- Usage in publication:
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- Outlet Tunnel quartz latite*
- Modifications:
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- Original reference
- Dominant lithology:
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- Quartz latite
- AAPG geologic province:
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- San Juan Mountains province
Summary:
Outlet Tunnel quartz latite of Alboroto group of Potosi volcanic series. Is a chaotic aggregate of lava flows and breccia beds. Found in only two small bodies in canyon of East Willow Creek a short distance north of Ridge Mine [in SW/4 sec. 18] and has not been recognized in reconnaisance of adjoining region. Is basal formation of Alboroto group of Potosi volcanic series. Unconformably underlies at least a part of Willow Creek rhyolite. Thickness 250 to 350+ feet. Age is Miocene.
Named from development at Outlet Tunnel [now Outlet Mine], Creede district, southwestern CO. [Outlet Mine in center of N/2 sec. 18, T. 42 N., R. 1 E., San Luis Peak 7.5-min quadrangle, Mineral Co., Creede district, southwestern CO (USGS historical topographic map collection TopoView, accessed February 28, 2013).]
Source: US geologic names lexicon (USGS Bull. 896, p. 1578).
- Usage in publication:
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- Outlet Tunnel Member*
- Modifications:
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- Revised
- AAPG geologic province:
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- San Juan Mountains province
Summary:
Reduced in stratigraphic rank (Outlet Tunnel Quartz Latite of Emmons and Larsen, 1923) to Outlet Tunnel Member, older member of the La Garita Quartz Latite (in this paper). Assigned to the middle and late Tertiary. Formed before the Phoenix Park Member and prior to subsidence of the La Garita cauldron in the San Juan Mountain province.
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
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- Outlet Tunnel Memberâ€
- Modifications:
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- Abandoned
- AAPG geologic province:
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- San Juan Mountains province
Summary:
Pg. A34-A35, A78. Outlet Tunnel Member†of La Garita Tuff. Steven and Ratte's (1964) Outlet Tunnel Member is same as large mass of intracaldera rocks of the La Garita Member (revised) of Fish Canyon Tuff (revised) and is herein abandoned.
Source: Publication.
- Usage in publication:
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- Outlet Tunnel Member*
- Modifications:
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- Age modified
- AAPG geologic province:
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- San Juan Mountains province
Summary:
Outlet Tunnel Member of La Garita Tuff. Age changed from Oligocene --to-- late Oligocene.
Source: Changes in stratigraphic nomenclature, 1974 (USGS Bull. 1405-A, p. A16-A17).
- Usage in publication:
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- Outlet Tunnel unit*
- Modifications:
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- Reinstated
- AAPG geologic province:
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- San Juan Mountains province
Summary:
Reinstated as an informal unit within Carpenter Ridge Tuff. Study is in Creede area, Mineral Co, CO, San Juan Mountain province. Unit now interpreted as landslide and talus breccia, composed of Fish Canyon Tuff, derived during subsidence of Bachelor caldera (in La Garita Mountains). Bachelor caldera was source of Carpenter Ridge. Previous workers have interpreted unit to be part of main mass of intracaldera Fish Canyon in resurgent dome of La Garita caldera and was thought to be part of floor of Bachelor caldera. All previously mapped Fish Canyon for 4 km up East Willow Creek from Outlet Tunnel mine is landslide and talus debris within Bachelor caldera, rather than in-place fill of La Garita caldera. Unit had similar origin as Phoenix Park unit (revised to informal status), though Outlet Tunnel occurs lower in caldera fill. Oligocene age.
Source: GNU records (USGS DDS-6; Denver GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).