1 New advances in geological and geophysical research on the Appalachian orogen.
We invite contributions that discuss new research on the Appalachian orogen. Submissions should include, but are not limited to, geological or geophysical studies or works comprising a combination of both methods.
Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Room 22/23
Reflections on the Stratigraphy and Structure of the Frederiction Belt in South - Central and Central Maine
Paper number: 1-9
Program: Technical Sessions
Time: 10:40 AM – 11:00 AM
Authors
Abstract
The stratigraphic succession between the Bucksport and Appleton Ridge formations has been debated and changed over time. A fall 2025 visit to the exposed contact between the two units by independent parties confirmed the succession shown in one earlier map of the Belfast 15’ quadrangle and the current 7.5’ map of the Belfast quadrangle. The correct upward stratigraphic succession is confidently understood to be Bucksport Formation underlying Appleton Ridge Formation which in turn underlies Ghent Phyllite. The two upper units are not present northeast of the Mt Waldo pluton. In south central Maine the Bucksport is divided into two members a lower biotite granofels and schist and an upper medium to thickly layered granofels with thin bedding parallel layers of calcsilicate. These formations constitute a belt of southeast younging rocks assigned to a tectono-stratigraphic unit commonly referred to as Fredericton belt or Fredericton trough.
Long distant correlations with rocks in eastern Maine and New Brunswick using the incorrect Appleton Ridge underlying Bucksport succession need re-evaluation along with rethinking reported detrital zircon data.
Fredericton belt rocks are bounded by significant faults. The Sennebec Pond Fault separates the Fredericton trough from the St Croix belt on the southeast. In south central Maine the Liberty – Orrington Fault separates the Fredericton belt from migmatite and migmatite – like rocks assigned to the Passagassawakeag Gneiss on the northwest. The Liberty – Orrington Fault changes character along strike ranging from striped gneiss to ultramylonite with pseudotachylte injections. It is folded in the northeast. The fault changes from a northeast to a northwest trend where it terminates against the Ray Corner Mylonite. In central Maine the Ray Corner Mylonite separates the Fredericton Belt from rocks currently thought to belong to the Casco Bay Group.
Geological Society of America Abstracts with Programs. Vol. 58, No. 2
doi: 10.1130/abs/2026NE-411420
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