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![Figure 5. Geometry of the La Garita and Cochetopa Park calderas and associated rocks of the central San Juan caldera cluster. After eruption of the Fish Canyon Tuff at 27.8 Ma, seven additional large ignimbrite eruptions and associated calderas were localized within the La Garita caldera within 0.9 m.y. Map was modified from Lipman et al. (1997) and Lipman (2006), incorporating unpublished mapping in the Cochetopa Park area (2001–2005).]()
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![Oblique view (Google Earth), looking north at Cochetopa and North Pass calderas. The topographic rim of Cochetopa Park caldera (~30 km across) is morphologically well preserved (dashed white lines): along its northwest and north sides, high points on the rim are marked by Sawtooth Mountain (STM) and Razor Creek Dome (RCD); the east rim is along the Continental Divide, which defines the boundary with the older North Pass caldera farther to the east; and the south boundary also follows the Continental Divide where the Cochetopa Park caldera merges with the northern segment of the La Garita caldera. The northeast-trending Los Pinos graben formed at the time of collapse at La Garita, and the parallel Cochetopa graben, which breaches the north wall of La Garita caldera and forms a low segment of Cochetopa rim, is filled by thick tongue of Nelson Mountain Tuff. This lobe of densely welded tuff was channeled northeast from its eruptive source within the San Luis caldera complex at lower left of image, and flowed into the Cochetopa Park caldera where it thins to only a few meters of nonwelded tuff in the southeastern parts of the caldera basin. Other geographic localities: CC—upper Cochetopa Creek; CCn—Cochetopa Canyon (outlet from Cochetopa Park caldera, carved in Precambrian granitic rocks); CD—Cochetopa Dome (sequence of crystal-poor lava flows of petrologically evolved rhyolite that accumulated within Cochetopa caldera shortly after its collapse); LBB—Long Branch Baldy (high point along Continental Divide, where 33-Ma Bonanza Tuff banks against high-standing erosional remnants of a large andesitic stratocone); NP—North Pass (followed by Colorado Hwy 114); LPC—Los Pinos Creek; SaC—Saguache Canyon (outlet from La Garita caldera, carved in >32-Ma intermediate-composition lavas, and inherited from Oligocene topography); SM—Sargents Mesa (high flat along the Continental Divide, locally capped by Bonanza Tuff); SP—Saguache Park (Carpenter Ridge and Wason Park Tuffs, banked against the northern La Garita caldera wall); TM—Table Mountain (high-standing erosional remnant of Nelson Mountain Tuff that ponded within the La Garita caldera).]()
![Photographs, landslide breccia of Fish Canyon Tuff at west margin of Cochetopa Park caldera. (A) Typical exposure of monolithologic angular to rounded clasts, framework supported, with little or no interstitial matrix. Paleomagnetic measurements at this site (NM3036, Table 3) show that the clasts were emplaced at low temperature. (B) Rare clasts of phenocryst-poor rhyolitic Carpenter Ridge Tuff (CR), intermixed with dominant Fish Canyon fragments (same site as 14A), document that landsliding was unrelated to eruption of the Fish Canyon.]()
![Geochronology of the Fish Canyon (Colorado, United States) magmatic system. A: Comparison of previously published zircon and titanite U-Pb and sanidine 40Ar/39Ar dates with zircon U-Pb dates obtained in this study. All U-Pb dates are 206Pb/238U dates corrected for initial 238U-230Th disequilibrium using Th/Umelt of 2.2 (Schmitz and Bowring, 2001). Δt denotes age difference between oldest and youngest zircon date of each sample. Probability density functions show distribution of 206Pb/238U dates. FCT—Fish Canyon Tuff; NCD—Nutras Creek Dacite; MLX—andesite enclave. B: Caldera map of the Central San Juan caldera cluster showing locations of samples analyzed in this study; inset map (top left) shows location of San Juan volcanic field (SJVF) within the state of Colorado. CPC—Cochetopa Park caldera; SLC—San Luis complex; SR—South River caldera.]()
![North-south section depicting inferred variations in mid-Cenozoic crustal thickness from the Platoro caldera north to Mount Princeton batholith in Colorado (USA). Data to 30 km are projected into section. BC—Blue Creek; CP—Cochetopa Park; MA—Mount Aetna. Location of section and other abbreviations are given in Figure 1.]()
![(a) Map of the San Juan volcanic field, Colorado, showing the general area of the present study. The area of previous study by Eberl et al. (1987), on sericite from the Silverton caldera is also noted. Calderas of the western San Juan Mountains include the Ute Creek (U), Lost Lake (L), Uncompahgre (U), San Juan (SJ), Silverton (S), and Lake City (LC) calderas. Calderas from the central and eastern San Juan Mountains include: La Garita (LG), Bachelor (B), Creede (C), South River (SR), Mount Hope (MH), Cochetopa Park (CP), Silverton? (S), Platoro (P), and Bonanza (B). Modified from Lipman et al. (1997) and Lipman and Steven (1976). (b) Map showing location of Red Mountain and deep drill hole.]()
![Map of Southern Rocky Mountain Volcanic Field, showing ignimbrite calderas, major erosional remnants and inferred original extent of mid-Tertiary volcanic cover, caldera-related granitic intrusions, and later sedimentary fill of the Rio Grande rift zone. Arrows indicate trend of late Cretaceous–early Tertiary (Laramide) intrusions of the Colorado Mineral Belt. Calderas: B—Bonanza; Ba—Bachelor; C—Cochetopa Park; Cr—Creede; LGn—La Garita north segment; LGs—La Garita, south segment; MC—Marshall Creek; Pl—Platoro; S—Silverton; SL—San Luis complex; SR—South River. Geographic locality: G—Gunnison. Modified from McIntosh and Chapin (2004); inferred original limit of volcanic rocks modified from Steven, 1975); intrusions from Tweto (1979) and Lipman (1988, 2000).]()
![Generalized maps showing preserved remnants of composite Southern Rocky Mountain volcanic field, modified from McIntosh and Chapin (2004) and Lipman (2007); inferred original limit of volcanic rocks is from Steven (1975); intrusions are from Tweto (1979) and Lipman et al. (2013). (A) Ignimbrite calderas, associated granitic intrusions, inferred original extent of once nearly continuous mid-Tertiary volcanic cover, and later Tertiary sedimentary fill of the Rio Grande rift zone. Calderas and associated intrusions: B—Bachelor; Bz—Bonanza; Cr—Creede; C—Cochetopa Park; GP—Grizzly Peak; LG—La Garita; LGn—La Garita north; LGs—La Garita south; M—Marshall; MP—Mount Princeton–Aetna; NP—North Pass; Pl—Platoro; S—Silverton; SL—San Luis; SR—South River. Arrows indicate trend of Late Cretaceous–Early Tertiary (Laramide) intrusions of the Colorado mineral belt. (B) Ignimbrite calderas and eruption ages, documenting general southward progression and focusing of Oligocene ignimbrite eruptions in central San Juan region at 28–27 Ma. Ages are from Table 1; calderas are color-coded by regional location, as guide to Tables 1–2.]()
![Generalized maps showing preserved remnants of composite Southern Rocky Mountain volcanic field, modified from McIntosh and Chapin (2004) and Lipman (2007); inferred original limit of volcanic rocks is from Steven (1975); intrusions are from Tweto (1979) and Lipman et al. (2013). (A) Ignimbrite calderas, associated granitic intrusions, inferred original extent of once nearly continuous mid-Tertiary volcanic cover, and later Tertiary sedimentary fill of the Rio Grande rift zone. Calderas and associated intrusions: B—Bachelor; Bz—Bonanza; Cr—Creede; C—Cochetopa Park; GP—Grizzly Peak; LG—La Garita; LGn—La Garita north; LGs—La Garita south; M—Marshall; MP—Mount Princeton–Aetna; NP—North Pass; Pl—Platoro; S—Silverton; SL—San Luis; SR—South River. Arrows indicate trend of Late Cretaceous–Early Tertiary (Laramide) intrusions of the Colorado mineral belt. (B) Ignimbrite calderas and eruption ages, documenting general southward progression and focusing of Oligocene ignimbrite eruptions in central San Juan region at 28–27 Ma. Ages are from Table 1; calderas are color-coded by regional location, as guide to Tables 1–2.]()
![Figure 8. Age-compositional comparison of ignimbrite sheets and associated subcaldera intrusions. Intrusions tend to be more mafic than associated tuff, especially when close in age. Ignimbrite sheets that contain large ranges of SiO2 are compositionally zoned, reflecting gradients in source magma chambers. Some late intrusions are highly differentiated granite and rhyolite. Related tuffs and intrusions are connected by dashed lines. Areas of ellipses plotted for intrusions reflect age uncertainties and compositional range, without conveying information on pluton size or dominant composition. Locations of ignimbrite sources are color-coded as on Figure 4. Ignimbrites and related volcanic rocks: AT—Amalia Tuff; BC—Badger Creek Tuff; CL—Crystal Lake Tuff; GP—Gribbles Park Tuff; NC—Needle Creek flow-dome complex; NM—Nelson Mountain Tuff (San Luis caldera complex); SC—Saguache Creek Tuff; SP—Sunshine Peak Tuff; TM—tuff sheets of Treasure Mountain Group (Platoro caldera complex); WM—Wall Mountain Tuff; WP—Wason Park Tuff. Intrusions: A—Antero Granite; CP—Cochetopa Pass dacite porphyry; LG—Lincoln Gulch laccolith; LP—Lucero pluton; MA—Mount Aetna pluton; MM—Moly Mine and associated plutons along south margin of Questa caldera; MP—Mount Princeton granodiorite; MR—Mineral–Rough Creek intrusions of San Luis caldera complex; NCI—Needle Creek intrusive complex; NC—Nellie Creek rhyolite plugs; P—Platoro caldera intrusions; PG—Piedra–Goose Creek intrusions; RH—dominant granodiorite phase of Rio Hondo pluton; RH(gr)—granitic roof rocks of Rio Hondo pluton; RM/PP—Rito del Medio and Pinabete Peak resurgent intrusions of Questa caldera; SL—resurgent intrusions of San Luis caldera complex.]()
![Map of the Southern Rocky Mountain volcanic field (SRMVF) and Rio Grande rift in southern Colorado and northern New Mexico (USA). Large rectangle, location of study area for the Platoro-Dulce dike swarm (Fig. 2); smaller rectangle, Platoro caldera map area (Fig. 3). Also shown are other ignimbrite calderas of the SRMVF, major erosional remnants and inferred original extent of mid-Cenozoic volcanic cover (Steven, 1975), caldera-related granitic intrusions (Tweto, 1979; Lipman, 2007), and later sedimentary fill in asymmetric grabens of the Rio Grande rift. Rift graben asymmetry and boundary-fault geometry reverse from east-dipping in the San Luis Valley segment to west-dipping in the Sawatch Range–upper Arkansas River valley segment to the north. Blue-dashed lines, major bounding faults of asymmetrical rift grabens. Arrows indicate the trend of Late Cretaceous–early Cenozoic (Laramide) intrusions of the Colorado Mineral Belt. Calderas: B—Bachelor; Bz—Bonanza; C—Cochetopa Park; Cr—Creede; GP—Grizzly Peak; LGn—La Garita, north segment; LGs—La Garita, south segment; M—Marshall; MA—Mount Aetna; NP—North Pass; Pl—Platoro; S—Silverton; SL—San Luis complex; SR—South River. Other features: BP—Buffalo Peak; SC—Summer Coon volcano. CO—Colorado; NM—New Mexico. Modified from McIntosh and Chapin (2004). Rge—Range; Mts.—Mountains.]()
![Map of Southern Rocky Mountain volcanic field, showing ignimbrite calderas, major erosional remnants and inferred original extent of mid-Tertiary volcanic cover, caldera-related granitic intrusions, and later sedimentary fill in asymmetric grabens of the Rio Grande rift zone. Graben asymmetry and boundary-fault geometry reverse from east-dipping in the San Luis Valley segment to west-dipping in the Sawatch Range–Upper Arkansas segment to the north. Blue dashed lines, major bounding faults of asymmetrical rift grabens. A diffuse structural-transition boundary lies south and east of the Bonanza area (green dashed line). Arrows indicate trend of Late Cretaceous–early Tertiary (Laramide) intrusions of the Colorado Mineral Belt. Calderas: Bz—Bonanza; B—Bachelor; C—Cochetopa Park; Cr—Creede; GP—Grizzly Peak; LGn—La Garita north segment; LGs—La Garita, south segment; M—Marshall; MA—Mount Aetna; Pl—Platoro; S—Silverton; SL—San Luis complex; SR—South River. Geographic locations: BP—Buffalo Peaks; LO—Lookout Mountain; SK—Summer Coon volcano; SK—Storm King Mountain; WMT—distal Wall Mountain Tuff on High Plains. Location of Figure 2 indicated by rectangle. Modified from McIntosh and Chapin (2004); inferred original limit of volcanic rocks modified from Steven (1975); intrusions from Tweto (1979) and Lipman (1988, 2000).]()
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![Generalized geometric configurations of dikes associated with main Conejos volcanoes and intrusive centers: red—symmetrically radial, blue—sector radial, green—preferential alignment. Dike trends are generalized from Figures 3, 7, 10, 12, 14, 16, 18, and cited publications. Red star symbols—intrusions without exposed dikes; black star symbols—other eruptive centers inferred from thick proximal lava sections. S.T.—Sawatch trend. Volcanoes: BC—Baughman; BL—Blue Creek; BLVC—Biedell-Lime volcanic complex; BA—Barret Creek; CC—Cow Creek; CV—Cimarron; DN—Del Norte; GC—Grays Creek; JC—Jacks Creek; L—Larsen; MT—Matterhorn; NC—Needle Creek; SA—Sargents Mesa; SC—Summer Coon; SK—Sky City; ST—Sawtooth; TV—Tracy volcano. Calderas: B—Bachelor; Bz—Bonanza; C—Cochetopa Park; Cr—Creede; LGn—La Garita, north segment; LGs—La Garita, south segment; M—Marshall; NP—North Pass; Pl—Platoro; S—Silverton; SL—San Luis complex; SR—South River. Figure is modified from Figure 1.]()
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![Relations among regional gravity lows, Middle Tertiary calderas, and associated intrusions of the Southern Rocky Mountain volcanic field (SRMVF). (A) Regional Bouguer gravity map (Behrendt and Bajwa, 1974; volcanic rocks, calderas, and associated intrusions from Lipman, 2007) for central parts of the SRMVF, showing locations of calderas and intrusions. Contour interval = 5 mGal. Two large negative gravity anomalies (blue colors) aligned along the axis of the SRMVF, both much larger than any individual ignimbrite caldera, are interpreted to image subvolcanic batholiths, approximately delimited by the –300 mGal contour (at boundary between green and blue colors). A southern steep-sided, flat-floored, 50 mGal gravity low that trends east-west coincides with most calderas of the San Juan volcanic locus (Plouff and Pakiser, 1972; Drenth et al., 2012). A northern low (Isaacson and Smithson, 1976; Case and Sikora, 1984) encloses earlier calderas of the Sawatch Range trend (Princeton, Aetna, Grizzly Peak) and trends northeast along the Colorado mineral belt (arrows). Most individual calderas have little or no gravity expression, probably because any shallow low-density fill has been largely removed by erosion. Exposed caldera-related intrusions are small, except Mount Princeton, which underlies the inferred source of the 37 Ma Wall Mountain Tuff. Small intrusive cores to many of the early intermediate-composition volcanoes of the San Juan locus (not plotted) lie outside the southern gravity low, as do Oligocene laccolithic intrusions in the West Elk Mountains. The San Juan batholith largely intrudes the northeastern flank of the Colorado Plateau structural block, while the Sawatch Range batholith was emplaced into uplifted crust of the Southern Rocky Mountains. Calderas and associated intrusions: B—Bachelor; Bz—Bonanza; C—Creede; CP—Cochetopa Park; GP—Grizzly Peak; LG—La Garita; LGN—La Garita north; LL—Lost Lakes; M—Marshall; MP—Mount Princeton–Aetna; NP—North Pass; P—Platoro; S—Silverton; SJ—San Juan; SL—San Luis; SR—South River; U—Uncompahgre. (B) Sawatch Range and mid-Tertiary Princeton batholith, the largest exposed mid-Tertiary intrusion in the eastern Cordillera, as viewed from the east toward the western fault-scarp boundary of the Rio Grande rift zone. Exposed granodiorite and quartz monzonite are 2 km thick, from floor of Upper Arkansas Valley (2340 m at Nathrop, Colorado) to summit of Mount Princeton (4327 m). The Princeton batholith is interpreted to underlie the now-eroded caldera source of the 37 Ma Wall Mountain Tuff, the initial large regional ignimbrite erupted from the SRMVF, but interpretation of timing of pluton crystallization in relation to the ignimbrite eruption has been controversial (Zimmerer and McIntosh, 2012a; Mills and Coleman, 2013).]()
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Figure 5. Geometry of the La Garita and Cochetopa Park calderas and associa... Open Access
in Incremental assembly and prolonged consolidation of Cordilleran magma chambers: Evidence from the Southern Rocky Mountain volcanic field
> Geosphere
Published: 01 February 2007
Figure 5. Geometry of the La Garita and Cochetopa Park calderas and associated rocks of the central San Juan caldera cluster. After eruption of the Fish Canyon Tuff at 27.8 Ma, seven additional large ignimbrite eruptions and associated calderas were localized within the La Garita caldera within 0.9
Journal Article
Eruptive and noneruptive calderas, northeastern San Juan Mountains, Colorado: Where did the ignimbrites come from? Available to Purchase
Journal: GSA Bulletin
Publisher: Geological Society of America
Published: 01 July 2008
GSA Bulletin (2008) 120 (7-8): 771–795.
... tuffs vented directly from the adjacent Cochetopa Park caldera, which is morphologically beautifully preserved. Instead, Cochetopa Park subsided passively as the >500 km 3 Nelson Mountain Tuff vented at 26.9 Ma from an “underfit” caldera (youngest of the San Luis complex) 30 km to the SW. Three...
FIGURES
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Oblique view ( Google Earth ), looking north at Cochetopa and North Pass ca... Available to Purchase
in Eruptive and noneruptive calderas, northeastern San Juan Mountains, Colorado: Where did the ignimbrites come from?
> GSA Bulletin
Published: 01 July 2008
Figure 3. Oblique view ( Google Earth ), looking north at Cochetopa and North Pass calderas. The topographic rim of Cochetopa Park caldera (~30 km across) is morphologically well preserved (dashed white lines): along its northwest and north sides, high points on the rim are marked by Sawtooth
Book Chapter
From ignimbrite to batholith, northeastern San Juan Mountains, Colorado: Bonanza, Cochetopa Park, and North Pass calderas Available to Purchase
Series: GSA Field Guide
Publisher: Geological Society of America
Published: 01 January 2013
DOI: 10.1130/2013.0033(14)
EISBN: 9780813756332
... volcanologic problems. The initial part of the guide summarizes results from recently completed mapping and new geochronologic results for the Cochetopa Park and North Pass calderas and associated eruptive deposits ( Lipman and McIntosh, 2008 ; Lipman, 2012 ). The main focus is on the extraordinarily exposed...
Image
Photographs, landslide breccia of Fish Canyon Tuff at west margin of Cochet... Available to Purchase
in Eruptive and noneruptive calderas, northeastern San Juan Mountains, Colorado: Where did the ignimbrites come from?
> GSA Bulletin
Published: 01 July 2008
Figure 14. Photographs, landslide breccia of Fish Canyon Tuff at west margin of Cochetopa Park caldera. (A) Typical exposure of monolithologic angular to rounded clasts, framework supported, with little or no interstitial matrix. Paleomagnetic measurements at this site (NM3036, Table 3 ) show
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Geochronology of the Fish Canyon (Colorado, United States) magmatic system.... Available to Purchase
in Tracking the evolution of large-volume silicic magma reservoirs from assembly to supereruption
> Geology
Published: 01 August 2013
: Caldera map of the Central San Juan caldera cluster showing locations of samples analyzed in this study; inset map (top left) shows location of San Juan volcanic field (SJVF) within the state of Colorado. CPC—Cochetopa Park caldera; SLC—San Luis complex; SR—South River caldera.
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North-south section depicting inferred variations in mid-Cenozoic crustal t... Available to Purchase
in Raising the West: Mid-Cenozoic Colorado-plano related to subvolcanic batholith assembly in the Southern Rocky Mountains (USA)?
> Geology
Published: 03 June 2021
Figure 3. North-south section depicting inferred variations in mid-Cenozoic crustal thickness from the Platoro caldera north to Mount Princeton batholith in Colorado (USA). Data to 30 km are projected into section. BC—Blue Creek; CP—Cochetopa Park; MA—Mount Aetna. Location of section and other
Image
( a ) Map of the San Juan volcanic field, Colorado, showing the general are... Available to Purchase
in Characterization and modeling of illite crystal particles and growth mechanisms in a zoned hydrothermal deposit, Lake City, Colorado
> American Mineralogist
Published: 01 November 2002
Lake (L), Uncompahgre (U), San Juan (SJ), Silverton (S), and Lake City (LC) calderas. Calderas from the central and eastern San Juan Mountains include: La Garita (LG), Bachelor (B), Creede (C), South River (SR), Mount Hope (MH), Cochetopa Park (CP), Silverton? (S), Platoro (P), and Bonanza (B
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Map of Southern Rocky Mountain Volcanic Field, showing ignimbrite calderas,... Available to Purchase
in Eruptive and noneruptive calderas, northeastern San Juan Mountains, Colorado: Where did the ignimbrites come from?
> GSA Bulletin
Published: 01 July 2008
Cretaceous–early Tertiary (Laramide) intrusions of the Colorado Mineral Belt. Calderas: B—Bonanza; Ba—Bachelor; C—Cochetopa Park; Cr—Creede; LGn—La Garita north segment; LGs—La Garita, south segment; MC—Marshall Creek; Pl—Platoro; S—Silverton; SL—San Luis complex; SR—South River. Geographic locality: G
Image
Generalized maps showing preserved remnants of composite Southern Rocky Mou... Open Access
in Ignimbrites to batholiths: Integrating perspectives from geological, geophysical, and geochronological data
> Geosphere
Published: 01 June 2015
) . (A) Ignimbrite calderas, associated granitic intrusions, inferred original extent of once nearly continuous mid-Tertiary volcanic cover, and later Tertiary sedimentary fill of the Rio Grande rift zone. Calderas and associated intrusions: B—Bachelor; Bz—Bonanza; Cr—Creede; C—Cochetopa Park; GP—Grizzly Peak; LG—La
Image
Generalized maps showing preserved remnants of composite Southern Rocky Mou... Open Access
in Ignimbrites to batholiths: Integrating perspectives from geological, geophysical, and geochronological data
> Geosphere
Published: 01 June 2015
) . (A) Ignimbrite calderas, associated granitic intrusions, inferred original extent of once nearly continuous mid-Tertiary volcanic cover, and later Tertiary sedimentary fill of the Rio Grande rift zone. Calderas and associated intrusions: B—Bachelor; Bz—Bonanza; Cr—Creede; C—Cochetopa Park; GP—Grizzly Peak; LG—La
Image
Figure 8. Age-compositional comparison of ignimbrite sheets and associated ... Open Access
in Incremental assembly and prolonged consolidation of Cordilleran magma chambers: Evidence from the Southern Rocky Mountain volcanic field
> Geosphere
Published: 01 February 2007
Tuff; SP—Sunshine Peak Tuff; TM—tuff sheets of Treasure Mountain Group (Platoro caldera complex); WM—Wall Mountain Tuff; WP—Wason Park Tuff. Intrusions: A—Antero Granite; CP—Cochetopa Pass dacite porphyry; LG—Lincoln Gulch laccolith; LP—Lucero pluton; MA—Mount Aetna pluton; MM—Moly Mine and associated
Image
Map of the Southern Rocky Mountain volcanic field (SRMVF) and Rio Grande ri... Open Access
in Magmato-tectonic links: Ignimbrite calderas, regional dike swarms, and the transition from arc to rift in the Southern Rocky Mountains
> Geosphere
Published: 30 September 2019
Cenozoic (Laramide) intrusions of the Colorado Mineral Belt. Calderas: B—Bachelor; Bz—Bonanza; C—Cochetopa Park; Cr—Creede; GP—Grizzly Peak; LGn—La Garita, north segment; LGs—La Garita, south segment; M—Marshall; MA—Mount Aetna; NP—North Pass; Pl—Platoro; S—Silverton; SL—San Luis complex; SR—South River
Image
Map of Southern Rocky Mountain volcanic field, showing ignimbrite calderas,... Open Access
in An ignimbrite caldera from the bottom up: Exhumed floor and fill of the resurgent Bonanza caldera, Southern Rocky Mountain volcanic field, Colorado
> Geosphere
Published: 01 December 2015
of the Bonanza area (green dashed line). Arrows indicate trend of Late Cretaceous–early Tertiary (Laramide) intrusions of the Colorado Mineral Belt. Calderas: Bz—Bonanza; B—Bachelor; C—Cochetopa Park; Cr—Creede; GP—Grizzly Peak; LGn—La Garita north segment; LGs—La Garita, south segment; M—Marshall; MA—Mount
Journal Article
Incremental assembly and prolonged consolidation of Cordilleran magma chambers: Evidence from the Southern Rocky Mountain volcanic field Open Access
Journal: Geosphere
Publisher: Geological Society of America
Published: 01 February 2007
Geosphere (2007) 3 (1): 42–70.
...Figure 5. Geometry of the La Garita and Cochetopa Park calderas and associated rocks of the central San Juan caldera cluster. After eruption of the Fish Canyon Tuff at 27.8 Ma, seven additional large ignimbrite eruptions and associated calderas were localized within the La Garita caldera within 0.9...
FIGURES
Journal Article
An ignimbrite caldera from the bottom up: Exhumed floor and fill of the resurgent Bonanza caldera, Southern Rocky Mountain volcanic field, Colorado Open Access
Journal: Geosphere
Publisher: Geological Society of America
Published: 01 December 2015
Geosphere (2015) 11 (6): 1902–1947.
... of the Bonanza area (green dashed line). Arrows indicate trend of Late Cretaceous–early Tertiary (Laramide) intrusions of the Colorado Mineral Belt. Calderas: Bz—Bonanza; B—Bachelor; C—Cochetopa Park; Cr—Creede; GP—Grizzly Peak; LGn—La Garita north segment; LGs—La Garita, south segment; M—Marshall; MA—Mount...
FIGURES
Includes: Supplemental Content
Image
Generalized geometric configurations of dikes associated with main Conejos ... Open Access
in Precursors to a continental-arc ignimbrite flare-up: Early central volcanoes of the San Juan Mountains, Colorado, USA
> Geosphere
Published: 20 December 2023
—Grays Creek; JC—Jacks Creek; L—Larsen; MT—Matterhorn; NC—Needle Creek; SA—Sargents Mesa; SC—Summer Coon; SK—Sky City; ST—Sawtooth; TV—Tracy volcano. Calderas: B—Bachelor; Bz—Bonanza; C—Cochetopa Park; Cr—Creede; LGn—La Garita, north segment; LGs—La Garita, south segment; M—Marshall; NP—North Pass; Pl
Journal Article
Early incubation and prolonged maturation of large ignimbrite magma bodies: Evidence from the Southern Rocky Mountain volcanic field, Colorado, USA Available to Purchase
Journal: Geology
Publisher: Geological Society of America
Published: 09 May 2022
Geology (2022) 50 (8): 944–948.
... from overlying ignimbrites ( Fig. 3 ; Table S2). The youngest ages from upper Conejos lavas proximal to the caldera and a late intrusion are all several million years older than the Fish Canyon Tuff. Around the north margin of La Garita and the adjacent Cochetopa caldera, where modest early subsidence...
FIGURES
Image
Relations among regional gravity lows, Middle Tertiary calderas, and associ... Open Access
in Ignimbrites to batholiths: Integrating perspectives from geological, geophysical, and geochronological data
> Geosphere
Published: 01 June 2015
and associated intrusions: B—Bachelor; Bz—Bonanza; C—Creede; CP—Cochetopa Park; GP—Grizzly Peak; LG—La Garita; LGN—La Garita north; LL—Lost Lakes; M—Marshall; MP—Mount Princeton–Aetna; NP—North Pass; P—Platoro; S—Silverton; SJ—San Juan; SL—San Luis; SR—South River; U—Uncompahgre. (B) Sawatch Range and mid
Journal Article
Precursors to a continental-arc ignimbrite flare-up: Early central volcanoes of the San Juan Mountains, Colorado, USA Open Access
Journal: Geosphere
Publisher: Geological Society of America
Published: 20 December 2023
Geosphere (2024) 20 (1): 23–73.
...—Grays Creek; JC—Jacks Creek; L—Larsen; MT—Matterhorn; NC—Needle Creek; SA—Sargents Mesa; SC—Summer Coon; SK—Sky City; ST—Sawtooth; TV—Tracy volcano. Calderas: B—Bachelor; Bz—Bonanza; C—Cochetopa Park; Cr—Creede; LGn—La Garita, north segment; LGs—La Garita, south segment; M—Marshall; NP—North Pass; Pl...
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