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
Metamorphic > Gneissquartzose-feldspathic gneiss
Metamorphic > Schist > Mica-schist > Biotite-schist
Metamorphic > Granoblastic > Granofels
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.

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.

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