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

Tectonic Boundaries and Terrane Relations in the Western Bay of Fundy (Canada) and Adjacent Gulf of Maine (USA)

Paper number: 1-4
Program: Technical Sessions
Time: 9:05 AM – 9:25 AM

Authors

Abstract

The New River, Kingston, Brookville, and Caledonia terranes of southern New Brunswick and the Cobequid Highlands and Meguma terranes of Nova Scotia converge in the western part of the Bay of Fundy and their continuations into the Gulf of Maine are uncertain. Geological relationships are complicated not only by the complex Paleozoic history of transpressional and transtensional terrane accretion, but also by subsequent Mesozoic extension which led to the opening of the North Atlantic Ocean. The location and nature of boundaries among Early Paleozoic and older crustal fragments is challenging to interpret onshore and even more so offshore where such interpretations rely on geophysical data with few direct constraints on the nature of the bedrock.

Grand Manan and offshore islands and ledges to the south and west play a crucial role in providing geological constraints. Rock types and ages suggest linkages to the New River and Brookville terranes. Similarities in U-Pb zircon patterns obtained from quartzite and conglomerate units on Grand Manan Island and offshore islands to the south, in the New River belt on the mainland, and Hutchins Island in Penobscot Bay (Maine) provide evidence for linkages in sediment provenance among these now widely separated areas of Ganderia.

The Meguma terrane was thrust over southern New Brunswick during Carboniferous accretion and subsequently slid back during Mesozoic extension producing the Fundy Basin and Grand Manan Sub-basin which were sites of sediment deposition and basalt eruption. The Headlands normal fault system follows the New Brunswick coastline and juxtaposes Mesozoic rocks of the Fundy Basin against varied terranes and terrane-bounding faults of southern New Brunswick. The leading edge of the Meguma terrane is in the subsurface under the Fundy Basin and hence Mesozoic rocks in the southwestern Fundy Basin overlie Ganderian rocks. They are truncated on the west by the Grand Manan Fault along the eastern edge of Paleozoic and Precambrian rocks of the Brookville and New River terranes which underlie eastern Grand Manan and adjacent offshore areas. Brookville terrane rocks on The Wolves Islands lie west of the Grand Manan Fault and continue to Grand Manan Island. South of Grand Manan Island, the Fundy Fault separates Ganderia from Avalonia. The more outboard Avalonia-Meguma terrane boundary is southeast of the Fundy Fault.  

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411186

© Copyright 2026 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.