20 Mesozoic Magmatism, Postrift Tectonics, and Passive Margin Development of Northeastern North America

The northeastern region experienced protracted Mesozoic (Triassic-Cretaceous) magmatism associated with continental rifting and subsequent passive margin development. We welcome contributions related to the occurrence, tectonics, or driving mechanisms of these syn- and postrift events.

Monday, 23 March 2026
8:00 AM - 12:00 PM
CCC, Room 27

New Constraints on the Structure and Evolution of the Northern Appalachian Anomaly, New England, USA

Paper number: 20-10
Program: Technical Sessions
Time: 11:00 AM – 11:20 AM

Authors

Abstract

The Northern Appalachian Anomaly (NAA) is an enigmatic low velocity anomaly in the asthenospheric upper mantle centered beneath New England, USA. Given its prominence and its co-location with post-rifting volcanism in New England, it represents a prime opportunity to study processes associated with passive margin evolution. The age, origin, and evolution of the NAA have been debated, with a suite of models being proposed that variously invoke one or more deep mantle plumes (particularly the passage of the Great Meteor Hotspot), small-scale or edge-driven convection, recent to ongoing upper mantle upwelling, lithospheric foundering and/or thinning, or some combination of these processes. The recent deployment of dense broadband seismic arrays in New England, including the NEST, GENESIS, and SEISConn experiments, have enabled new high-resolution imaging of the NAA and its possible effects on mantle flow and on the structure of the lithosphere above it. Here we synthesize a suite of recent results that constrain the origin and evolution of the NAA, including receiver-function based imaging of the lithosphere-asthenosphere boundary above the anomaly, high-resolution finite-frequency P wave tomography of the upper mantle, and scattered wave migration imaging of the mantle transition zone discontinuities beneath New England. Taken together, this suite of results yield new insights into the dimensions, characteristics, and origin of the NAA. Furthermore, detailed study of unusual upper mantle features such as the NAA have the potential to shed new light on fundamental processes that are important for the evolution of passive continental margins.

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

doi: 10.1130/abs/2026NE-411338

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