Fitchburg Complex

Dfgd containing many zones of foliated biotite-muscovite granite gneiss and inclusions of mica schist and feldspathic granulite.
State Massachusetts
Name Fitchburg Complex
Geologic age Lower Devonian or younger
Lithologic constituents
Major
Metamorphic > GneissDfgd containing many zones of foliated biotite-muscovite granite gneiss
Incidental
Metamorphic > Schist > Mica-schistDfgd and inclusions of mica schist
Metamorphic > GranuliteDfgd and inclusions of feldspathic granulite
Comments Part of Merrimack Belt (Silurian, Devonian and Pennsylvanian Rocks). Secondary unit description per MA007 as reported in USGS Geologic Names lexicon (ref. MA024): Fitchburg Complex mapped as three small stocks intruding Worcester Formation east of Wekepeke fault and west of Clinton. Also intrudes Paxton and Littleton Formations. U-Pb zircon age of 390 +/-15 Ma and Rb-Sr whole-rock age of 402 +/-11 Ma were both reported by Zartman and Naylor (1984) (Wones and Goldsmith, 1991).
References
NGMDB product
Counties Middlesex - Worcester