Sharpners Pond Diorite

Non-foliated, medium-grained equigranular biotite-hornblende tonalite and diorite. Intrudes Soagr, OZn, OZf.
State Massachusetts
Name Sharpners Pond Diorite
Geologic age Silurian
Lithologic constituents
Major
Igneous > Plutonic > Granitic > TonaliteNon-foliated, medium-grained equigranular biotite-hornblende tonalite and diorite.
Igneous > Plutonic > Dioritic > DioriteNon-foliated, medium-grained equigranular biotite-hornblende tonalite and diorite.
Comments Part of Nashoba Zone (Silurian and Older Rocks). Sharpners Pond Diorite covers an area of about 150 sq km. Includes diorite, tonalite, and small amounts of granodiorite. Intrudes Nashoba and Marlboro Formations, and older gneissic phase of Andover Granite. Intruded by pegmatites, younger phase of Andover Granite, and biotite granite. Age is Silurian based on reliable U-Pb zircon date of 430 +/-5 Ma (Zartman and Naylor, 1984) (Wones and Goldsmith, 1991) per MA007.
References
NGMDB product
Counties Essex - Middlesex