Magma-assisted fragmentation of Pangea: Continental breakup initiation and propagation

Guan, Huixin; Geoffroy, Laurent; Xu, Min

doi:10.1016/j.gr.2021.04.003

Cited by 14 publications

(1 citation statement)

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“…Magmatism greatly affects the style of continental breakup, to the point where rifted continental margins are broadly categorized as magma‐rich and magma‐poor types (Louden et al., 2013; Tugend et al., 2020). Seismic observations at magma‐rich margins, such as the eastern US seaboard (e.g., Holbrook & Kelemen, 1993), commonly reveal a continent‐ocean transition (COT) with thicker than average transitional crust due to lower‐crustal igneous underplating or intrusions and subaerial lava flows (e.g., Hinz et al., 1987; Quirk et al., 2014; Voss et al., 2009) that result from early inception of decompression melting during continental rifting (Guan et al., 2021; Tugend et al., 2020). Magma‐poor margins show wider transition zones resulting from a less uniform breakup process that leaves asymmetric structures between the conjugate margin pairs.…”

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confidence: 99%

New Insights Into the Rift to Drift Transition Across the Northeastern Nova Scotian Margin From Wide‐Angle Seismic Waveform Inversion and Reflection Imaging

et al. 2021

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Sparse wide‐angle seismic profiling supported by coincident reflection imaging has been instrumental for advancing our knowledge about rifted margins. Nevertheless, features of critical importance for understanding rifting processes have been poorly resolved. We derive a high‐resolution velocity model by applying full waveform inversion to the dense OETR‐2009 wide‐angle seismic profile crossing the northeastern Nova Scotian margin. We then create a coincident reflection image by prestack depth migrating the multichannel seismic data. This allows for the first detailed interpretation of the structures related to the final stages of continental breakup and incipient oceanic accretion at the Eastern North America Margin. Our interpretation includes a hyperextended continental domain overlying partially serpentinized mantle, followed by a 10‐km‐wide domain consisting of a continental block surrounded by layered and bright reflectors indicative of magmatic extrusions. A major fault, representing the continent‐ocean boundary, marks a sharp seaward transition to a 16‐km‐wide domain characterized by smoother basement with chaotic reflectors, where no continental materials are present and a 3‐km‐thick embryonic oceanic crust overlying partially serpentinized mantle is created by the breakup magmatism. Further seaward, thin oceanic crust overlies the serpentinized mantle suggesting magma‐poor oceanic spreading with variable magma supply as determined from variable basement topography, 2–4 km thick volcanic layer, and magnetic anomalies. Our results demonstrate that magmatism played an important role in the lithospheric breakup of the area crossed by the OETR‐2009 profile. Considering that the northeastern Nova Scotian margin has been classified as amagmatic, large margin‐parallel variations in magma supply likely characterize a single rift segment.

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