Yuan, Huaiyu; Levin, Vadim; Darbyshire, Fiona et Menke, William
(2025).
« Crust of eastern North America preserves a record of the supercontinent cycle ».
Geological Society, London, Special Publications, 557, pp. 15-28.
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Résumé
The Northeastern North American lithosphere, integral to supercontinent cycles and the Wilson Cycle concept, remains largely inaccessible at depth. Employing innovative P-wave receiver function methods, we unveil the upper ~60 km of the lithosphere, focusing on the Appalachian Front (AF). Three distinct lithospheric blocks emerge, revealing a central 150 km-wide region of thick (45+ km) crust with a gradational Moho and elevated P-to-S velocity ratio (κ), flanked by thinner (35-40 km) crust regions with lower κ and a sharp Moho. Abrupt changes align with Proterozoic (SFSZ) and Paleozoic (BVBL) tectonic boundaries, but not with AF and the Red Indian Line (RIL), two of the first order structural boundaries in the region. An elevated κ area coincides with the ~450 Ma Charlevoix impact crater. Lithosphere northwest of BVBL retains Neoproterozoic supercontinent assembly structures, while the lithospheric affinity of the southeast region remains unclear. Despite the Red Indian Line marking the Pangean suture, connecting Paleozoic Laurentian and Gondwanan rocks, no changes are observed at depth. This suggests a thin-skinned tectonic regime and/or significant lateral transport. We propose either Gondwanan lithosphere extension to BVBL or a subsurface Laurentia-Gondwana suture southeast of its surface trace.
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