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Topo

Rock Formations

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Biotite Granodiorite and Biotite Granite (VAZgd;0)

Geologic Formation in VA

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Lithology

Granite

Granodiorite

Aplite

Other (84 mi²)

Geologic Age

Neoproterozoic (1000 Ma – 542 Ma ago)

Geologic Unit Label

Zgd

Leucocratic to mesocratic, medium-grained, equigranular, vaguely foliated, epidote-, garnet-, fluorite- and/or allanite-bearing, two-feldspar muscovite-biotite granodiorite to granite; salt-and-pepper appearance is characteristic; associated aplite and pegmatite dikes common. Geophysical signature: weak positive radiometric anomaly. The plutons of this suite are widespread in the southeastern portion of the basement complex, and are correlated with Rockfish River, Mobley Mountain, Striped Rock plutons, and with Robertson River Igneous Suite.

— USGS

Taxonomy

Classified As

Geologic Formation