- Usage in publication:
-
- Lunga Reservoir Formation*
- Modifications:
-
- Named
- Dominant lithology:
-
- Diamict
- AAPG geologic province:
-
- Piedmont-Blue Ridge province
Summary:
A block-in-metadiamictite melange in north-central VA is here named the Lunga Reservoir Formation, for Lunga Reservoir, Stafford Co. It consists of a nonstratified, micaceous quartzofeldspathic (metadiamictite) matrix with embedded clasts of metasedimentary and meta-igneous rocks ranging in size from granule to boulder and larger. Clasts include quartz (distinctive) and garnetiferous mica schist in the southern part, and mafic and ultramafic rocks in the northern part. Melange formed in a Cambrian-Ordovician back-arc basin or marginal basin that lay on the continentward side of an island arc system (Central Virginia Volcanic-Plutonic Belt) that had formed in Cambrian time. Diamictite was thrust on and across basement rocks during the Taconic Orogeny.
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 ([ ]).