Unit correlates with Gribbles Park Tuff
ES 5500-30
32.92
Fish Canyon Tuff
Map 8690-8700
Medano Ranch
Laser-fusion weighted-mean age.  Sample from well-cuttings.
Gribbles Park Tuff
Map 9304-50
32.9
Map 9360-70
32.86
Map 9370-80
0.14
32.84
Map 9390-9400
33.03
Map 9400-9410
0.13
32.77
Res 5180-90
Hooper East
25.13
Res 5210-40
27.88
Res 5610-40
0.58
27.4
Res 6200-30
0.39
27.93
Carpenter Ridge Tuff
Tenn 2120-40
Del Norte
La Garita
27.37
Laser-fusion weighted-mean age of well-cuttings; may have some xenocrysts in sample.
Tenn 2440-50
Laser-fusion weighted-mean age of well-cuttings
Lower Treasure Mountain Tuff (?)
Tenn 3460-80
0.23
30.17
Laser-fusion weighted-mean age of well-cuttings.
Tuck 3675
Center North
27.44
Tuck 3900-05
27.92
Biotite-hornblende-plagioclase gneiss
Proterozoic gneiss degassed by Eldora stock
EL-24a
Tungsten
35
Brookins and Abashian (1981)
Biotite partly degassed by heat from stock (?).
EL-26
Nederland
2.2
Biotite degassed by heat from Eldora stock.
Biotite-hornblende gneiss
EL-27a
2.7
Biotite degassed and K-feldspar partly degassed by heat from Eldora stock.
EL-28
K-feldspar partly degassed by heat from stock.
Biotite-hornblende-pyroxene gneiss
EL-29a
Biotite and K-feldspar partly degassed by heat from stock.
Biotite hornblende felsic gneiss
Gneiss cut by apophyses of Eldora stock
EL-3
Gneiss cut by apophyses of Eldora stock.
Pegmatite-bearing felsic gneiss
EL-6B
Grottos pluton
D-10
Aspen
12.8
52.5
Bryant and Naeser (1980)
Age only approximate.
DF-1339
Biotitic migmatite
Metasedimentary gneiss
C-39
Hayden Peak
3.9
27.9
Annealing age due to uplift.
Biotite quartz monzonite
DF-1344
5.5
51.1
Intrusive rock
Twin Lakes stock
TL-F-6-16
Mount Elbert
2.9
20
Monitor Rock plug
73N7
4.4
19.9
73N8
Independence Pass
29.9
Aplite
Dike in Twin Lakes stock
73N9
2.4
Hornblende-biotite-plagioclase-quartz crystal tuff
Link Springs Tuff Member of the South Park Formation
150
Bailey
Milligan Lakes
Bryant and others (1981)
Pyroxene-bearing hornblende-biotite granodiorite
Plug in Pierre Shale and Williams Range thrust
222
Boreas Pass
1.7
Biotite mixed with hornblende
1.6
1.8
Porphyritic biotite-hornblende quartz monzonite
Sill (?) in Pierre Shale
223
Keystone
Determinations on three biotite separates from same sample.
1.00
Porphyritic biotite granodiorite
South end of Bald Mountain sill
233
Como
1.4
Dacite
Flow near base of South Park Formation
325
About 160 m above base of South Park Formation.
Porphyritic hornblende-biotite trachydacite
Sill in Benton Group
328
Jefferson
Dacite ash flow tuff
In Antero Formation
420
Mt. Logan
Fills paleovalley graded to Elkhorn surface.
Dacite flow breccia
Underlies Wall Mountain Tuff
430a
Garo
1.3
Felsic crystal tuff
Base of South Park Formation
444
Elkhorn
Brecciated and contact metamorphosed gneiss
Williams Range thrust zone
466
Altered porphyritic monzogranite
Probably sill in Pierre Shale
502
Porphyritic hornblende-biotite monzogranite
503
Biotite mixed with minor chlorite and ho
Biotite monzogranite
Mount Guyot plug
74
About 1600 me above base of South Park Formation
W-1-75
About 1600 m above base of South Park formation.
About 1600 m above base of South Park Formation
Quartz monzonite
AS-1
31.9
Bryant and others (1990)
451
Aplite porphyry
AS-10
48.7
Hornblende quartz diorite
Pre-Twin Lakes diorite
AS-11
53.4
Uplift age.
Quartz porphyry
Little Annie sill
AS-12
7.2
9.2
22.3
Middle Proterozoic rocks
AS-2
111
586
69.8
Sandstone
Gothic Formation
AS-3
852
Maroon Formation
AS-4
186
648
AS-5
52.1
AS-6
6.1
58.6
AS-7
AS-8
53.1
AS-9
5.3
28.7
Altered wallrock
Speckle Pay Mine.
Bald Eagle
Central City
61.9
Caine and others (2006)
Plateau age; sericite ultrasonically separated.
Speckle Pay
Idaho Springs
65.4
Plateau age; sericite separate hand-picked.
Weighted-average age; sericite ultrasonically separated.
1360
Carr and Kulp (1957)
Location and recalculated age from Shaw and others (2005).
Feldspar
40
835
Location from Shaw and others (2005).
855
Metagabbro
Buckhorn Creek
BC613-3
Fort Collins
Buckhorn Mountain
Cavosie and Selverstone (2003)
Integrated age.  70% of gas yields steps >1600 Ma with older steps >1800 Ma.
Mylonite
BT162
Integrated age. Spectrum suggest Early Proterozoic growth of hornblende followed by partial resetting during ~1.4 Ga mylonitization and/or heating.
Whitehorn stock
S2
66
Chualaowanich (1996)
73.4
Whitehorn stock; satellite body
ss5
66.1
85
A38G-II
54 ± 13
Church and Bickford (1971)
Laramide annealing zone.  Location approximate.
44
46 ± 11
Quartz Monzonite of Cochetopa Creek
CO-74
30
300 ± 30
Annealing date.
160 ± 16
Greisen
West Greisen stock
B-11
Saint Elmo
Muscovite
1.1
Coolbaugh (1985)
Location estimated from page-size map.
Browns Creek plug
B-93
30.3
Rhyolite ash flow
South of Cameron Pass, Neversummer volcanics
306S
Chambers Lake/Fall River Pass
Corbett (1968)
Italian Mountain intrusive
I-368
Pearl Pass
33.0 ± 1.8
Cunningham and Naeser (1975); Cunningham and others (1994)
Same as sample I-1 of Cunningham and others (1994).
West Cross Creek stock
D2499B
Mount Jackson
61.8
Cunningham and others (1977)
West Tennessee Creek stock
D2568B
Homestake Reservoir
66.4
Quartz Creek stock
DF-1118
Antonito
Wolf Creek Pass
24.2 ± 2.5
Tincup porphyry sill
DF-1150
Fairview Peak
34.5
Age recalculated by Cunningham and others (1994).
DF-1151
Epidote
37.3
DF-1164
10.3
46.4
Evans Gulch Porphyry
DF-1445
47
White Cloud mine.  Age recalculated by Cunningham and others (1994).
East Lake Creek stock
DF-848
65.3 ± 5.5
DF-849
8.1
59.5 ± 7.5
DF-850
6.9
59.3
Fulford stock
Fulford-1
Vail
Fulford
65.3 ± 6.0
I-22
62.2
Porphyry Creek stock
D2569B
Sargents
0.9
38.4
Cunningham and others (1977); Cunningham and others (1994)
DF-1152
35.3
Rhyolite porphyry intrusion
Eureka pipe, Leadville
D2642S
38.5
Dump of the Big Six mine.  Age recalculated by Bookstrom (1989).
Hornblende-biotite quartz monzonite
Apex stock
A-1
Cunningham and others (1994)
Dike intruding Apex stock
A-2
5.2
Biotite-hornblende quartz monzonite
Eldora stock
E-1
6.4
Biotite-sanidine quartz monzonite
Italian Mountain intrusive complex
I-1
33.9
Same as sample I-368 of Cunningham and Naeser (1975).
Biotite-fluorite vein
Cuts granodiorite stock
JS-1
Gold Hill
Sodic granite
Porphyry Mountain stock
JS-2a
5.7
Vertical drill core 12.5 m depth.
JS-2B
Vertical drill core 1024 m depth.
Jamestown stock
JS-3
Johnson Gulch Porphyry
L-3
34.8
Porphyritic quartz monzonite
Small stock 5 km south of Montezuma stock
M-1
Mount Sopris stock
MS-1
Carbondale
Mount Sopris
4.1
34.3
0.8
34.2
Rhyolite
Round Mountain stock
RM-1
Cement Mountain
11.5
9.8
13.9
Felsic gneiss/amphibolite
Gore Range
Mount Powell
Sm-Nd
90
1800
DePaolo (1981)
Isochron based on 6 samples.  Location from Wallace (1993, 1995).
Granite of Taylor River
6-30-82-6
Matchless Mountain
1406
DeWitt and others (2002)
207Pb/206Pb date.
Latite
Fossil Ridge Latite
7-14-82-3
Crystal Creek
1
69
8-12-82-2
1693
Roosevelt pluton
8-13-82-2
1720
Fairview Peak Granodiorite
8-7-82-1
Fairview
1640
Gold Creek plug
9-6-83-4
Intrusion cooling age
FR-UM-AND
Taylor Park Reservoir
70.3
Partial plateau age.
6.85
56.6
Regional uplift age
X-61962
Muscovite; trace biotite
1326
St. Kevin Granite
C-2
1420
Doe and Pearson (1969)
Upper intercept age.  Location and recalculated age by Wallace (1993, 1995).
C-3
HWDT
Welded ash flow tuff
Wall Mountain Tuff
Eagle Rock
Epis and Chapin (1968); Sawatzky (1967)
Some contamination by Proterozoic basement rock.  2% rock fragments and impurites.
Basalt
Flow on South Table Mountain
KA978
Golden
Evernden and others (1964)
Dacitic pumice
Denver Formation
KA992
Pyroxene syenite
Iron Hill alkaline complex
IH14
9
1487 ± 9
Fenton and Faure (1970)
Isochron based on 4 samples.  (Sample 2 of 4).  Location approximate; good to 1/4 section.
Uncompahgrite
IH16
Rudolph Hill
Isochron based on 4 samples.  (Sample 1 of 4).  Location approximate; good to 1/16 section.
Epidote-quartz rock
IH18
Isochron based on 4 samples.  (Sample 4 of 4).  Location approximate; good to 1/16 section.
IH18a
Isochron based on 4 samples.  (Sample 3 of 4).  Location approximate; good to 1/16 section.
Hornblende syenite
MM-2
517 ± 14
Isochron based on 5 samples. (Sample 1 of 5)  Date is 704 ± 70 if altered sample MM-5 is excluded.  Location approximate to nearest quarter section.
Shonkinite
MM-3
Isochron based on 5 samples.  (Sample 2 of 5)  Date is 704 ± 70 if altered sample MM-5 is excluded.  Location approximate to nearest quarter section.
Nepheline syenite
MM-4
Isochron based on 5 samples.  (Sample 3 of 5)  Date is 704 ± 70 if altered sample MM-5 is excluded.  Location approximate to nearest quarter section.
Cancrinite syenite
MM-5
Isochron based on 5 samples.  (Sample 4 of 5)  Date is 704 ± 70 if altered sample MM-5 is excluded.  Location estimated from Fig. 2 in Fenton and Faure (1970).
Carbonatite
MM-81
Isochron based on 5 samples.  (Sample 5 of 5)  Date is 704 ± 70 if altered sample MM-5 is excluded.  No location given; latitude/longitufe given only for plotting purposes are very approximate.
Grizzly Peak Tuff near Mount Sopris
(D)-A
36.3
Fridrich and others (1991)
Outflow of Grizzly Peak Tuff
AVG-1
33.3
Near Twin Lakes dam.
Intracaldera Grizzly Peak Tuff
MA-1
33.4
contains rhyolite fiamme.
Drill core from Middle Mountain stock
MM-1
37.8
Ranta (1974), Fridrich and others (1991)
Middle Mountain Porphyry
38.9
Pine Creek stock
PC-1
New York Peak
35.7
Sample probably contained excess Ar.
36.8
Sawmill stock
SAWM-1
ZB-2
33.8
contains latite fiamme.
IC-6
Italian Creek
1446
Upper intercept; only two points so no uncertainty calculated.
No sample number
1645
Date given in text of pamphlet accompanying map of Fridrich and others (1998), but not shown on map or in Table 1.
Diorite
Mafic border zone of Twin Lakes pluton
R8-28-84-8
63.82
Weighted average plateau age.  Location from Wallace (1993, 1995).
Mount Princeton pluton
Mount Antero
Th-Pb
36.6
208Pb/232Th date on single fraction of -400-mesh zircon; identical lower-intercept age given by forcing discordia through data point and upper-intercept of 1,700 Ma.  Location approximate.
Urad Mine porphyry
Orthoclase
Geissman and others (1992)
Disturbed spectum, preferred age.
28.6
Disturbed spectrum, preferred age.
28.3
Plateau age, small sample.
Urad-Henderson in Henderson Granite
Excess Ar loss to 28.1 Ma
Urad-Henderson in Seriate Porphyry
Orthoclase, altered
Urad-Henderson, Seriate Porphyry
23
Urad-Henderson in Vasquez Porphyry
0.08
Disturbed spectrum; preferred age.
Magnetite-sericite alteration zone
27
0.03
Urad-Henderson, Vasquez Porphyry
29
27.83
Urad-Henderson, border of Ute Porphyry
31
32
Urad Mine Porphyry
13, Table 4
23.8
Geissman and others (1992); Naeser and others (1973)
11, Table 4
33.7
Geissman and others (1992); Shannon (1982)
12, Table 4
28.5
Trout Creek Pass area
PUF-24B
Antero Reservoir
Mica
1430
Giffin and Kulp (1960)
Royal Gorge.
PUF-29B
Royal Gorge
1540
Monarch Pass area
PUF-34B
Pahlone Peak
1330
Arkansas River Canyon area.
PUF-7M
1290
1300
East end of Arkansas River Canyon
PUF-8B
1470
PUF-9
Silver Plume Granite
Graubard and Mattinson (1990)
Preliminary result; final not published.
2.8
522.8
Harrison (1981)
Location approximate.  Weighted-average date calculated using 3gr as the primary standard.
4.5
513.4
Location approximate.  Plateau age.
Monzonite
Audubon stock
Ward
Hart (1960)
Composite date.  No individual sample locations.  Average of biotite from stock and four samples of country rock from contact zone.
Feldspar-quartz-biotite-muscovite pegmatite
South of Barker Reservoir
22500
Biotite, coarse
Hart (1964)
Regional cooling age.
Amphibolite included in pegmatite
South of Nederland
9400
BCOA
Fine biotite and hornblende
Granite aplite
Boomer cupola of Redskin stock
Ppb-1K
Tarryall
Microcline
Hawley and others (1966)
Ppb-lm
Ppb-lmg
Porphyritic granite
Porphyritic facies of Redskin stock
Pprs-1K
Greisen in Redskin stock
Pprs-lmg
Pps-lb
Hornblende granite
Pikes Peak pluton and Rosalie lobe
1221
Cripple Creek North
1041 ± 13
Hedge (1970)
Isochron based on 13 samples.  Four samples on Colorado Springs and 7 samples on Bailey 1:100,000 quadrangle.
Westcreek pluton of Pikes Peak
1222
Westcreek
Biotite granite
Pikes Peak pluton, north
1223A
Green Mountain
Aplite Dike
1223B
PP-2
Deckers
PP-B
Lone rock pluton of the Pikes Peak batholith
rlg-1
Formerly called the Rosalie lobe.
rlg-2
rlg-3
3.16.1
1735
Hill and Bickford (2001)
SHRIMP 207Pb/206Pb date on rim of zircon.  Same sample as B-81-61 of Bickford, Shuster, and Boardman (1989); suggests TIMS date is too old because of inherited cores.  Location estimated from Montrose 1:250,000
3.36.1
1729
Henry Mountain pluton (?)
7.46.2
1708
SHRIMP 207Pb/206Pb date on rim of zircon.  Same sample as B-81.70 of Bickford, Shuster, and Boardman (1989).
Flagstaff Mountain sill
Flag 28-65
Boulder
3.5
Hoblitt and Larson (1975)
Potassic basalt
Ralston Reservoir intrusive
Left Hand Canyon sill
Lyons
Lyons quarry sill
Biotite-muscovite granite
Kenosha batholith
P-10
Observatory Rock
Hutchinson (1960)
Cooling age.
Hornblende-bearing biotite granite
Outer zone of Pikes Peak pluton
P-4
Pine
Hornblende-biotite monzogranite
Intermediate zone of Pikes Peak batholith
P-5
Granodiorite wedge in outer zone of Pikes Peak batholith
P-9
Boulder Creek Granodiorite
Steamboat Springs
Parshall
1700 ± 50
Izett (1968)
From Byers Canyon.  Rb-Sr model age; analytical data not reported.  Location approximate.
Quartz monzonite of Byers Canyon
1650 ± 40
Troublesome Formation; Gravel Gulch Tuff
Kremmling
11.2 ± 1.8
Izett (1975)
Location approximate; good to 1/16 section.
Glass
8.3 ± 1.2
Troublesome Formation; Camel Tuff
Junction Butte
12.8 ± 2.0
10.9 ± 1.4
Troublesome Formation; CW (Chalky White) Tuff
18.0 ± 2.0
CW (Chalky White) tuff of Izett (1968).  Location aproximate; good to 1/16 section.
20.0 ± 2.3
Location aproximate; good to 1/16 section.
Rhyolitic ash
Browns Park Formation; lowest part
Green Ridge
23.5 ± 2.5
Camel
0.04
15.2
Izett and Obradovich (2001)
Weighted-mean age of 8 samples (95Z0649; 95Z0650; 97Z0538; 97Z0525; 99Z0253; 99Z0254; 99Z0255; 99Z0256).  Location approximate; good to 1/16 section.
Chalky White (CW tuff)
0.22
18.9
CW (Chalky White) tuff of Izett (1968).  Sample 94Z0303.  Location approximate; good to 1/16 section.
Gravel Gulch
0.05
Izett and Obradovich (2001) report it as a weighted-mean age of 4 sanidine samples but list 3 sanidine (94Z0346; 95Z0246; 98Z0152) and 2 plagioclase (95Z0238; 95Z0239) in data table.
Troublesome Formation; LTW Tuff
LTW
0.06
17.1
Weighted-mean of four analyses (94Z0325; 94Z0326; 94Z0327; 94Z0328) from two locations.  Barger Gulch site plotted; Horse Gulch site at 40° 05' 00" N; 106° 21' 59" W.  Location sites good to 1/16 section.
Troublesome Formation; Moore Reservoir Tuff
Moore Reservoir
23.5
Age is weighted-mean of five samples (94Z0310; 94Z0311; 94Z0312; 94Z0313; 94Z0285) from the tuff.  Location approximate; good to 1/4 section.
Troublesome Formation; Pure White Tuff
Pure White
0.07
18.3
Weighted-mean of two samples (94Z0344; 94Z0345) from tuff.  Location approximate; good to 1/16 section.
Troublesome Formation; Road White Tuff
Road White
15.6
Weighted-mean age of 5 samples (95Z0298; 95Z0299; 95Z0300; 95Z0647; 95Z0648).  Location approximate; good to 1/16 section.
Troublesome Formation; Spring Tuff
Spring
Plagioclase/sanidine
0.01
15.8
Weighted-mean age for two plagioclase (94Z0330; 94Z0317) and one sanidine (98Z0210) sample.  Location approximate; good to 1/16 section.
Quartzite
Blue Ridge quartzite
J01-BR1
Rice Mountain
Zircon (detrital)
Jones (2005)
Cited date is the statistical median of 207Pb/206Pb age distribution; range is 1650 - 3180 Ma.
Conglomerate
Blue Ridge basal conglomerate
J01-BR2
1710
Basal conglomerate.  Cited date is the statistical median of 207Pb/206Pb age distribution; range is 1650 - 1910 Ma.
J01-BR3
[+5 / -3]
Age is upper intercept based on three fractions.  Location from J.V. Jones (written communication, 2006).
In Five Points Gulch shear zone
J01-FP1
[+3 / -5]
Syn-deformational.  Upper intercept age based on three fractions of mechanically-broken zircon tips; two fractions of zircon cores yielded ages of 1451 and 1449 Ma.
Small body along Hardscabble Creek
J01-RG1
Hardscrabble Mountain
1679
Upper intercept age based on three fractions of zircons with no recognizable overgrowths.  Two fractions with secondary overgrowths are interpreted by Jones (2005) to indicate metamorphism at 1640.
Felsic gneiss
Hardscabble Creek area
J01-RG2
1691
Three fractions yield 207Pb/206Pb ages of 1643, 1659, 1691; Jones (2005) interprets 1691 Ma as the approximate age of basement gneisses in the area.
Amphibolite
J01-RG3a
1680
Upper intercept of two fractions; interpreted by Jones (2005) to be the time of crystallization of protolith.  He also interprets a single fraction at 1436 Ma to indicate metamorphism.
Titanite
1390
Average of 207Pb/206Pb ages from three fractions; interpreted by Jones (2005) to indicate metamorphic recrystallization of titanite.
Inclusion in granite of Bear Creek
J01-WC1
1436
Date is average 207Pb/206Pb age of three fractions; interpreted by Jones (2005) to be a metamorphic age.
Gneissic granite
Granite of Bear Creek
J01-WC2
1435
Date is average 207Pb/206Pb age of three fractions which overlap concordia; interpreted by Jones (2005) to be age of granite crystallization.
1375
Age is upper intercept based on three fractions; two other fractions give upper intercept of 1362 Ma.  Interpreted by Jones (2005) to indicate metamorphism due to intrusion of the San Isabel granite.
J01-WC3
Sill.  Age is lower intercept based on three fractions.  Interpreted by Jones (2005) to be age of crystallization of the sill.
In Blue Ridge quartzite
J03-BR4
Pegmatite cuts sheared granodiorite and folded quartzite at Blue Ridge.  Inherited Pb makes interpretation difficult.
Phantom Canyon quartzite
J03-PC1
Date is average of three 207Pb/206Pb ages on fractions of detrital zircons; all fractions are highly discordant (up to 42%).
Cited date is the statistical median of 207Pb/206Pb age distribution; range is 1520 - 2630 Ma.
J03-TM1
1404 - 1443
Three fractions yield 207Pb/206Pb ages of 1404, 1422, and 1443 Ma.  Jones (2005) interprets these dates to indicate recrystallization during a protracted metamorphic event.
K00-BR-25
1698
Date is average of 207Pb/206Pb ages of three fractions; fourth fraction apparently has inherited core.  Location from J.V. Jones (written communication, 2006).
K00-BR-26
Marshall Gulch monzogranite
J01-MG1
Rito Alto Peak
1695
Jones (2005); Jones and Connelly (2006)
Date is average 207Pb/206Pb age of two concordant fractions.
1637
238U/204Pb-206Pb/204Pb isochron age based on three points.  Jones (2005) interprets date as time of metamorphic recrystallization.
Small stock in Crestone pluton
J01-MG2
Xenolith in Marshall Gulch pluton.  Upper intercept age based on three (of five) fractions.
Intrudes tonalite stock in Crestone pluton
J01-MG3
1407
Pegmatite cuts Marshall Gulch pluton.  Upper intercept age based on three (of four) fractions.
Music Pass pluton
J01-MP1
Crestone Peak
1434
Upper intercept age based on four fractions.
1412
Upper intercept age based on three fractions; interpreted by Jones (2005) to be the age of metamorphic recrystallization.
Intrudes Music Mountain pluton
J01-MP2
Pegmatite cuts foliation in Music Pass quartz monzonite.  Age is estimate based on 207Pb/206Pb dates for two (of four) fractions, one of which overlaps concordia at 1434 Ma.
Crestone quartz monzonite
J01-RA60
1682
Upper intercept age based on four (of four) fractions.
Upper intercept age based on three (of four) fractions; interpreted by Jones (2005) to be the age of metamorphic recrystallization.  The fourth fraction yields a concordant age of 1489 Ma.
Near Crestone pluton
J02-C1
Crestone
1760
Amphibolite in contact aureole of Crestone pluton.  Upper intercept based on two (of seven) fractions. Zircon imaging indicates multiple zones.
Boulder Creek batholith, near Wallstreet
BCG
Kane (1988)
Preferred age.
Preferred age; some Ar loss.
Preferred age, thermally disturbed.
Hydrothermal breccia zone
Copper Rock, near Sunset
CPR 4
Adularia
Kane (1988); Kane and others (1988)
Probably cored by Precambrian feldspar.
Pb/Ag vein
Mud vein
Log 19A
0.37
Alkali syenite
Sugarloaf stock
Tas 2
Total fusion age.
Poison Ridge stock
BBD 25
Parkview Mountain
0.5
23.9
Karimpour (1982); Karimpour and Atkinson (1983)
A.O. Complex porphyry copper deposit.  Drill hole sample from 1,350 feet depth.
DDH 105/1000
A.O. Complex porphyry copper deposit.  Drill hole sample from 1,000 feet depth.
24.04
DDH 105/550
A.O. Complex porphyry copper deposit.  Drill hole sample from 550 feet depth.
Metasedimentary rock
West-central Park Range
97PARK01
Walden
Hahns Peak
5.8
53.8
Kelley (2005)
Track lengths measured.
Buffalo Pass pluton
97PARK02
Mount Werner
69.2
West side of Rabbit Ears Pass
97PARK03
Walton Peak
Migmatite
97PARK04
4.7
63.8
97PARK05
Blacktail Mountain
6.7
68.9
Granitic gneiss
97PARK07
97PARK08
73.5
97PARK09
64.1
97PARK10
Buffalo Pass
5.4
Mt. Ethel pluton
97PARK12
55.1
South-central Park Range
97PARK13
13.6
57.6
97PARK15
Floyd Peak
63.2
97PARK16
Rocky Peak
46.5
97PARK17
North of Steamboat Springs
97PARK18
Mad Creek
58.9
97PARK19
60.1
North of Buffalo Mountain, Park Range
97PARK20
97PARK21
64.6
97PARK22
68.8
97PARK23
71
Central Park Range
97PARK24
Farwell Mountain
76.1
97PARK25
67.8
97PARK26
70.9
Schist
97PARK27
51.5
97PARK29
Clark
50.8
Siltstone
Chugwater Formation
97PARK30
66.8
98PARK88
Pitchpine Mountain
54.6
West of Elevenmile Reservoir
11e
Spinney Mountain
7.4
94.1
Kelley and Chapin (2004)
11n
264.7
South of Elevenmile Reservoir
11s
12.1
127.6
Cripple Creek pluton
92PP03
Farisita
11.2
123.6
92PP04
Big Bull Mountain
26.9
92PP05
211.7
92PP06
Cooper Mountain
66.2
Phantom Canyon pluton
92PP07
66.6
Migmatitic gneiss
92PP08
8.9
56.8
92PP09
59.7
92PP10
57.1
Oak Creek pluton
92WM01
11.8
195.1
92WM03
298.8
92WM04
14.5
290.2
92WM05
80.8
Mount Tyndall area
92WM07
11.4
188.6
92WM08
10.2
140.6
92WM09
Westcliffe
180.8
McKenzie Junction
92WM10
8.8
123
92WM11
109.5
92WM12
92WM13
10.6
115.9
Deer Peak area
92WM14
Deer Peak
138.4
92WM15
8.6
118.8
Greenhorn Peaks area
92WM16
16.6
228.3
Granite of Custer Creek
92WM19
12.9
219.8
92WM20
13.2
187.4
Williams Creek pluton
92WM22
12.6
210.7
92WM24
199.1
93GP01
Cripple Creek South
110.9
93GP02
17.9
172.2
93GP03
18.5
170.5
93GP04B
11.6
156.3
93GP05
17.7
194.6
93GP06
66.9
93GP07
93RG01
115
93WM29
8.3
122.3
San Isabel area
93WM31
31.1
Garrell Peak pluton
94ARK01
77.5
94ARK03
54.7
Texas Creek area
94ARK05
74.9
94ARK06
164
94ARK07
9.9
91.7
94ARK08
11.3
169.8
94ARK09
11.9
173.8
94ARK10
15.3
171.3
94ARK11
134
Stoll Mountain pluton
94SPR02
80.9
94SPR03
143
94SPR04
138.7
94SPR06
252.1
West McCoy Gulch stock
95ARK04
75.8
95ARK07
126.2
95ARK11
10.8
128.8
97ARK12
4.6
62.5
97ARK13
97ARK17
Howard
46.7
97ARK18
5.1
54.9
97ARK21
59
Arkose
Pennsylvanian arkose
97ARK22
63.9
Track lengths measures.
North of Texas Creek
97ARK24
87.9
97ARK25
12.2
212.1
97ARK26
95.9
Agate Mountain area
CC-Ft
Agate Mountain
97.5
Egd
Gribble Mountain
230
North of Crampton Mountain
Egn
16.7
199.7
EGN2
Cover Mountain
84.8
Eqd
Wgn
183.9
Wqd
85.4
84MP01
12.3
Kelley and others (1992)
84MP02
14.1
84MP03
84MP04
9.5
84MP05
9.6
84MP06
22.9
84MP07
84MP08
23.1
84MP09
17.8
84MP10
20.1
84MP11
84MP12
14.8
Medano Peak area
88SG01
Mosca Pass
Pluton of Medano Peak
88SG03
10.4
Metasediment
Minturn Formation
88SG05
Zapata Ranch
88SG06
Trinchera Peak
5.9
37.2
88SG07
31.4
Sangre de Cristo Formation
88SG08
18.6
88SG09
Cucharas Pass
19.4
88SG10
La Veta Pass
88SG11
Russell
2.6
La Veta Pass area
88SG12
Gabbro of Little Bear
88SG13
Blanca Peak pluton
88SG14
Twin Peaks
20.3
Tertiary stock, east of Blanca Peak
88SG16
Central Culebra Range
89SG19
Ojito Peak
29.3
89SG20
89SG21
Pegmatite granite
89SG22
Taylor Ranch
Trinchera Ranch pluton
89SG23
32.5
89SG24
89SG26
Culebra Peak
7.9
42.3
90SG30
13.4
90SG31
17.5
90SG32
12.7
North of Eagle
1ABS13-9-99
Castle Peak
Matrix
23.49
Kunk and others (2001)
Isochron age.   Preferred age is 22.80 ± 0.12 based on multiple samples from same flow.
1CBS13-9-99
22.68
1DBS13-9-99
22.91
2ABS13-9-99
0.26
22.25
Isochron age.   Preferred age is 22.49 ± 0.23 based on multiple samples from same flow.
2BBS13-9-99
22.59
2CBS13-9-99
0.27
22.62
Flattops area
3BBS13-9-99
Meeker
Devils Causeway
0.41
22.61
Isochron age.   Preferred age is 22.58 ± 0.18 based on multiple samples of same flow.
3CBS13-9-99
0.18
22.56
Basalt area
Ba36(1)
0.25
13.81
Isochron age.
BR6(3)
13.57
Chester Mountain area
C69B
Center Mountain
10.38
Kunk and Snee (1998)
Carbondale area
CC-132
Cattle Creek
9.68
CC-140
10.14
CCLA-5
7.71
CD-152
13.29
GL-100
Glenwood Springs
22.04
Isochron age.   Preferred age is 22.56 ± 0.13 based on multiple samples from same flow.
Silicic dike
JS-98-13
Burns South
20.16
Weighted mean age.
K97-10-8A2
9.88
Plateau age.   Preferred age is 9.89 ± 0.06 based on multiple samples of same flow.
K97-10-8A4
9.89
K97-10-8C2
0.33
23.05
Isochron age.  Preferred age is 22.56 ± 0.13 based on multiple samples from same flow.
K97-10-8C4
K97-10-8E1
9.75
K97-10-8E3
2.34
10.47
Isochron age.  Preferred age is 9.75 ± 0.06 based on multiple samples from same flow.
K97-10-8F3
10.72
Isochron age.  Preferred age is 9.91 based on multiple samples of same flow.
K97-10-8F4
10.28
K97-8-11A1
Leon
Isochron age.  Preferred age is 10.49 ± 0.07 based on multiple samples from same flow.
K97-8-11A2
10.49
K97-8-11B
9.87
Total gas age.
K97-8-11C1
10.18
K97-8-11C3
10.16
Isochron age.  Preferred age is 10.18 ± 0.06 based on multiple samples from same flow.
K97-8-11D3
11.39
K97-8-11E1
0.17
10.07
K97-8-11E2
Isochron age.   Preferred age is 10.07 ± 0.17 based on multiple samples from same flow.
K97-8-11F
35.21
Laser fusion, weighted mean age.
Independence Pass area
K97-8-12A2
Woody Creek
1.51
Isochron age.  Preferred age is 1.36 ± 0.04 based on multiple samples from same flow.
K97-8-12B1
1.44
Isochron age.  Preferred age is 1.42 ± 0.13 based on multiple samples from same flow.
K97-8-12B2
K97-8-12E1
10.7
K97-8-12E2
0.34
8.96
Isochron age.  Preferred age is 10.70 ± 0.15 based on multiple samples of same flow.
K97-8-12F1
10.84
K97-8-12F2
11.07
Isochron age.  Preferred age is 10.84 based on multiple samples of same flow.
K97-8-12G
3.01
K97-8-12H
0.02
3.09
Yarmony Mountain
K97-8-13A1
McCoy
22.95
Isochron age.  Preferred age is 22.89 ± 0.12 based on multiple samples from same flow.
K97-8-13A1-3
22.71
Isochron age.  Preferred age is 22.65 ± 0.20 based on multiple samples from same flow.
K97-8-13A1-4
K97-8-13A2
22.92
Plateau age.  Preferred age is 22.89 ± 0.12 based on multiple samples from same flow.
K97-8-13B2
K97-8-13B3
22.88
State Bridge area
K97-8-13C2
State Bridge
0.36
23.88
Isochron age.  Preferred age is 23.97 ± 0.29 based on multiple samples from same flow.
K97-8-13C3
0.29
24.06
K97-8-15A3
10.63
Plateau age.  Preferred age is 10.60 ± 0.07 based on multiple samples of same flow.
K97-8-15A4
10.56
K97-8-15B
9.83
K97-8-15C2
10.42
Isochron age.  Preferred age is 9.97 ± 0.06 based on multiple samples from same flow.
K97-8-15C4
9.97
Eagle area
K99-10-24A3
Gypsum
22.52
K99-10-24A5
0.35
22.51
Isochron age.  Preferred age is 22.52 ± 0.08 based on multiple samples from same flow.
K99-8-22A1
1.36
K99-8-22A4
1.41
Plateau age.  Preferred age is 1.36 ± 0.04 based on multiple samples from same flow.
K99-8-22B2
1.34
K99-8-22B3
KH-95-24
0.31
L-176
L-181
9.55
L-187A2
9.84
L-187B3
9.38
L-187D1
L-223
13.38
L-244
Laser fusion, weighted mean age.  Sanidine is xenocrystic in basalt flow.
L244-1
2.87
Plateau age.  Preferred age is 2.90 ± 0.02 based on multiple samples from same flow.
L244-2
L-245
2.96
L-37
L-38A
9.66
L-39
L60
7.75
L6681B
Wolcott
22.8
L6844
22.31
L-91A1
9.71
Gypsum area
CP8
Cottonwood Pass
7.74
CP-86
3.17
CP-89
7.72
Glenwood Springs area
DT-R2
Dotsero
22.38
Isochron age.  Preferred age is 23.41 ± 0.13 based on multiple samples from same flow.
DT-R3
0.38
Plateau age.  Preferred age is 0.28 ± 0.04 based on multiple samples from same flow.
GS96-1
9.72
Silicic tuff
JS-98-17
Sugarloaf  Mountain
19.35
Laser fusion, weighted mean age.  Preferred age is 19.40 ± 0.05 based on multiple samples from same flow.
JS-98-2
19.45
Laser fusion, isochron age.  Preferred age is 19.40 ± 0.05 based on multiple samples from same flow.
JS-98-25
JS-98-5
19.43
JS-98-93
19.42
Volcanic clast in Poison Creek debris flow deposit
JS-99-10
14.87
JS-99-8A
14.83
JS-99-8B
14.74
JS-99-8C
15.09
JS-99-9
14.51
Isochron age.  Preferred age is 14.48 ± 0.08.
K97-10-7F
Isochron age.  Preferred age is 0.28 ± 0.04 based on multiple samples from same flow.
K97-10-7G
K97-10-7K5
23.41
Plateau age.  Preferred age is 23.41 based on multiple samples from same flow.
K97-10-8B1
11.11
Isochron age.  Preferred age is 9.78 ± 0.23 based on multiple samples from same flow.
K97-10-8B3
9.78
K97-10-8D1
Plateau age.  Preferred age is 7.77 ± 0.05 based on multiple samples from same flow.
K97-10-8D2
7.79
K97-8-13D
19.41
K99-8-24A
Sweetwater Lake
13.45
K99-8-24B1
14.06
K99-8-24B3
14.27
Isochron age.  Preferred age is 14.06 ± 0.05 based on multiple samples from same flow.
K99-8-24C
14.36
K99-8-24D1
14.91
Isochron age.  Preferred age is 15.01 ± 0.18 based on multiple samples from same flow.
K99-8-24D2
15.11
K99-8-24E
15.57
KH-95-26
3.03
KH-95-32
7.8
SH-267
Shoshone
3.97
Isochron age.  Sanidine is xenocrystic in basalt.
513.9
Lanphere and others (1990)
514.3
Location approximate.  Total-fusion age.
Shoshonite
Table Mountain
VD.1
Niwot
Whole-rock (?)
64.9
Larson and Drexler (1988)
Valmont dike.
7.86
Larson and others (1975)
No sample number reported.  Age recalculated by Wallace (1993, 1995).
8.78
8.68
10.1
Trappers Lake
20.63
20.05
22.2
20.7
21.4
Basaltic andesite
Dome
13.17
1.98
1.25
McCoy flow
0.64
No sample number reported.  Recalculated by Wallace (1993, 1995).
Gore Canyon area
Radium
23.2
Burns North/Dome Peak
22.1
519.7
Lee and others (1991)
Location approximate.  Integrated age.
Kimberlite
Chicken Park kimberlite
Diamond  Peak
Phlogopite
Lester and others (2001)
Naeser suggest that phlogopites in kimberlites may be much older than their emplacement age as shown by age of rocks intruded.
PRC-113-15
Limbach (1975)
Lower Chalk Creek
PRC-113-24
Quartz monzonite porphyry
PRC-113-26
Rasberry Gulch rhyolite
PRC-113-27
A-83
23.7
Lindsey and others (1986)
Annealing age due to uplift.  Location approximate.
612
Clast in Sangre de Cristo Formation
SC-1090
Mirage
17.3
265
Wild Cherry Creek, Sangre de Cristo Mountains
SC-1091
SC-221
594
SC-222
Horn Peak
307
SC-273A
299
Felsite
Felsite dike. central Sange de Cristo Mountains
SC-377
26.5
Annealing age.
SC-4
106
521
Quartz latite
Tuff of Masonic Park
735
South Fork West
28.2
Lipman and others (1970)
Fisher Quartz Latite, Wagon Wheel Gap flow
736
Wagon Wheel Gap
Mammoth Mountain Rhyolite
737
Treasure Mountain Rhyolite, tuff from Treasure Mountain
65L-132
29.6
Hinsdale Formation, Beaver Creek flow
65L-161-A
Beaver Creek Reservoir
Obsidian
21.9
Treasure Mountain Rhyolite, intracaldera tuff
65L-231
Platoro
Rhyodacite
Upper flow, Green Ridge area
66L-101-B
Fulcher Gulch
26.2
Conejos Formation, Summer Coon volcanic center
66L-120
Twin Mountains SE
32.4
Olivine basalt
67L-107-B
Del Norte Peak
23.4
Lower flow, Green Ridge area
67L-109
Green Mountain/Fulcher Gulch
31.8
31.6
Alamosa River stock
67L-113
Summitville
29.1
67L-124
Hinsdale Formation, Los Mogotes flow
67L-16
Fox Creek
Diabase
Hinsdale Formation, Los Mogotes dike
67L-17-A
Conejos Formation
68L-105
34.1
Late flow, lower member, Summitville area
68L-107
Elwood Pass
25.8
Hinsdale Formation, La Jara flow
68L-17
Vicente Canyon
68L-20
Twin Mountains
34.4
68L-91
Chama Peak
Andesite
Ds141B
Saddle Mountain
Conejos Formation, Beidell volcanic center
Ds196
Lime Creek
Tuff from Storm King Mountain
RD-1901-57
Buckhorn Lakes
San Juan Formation
RD-336-68
32.1
Rawley Andesite, Bonanza volcanic center
V-998
Poncha Pass
33.2
V-999
Uranium ore, Schwartzwalder mine
Illinois and Titan veins
Ralston Buttes
69.3
Ludwig and others (1985)
Isochron using  9 samples.
Disseminated uraninite
West of Mount Albion
Monarch Lake
Uraninite
Ludwig and Young (1975)
Concordia; disturbed at 880 and 130 Ma.
Windy Point pluton of Pikes Peak batholith
PP76-2
K-Ca
Mineral/Whole-rock
1041
Marshall and DePaolo (1982)
Mineral, whole-rock isochron based on 5 points.
37
Marvin and Cole (1978)
Lower Chalk Creek dike
38
Thirtynine Mile volcanic field(?)
R-3502
35.2
Ash flow, near Basalt
USGS(D)-A
Gangue,  Schwartzwalder Mine
Schwartzwalder Mine
D2377F
12
Marvin and Dobson (1979)
Possible mixture of Proterozoic country rock feldspar and feldspar from vein.
Schwartzwalder Mine,orthoclase and adularia gangue of uranium vei
D2378F
Mixed age.
Sheared pegmatite, Schwartzwalder Mine
Sch-164
Sheared pegmatite with ore minerals, Schwartzwalder Mine
Sch-74
Minimum age of pegmatite.
Holy Cross area
USGS(D)-2-D-62
483
USGS(D)-72-92
63
Granite intruding Twin Lakes stock
USGS(D)-73-N7
33.6
36.2
USGS(D)-73-N8
45.9
USGS(D)-73-N9
43.4
Silver Plume pluton
USGS(D)-91
1150
Intrusion age is about 1,450 Ma.
Grizzly Peak Tuff
30.1
30.2
Humbug stock
USGS(D)-D96
Copper Mountain
42.4
Augen gneiss
USGS(D)-E-628
1590
Minimum age of metamorphic crystallization.
Buckskin Gulch dacite
USGS(D)-HBD-4
69.9
Age slightly too old; dike cuts granodiorite which is 66.7 Ma.
USGS(D)-K150
Breckenridge
41.5
Buckskin Gulch leucogranite
USGS(D)-LG-15
66.7
Melagranodiorite
Buckskin Gulch melagranodiorite
USGS(D)-MG-4
71.2
Carbonitite
Sloan diatreme
USGS(D)-SLOAN-2
Haystack Gulch
USGS(D)-TL-F6-16
45.5
Unamed rhyolite
USGS(D)VA-217
Marvin and others (1989)
Age probably too old.  Poor location.
Marvin and others (1974)
Rabbit Ears Volcanics
43
Gunsight Pass
Radial Mountain dike
Radial Mountain
Haystack stock
55
24.4
Tucker Mountain quartz monzonite
42.8
Age recalculated by Wallace (1993, 1995).
Tucker Mountain rhyolite porphyry
91
Sanidine (?)
92
43.6
93
Age recalculated by Wallace (1993,1995).
94
46.8
95
Chalk Mountain rhyolite
98
162
Blackhead Peak
Location approximate.  Analytical data not available.
Cropsy Mountain
181
Altered rock
South Mountain area
183
Alunite
22.4
198
Nathrop
Perlite
Nathrop Volcanics
199
Nathrop/Buena Vista East
200
Buena Vista East
201
Unnamed
Upper Buckskin Gulch stock
203
64
Thirtynine Mile Andesite, upper member
206
Thirtynine Mile Mountain
Phonolite
Phonolite of Cripple Creek
212
216
Hall Gulch
Sample probably contaminated with Precambrian detritus.  Location approximate.
Andesite of Waugh Mountain
217
220
Hillside
Round Mountain, Silver Cliff
3.8
83.5
Age too old; concentrate probably contaminated with older material.  Location approximate.
Trachyte
stock of Game Ridge
225
Rosita
Age probably too old due to xenocrysts.  Location approximate.
Andesite, east Flank of Sangre de Cristo Mountains
229
Beck Mountain
Feldspar-quartz
41.2
Age probably too old.
Zapata Creek area
231
55.2
232
Biotite-amphibole
50.1
32.2
Sill, west of Sheep Mountain
234
Little Sheep Mountain
37.4
Vitric tuff
In Devil's Hole Formation
235
Whole-rock, non-magnetic fraction
113
Age questionable due to probable contamination with older material.  Location approximate.
236
Biotite (impure)
38.2
Age probably too old.  Location approximate.
4233
Mount Sherman
#1-3-1
Location approximate.  Age recalculated by Wallace (1993, 1995).
#1-4-1
#1-5-1
#1-5-2
#1-6-1
#1-7-1
#1-8-1
20.6
10A
16A
Porphyry at Hahns Peak
1A
9.4
Quartz andesite
1C
Quartz monzonite(?)
Caribou stock
458
4A
24.3
5-70-1
34.7
Spanish Peaks radial dike swarm
641-c
21.5 ± 3.0
Age may be in error due to large number of crystal defects within apatite.
Ash in Troublesome Formation
65G57
66L-26
26.8
66L-30
66L-36
66L-98
18.8
68-0-39
Lake George
68-0-40
Black Mountain
Ash flow
68-0-42
29.5
Tuff in conglomerate of Fear Creek
68-0-43
28.8
27.8
68G105
68L-134I
68L-16A
19.8
Rhyolite flow
Neversummer Range, west of Shadow Mountains reservoir
71G 103
Trail Mountain
Pumice
Devils Hole Formation
71-S-2
Latite porphyry
Green Mountain sill
72N2
King Creek
29.9 ± 2.4
Plug on Porphyry Peak
72N6
Bowen Mountain
25.4 ± 2.3
East of Hahns Peak
7K
8A
Audubon stock, west
AOA
Dike, north of Fourmile Canyon
B1379
Dike
Monzonite porphyry
Stock, south of Left Hand Creek
B1382
Dike, west of Boulder
B204
Dike, north of Left Hand Creek
B743
CM-201
70
Missouri Creek stock
D-6
Mount of the Holy Cross
D-7
DK-2
Northwest of Hahns Peak
KA1846
Craig
Shield Mountain
Poison Creek stock area
Kit-8
Hahns Peak stock
L-1030
L-1035
69.4
70.4
Syenite of Cripple Creek
L-945
Aegirine
Florissant Lake Beds
OHM-65-01
Thirtynine Mile upper andesite
OHM-65-02
Mafic latite
Ralston sill
R-14
Silver Cliff rhyolite
R4226
40 ± 13
Model age.  Location approximate.
Rito Alto stock
RA-3-70
Electric Peak
31.8 ± 2.3
27.1 ± 3.2
Rhyolite of Antrim Lode
SC-594
Rhyolite of Antelope Butte
SC-595
27.3
Badger Creek Tuff
SM-5-72
Castle Rock Gulch
31.8 ± 3.5
Mafic schlieren
39.2 ± 4.2
south of Rosita
TRT-1-72
27.5 ± 2.8
Trachyandesite
Rawley Andesite
V-567
Squirrel Gulch Latite (?)
Empire stock
Diorite-monzonite stock
Possibly Long Gulch stock
No rock of this composition shown at this location on detailed map.  Possibly Long Gulch stock 1.5 mi NE.
Jamestown Stock
12.4
No sample number reported.
Hornblende quartz latite porphyry
Rustic Dike
D-1
Rustic
Marvin and others (1974); Bole (1971)
72N7
Marvin and others (1974); Braddock and Cole (1990)
Mount Richtofen stock
305B
Marvin and others (1974); Corbett (1968)
Quartz latite flow
Ash flow south of Cameron Pass, Neversummer Volcanics
307B
Flow in lowest part of Troublesome Formation
72G-42
0.40
Marvin and others (1974); Izett (1974)
Rhyolitic ash fall
Lowest part of Troublesome Formation
72G-52
Plug intrudes basal Troublesome Formation
Date originally reported as 27.6 Ma.  Recalculated gy Braddock and Cole (1990).
75CS69
75CS78
75CS84A
75CS88
Intrusive rocks of Treasure Vault Lake
83P100
Metavolcanic gneiss
USGS(D)1028
Davis Peak
1576
207Pb/206Pb age; considered too young as geologic relationships require an age of at least 1,800 Ma.
Swan Mountain sill
USGS(D)75CS86
Frisco
44.1
USGS(D)BMG-1QC
Core from Benson-Montin-Greer No. 1 Quartz Creek well.
Pando Porphyry, Granite area
USGS(D)G-A-82
65.3
USGS(D)JH-9-82
61.4
Hornblende andesite
Ring andesite, Rosita
USGS(D)S69-404
Aldrich Gulch
Biotite concentrate probably altered or impure as indicated by low K content.
Andesitic tuff
USGS(D)SBNM-1
Diabasic diorite
Dioritic phase of gabbro of Elkhorn Mountain
USGS(D)SS1
207Pb/206Pb age; approximates time of emplacement of the pluton.
Unnamed Rhyolite
USGS(D)V-866
69.7
Poor location.
Methodist Mountain
USGS(D)V-997
Considered to be a minimum age.
Intrusive breccia, East Lake Creek
W3127
Biotite granodiorite
Rawah pluton
USGS(D)-KC438
Glendevey
McCallum and Hedge (1976)
Flow banded rhyolite
Rhyolite flow, east of Manhattan
USGS(D)-5-39A
McCallum and Naeser (1977)
Quartz-rich dacite porphyry
Manhattan dike swarm
USGS(D)-5-43
USGS(D)-5-44
Porphyritic rhyodacite
USGS(D)-73N1
Dacite porphyry
USGS(D)-73N2
Porphyritic rhyodacite to quartz latite
USGS(D)-73N3
Sodic, quartz-rich dacite porphyry
USGS(D)-73N4
Porphyritic hornblende dacite
USGS(D)-73N5
L-1031
McDowell (1971)
L-1125
Location and age recalculation from Wallace (1993, 1995).
L-1032
McDowell (1971); Marvin and others (1974)
L-1124
Poncha Springs NE
36.7
McIntosh and Chapin (2004)
Laser-fusion weighted-mean age.  Data in Appendix 5 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
Florissant Formation
34.03
Laser-fusion weighted-mean age.
34.14
4.01
Latite of Waugh Mountain
101
Jack Hall Mountain
31.61
31.74
102
0.69
32.44
103
31.28
Andesitic intrusion at Guffey
2.92
38.12
Llocation not given in source paper.  Guffey townsite used as location in order to plot on map.  Plateau age; considered to be inaccurate or imprecise.
202
0.49
36.06
Location not given in source paper.  Guffey townsite used as location in order to plot on map.  Plateau age.
35.97
204
1.59
36.92
531
Gribbles Park
36.61
534
Tuff of Stirrup Ranch
36.5
Laser-fusion weighted-mean age.   Data in Appendix 5 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
537
32.91
East Gulch Tuff
538
33.69
Thorn Ranch Tuff
539
33.59
Antero Formation
540
33.87
541
Lake Mountain NE
32.85
Bonanza Tuff (lower)
695
Klondike Mine
1.21
34.19
Laser-fusion weighted-mean age; considered to be inaccurate.  Table 2 of McIntosh and Chapin (2004) indicates sample was plagioclase which is consistent with the K/Ca reported in their Appendix 5.
33.21
Plateau age; considered to be inaccurate or imprecise.
696
33.23
33.41
Plateau age; considered to be inaccurate or imprecise.  Data in Appendix 6 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
697
699
32.89
0.24
33.24
700
33.01
7.18
44.16
Total gas age; considered to be inaccurate or imprecise.
701
32.83
702
33.81
703
33.82
705
33.83
706
Latite of Badger Creek
707
33.68
708
709
33.96
710
33.75
711
32.94
712
32.98
779
27.71
782
34.07
786
33.98
789
Laser-fusion weighted-mean age; considered to be inaccurate or imprecise.
790
791
792
27.38
1130
33.54
1131
33.63
Bentonitic ash
Pitch-Pinnacle Forrmation
1132
35.13
Laser-fusion weighted-mean age; considered to be inaccurate or imprecise.  Data in Appendix 5 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
Vitrophyre
1133
Badger Creek Tuff clast in Pitch-Pinnacle Formation
1134
Chester
33.85
1135
33.93
1136
0.59
34.11
1137
33.38
1138
33.72
1140
1141
33.67
Bonanza Tuff (upper)
1143
32.81
1144
32.79
1146
1147
32.95
1148
33.73
1149
33.49
33.65
1151
1152
36.78
1153
1154
32.96
Dacite of Triad Ridge
1295
36.14
Tuff of Triad Ridge
1296
36.22
1297
37.34
37.32
1298
37.48
Plateau age.  Data in Appendix 6 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
1299
37.62
Rhyolite of Ruby Mountain
30.08
Upper tuff of Buffalo Peaks
1303
Marmot Peak
38.18
1304
34.27
1305
34.36
1306
257.49
1307
36.66
Rhyolite of Bald Mountain
1308
Anorthoclase
28.88
1309
30.35
Intracaldera tuff of Mount Aetna (Badger Creek Tuff)
1310
Garfield
34.34
Badger Creek Tuff in Table 1 of McIntosh and Chapin (2004).  Laser-fusion weighted-mean age; considered to be inaccurate or imprecise.
1311
33.66
Badger Creek Tuff in Appendix 1 of McIntosh and Chapin (2004).  Laser-fusion weighted-mean age.  Data in Appendix 5 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
Mount Aetna stock
1312
0.52
1313
34.28
0.73
36.42
1319
34.51
Near plateau age.  Data in Appendix 6 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
38.24
Bonanza Tuff (intracaldera)
1400
Bonanza
1401
33.17
1402
32.88
1404
33.25
1405
31.67
34.21
Mount Aetna ring dike
333.1
Total gas age;  considered too old.
235.6
Total gas age; considered too old.
Mount Antero Granite
0.53
28.65
Biotite (altered)
29.12
Total gas age; considered to be inaccurate or imprecise.  Data in Appendix 6 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
1408
34.13
Total gas age.  Data in Appendix 6 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
0.72
42.74
otal gas age; considered to be inaccurate or imprecise.
1409
31.69
34.12
34.55
1411
26.77
29.64
29.58
27.77
29.53
1413
30.05
Data in Appendix 6 and Table 2 (used herein) of McIntosh and Chapin (2004) differ.
38.23
1414
Basalt of Herring Park
1415
8.5
1418
32.82
Rhyolite of Silver Cliff
1419
35.41
35.35
1421
Pringle Latite
0.56
31.99
1424
32.7
Andesite of Greenhorn Mountain
1860
0.57
Dacite flow related to State Line cinder cone
DM-98-14
12.08
Miggins (2002)
Picketwire rhyodacite
DM-98-2
Stonewall
20.92
Preferred age; isochron age is 20.93 ± 0.27.
Devil's Park cinder cone
DM-98-22-7
11.95
Preferred age; isochron age is 11.90 ± 0.21.
Lamprophyre
Mafic sill next to dacitic intrusion at Picketwire
DM-98-29
22.32
Preferred age; isochron age is 25.13 ± 1.52.
Dike west of Monument Lake
DM-98-31-2
Preferred age; isochron age is 26.03 ± 0.41.
Dike south of Cuchara
DM-98-33-3
24.41
Preferred age; isochron age is 23.59 ± 0.15.
Sill located north of North Lake Sill Sequence
DM-98-35
21.92
Sill located east of North Lake Sill Sequence
DM-98-36
23.58
Preferred age; isochron age is 22.81 ± 0.78.
Sill from North Lake sill sequence
DM-98-3-6-2
DM-98-37
0.63
23.46
Mafic sill
Near La Veta
DM-98-38
La Veta
Preferred age; isochron is 22.55 ± 0.16.
DM-98-39
Sill east of Sulfur
DM-98-40-1
Cuchara
0.44
21.13
Preferred age; isochron age is 19.16 ± 1.65.
Sill at Cucharas Pass
DM-98-43
21.18
Preferred age; isochron age is 21.18 ± 0.11.
Sill north of North Lake sills
DM-98-44
23.26
Preferred age; isochron age is 22.90 ± 0.16.
DM-98-44B
20.98
20.83
Pugatoire River
DM-98-45
Torres
Preferred age; isochron age is 21.95 ± 0.12.
Sill at North Lake
DM-98-47
0.97
Preferred age; isochron age is 21.98 ± 0.16.
South White Peak Dacite
DM-99-32
16.8
DM-99-59
Preferred age; isochron age is 22.24 ± 0.23.
Hornblende porphyry
Dike east of Mount Maestas
DM-99-60
Sill east of Mount Maestas
DM-99-61
33.56
Tercio Valley sill
DM-99-65B
8.56
Plateau age.  Sanidine may be secondary.
DM--99-66
DM-99-67
20.9
DM-99-68
22.65
Preferred age; isochron age is 22.47 ± 0.33.
Sill just south of San Francisco Pass
DM-99-71
0.55
25.85
Preferred age; isochron age is 26.29 ± 0.54.
South Valley
DM-99-73
0.45
Preferred age; isochron age is 21.86 ± 0.79.
DM-99-79
22.19
Mount Maestas stock
P646-DM
25.17
Flatiron basalt in Santa Fe Group
B-S-2-DM
La Valley
15.16
Miggins and others (2002)
B-S-4-DM
14.97
Basalt flow related to Devil's Park cinder cone
DM-98-16
DM-98-22-2
11.87
Basalt flow
Sanchez Reservoir area
DM-99-51
4.37
DM-99-52A
10.74
DM-99-52B
11.98
Servilleta Basalt
DM-99-53
San Luis
4.59
DM-99-53A
Fort Garland SW
4.75
DM-99-54
4.55
Basalt flow in Santa Fe Group
P80-23B-DM
Plateau.  Sample  number is apparently misreported as P83-23B-DM in Table 1 of Miggins and others (2002)
Sweet Home mine
92SH01
30.6
Misantoni and others (1998)
Location approximate; estimated from description.
92SH02
92SH03
100 ± 11
Moorbath and others (1967)
4534
Mount Elbert(?)
56 ± 10
Locations and recalculated ages by Fridrich and others (1991) using initial ration of 0.706.
Climax - orebody
4550
73 ± 8
Age too old based on more recent geochronology.
Feldspathic gneiss
4579
1520
Locations  and recalculated ages by Fridrich and others (1991) using initial ration of 0.706.
Denny Creek pluton
4582
1670
Moorbath and others (1967).
Locations and recalculated ages by Fridrich and others (1991). Model ages.
4580a
1395 ± 35
4580b
4581a
Thimble Rock
1750
4581b
1970
Drill core
Hooper West
65
1260
Muehlberger and others (1966)
Drill core sample.  Location and recalculated age in Shaw and others (2005).
Pyroxene-hornblende trachydacite
Signal Butte
SB-8
Naeser (unpub); sample collected by R.B. Colton
Plug rises 150 m above well developed erosion surface.
33.6 ± 2.8
Naeser and Cunningham (1976)
Tomichi Creek stock
DF-1157
34.4 ± 3.3
DF-1159
Kimberlite*
Schaffer no. 3 diatreme
Schaffer no. 3 pipe
Diamond Peak
Haggerty and others (1983)
Six zircon grains from xenoliths.
Henderson mine, East Knob porphyry
1, Table 4
Naeser and others (1973); Geissman and others (1992)
2, Table 4
This and the following 42 samples are from Henderson mine about 1 km below the valley bottom and in the Red Mountain area above it.  Except for 6 samples, locations are generalized.
Red Mountain-Henderson
70-169
Naeser and others (1973); Marvin and others (1974)
72-123
72-125
72-126
72-143
72-144
Troublesome Formation
Volcanic ash bed
Naeser and others (1990)
13.5
13.3
10.5
Cross Creek pluton
87N1
Minturn
29.7
Location from Wallace (1993, 1995).
87N2
87N3
87N4
39.6
96
500
87N6
32.3
Ore
Ore from Gilman
Gil 1
Gil 11
170
771
Gil 12
39.8
904
Gil 13
58
Gil 14
40.1
Gil 15
Gil 16
Gil 17
Gil 18
46.6
Gil 19
877
Gil 2
8.7
Gil 20
Gil 21
542
Gil 22
550
Gil 23
84
562
Gil 24
213
Zircons from this sample had two age populations.  Location from Wallace (1993, 1995).
994
Gil 25
Gil 3
Gil 4
Gil 40
Gil 41
48
Gil 42
58.1
Gil 43
Red Cliff
44.5
Gil 44
49.7
Gil 45
48.2
Gil 46
Gil 47
Gil 48
42.9
Gil 49
8.4
Gil 5
486
Gil 50
40.4
Gil 6
180
766
Gil 7
671
Gil 8
41.1
Gil 9
Plug at Red Cliff
Gil 10
758
Arkosic sandstone
87GR11
Vail East
Naeser and others (2002)
87GR-4
Central age (Galbraith and Laslett, 1993).
GR-7
Track length measured.  Central age (Galbraith and Laslett, 1993).
Pyroxene-plagioclase hornblende granofels
Pluton of Officers Gulch
GR-F-1
GR-MP-1
Biotite quartz diorite
GR-MP-2
20.4
Track length measured.
GR-PP-1
Piney Peak
31.2
Migmatitic biotite granite
GR-PP-2
Pyroxene-hornblende-quartz-plagioclase granofels
Copper Mountain area
GR-VP-1
Vail Pass
GR-VP-10
GR-VP-11
19.2
GR-VP-12
GR-VP-13
30.8
GR-VP-14
32.6
GR-VP-8A
Granofels
GR-VP-9
25.4
Mafic inclusion
GR-WL-1
Willow Lakes
15.9
GR-WL-10
GR-WL-11
GR-WL-12
28.9
GR-WL-13
GR-WL-2
GR-WL-3
3.4
GR-WL-4
GR-WL-5
GR-WL-6
10.9
GR-WL-7
Migmatitic granite
GR-WL-8
Track lengths measured.  Central age (Galbraith and Laslett, 1993).
GR-WL-9
Blue River Valley
K98-9-21A
Squaw Creek
26.88
Laser fusion technique.
Silicic welded tuff
K98-9-21B
Volcanic rocks of the Green Mountain area
K98-9-21C
23.61
K98-9-21D
23.62
K98-9-21E
23.66
Green Mountain sills
K98-9-21F
31.51
Laser fusion technique.  Apparent typographical error, Naeser and others (2002) cite sample number K98-9-8F in text (p.45) butr data and location tables indicate the sample is K98-9-21F.
MP-97-284
Biotite-muscovite gneiss
MP-97-285
104
Biotite granite gneiss
MP-97-286
24.7
MP-97-287
MP-97-288
MP-97-289
MP-97-290
Windy Point pluton of the Pikes Peak batholith
PPG-14
130
1045
SJ86-100
SJ86-101
SJ86-105
22.7
SJ86-109
24.2
Ute Peak area
UP-1
Ute Peak
27.5
410
Granodiorite gneiss
UP-2
UP-3
35.9
Andesitic cobble
South Table Mountain andesite
70-0-10
Obradovich and Cobban (1975); Obradovich (2002)
50 m below trachybasalts on South Table Mountain and 21 m above K-T boundary.
Granite of Treasure Mountain
348
Snowmass Mountain
12.5
Obradovich and others (1969)
Snowmass pluton
386
Snowmass Creek sill
389
Capitol Peak
Paradise stock
390
Paonia
Oh-Be-Joyful
Soda granite porphyry
Crystal pluton
391
Crested Butte laccolith
472
Gothic
29.1± 1.0
70.0 ± 2.3
67.4 ± 2.2
Quartz-muscovite porphyry
Little Annie sill (?)
HNMP
72.2
Lincoln Creek stock
NY-5
33.9 ± 1.1
TL
41.7
Whiterock pluton
WR-2
Biotite syenite
Alkalic stocks in northwest part of Powderhorn district
2G3200
Olson and others (1977)
Gem Park Complex
52-B-53
504
63-B-20
519
63-B-23
485
63-B-24
560
63-B-24b
427
Mafic syenite
C9803
Carpenter Ridge
1380
Biotite-calcite syenite
G3730N
Melasyenite
Alkalic complex at Powderhorn district
IH-11
568
Powderhorn district
579 ± 10
Isochron based on 5 mineral-whole-rock samples.  (Sample 3 of 5).
Alkalic complex at Iron Hill
IH-1-2
Isochron based on 5 mineral-whole-rock samples.  (Sample 2 of 5).
IH-18
573
IH-21
762
IH-2-2d
Powderhorn/Rudolph Hill
Vermiculite (?)
574
IH-23-2a
553
IH-3-3
IH-4
543
May be reset by cross-cutting late-phase diabase dike.
Isochron based on 5 mineral-whole-rock samples.  (Sample 4 of 5).
Isochron based on 5 mineral-whole-rock samples.  (Sample 5 of 5).
J256
561
Pyroxenite
J365N
567
Isochron based on 5 mineral-whole-rock samples.  (Sample 1 of 5).
Augite-biotite-hornblende syenite
P7406
1,390
Ijolite
P8649
55 ± 12
Annealing date due to regional uplift.
54
550 ± 54
P-9-901
731
Spurious date; probable excess radiogenic argon incorporated during crystallization.
Biotite-hornblende syenite
WM-12-71
521 ± 10
Isochron based on 8 whole-rock and mineral samples.  (Sample 3 of 8).
Isochron based on 8 whole-rock and mineral samples. (Sample 4 of 8).
Red syenite dikes in and near the McClure Mountain and Gem Park C
WM-14-71
495 ± 10
Isochron based on 4 samples.  (Sample 2 of 4).
WM-20-71
Beckwith Mountain
Isochron based on 4 samples. (Sample 3 of 4).
WM-21-71
Isochron based on 8 whole-rock and mineral samples.  (Sample 5 of 8).
Isochron based on 8 whole-rock and mineral samples.  (Sample 6 of 8).
WM-2-71
Isochron based on 4 samples.  (Sample 1 of 4).
WM-4-71
Isochron based on 8 whole-rock and mineral samples.  (Sample 7 of 8).
Isochron based on 8 whole-rock and mineral samples.  (Sample 8 of 8).
WM-62-114
509
Mafic nepheline-bearing rock
WM-62-115
507
532
Hornblende-biotite syenite
WM-62-140
510
523
WM-62-143
62
293 ± 62
506 ± 43
506
516
WM-63-169
Isochron based on 4 samples.  (Sample 4 of 4).
Fenite (altered)
WM-63-707
Vermiculite
46
323
Fenite
WM-63-723
Riebeckite
551
WM-66-116c
Pyroxene
Nepheline
479
Altered mafic rock
WM-67-1029a
WM-67-728
439
WM-8-71
Isochron based on 8 whole-rock and mineral samples.  (Sample 1 of 8).
Isochron based on 8 whole-rock and mineral samples.  (Sample 2 of 8).
Rhyolite/trachydacite
Tincup area, west
Dustin Gulch
Cumberland Pass
76.3
Ouimette and others (1991); Ouimette (1995)
location approximate.
Napolean Sill on Gold Hill (?)
38.8
Trachydacite
Hillerton
Tincup
41.4
Location provided by M. Ouimette (written communication to A. Wilson, USGS, 2004).
Seeton Mine
39.7
Biotite-quartz-plagioclase porphyry
Dike, west of Audubon
Allens Park
Pearson and U.S. Bureau of Mines (1980)
C-10
Pearson and others (1962)
C-21
41
Pearson and others (1962) suggest date is too young due to Ar loss.  Recalculated age and location from Wallace (1993, 1995).
Pando Porphyry (?)
C-7
Location and recalculated age by Wallace (1993, 1995).
Paragneiss
Turquoise Lake area
C-1
1240
Pearson and others (1966)
Hornblendite
Homestake area
C-15
2020
C-16
1250
Metalamprophyre
C-17
1320
C-18
67
C-19
68
1320 ± 70
1200
C-20
1,260 ± 60
Model age.  Location from Wallace (1993, 1995).
1290 ± 60
1350
1430 ± 130
72
Isochron based on 7 samples. (Sample 1 of 7).  Age recalculated by Wallace (1993, 1995).
Granite of Holy Cross City
C-22
1175
C-23
C-24
C-25
1230
1250 ± 60
1310 ± 130
Isochron based on 7 samples. (Sample 6 of 7).  Age recalculated by Wallace (1993, 1995).
C-4
C-5
1440
Red Cliff area
C-6
Missouri Creek granodiorite
C-8
C-9
D-1418
Isochron based on 7 samples. (Sample 3 of 7).  Age recalculated by Wallace (1993, 1995).
D-1419
Isochron based on 7 samples. (Sample 2 of 7).  Age recalculated by Wallace (1993, 1995).
D-1773
Isochron based on 7 samples. (Sample 5 of 7).  Age recalculated by Wallace (1993, 1995).
E-2208
Isochron based on 7 samples. (Sample 4 of 7).  Age recalculated by Wallace (1993, 1995).
E-2209
Isochron based on 7 samples. (Sample 7 of 7).  Age recalculated by Wallace (1993, 1995).
Pyroxene hornblendite
Mafic enclave in Black Hills laccolith
SP119
Penn (1994)
Plateau age.  Considered to have equilibrated in host magma and to date the laccolith.
Alkali-feldspar syenite
Radial dike associated with Spanish Peaks intrusive center
SP67
Plateau age.  Location approximate.
SP95
23.3
West of Horsetooth Reservoir
5-4-6R
Horsetooth Reservoir
Peterman and others (1968)
Buckhorn Canyon
0C188Hb
Log Cabin batholith
1-0-1R
Livermore
Isochron based on 6 samples.
Boulder Creek granodiorite
14-A-12R
Glen Haven
Approximate fit to Boulder Creek isochron.
14-A-20R
Hornblende-biotite granite
Sherman Granite
3-0-8B
Livermore/ LaPorte
10 point isochron for 8 rocks and 2 minerals.
3-0-8Hb
3-0-8R
Biotite-hornblende granite
31-42aR
Cherokee Park
10 point isochron.
5-4-1R
Small concordant body.
5-4-2R
5-4-3R
5-5-8Mi
Retrograde muscovite after sillimanite
Stove Prairie
6-2-49Mu
6-3-21R
6-3-32R
6-4-98cM
Mineral isochron.
6-4-98cMu
6-4-98cT
Tourmaline
81-46R
Virginia Dale
C-211R
Poudre Park
C-235.1R
10 point isochron for 8 rocks and 2 minerals from Sherman Granite.
C-239R
C-28.1R
Biotite-quartz monzonite
Mount Olympus pluton
D1192R
Isochron, 3 samples.
Quartz Monzonite
Longs Peak -St. Vrain pluton
D1196R
Pinewood Lake
Isochron, 8 samples.
D1198R
D1199R
D1200R
D1206R
Raymond
D1208R
D1209R
D1210R
E-30-1M
Isochron based on 6 samples.  Muscovite-microcline-whole rock isochron.
E-30-1Mu
E-30-1R
Porphyritic biotite quartz monzonite
E-33-4B
E-33-4M
E-33-4R
GH-40R
Quartz-biotite-hornblende gneiss
Near Golden
HP-13R
Evergreen
Isochron from 7 samples.
HP-14R
Blackhawk
Isochron based on 4 samples.  Rock-mineral isochron for this sample.
Isochron based on 4 samples.  Rock-mineral isochron.
HP-15R
Isochron based on 4 samples.
HP-16R
Hornblende-biotite granodiorite
HP-17R
Isochron, 4 samples.
HP-18R
Sillimanite-biotite-quartz gneiss
Near Morrison
HP-5R
Morrison
Muscovite-biotite-quartz-feldspar gneiss
Near Idaho Springs
HP-7R
Squaw Pass
Lower Thompson Canyon
NFR-128Hb
Masonville
PAP-1R
Panorama Peak
W-2-18R
W-2-20R
W-2-7R
W-5-15R
Laporte
10 point isochron for 8 rocks and 2 minerals.  U-Pb date on Sherman Granite just north of 41 is 1412¦ Ma from concordia diagram based on 15 samples from drill core (Aleinikoff, 1983).
C87-100
Comanche Peak
Plymate and others (2005)
Concordia, upper intercept; composite of 9 fractions from 3 samples.  Upper intercept of four fractions of only this sample yields age of 1724 ± 17 Ma.
Monzogranite, melanocratic
C87-87A
1673
Concordia, upper intercept; composite of 3 fractions from 2 samples.  207Pb/206Pb ages of two fractions from only this sample are 1655 and 1660 Ma.
C88-231A
Concordia, upper intercept; composite of 6 fractions from 2 samples.  Upper intercept of 3 fractions of only this sample yields age of 1689 ± 3 Ma.
Tectonized Granite pluton, near Comanche Reservoir
C89-266
Concordia, upper intercept; composite of 9 fractions from 3 samples.  Upper intercept of three fractions of only this sample yields age of 1693 ± 5 Ma.
C89-335
Concordia, upper intercept; composite of 3 fractions from 2 samples.  207Pb/206Pb age of one fraction from only this sample is 1654 Ma.
St. Vrain pluton
C90-421
1393
Concordia, upper intercept; composite of 4 fractions from 2 samples.  Upper intercept of 2 fractions of only this sample yields age of 1406 ± 2 Ma.
Near Crown Point
C92-556
1702
Concordia, upper intercept; three data points.
C92-561
Concordia, upper intercept; composite of 9 fractions from 3 samples.  207Pb/206Pb ages of two fractions from only this sample are 1638 and 1656 Ma.
C94-768
Concordia, upper intercept; composite of 6 fractions from 2 samples.  Upper intercept of 3 fractions of only this sample yields age of 1706 ± 6 Ma.
C94-775
1764
C95-781
Concordia, upper intercept; composite of 4 fractions from 2 samples.  Upper intercept of 2 fractions of only this sample yields age of 1404 ± 4 Ma.
C96-801C
1276
207Pb/206Pb age of single analysis.
82-17
Boston Peak
Premo and Van Schmus (1989)
Boulder Creek batholith
83-01
Mount Antero granite
Maysville
Pulfrey (1971)
Location approximate.  Mineral concentrate was 85 percent biotite, 10 percent muscovite, and 5 percent groundmass and accessory minerals.
Phonotephrite
Cripple Creek intrusive complex
CC40a
31.15
Rampe and others (2005)
CC40b
31.17
Integrated plateau age.  Location approximate.
Cripple Creek intrusive complex; Pinto dike
CC57
30.41
Weighted mean plateau age.  Location approximate.
Tephriphonolite
CC58
31.12
Foid syenitoid
Cripple Creek intrusive complex; xenolith in Cresson Pipe
CC70
28.95
Final step in spectrum interpreted to indicate emplacement age of Cresson Pipe.  Location approximate.
CC70b
28.38
Weighted mean spectrum age interpreted to indicate emplacement age of Cresson Pipe.  Location approximate.
Cripple Creek intrusive complex, Isabella dike
CC73
Aegerine
Flat part of spectrum; probably aegerine. Location approximate.
CC74
31.59
Four-point isochron age.  Location approximate.
523.4
Renne (1995)
Location approximate.  Mean total-fusion age.
523.1
Renne and others (1998)
Location approximate.  Date calculated using GA-1550 as the primary standard.
525.1
Location approximate.  Date calculated using GHC-305 as the primary standard.
510.1
Rex and others (1993)
9.1
516.7
The Patch
125
Rice and others (1982)
125A
Hornblende quartz monzonite
Dump of Anchor mine
157
Dump of Elkhorn mine
159
breccia matrix in Proterozoic rock
Gold Cup pipe
246A
Small admixtures of mica from brecciated Proterozoic rock.
246B
246C
Upper Eureka Gulch
247
Dump of East Notaway mine
256
Dump of Alcan mine
270
Upper Gibson Gulch
276
Dike, south of Idaho Springs
293C
2-5 mm size fraction.
1-2 mm size fraction.
Biotite quartz latite
Dike on Chicago Creek
297
Stock on Fall River
298
Dump of Saratoga mine
302
Bostonite
Dike on Bellevue Mountain
78
Matrix of breccia
Gold Cup Pipe, brecciated Proterozoic rock
88A
Fragments of pegmatitic muscovite in breccia
88B
Regional mica age.
Gold Cup Pipe
88C
88F
88H
Elkhorn stock
Bobtail Hill
E31
Carroll mine
K13
2.00
Dump of Winabago mine
K19
Dump of Clay Co. mine
Y37
A
24.8
Romer and Lueders (2006)
206Pb/204Pb vs. 238U/204Pb isochron age.  MSWD = 1.0.
H
Huebnerite
25.7
Weighted average of three 206Pb/238U ages from same crystal.
Tonalitic gneiss
Twin Peaks pluton
CO92-1
1732.10
Sabin (1994)
Gabbroic gneiss
CO92-28
Mixed gneiss
Medano Creek
CO92-3
1695.50
Hornblende gneiss
LaVeta Pass
CO92-35
168
1675
Quartz diorite gneiss
Zapata Creek pluton
CO93-3
1749.10
Dioritic gneiss
CO93-6
520.4
Samson and Alexander (1987)
Lowest outcrop in South Park formation
Sawatsky (1967); Bryant and others (1981)
Climax porphyritic granite
G-MO146
Schassberger (1972)
Age recalculated by and location from Wallace (1993, 1995).
Mineralized granite
Urad mine
No. 3
0.90
0.74
523.98
Schoene and Bowring (2006)
Location approximate.  Date is a weighted mean 207Pb/235U age based on ten analyses of chemically abraded zircons.
Baddeleyite
1.03
522.41
Location approximate.  Date is a weighted mean 207Pb/235U age based on analyses of four fractions.  Open isotopic system behavior is evident; doubtful that this is a crystallization age.
1.27
523.26
Location approximate.  Date is a weighted mean 207Pb/235U age based on analyses of eight fractions.
523.51
Location approximate.  Date is a weighted mean 207Pb/235U age based on analyses of six fractions.
Quartzo feldspathic schist
North of Moose Mountain shear zone
CL1-96
Carter Lake Reservoir
Selverstone and others (2000)
1758 to ~3450; peak at 1800. SHRIMP data, 51 determinations.
South of Moose Mountain shear zone
BT150LY
Peak at 1825; none>2650.  SHRIMP data, 47 determinations.
Dike associated with Mount Aetna cauldron
63-B-88
Shannon (1988)
Intrusive tuff dike.
Mount Aetna cauldron
North Fork intrusion
84-280
19.7
Monazite
Intracauldron Badger Creek Tuff
84-282
Allanite
Mount Aetna resurgent intrusion
84-290
30.4
29.8
84-295
California intrusion
84-299
Mount Antero intrusion
84-300
Basal vitrophyre of the Wall Mountain Tuff
85-127
85-127a
Devitrified welded flow.
85-128
Previously thought to be Outflow of Badger Creek Tuff.
85-42c
34.6
Intrusive tuff dike associated with Mount Aetna cauldron
85-53
85-70
39.4
BCP7
Location approximate.  Interpreted by Shannon (1988) to be an uplift-cooling age related to Rio Grande rift tectonism.
TMPM-CCQ
29.4
Big Thompson Canyon
BTCBT12D-a
Shaw and others (1999)
Preferred/Plateau age. High Magesium hornblende.  High titanium biotite.
Preferred/Plateau age. High magnesium hornblende.  High titanium biotite.
Micaceous schist
Carter Lake
BTCR30409-1a
Preferred/Plateau age.
Quartzo-feldspathic schist
BTCR30409-1b
Total gas age.  Concave upward spectrum.  Meaningless age.
Micaeous schist
BTCR30409-2c
Phengite
Palisade Mountain pluton
BTCR30409-3a
Total gas age.  Continuous loss pattern.  Meaningless age.
BTCR30409-3b
Actinolite
Total gas age.  Erratic spectrum with continuous loss.. Meaningless age.  Actinolite cores
BTCR30409-3c
Total gas age.  Maximum age 1500 Ma. 5-10% actinolite cores
BTCR30409-4a
Total gas age.  Continuous loss pattern. Maximum age 1525 Ma. High potassium hornblende.
BTCR30409-4b
Preferred/Plateau age. Metamict biotite.
Quartz-feldspar schist
BTCR30409-6a
Preferred/Plateau age. High iron biotite.
BTCR30409-6b
BTCR30409-5a
Preferred/Plateau age. Low iron biotite.
Amphibolite gneiss
7520-4
1392
Siddoway and others (2000)
KEK-2
1355
KEK-3a
1342
KEK-4a
1357
KEK-4b
1369
KEK-4c
1365
KEK-5b
1234
KEK-6
1344
KEK-7b
1356
KEK-7c
1338
1282
Total gas date.  Location approximate.
25T56
Simmons and Hedge (1978)
31T55
75C88
Hornblende-pyroxene monzonite
75CS67
Mafic monzonite
75CS70a
75CS72a
East of Burnt Mountain
75CS73
Leucocratic monzonite
Bostonite, near Lawson
75CS76
75CS77a
Central City/ Nederland
Quartz-bearing monzonite
Hornblende Latite
Dike south of Nederland
75-CS79
75CS80
75CS86
Audubon-Albion stock
76CS100
Wood Dike
76CS101
76CS102
76CS103
Table Mountain lava flow
76CS89
Table Mountain basalt lava flow
76CS90
76CS91
76CS92
Ralston dike
76CS93
Valmont dike
76CS94
76CS96
Porphyritic monzonite
76CS97
76CS98
76CS99
90T53
Boulder Creek pluton
BC-3
HMN-1
Hornblende latite
Dike north of Eldora
HMN-10
Nederalnd
Hmn-13
HMN-2
HMN-3
Biotite latite
HMN-8
HMN-9
Estes Park diatreme
Longs Peak
Smith (1979)
Isochron.
Volcanic ash
Browns Park Formation
Elkhorn Mountain
9.0 ± 2.1
Snyder (1980a)
Browns Park Formation.
Meaden Peak
9.2 ± 1.7
11.5 ± 1.8
15.8 ± 2.6
Flow of North Park
17.0 ± 1.5
Snyder (1980b)
Analytical data not reported.
7A
20.2 ± 1.9
Mount Ethel pluton
520
1470 ± 50
Snyder and Hedge (1978)
Isochron based on 7 samples.  (Sample 1 of 7).
Isochron based on 7 samples.  (Sample 2 of 7).
522
Mount Ethel
Isochron based on 7 samples.  (Sample 3 of 7).
Isochron based on 7 samples.  (Sample 4 of 7).
525
Isochron based on 7 samples.  (Sample 5 of 7).
526
Isochron based on 7 samples.  (Sample 6 of 7).
527
Isochron based on 7 samples.  (Sample 7 of 7).
544
1800 ± 100
Isochron based on 5 samples.  (Sample 1 of 5).
Quartz monzonite gneiss
Isochron based on 5 samples.  (Sample 2 of 5).
Isochron based on 5 samples.  (Sample 3 of 5).
554
Isochron based on 5 samples.  (Sample 4 of 5).
555
Isochron based on 5 samples.  (Sample 5 of 5).
Feldspathic-biotite gneiss
Gneiss intruded by Buffalo Pass pluton
593
Teal Lake
1690 ± 100
Isochron based on 3 samples.  (Sample 1 of 3).
616
Isochron based on 3 samples.  (Sample 2 of 3).
631
Isochron based on 3 samples.  (Sample 3 of 3).
523.2
Spell and McDougall (2003)
Mafic hornblende-bearing biotite quartz monzonite
58GP1
Stern and others (1971)
Concordia based on 6 samples.
Hornblende-bearing leuco-quartz monzonite gneiss
63GP15
Hornblende-bearing biotite quartz diorite
63GP40
Muscovite-biotite granite
Dike intruding quartz diorite of Boulder Creek batholith
63GP-41
Biotite granodiorite gneiss
63GP99
Leuco-quartz monzonite gneiss
GP509
Eldorado Springs
One of 6 samples forming chord with upper intercept at 1725 Ma.
Amphibolite inclusion in Boulder Creek
GP721
BC5793
Sapinero
Steven and others (1967)
Fisher Quartz Latite, Fisher Mountain flow
Ds10
Spar City
25.9
Ds28
Pool Table Mountain
Summitville area
Ds29c
Location from Marvin and others (1974).
La Garita Quartz Latite
S292
Halfmoon Pass
S318
San Luis Peak
S332
Fisher Quartz Latite, Copper Mountain flow
S333
Biotite gabbro
Spanish Peaks area
855-432
Stormer (1972)
Syenodiorite lamprophyre
CSP-17
Rhyolite tuff breccia
Possibly derived from Red Mountain center
No. 2, Table 1
Fraser
Taylor and others (1968)
Red Mountain plug
No. 3, Table 1
33
Taylor and others (1968); Izett (1966)
Location approximate; good to 1/4 section.
CSU-1
Thompson and Arehart (1990)
CSU-10
CSU-11
CSU-3
CSU-4
CSU-5
CSU-6
CSU-7
CSU-8
38.3
CSU-9
37.7
FT-4
24.6
FT-6
Block of Servilleta Formation in landslide debris at San Pedro Me
77LRG107
Costilla
Thompson and Machette (1989)
Block of Servilleta Formation in landslide debris at San Pedro Mesa.
Stock of South Piñon Hills
KA 71-52
Kiowa Hill
29.2
Stock in Fairy Hills
SP-11-2
Mesita Reservoir
30.9
28.4
Dike in Fairy Hills
SP-11-8
25.6
25.3
Quartz-alunite replacement vein
Fairy Hills
SP-231
Manassa NE
Flow at South Piñon Hills
T84089
Flow at Flat Top
T84098
26.4
T84150
Flow at Piñon Hills
T84163
7435
Toulmin and Hammarstrom (1990)
36.1
7438
Preferred age based on high-temperature steps in Ar-release spectrum; no distinct plateau.
Approximate cooling age.
Monarch Pass
7457
46.3
7569
37.1
7570
36.4
36.9
7574
Ash-flow tuff
Sewanee Peak Volcanics
7723
Hoffman Park Granite
7788
64B76
Location not given in text; provided by P. Toulmin, 2007, written communication.
Grouse Mountain
Tweto and Lovering (1977)
Mount Champion area
MM-01
Van Loenen and others (1989)
Halfmoon Creek stock
MM-12
Mount Massive
44.3
Location from Wallace (1993, 1995).  Intensely altered.
West of Leadville
MM-35
MM-90
54.4
Pluton of Wilson Park
BR-1
1722 ± 50
Vera and Van Schmus (1974)
Average of 4 model ages (initial 87Sr/86Sr=0.705) of highly radiogenic samples.  (Sample 1 of 4)  Fourth sample on Canon City 1:100,000 quadrangle.
BR-10
1781 ± 66
Isochron based on 8 samples.  (Sample 5 of 8)  Other samples on Canon City 1:100,000 quadrangle.
Intrudes pluton of Wilson Park
BR-13
1571
Model age; initial 87Sr/86Sr=0.705.
1513
BR-14A
Isochron based on 8 samples.  (Sample 6 of 8)  Other samples on Canon City 1:100,000 quadrangle.
Plagioclase, K-feldspar, muscovite, whol
1430 ± 50
Mineral whole rock isochron "normalized" with similar isochron from sample BR-19A (on Canon City 1:100,000 quadrangle).  Approximate time of metamorphism.
BR-15
Average of 4 model ages (initial 87Sr/86Sr=0.705) of highly radiogenic samples.  (Sample 3 of 4)  Fourth sample on Canon City 1:100,000 quadrangle.
BR-17
Isochron based on 8 samples.  (Sample 1 of 8)  Other samples on Pikes Peak 1:100,000 quadrangle.  Location approximate.
BR-18
Average of 4 model ages (initial 87Sr/86Sr=0.705) of highly radiogenic samples.  (Sample 4  of 4).  Other samples on Pikes Peak 1:100,000 quadrangle.  Locations approximate.
BR-19A
Isochron based on 8 samples.  (Sample 2 of 8)  Other samples on Pikes Peak 1:100,000 quadrangle.  Location approximate.
Mineral/whole-rock isochron "normalized" with similar isochron from sample BR-14A (on Pikes Peak 1:100,000 quadrangle). Approximate time of metamorphism.  Location approximate.
BR-19B
Isochron based on 8 samples.  (Sample 3 of 8)  Other samples on Pikes Peak 1:100,000 quadrangle.  Location approximate.
BR-2
Average of 4 model ages (initial 87Sr/86Sr=0.705) of highly radiogenic samples.  (Sample 2 of 4)  Fourth sample on Canon City 1:100,000 quadrangle.
BR-21
Isochron based on 8 samples.  (Sample 7 of 8)  Other samples on Canon City 1:100,000 quadrangle.
BR-22
Isochron based on 8 samples.  (Sample 8 of 8)  Other samples on Canon City 1:100,000 quadrangle.
BR-3
1624
Intrudes Wilson Park quartzite
BR-5
1547
BR-8
Isochron based on 8 samples.  (Sample 4 of 8)  Other samples on Canon City 1:100,000 quadrangle.
Biotite rhyolite porphyry
1619-600
26.1 ± 1.2
Wallace (1993), (1995)
1650-525
18.2
Altered rhyolite porphyry
Climax "Central Mass"
1683-623
23.3 ± 1.1
66-281
66-282
66-283
51.3
Elk Mountain porphyry
67-1
37.6
67-2
Climax, late rhyolite porphyry
76-15
25.5 ± 1.2
Climax, rhyolite porphyry
77-821
Treasure Vault stock
15.7
52
87N12
41.9
50.9
Quail Porphyry
87N13
41.6
44.4
87N14
46.1
87N15
87N16
Stock of Tucker Mountain
90N1
90N2
41.8
90N3
90N4
90N5
45.3
51
Precambrian granite at Climax mine
B-230
B-232
96.4
FT-10
43.1
Mount Bellview quartz monzonite
MB-4
Biotite (?)
MM-54
Mount Champion
399
Too old; excess radiogenic argon or Proterozoic xenocrysts.
W3122
West Cross Creek diorite
W3123
W3124
65.9
W3125
Timberline Lake breccia
45
Turquoise Lake Porphyry
35.6
Buckskin Gulch stock
71.4
Green Mountain trachyte dike
1275 ± 30
Wetherill and Bickford (1965)
Whole-rock/mineral isochron.  Location approximate.
1650 ± 35
Isochron based on 13 samples. (Sample 4 of 13)  Other samples on Gunnison, Montrose, Leadville, and Vail 1:100,000 quadrangles.  Location approximate.
Pegmatite wall rock
Brown Derby area
CO-1
1395
Model age.
CO-16
1416
1465
Biotite (replicate)
1444
1433
CO-2
1366
1437
CO-20
Apatite, plagioclase, muscovite, biotite
1384 ± 20
Isochron based on 13 samples. (Sample 1 of 13).  Other samples on Saguache, Montrose, Leadville, and Vail 1:100,000 quadrangles.
CO-36
Isochron based on 13 samples. (Sample 13 of 13).  Other samples on Gunnison, Saguache, Montrose, and Leadville 1:100,000 quadrangles.  Location from Wallace (1993, 1995).
Cross Creek pluton dike
CO-37
Isochron based on 13 samples. (Sample 12 of 13).  Other samples on Gunnison, Saguache, Montrose, and Vail 1:100,000 quadrangles.  Location from Wallace (1993, 1995).
Big Union pluton
CO-38
Isochron based on 13 samples. (Sample 11 of 13).  Other samples on Gunnison, Saguache, Montrose, and Vail 1:100,000 quadrangles.  Location from Wallace (1993, 1995).
Denny Creek pluton (?)
CO-42
Isochron based on 13 samples. (Sample 10 of 13).  Other samples on Gunnison, Saguache, Montrose, and Vail 1:100,000 quadrangles.  Location and recalcultated age from Fridrich and others (1991).
CO-55
Isochron based on 13 samples. (Sample 5 of 13).  Other samples on Gunnison, Montrose, Leadville, and Vail 1:100,000 quadrangles.  Location approximate.
Near Sargents
CO-58
Isochron based on 13 samples. (Sample 6 of 13).  Other samples on Gunnison, Montrose, Leadville, and Vail 1:100,000 quadrangles.  Location approximate.
CO-59
Isochron based on 13 samples.( Sample 8 of 13).  Other samples on Gunnison, Montrose, Leadville, and Vail 1:100,000 quadrangles.  Location approximate.
Near Doyleville
CO-6
1031
CO-61
Minimum age.  Isochron based on 13 samples. (Sample 3 of 13).  Other samples on Saguache, Montrose, Leadville, and Vail 1:100,000 quadrangles.
CO-64
Almont
1397 ± 35
Mineral-whole rock isochron.  Recalculated date in DeWitt and others (2002).  Location approximate.
Isochron based on 13 samples. (Sample 2 of 13).  Location approximate.  Other samples on Saguache, Montrose, Leadville, and Vail 1:100,000 quadrangles.
South Beaver Creek pluton
CO-73
Big Mesa
Isochron based on 13 samples. (Sample 9 of 13).  Other samples on Gunnison, Saguache, Leadville, and Vail 1:100,000 quadrangles.  Location approximate; estimated from Montrose 1:250,000 scale geologic map.
Whole-rock, biotite
1356 ± 25
Whole-rock/mineral isochron.
Isochron based on 13 samples. (Sample 7 of 13).  Other samples on Gunnison, Montrose, Leadville, and Vail 1:100,000 quadrangles.
1384
1129
Climax, late barren stage sericite
White and others (1981)
Altered granite
Climax, upper orebody
79
Young (1972)
Location very approximate.  Age recalculated by Chualaowanich (1996).
80
CR-48
Zielinski and others (1981)
Isochron defined by 6 samples from drill core.
trachyandesite
45-C-7
Trinidad
Herlick Canyon
27.3 ± 4.8
Smith (1975)
Approximate location.
609-C-14
latite
657-C-46
22.5
West Spanish Peak stock
WSP-1
Spanish Peaks
23.0
East Spanish Peak stock
ESP-1
biotite
21.7
Biotite-pyrite-quartz vein
Cripple Creek deposit
37K122
Kelley and others (1998)
530N2
Altered phonolite
CC001A
Sanidine-adularia
CC001B
Adularia-biotite-pyrite vein
CC003
31.3
CC004
CC005
Isochron age; preferred age is 28.7 Ma based on mimimum age in spectrum and regarded as maximum possible age for sample.
CC007
Weighted mean age; regarded as maximum possible age.
CC009
CC010S
Adularia-quartz vein
CC2
CCPH1
Breccia matrix with gold and pyrite
CRESA-4
Garrel Peak pluton
081297-1
1536
Shaw and others (2005)
Plateau age.  Used decay constant of Kwon and others (2002).
0817-1
Total gas age.  Continuously climbing spectrum.  Meaningless age.  Decay constant of Kwon and others (2002). Conflicting locations.
97PARK10h
1570
Total gas age.  Erratic spectrum.  Meaningless age.  Maximum age is 1605 Ma.  Used decay constant of Kwon and others (2002).
97PARK11
1598
Total gas age.  Erractic spectrum.  Meaningless age.  Maximum age is 1620 Ma.  Used decay constant of Kwon and others (2002).
1456
Total gas age. Erractic spectrum.  Meaningless age. Maximum age is 1620 Ma.  Decay constant of Kwon and others (2002).
97PARK12C
1449
Total gas age.  Continually declining spectrum.  Meaningless age.  Maximum age is 1460 Ma.  Used decay constant of Kwon and others (2002).
97PARK2B
1707
Total gas age.  Erractic spectrum.  Meaningless age.  Maximum age is 1730 Ma.  Used decay constant of Kwon and others (2002).
97PARK-6
Total gas age.  Erractic spectrum.  Meaningless age.  Maximum age is 1740 Ma.  Used decay constant of Kwon and others (2002).
1454
97PARK-9B
1377
Total gas age.  Erractic spectrum.  Meaningless age.  Used decay constant of Kwon and others (2002).
Homestake shear zone
C97HS-3
C97HS-4H
1512
Total gas age.  Erratic spectrum.  Meaningless age. Used decay constant of Kwon and others (2002).
C99HS-1
1544
Total gas age.  Concave upward spectrum.  Meaningless age. Used decay constant of Kwon and others (2002).
C99HS-16
Total gas age.  Continuous loss pattern. Maximum age 1370 Ma.  Meaningless age. Decay constant of Kwon and others (2002).
CD-1
CD-2
1389
Fourmile pluton
CD-4
1364
Near Plateau.  Used decay constant of Kwon and others (2002).
CD-5a
1373
Metasediments (?)
CD-7
COO HS-11
1391
1403
Total gas age.  Lowest age at highest retention temperature.  Meaninlgess age.  Used decay constant of Kwon and others (2002).
COOHS-12
1388
Near Plateau age.  Used decay constant of Kwon and others (2002).
COO HS-3
Total gas age.  Erratic spectrum.  Meaningless age.  Used decay constant of Kwon and others (2002).
Mafic metavolcanic rocks
FM-00-04
Total gas age.  Continually declining age.  Maximum age 1460 Ma.  Used decay constant of Kwon and others (2002).
1494
Total gas age.  Continually declining age.  Maximum age 1540 Ma.  Used decay constant of Kwon and others (2002).
Metasedimetary rocks
K98 PK 27A
Total gas age.  Constantly declining spectrum.  Maximum age 1560 Ma.  Used decay constant of Kwon and others (2002).
Mixed metavolcanic and metasedimentary rocks
Salida area
K98-SAL-2
1347
Total gas age.  Continuously climbing sprectrum.  Meaningless age.  Used decay constant of Kwon and others (2002).
K98-SAL-3
1452
Hardscrabble Creek area
KEK-3b
1382
1385
Total gas age.  Concave upward spectrum.  Meaningless age.  Actinolitic.  Used decay constant of Kwon and others (2002).
1358
Near plateau age.  Used decay constant of Kwon and others (2002).
1376
Total gas age.  Continually declining spectrum.  Meaningless age.  Actinolitic.  Used decay constant of Kwon and others (2002).
1381
1252
1361
1422
Total gas age.  Erratic spectrum.  Meaningless age.   Used decay constant of Kwon and others (2002).
KHS99-1
1565
KHS99-2
1649
KHS99-3
Total gas age.  Continuous loss pattern.  Maximum age 1440 Ma. Meaningless age.  Used decay constant of Kwon and others (2002).
Mixed metsedimentary and metavolcanic rock
Pearl area
KK99-PK-65
Pearl
1,612
Total gas age.  Erratic spectrum.  Used decay constant of Kwon and others (2002).
KOO BR 20
KOO BR-21
1479
Total gas age.  Continuously climbing spectrum.  Maximum age. 1585 Ma.  Meaningless age.  Decay constant of Kwon and others (2002).
Wilson Park area
KOO BR-10-5
1275
Total gas age.  Erratic spectrum.  Maximum age 1410 Ma.  Meaningless age.  Used decay constant of Kwon and others (2002).
KOO BR 21
Total gas age.  Continuously climbing spectrum.  Maximum age 1360 Ma.  Meaningless age.  Decay constant of Kwon and others (2002).
Mafic metavolcanic
KOO FM-1
1510
Total gas age.  Erratic spectrum.  Constantly declining spectra.  Maximum age 1705 Ma.  Used decay constant of Kwon and others (2002).
1314
Total gas age.  Erratic spectrum.  Constantly declining spectra.  Used decay constant of Kwon and others (2002).
KOO FM-2
1572
Total gas age.  Erratic spectrum,  Constantly declining spectra.  Maximum age 1630 Ma.  Used decay constant of Kwon and others (2002).
KOO-BR-1
KOO-FM-3
1553
KOO-HS-10
Total gas age.  Continuous loss pattern.  Maximum age 1402 Ma  Used decay constant of Kwon and others (2002).
KOO-HS-2
KTM-99-2
Total gas age.  Ages declines with increasing temperature.  Meaningless age.  Decay constant of Kwon and others (2002).
KTM-99-7
Total gas age.  Concave upward spectrum.  Meaningless age.  Used decay constant of Kwon and others (2002).
Metasedimentary rocks
Lester Peak
LMOO-15
1671
Total gas age.  Constantly declining spectrum.  Meaningless age.  Used decay constant of Kwon and others (2002).
Hayden Pass
SC97-1
Coaldale
1378
McCoy Gulch pluton
SC97-10A
1370
SC97-11A
SC97-11B
SC97-11C
1457
SC97-11D
1476
SC97-11E
1367
SC97-11F
1329
Total gas age.  Continuously climbing spectrum.  Maximum age 1365 Ma.  Used decay constant of Kwon and others (2002).
SC97-12
1487
1301
Metavolcanic rocks
SC97-13E
1432
SC97-14B
Mafic metavolcanic rocks (?)
Dubois greenstone
SC97-17A
Total gas age.  Erratic spectrum. Meaningless age.  Used decay constant of Kwon and others (2002).
SC97-17B
SC97-18
McIntosh Mountain
Total gas age.  Erratic spectrum.  Two fractions at 1700 ma Used decay constant of Kwon and others (2002).
1081
Total gas age.  Erratic spectrum.  Two fractions at 1700 ma.  Used decay constant of Kwon and others (2002).
SC97-19
Total gas age.  Erratic spectrum.  Constantly declining spectra.  Two fractions at 1700 ma.  Decay constant of Kwon and others (2002).
SC97-2
1447
Total gas age.  Erratic spectrum.  Maximum age. 1520 Ma.   Used decay constant of Kwon and others (2002).
SC97-3
Total gas age.  Continuously climbing spectrum.  Maximum age 1395 Ma.  Used decay constant of Kwon and others (2002).
SC97-4
1398
Total gas age.  Continuously climbing spectrum.  Maximum age 1460 Ma.  Used decay constant of Kwon and others (2002).
SC97-5A
Bushnell Peak
Unknown
SC97-6A
Total gas age.  Erratic spectrum and declining spectrum.aningless age.  Used decay constant of Kwon and others (2002).
SC97-6B
SC97-7A
1514
Total gas age.  Constantly declining spectrum. Meaninless age.  Used decay constant of Kwon and others (2002).
SC97-8A
Total gas age.  Concave upward spectrum.  Meaningless age.   Used decay constant of Kwon and others (2002).
SC97-8B
832
Metavolcanics rocks
SC97-9
1453
T-IL-10b
T-IL-1b
1349
Total gas age.  Erratic spectrum.  Meaninless age.  Used decay constant of Kwon and others (2002).
T-IL-3b
T-IL-4b
1346
T-IL-5b
BL-2
Lester (1992)
LI-2
LI-3
BL-17
Lamprophyre dike
Carlton Tunnel, Cripple Creek
not given
Jensen (2003)
Laser fusion? on unknown mineral.
Glomeroporphyritic phonolite
Altman Pit, Cripple Creek
Helms (2000)
Laser Fusion.
N-2 dike in Altman Pit
Biotite in vein
Vindicator Mine, Cripple Creek
Bull Cliffs Phonolite
Cripple Creek, east
Sanidind
Bull Cliffs phonolite
George Creek Kimberlite dike
Eaton Reservoir
Carlson and Marsh (1986)
Approximate age of weathered material.
Chicken Park Kimberlite
Perovskite
Heaman and others (2003)
Weighted average of four size fractions.
Minette
Dike east of Walsenburg
SP70
Cucharas Reservoir
14.3
Penn and Lindsey (2009)
Partial plateau.
Camptonite
East-trending parallel swarm, south of Spanish Peaks
SP37
26.6
Hornblende monzonite
Bradford Mesa
SP51
Maria Reservoir
21.5
Aproximate location. Plateau age.
SP33
SP134
Huerfano Butte
SP34-HB
Walsenburg North
25.2
Alkali basalt
SP34-TS
Walsenburg
SP131
21.3
Syenite porphyry
SP73
Ritter Arroyo
Lamproite
Lamproite body near Granby
6LT56
Thompson and others (1997)
Twin Lakes pluton
73-N8
Idaho Springs area
KIS0012
Total gas age.  Erractic spectrum.  Meaningless age.  Maximum age is 1620 Ma.  Decay constant of Kwon and others (2002).
Sherman Mountain
KIS004
Granodiorite (?)
Twin Spruce pluton
KIS012
Near Plateau.    Used decay constant of Kwon and others (2002).
At Sherman Granite contact
CB-97-2
Northern Front Range
CB-97-3
99-CP-02A
99-CP-02B
Musovite
Total gas age.  Concave downward spectrum.  Meaningless age.  Used decay constant of Kwon and others (2002).
99FF-01
McHenry's Peak
Total gas age.  Concave downward spectrum.  Meaningless age.   Used decay constant of Kwon and others (2002).
99SV-02
99SV-05
99SV-06
Total gas age.  Continuously climbing spectrum.  Meaningless age.  Used decay constant of Kwon and others (2002).
99TS-01
99TS-02
99CP-01
99LP-02
99LP-03
99LP-04
99LP-05
99LP-07
99LP-01
ISSZR30416-2
Near plateau.
ISSZR30416-3
ISSZR30416-4a
Black Hawk
Total gas age.  Maximum age 1290 Ma.
Coal Creek Canyon
ISSZR30416-1a
Total gas age.  Maximum age 1520 Ma.
ISSZR30326-3
Total gas age. Continuously climbing spectrum.  Maximum age 1560 Ma.
Metapelite
ISSZR30326-6
Golden Gate Canyon
ISSZR0706-6
Maximum age.  No spectrum
ISSZR0706-1
Mount Evans pluton
ISSZR0706-2
ISSZR0706-3
ISSZR0706-4
Near plateau age.
Total gas age.  Maximum age 1226 Ma.
Maximum age.  No spectrum.
ISSZR0706-5
207/206 age.
1020
FS44
Total gas age.  Sample number from Kirkham and Heimsoth (2002).
FS98
FG1B
Fort Garland
Wallace (1997)
Martinez Hill
LV51
Peters (2004)
Plateau age.  Reported in Kirkham and others (2004)
LV255
Total gas age.  Reported in Kirkham and others (2004)
LV396
LV334
CP504A
Kirkham and others (2005)
CP106
CP46
Minimum age.
Reinecker Ridge Volcanics
JP300
Widmann and others (2005)
Unreported age type.
Bald Mountain sill
CO197
Rhyolite clast
Lower Conglomerate of South Park Formation
JK365
Rhyolite tuff
E309P
Fairplay East
Kirkham and others (2006)
Mean age for 30% of gas released.  Total gas age 39.2 Ma.
Andesite clast
JK119
Complex continually declining high temperature spectrum.   Meaningless age.
Intermediate intrusive clast in conglomerate
Upper Conglomerate of the South Park Formation
JK099
Plateau age.  Cooling age
Andesite clast in conglomerate
JK083
Dacite tuff
K0447bi
Wallace and Keller (2003)
K0447hb
94SPRO7
Mount Logan
71.5
Laramide annealing  zone(?).
94SPR08
Laramide annealing zone.
96SPR44
134.7
Laramide partial annealing zone.
96SPR48
00BenTy01
Shawnee
78.9
00BenTy03
104.5
00BenTy04
00BenTy05
94SPR10
60.5
94SPR11
9.3
115.7
94SPR12
59.6
94SPR13
117.1
96SPR38
Platte Canyon
94SPR14
94SPR15
114.1
94SPR16
Sandstone dike float
97SPR37
Kassler
69.5
96SPR39
70.6
96SPR40
70.8
96SPR42
74.2
94SPR17
194.4
94SPR19
47.1
94SPR20
65.2
94SRP21
64.4
95SPR22
122.8
95SPR23B
16.1
151.9
95SPR24
Topaz Mountain
155.8
95SPR25
130.9
95SPR26
149.9
95SPR27
119.6
95SPR29
111.9
95SPR30
118.9
95SPR31
76.8
95SPR32
79.8
95SPR33
95SPR34
93.4
Gneiss and schist
95SPR35
94TAR01
94TAR02
Farnum Peak
78.4
Pyroxene amphibolite
501
Muscovite-biotite monzogranite
49.8
148
A-3
124
A-4
A-5
245
Laramide (and/or Late Paleozoic) partial annealing zone.
Biotite-muscovite monzogranite
A-7
473
A-9
Sulphur Mountain
352
South end of sill.
40.6
Porphyritic Hornblende-biotite trachydacite
2% rock fragments and impurties.  Has many defects.  Age only approximate.
South Park Formation
66.5
About 1600 m above base.
Dacite flow
South Park formation
63.3
About 160 m above base.
SB-1
Marvin and others (1974) [#208]
Tuffaceous sands
1315
33.76
Samples #65 and 66 (sample nos. 1315 and 1318) and six others from the Antero Fomation give a rounded age of 33.9 (McIntosh and Chapin, 2004).
Pumaceous sandstone
1318
Sulfur Mountain
33.78
Fayalite-quartz syenite
Pikes Peak batholith
B65D
1085.6
Smith and others (1999)
Quartz-fayalite syenite
1093
Schaerer and Allegre (1982)
Based on 12 fragments of a single grain.
LP-4
Loveland Pass
LP-2
19.5
GP-2
GP-7
21.8
GP-3
GP-1
LP-7
GP-6
Tertiary partial annealing (?}.
GP-4
Tertiary partial annealing.
GP-5
00GP02
Biotite-quartz-feldspar gneiss
45.1
Biotite monzogranite gneiss
334
Meridian Hill
68.5
Bryant and Naeser (1980); Naeser and others (2002)
Hornblende-biotite granodiorite gneiss
337
338
57.8
345
Mount Evans
90.2
341
94CC02
47.7
94CC04
52.4
95CC12
53.3
96COCO1
96COCO2
97VBO1
Ralston  Buttes
97VB02
48.8
97VB03
63.1
97VB04
67.3
97VB05
52.8
97VB06
52.6
97VB07
97VB08
74.7
95CC09
94CC03
55.6
95CC10
57.2
95CC07
Granitic lens in amphibolite
95GGC01
95GGC02
Phyllite/schist
96GGC03
142.8
95CC08
61
94CC05
62.3
95GG02
95CC11
96CC13
96CC14
56
96CC15
96CC16
59.4
94CC01
98.9
92GO02
100.8
96CC06
92GO01
149.7
92GO03
196
92GO04
17.6
263
Granite and biotite schist
99DC04
Indian Hills
233.1
99DC05
135
96SPR45
71.7
Biotite Gneiss
96SPR47B
58.5
FT-01
FT-02
109
Quartzite of Coal Creek
84-CA-4
1800-1880
Aleinikoff, Reed, and Wooden (1993)
U-Pb zircon ranges from 1800-1880 Ma.  Estimated provenance ages.  Probable multiple lead loss in three fractions of 1800-1880 Ma zircon.
207Pb/206Pb
1786
Rounded pale pink zircons.
1724
Euhedral pale pink zircons.
Dark magnetic zircons.
Boulder Creek quartz monzonite
83-02
Upper intercept on concordia diagram.
83-03
Premo and Fanning (2000)
SHRIMP age.  Upper intercept on concordia diagram.
SHRIMP age.  Upper intercept on concordia diagram.  This sample from the Henderson mine area.
A509182
Aleinikoff, Reed, and DeWitt (1993)
Granite of Rosalie Peak
A509181
1448
Mafic inclusion in Mt. Evans batholith
R0706-4
Harris Park
Location, rock type, and some comments are from an unpublished compilation by J.C. Reed, Jr.; hornblende megacryst
1410
Location, rock type, and some comments are from an unpublished compilation by J.C. Reed, Jr.
Amphibolite layer
R0706-1
Amphibolite lens
R0706-5
1220
Berger (1975)
Regional cooling age; coarse biotite.
Green Mountain diatreme
Whole-rock, minerals
49
572
367
Larson and Amini (1981)
Emplacement age.
77.1
Laramide partial (?) annealing zone.
EC-1
67.1
Marvin and others (1974) [#64]
73
Marvin and others (1974) [#78]
EM-1
Cunningham and others (1994), p. 3, 7, 19.
71.3
Dike intruding A-1.
Trachybasalt
63.94
Obradovich (2002); unpub. report from New Mexico geochronologic research lab. to
Green Mountain Conglomerate
Obradovich (2002)
Granite porphyry
Red Mountain porphyry
Distrubed spectrum, preferred age.
29.81
Rhyolite dike
Distrubed spectrum, excess argon.
1429
Marvin and others (1974) [#67]
Pluton.
50.6
Marvin and others (1974) [#69]
Stock.
Bald Mountain stock
Bos 1
48.19
96BT01
96BT02
57.9
96BT03
55.3
96BT04
45.4
96BT05
64.8
96BT06
96SV01
47.5
99SV02
Fountain Formation
99SV03
49.5
99SV05
99SV06
99SV07
60.2
99SV08
46.9
99TS01
99TS02
54.1
99LP01
51.7
99LP02
99LP03
99LP04
99LP05
49.2
99LP06
47.3
Pegmatite in schist
99CP01
Trail Ridge
Mica schist
99CP02b
Granodiorite in granite pluton
99FF01
McHenrys Peak
00IP02
Isolation Peak
Laramide (?) annealing zone.
00IP03
67.4
00IP04
58.8
00IP05
Granite Gneiss
96BCO1
Clinopyroxene latite porphyry
Sill in Benton Shale
Granby
Schroeder (1995)
Dike.
Rhyolite breccia
USGS(D)-73N6
Pipe.
00LIV02
00LIV03
Livermore Mountain
72.3
00LIV04
00LIV05
Biotite schist
00LIV06
81.2
Laramide annealing or partial annealing zone.
94PR01
94PR02
94PR03
Schist/gneiss
94PR04
70.5
94PR05
68.7
94PR06
74.4
94PR07
Big Narrows
94PR08
63.4
Granite breccia
94PR09
Tertiary partial annealing (?).
94PR10
94PR11
94PR12
57.3
94PR13
Chambers Lake
47.8
Bruce and Johnson (1991)
Location approximate.  One of many mapped felsic dikes.
Browns Pass pluton
1438
Leader and Jones (2008)
Location inferred.
WML-4-59
Waugh Mountain
Campbell (1994)
WMA-1-51
GPT-4-25
04-CO-GD1
28.53
Knox (2005)
04-CO-GD3
28.85
Rhyolite welded tuff
28.02
04-CO-IM3a
28.52
05-CO-JWR3
04-CO-RL1
Clark Peak
28.74
EEL-1
27.09
CP05-97
CP05-100
28.46
DM05-183
Deadman
27.65