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

Assembly of Pangea: variations in amalgamation styles along the Laurussia–Gondwana collision zone

Paper number: 1-1
Program: Technical Sessions
Time: 8:05 AM – 8:25 AM

Authors

Abstract

Assembly of Pangea as a result of the late Paleozoic convergence and collision between Laurussia and Gondwana occurred along the Alleghanian–Mauritanide–Variscan orogen. The orogen can be divided into two general geodynamic domains. In the northeast, the European Variscan belt records multiple subduction–collisional tectonic events between ~380 Ma and ~290 Ma, including indentation by Laurussian and later Gondwanan promontories and by Gondwana-derived terranes. Oroclines formed and extension initiated late during this period. In the southwest, the southern Appalachians of eastern North America and Mauritanides of West Africa were dominated by northwest- and southeast-verging thrust belts, respectively. Subduction of the Rheic ocean between them was probably to the northwest below Laurentia, based on the location of arc-magmatic rocks in North America.

The boundary between the northeastern and southwestern domains may be in southern New England, along the boundary between the southern and northern Appalachians in North America, and between the Meseta and Anti-Atlas domains in Morocco. In the southern Appalachians, the effects of the Alleghanian orogeny, including deformation, metamorphism and plutonism, are widespread. In the northern Appalachians, the effects are mostly restricted to reactivation of pre-existing shear zones and minor plutonic rocks. In the Anti-Atlas domain, south of the South Meseta (transform) Fault, the effects of the Variscan orogeny are minor compared to those in the Meseta domain north of the fault, although the Mauritanides south of the Oulad Dlim Massif in southern Morocco do show evidence for the Variscan orogeny. In the Meseta domain north of the South Meseta Fault, the effects of the Variscan orogeny, including deformation, metamorphism and plutonism are widespread. The Meseta domain was separated from European parts of the Variscan orogen by a promontory formed by the Avalonian and/or Megumian terranes. To the north of that, the Variscan orogeny in Europe was dominated by oroclines and opening and closing of ephemeral oceans, for which there are no equivalents elsewhere along the Alleghanian–Mauritanide–Variscan orogen. Our analysis may provide a basis for future work on the orogen at large, using geological and geodynamic data.

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

doi: 10.1130/abs/2026NE-411327

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