Massabesic Gneiss Complex

Quartzose-feldspathic gneiss and biotite schists (locally rusty), granofels, and cal-silicate rocks closely intruded by, and grading into, a pink gneissic granite (623 Ma) that produced a migmatite.
State New Hampshire
Name Massabesic Gneiss Complex
Geologic age Late Proterozoic
Lithologic constituents
Major
Metamorphic > Gneissquartzose-feldspathic gneiss
Metamorphic > Schist > Mica-schist > Biotite-schist
Metamorphic > Granoblastic > Granofels
Minor
Metamorphic > Metasedimentary > Calc-silicate-rock
Igneous > Plutonic > Granitic > Granitea pink gneissic granite
Metamorphic > Migmatite
Comments Part of the Nashoba-Casco-Miramichi Terrane (Merrimack Trough). Map page 2: Massabesic Gneiss Complex: 620-600 U/Pb, orthogneiss(?) per NH039. 646+/-? U/Pb, paragneiss, 475+/-? U/Pb, orthogneiss per NH038. 641+/-25 Rb/Sr, paragneiss(?) per NH040. 375+/-? U/Pb, monazite from aplite dike in Campbell Hill fault at western contact of Massabesic Gneiss per Barbara Barriero, oral commun., 1990. 384+/-2 and 275+/-2 U/Pb, monazite in paragneiss per J.N. Aleinikoff, oral commun., April 1993. 623+/-8 U/Pb ion probe, orthogneiss; earlier age of 475 (NH038) discredited per J.N. Aleinikoff, oral commun., Feb. 1994.
References

Lyons, J.B., Bothner, W.A., Moench, R.H., and Thompson, J.B., Jr., 1997, Bedrock Geologic Map of New Hampshire: Reston, VA, U.S. Geological Survey Special Map, 2 sheets, scale 1:250,000.

https://ngmdb.usgs.gov/Prodesc/proddesc_37338.htm

Aleinikoff, J.N., Zartman, R.E., and Lyons, J.B., 1979, U-Th-Pb geochronology of the Massabesic Gneiss and the granite near Milford, south-central New Hampshire; new evidence for Avalonian basement and Taconic and Alleghenian disturbances in eastern New England: Contributions to Mineralogy and Petrology, v. 71, p. 1-11.

Besancon, J.R., Gaudette, H.R., and Naylor, R.S., 1977, Age of the Massebesic Gneiss, southern New Hampshire [abs.]: Geological Society of America Abstracts with Programs, v. 9, p. 24.

Kelly, W.J., Olszewski, W.J., and Gaudette, H.E., 1980, The Massabesic orthogneiss, southern New Hamshire [abs.]: Geological Society of America Abstracts with Programs, v. 12, p. 45.

NGMDB product
Counties Hillsborough - Merrimack - Rockingham