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Falmouth Intrusive Suite

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Falmouth Intrusive Suite (Pavlides, 1980). Fine grained to pegmatitic granite, quartz monzonite, granodiorite, and tonalite; consists of dikes, sills and small plutons. Mineralogy: plagioclase + quartz + microcline + biotite + muscovite + hornblende ± garnet + epidote + apatite + titanite + opaque minerals; myrmekite common. The unit has been dated at 300-325 Ma (U-Pb zircon and Rb-Sr whole-rock; Pavlides and others, 1982). These rocks intrude the Ta River Metamorphic Suite (Cta), Falls Run Granite Gneiss (Sf), Holly Corners Gneiss (CZh), Quantico Formation (Oq) and porphyroblastic garnet-biotite gneiss (Ym; Po River Meta mor phic Suite of Pavlides, 1980).
State Virginia
Name Falmouth Intrusive Suite
Geologic age Mississippian - Pennsylvanian
Lithologic constituents
Major
Igneous > Plutonic > Granitic > Granite
Igneous > Plutonic > Granitic > Granodiorite
Igneous > Plutonic > Syenitic > Quartz-monzonite
Minor
Igneous > Plutonic > Granitic > Tonalite
Comments Central Virginia Volcanic-Plutonic Belt, Age update by Karen Hostettler
References

Virginia Division of Mineral Resources, 1993, Geologic Map of Virginia: Virginia Division of Mineral Resources, scale 1:500,000.

Virginia Division of Mineral Resources, 2003, Digital Representation of the 1993 Geologic Map of Virginia, Publication 174, CD ROM (ISO-9660) contains image file, expanded explanation in pdf, and ESRI shapefiles, scale 1:500,000.
NGMDB product
Counties Louisa - Spotsylvania - Stafford - Fredericksburg