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[Display omitted] • Ganderia's provenance in Amazonia. • Cambrian rifting and scissor-like opening of Rheic Ocean in Penobscot backarc region. • Complex Cambrian to Tremadocian interaction with East Avalonia along the margin of West Gondwana. • Diachronous accretion to Laurentia over time span of ca. 50 my. • Tectonic elements show marked non-cylindricity. West and East Ganderia in the northern Appalachians and Caledonides, respectively, represent a Gondwanan superterrane situated along the Tornquist margin of Amazonia prior to Furongian drift into the Iapetus Ocean, which opened the Rheic Ocean from west to east. The ocean-facing Penobscot arc-backarc system was established by 515 Ma in West Ganderia. A correlative arc formed at ca. 480 Ma in East Ganderia. In West Ganderia, the Tremadocian Penobscottian orogeny involved closure of the Penobscot backarc basin. Tremadocian Monian tectonism in East Ganderia was mainly related to oblique accretion to East Avalonia and the Megumian Cymru terrane. Penobscottian and late Floian Monian orogenesis led to termination of Early Ordovician arc magmatism, probably due to shallow subduction of buoyant oceanic lithosphere. Early to Middle Ordovician arc-backarc systems were erected on Penobscottian-Monian modified West and East Ganderia. The active edge of West Ganderia accreted diachronously to peri -Laurentia between 475 Ma and 455 Ma, followed by Wenlock to Ludlow Salinic accretion of the inboard Gander margin through closure of the intervening backarc basin. In the Caledonides, East Ganderia and East Avalonia accreted to Laurentia during the correlative Wenlock Scandian orogeny. The Ordovician to Silurian tectonic evolution of Ganderia was markedly non-cylindrical with pronounced partitioning of Salinic-Scandian convergence. Pridoli to Lochkovian closure of the Acadian seaway in the northern Appalachians led to Acadian accretion of West Avalonia to composite Laurentia. Shallow Early Devonian underthrusting of West and East Avalonia beneath Laurentia produced widespread Acadian tectonism and voluminous Early Devonian Acadian magmatism. The Appalachian Meguma terrane formed part of Megumia, which probably formed originally adjacent to East Avalonia and West Africa. The Meguma terrane accreted dextrally to Laurentia during and after the late Emsian to Famennian Neoacadian orogeny, mainly driven by outboard subduction of the Rheic Ocean. No correlative terrane docking took place in the Caledonides. [ABSTRACT FROM AUTHOR]

Inliers of late Neoproterozoic basement rocks exposed in southern Great Britain, described in summary herein, have been previously attributed to a series of terranes bounded by major crustal lineaments that form a dissected remnant of a single subduction complex. Together these terranes have been termed East Avalonia and interpreted as correlative with West Avalonia of the northern Appalachian Orogen. A review of age and Nd- and O-isotopic data shows an essentially ensialic complex with two broad overlapping divisions: (1) the Monian Composite Terrane of NW Wales and Fenland Terrane of eastern England that are characterised by felsic intrusions at around 615 Ma and have more evolved εNd(t) (− 7.5 to − 2.5), older T DM (1868 Ma to 1269 Ma) and generally more elevated δ 18 O (up to + 13.7‰); and (2) a more diverse assemblage represented by the Cymru, Wrekin and Charnwood terranes, including more substantive volcano-sedimentary successions and intrusions ranging in age between around 710 Ma and 566 Ma (in which 615 Ma magmatic rocks are not represented), less evolved εNd (t) (− 2.5 to + 3.5), younger T DM (1501–994 Ma) and lower δ 18 O (+ 6.5‰ to + 10.1‰). Comparison with other Neoproterozoic basement units throughout the northern Appalachian Orogen shows that both divisions from southern Great Britain have closer isotopic affinity with igneous components of Ganderia, which generally have evolved compositions interpreted to reflect an ensialic setting and the input of Gondwanan cratonic source components. They are mostly dissimilar from magmatic rocks of West Avalonia, which typically have less evolved compositions interpreted to reflect the contribution of juvenile Mesoproterozoic source components. [ABSTRACT FROM AUTHOR]