New England Peri-Gondwanan Arc Systems

Region East, Northeast
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Polygons originally extracted from Hibbard and others (2006). Modified polygons by extracting Ammonoosuc Volcanic rock polygons from Lyons and others (1997), buffering to 3 km, then trimming the polygon of barren areas according to MRDS data. Additional data come from volcanic arc-hosted deposits in the United States that occur on strike with the Bathurst mining district in New Brunswick (Mosier and others, 2009).
Identified resources Identified resources for arsenic, copper, gold, silver, and zinc from Bald Mountain deposit.
Production Unknown.
Status Past exploration, current exploration. Bald Mountain, Mt. Chase, Alder Pond, Ledge Ridge, Milan, Ore Hill, and Croydon (Mosier and others, 2009).
Estimated resources Estimated resources for Bald Mountain deposit (2004, in situ, total hypogene): 29,980,000 mt ore with 1.03% Cu, 0.51 g/mt Au, 14.4 g/mt Ag, 1.12% Zn, 0.42% As (Slack and others, 2003). Total resources for Pickett Mountain (Mt. Chase) as of 11/17/2021: 6,317,600 metric tons at 9.12% Zn. 3.83% Pb, 1.15% Cu, 101.9 g/t Ag, and 0.740 g/t Au (Wolfden Resources Corp., 2021).
Geologic maps Osberg and others (1985), scale 1:500,000; Moench and others (1995), scale 1:250,000; Boudette (1991), scale 1:62,500; Pollock (2020), scale 1:24,000; Wang (2018, 2019, 2021a, b), scale 1:24,000; Ludman (2020), scale 1:24,000; Thompson (2008a, b, 2016a, b, c), scale 1:24,000; Walsh and others (2020), scale 1:24,000.
Geophysical data Inadequate Rank 5 aeromagnetic and aeroradiometric coverage for most of the area; Munsungun area in Maine covered by current (2021) airborne geophysical survey.
Favorable rocks and structures Mafic and felsic volcanic rocks and associated sedimentary rocks. The Bald Mountain Cu-Zn-Au-Ag deposit occurs in marine metavolcanic rocks of the Ordovician Winterville Formation. Deposits are a part of the Ordovician Bronson Hill-Popelogan arc (see van Staal and others, 2016). The Pickett Mountain (Mt. Chase) deposit is hosted in Ordovician volcanic rocks (Dry Wall and Stacyville Volcanics) on the southeast limb of the Weeksboto-Lunksoos Lake Anticlinorium (Bakker and others, 2019).
Deposits Maine: Bald Mountain (MRDS dep_id: 10084601), Alder Pond (MRDS dep_id: 10307224), Ledge Ridge (MRDS dep_id: 10084507), Mount Chase (MRDS dep_id: 10048799); New Hampshire: Milan mine (MRDS dep_id: 10106478), Ore Hill (MRDS dep_id: 10150564), Croydon-Corbin Park (MRDS dep_id: 10081605).
Evidence from mineral occurrences MRDS; Mosier and others (2009); Stephens and others (1984).
Geochemical evidence Ayuso and others (2003), Slack and others (2003), Foley (2003).
Geophysical evidence The area in Maine has an ongoing Earth MRI airborne geophysical survey (see Comments column).
Evidence from other sources Unknown.
Comments A Phase 2 Earth MRI-funded airborne geophysical survey is underway, as of May 2021, around the Bald Mountain deposit in an area known as the Munsungun inlier. See the USGS press release here:
Cover thickness and description Glacial till covers perhaps 90% of area.
Authors Gregory J. Walsh, Fred M. Beck.
New data needs High resolution airborne mag and radiometric surveys to support detailed geologic mapping.
Geologic mapping and modeling needs Some detailed geologic mapping completed in the Munsungun area; other areas need detailed mapping.
Geophysical survey and modeling needs High resolution aeromagnetic and aeroradiometric coverage underway for the Munsungun portion in northern Maine.
Digital elevation data needs Lidar complete.