Supercontinents, Orogenesis and Magmatism
CONTAINS OPEN ACCESS

A tribute to the career of J. Brendan Murphy, this volume covers topics that encompass the three main fields of his influence: (i) supercontinents and the supercontinent cycle; (ii) orogenesis and terranes; and (iii) magmatism and magmatic processes. Papers range from strongly field-based studies to conceptual analyses, and focus on clarifying some crucial geological processes.
Late Devonian syntaxis in the Northern Appalachian orogen Available to Purchase
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Published:April 22, 2024
Abstract
The pre-accretionary shapes of cratonic margins form successions of promontories and re-entrants inherited from the rifting of supercontinents. In accretionary orogens, the extent of deformation related to a collision with a continent characterized by an irregular margin is obfuscated through the partitioning of deformation along pre-existing structures. In the Northern Appalachians, the extent of the deformation related to the oblique collision of the Meguma terrane with the composite Laurentian margin is disputed. Herein, we use a framework based on modern collisional settings to investigate the Late Devonian to Mississippian deformation inboard of the Avalonia–Meguma boundary and evaluate the regional tectonic setting. We combine published shear zone kinematic interpretations, deformation ages and regional 40Ar/39Ar cooling ages with structural interpretation of aeromagnetic and gravimetric depth slices covering the Northern Appalachians. We find that the deformation related to the collision of the Meguma terrane, attributed to the Neoacadian orogeny, has a larger structural footprint than previously documented. While this deformation is partitioned in multiple structures in the Canadian Appalachians, northern New England is characterized by rapid crustal deformation, high palaeoelevation and fast erosional exhumation, similar to modern syntaxis structures.