- Usage in publication:
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- Laurel Mills Granite
- Modifications:
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- First used
- Dominant lithology:
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- Granite
- AAPG geologic province:
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- Piedmont-Blue Ridge province
Summary:
Tollo and Arav (in press) propose that Robertson River Formation of Allen (1963) be revised as Robertson River Igneous Suite to emphasize the lithologic diversity that characterizes this belt. Rocks range in composition from alkali syenite to alkali feldspar granite to granite. This suite is the largest group of intrusives within the Blue Ridge province of VA. Extends from near Upperville, 70 mi southwest to northern suburbs of Charlottesville. Includes at least nine mappable lithologic units, among them, Laurel Mills Granite (new name). Rocks of the Laurel Mills are locally exposed along the western edge of both segments of the Robertson River outcrop belt. Characterized by prominent calcic amphibole. At petrochemical type locality, in contact with Arrington Mountain Alkali Feldspar Granite (new name) to the south and with the Amissville Alkali Feldspar Granite (new name) and Battle Mountain Complex (new name) to the east. Intruded by the Cobbler Mountain Alkali Feldspar Quartz Syenite (new name) in the northern segment of the Robertson River outcrop belt.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- Laurel Mills Granite*
- Modifications:
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- Named
- Dominant lithology:
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- Granite
- AAPG geologic province:
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- Piedmont-Blue Ridge province
Summary:
Named as part of Robertson River Igneous Suite (revised). Named for town of Laurel Mills. Type locality is roadcut on VA Hwy 618, approx 1.4 km (0.9 mi) south-southwest of Laurel Mills, Massies Corner 7.5-min quad. Consists of gray, ubiquitously coarse-grained, amphibole-bearing granite displaying abundant, outcrop-scale shear zones. Contact with Middle Proterozoic basement gneiss along western border of outcrop belt is both fault-bounded and intrusional. Intruded by felsite dikes of Battle Mountain Alkali Feldspar Granite (new), and by dikes of Amissville Alkali Feldspar Granite (new), Cobbler Mountain Alkali Feldspar Quartz Syenite (new), and Hitt Mountain Alkali Feldspar Syenite. Age is Late Proterozoic. Report includes geologic map.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
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- Laurel Mills Granite*
- Modifications:
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- Geochronologic dating
- AAPG geologic province:
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- Piedmont-Blue Ridge province
Summary:
U-Pb zircon age for Laurel Mills Granite of Robertson River Igneous Suite is 729+/-1 Ma.
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 ([ ]).