- Usage in publication:
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- Blackwater Creek Rhyolite Member*
- Modifications:
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- Named
- Dominant lithology:
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- Rhyolite
- AAPG geologic province:
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- Piedmont-Blue Ridge province
Summary:
Named as a member of Mechum River Formation. Named for Blackwater Creek, a nearby feature. Occurs in an area 3.6 km (2.2 mi) long between Castleton Mountain and Blackwater Creek, Castleton 7.5-min quad, Rappahannock Co., central VA. Consists of white, aphanitic rhyolite similar in composition to felsite of Battle Mountain Alkali Feldspar Granite (new). Occurs intercalated with metasedimentary rocks (including pale-green phyllite, meta-arkose, and metaconglomerate) assigned to Mechum River Formation. Encompasses at least three discontinuous layers within Mechum River. Total thickness is 100 m (328 ft). Metaconglomerate stratigraphically overlying rhyolite layers typically contain clasts of lithologically identical rhyolite, thus indicating that contacts are unconformable. Probably derived from Battle Mountain volcanic center (informal name) located north of Battle Mountain type locality 8.0 km (5.1. mi) to the northeast. Age is Late Proterozoic. Report includes geologic map.
Source: GNU records (USGS DDS-6; Reston 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 ([ ]).