Greater Avalonia—latest Ediacaran–Ordovician “peribaltic” terrane bounded by continental margin prisms (“Ganderia,” Harlech Dome, Meguma): Review, tectonic implications, and paleogeography

U-Pb zircon dates from North American and British Avalonia bracket the Lower–Middle Cambrian boundary interval, with evaluation of the Miaolingian Series as a global unit

“…The Avalon zone is bounded by fault-juxtaposed, coeval marine successions to the SE (Meguma zone, now brought to Avalonia) and what is regarded as a problematical ‘Gander Zone’ to the NW that corresponds to the traditional Appalachian ‘central mobile belt’ (e.g. review and references in Landing et al 2022; Landing et al 2023; Landing & Geyer, 2023; Landing et al 2023). Two differing syntheses of early Avalonian evolution exist.…”

“…Murphy et al 2018, and references therein). The ‘Peribaltic synthesis’ uses the terminal Ediacaran–Cambrian cover sequence that unconformably overlies a collage of Proterozoic blocks to define the Avalonia terrane and microcontinent (Landing et al 2022; Landing et al 2023). The Avalonian basement may have formed close to Baltica by accumulation of crustal and oceanic fragments along the Avalonian transform fault (Atf).…”

“…West–east cross-section of terminal Ediacaran–Lower Ordovician trans-Avalonian depositional sequences from Burin Peninsula (marginal platform) and east–west through Trinity–Conception bays (inner platform). Stratigraphy from Landing (1996; also Landing et al 2017, 2022). Lowest occurrence (LO) of trilobites in Avalonia (Landing et al 2013) and Siberia and Morocco (Landing et al 2021).…”

“…The cover sequence in SE Newfoundland and elsewhere in Avalonia is dominated by siliciclastic-dominated, limestone-poor, temperate latitude, shallow marine sedimentary rocks of the ‘Avalon Platform’ of Rast, O’Brien and Wardle (1976; see Landing et al 2022; Landing et al 2023). Cover sequence deposition was controlled by terminal Edicaran–Ordovician syndepositional faulting along the Avalon transform fault (Atf) (Landing, 1996; Landing et al 2022; Landing et al 2023). Activity on the Atf produced NNE-striking faults (modern coordinates) and elongated NNE-striking basins and uplifts in a transtensional regime that was not a ‘rift environment’ ( contra Álvaro, 2021; Álvaro et al 2022).…”

“…In addition, the production of coeval, minor, extensional and compressive igneous rocks including subaerial flows and tuffs in Avalonian sedimentary rocks (Figs. 3–6; Supplementary Appendix ) has analogues in other transform fault settings as along the North Anatolian fault (Landing et al 2022, In press). Volcanogenic sandstones, tuffs, local volcanic edifices and intrusives common in the lower and upper parts of an Ads (Landing et al .…”