Tectonic Evolution of Appalachians and Associated Terranes

The Appalachian orogen records a complex history of microcontinental drift, ocean basin closure and continental collision along the eastern margin of Laurentia from the Neoproterozoic through the Permian. Peri-Gondwanan terranes such as Avalonia, Meguma and Ganderia rifted from Gondwana and traversed the Iapetus and Rheic oceans before docking against Laurentia during successive orogenic events. The Taconic orogeny initiated closing of the Iapetus Ocean in the Ordovician, producing forearc and island-arc complexes. Continued convergence in the Devonian drove the Acadian orogeny, marked by high-grade metamorphism, terrane accretion and collisional magmatism. Late Devonian to Early Carboniferous strike-slip reactivation and basin opening accompanied partitioning of strain, while the Alleghanian orogeny in the Late Carboniferous to Permian welded together Gondwanan and Laurentian fragments to form Pangea. Throughout this evolution, magmatic arcs, back-arc basins and metamorphic belts imprinted characteristic lithologies and structures that now define the crustal architecture of eastern North America. This long-lived, multi-phase orogenesis has global significance as a natural laboratory for understanding terrane accretion, crustal growth and the controls on mineralisation in convergent settings.

Research from Nature Portfolio

Recent studies of detrital zircon populations in metasedimentary granulites reveal that Avalonia and the Meguma terrane remained contiguous throughout their transit from Gondwana into the Rheic realm. High-precision U–Pb ages between Cryogenian and Late Silurian, combined with three distinct metamorphic pulses at ca. 399 Ma, 377 Ma and 354 Ma, demonstrate synchronous granulite-facies metamorphism during early Acadian collision and subsequent syn- and post-collisional events. These findings constrain the timing of terrane coupling and highlight a prolonged orogenic maturation preceding final docking onto Laurentia.

Tectonic Evolution of Appalachians and Associated Terranes publication trend

The graph below shows the total number of articles in tectonic evolution of appalachians and associated terranes across all publications each year (not limited to Nature Index journals).

Technical terms

Terrane: A crustal fragment with a distinct geological history that becomes joined to a continental margin.

Orogeny: A mountain-building episode driven by lithospheric plate convergence and deformation.

Accretion: The addition of material or terranes to a continental edge through tectonic collision.

Subduction: The process by which one tectonic plate descends beneath another into the mantle at a convergent boundary.

Back-arc extensional setting: A zone of crustal stretching located landward of a volcanic arc, often induced by slab rollback.

Zircon U–Pb geochronology: A radiometric dating technique using uranium-lead decay in zircon to determine crystallisation ages precisely.

References

1. The age and origin of the South Mountain Batholith (Nova Scotia, Canada) as constrained by zircon U–Pb geochronology, geochemistry, and O–Hf isotopes. Canadian Journal of Earth Sciences (2022).
2. Long-lived association between Avalonia and the Meguma terrane deduced from zircon geochronology of metasedimentary granulites. Scientific Reports (2019).
3. Evolution of Subduction Dynamics beneath West Avalonia in Middle to Late Ordovician Times. Lithosphere (2020).
4. Geological interpretation of wide-angle seismic reflection/refraction profiles along the Scotian margin and across Nova Scotia, Canada. Tectonophysics (2024).