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A new tectono-magmatic model for the Lofoten/Vesteralen Margin at the outer limit of the Iceland Plume influence

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Title: A new tectono-magmatic model for the Lofoten/Vesteralen Margin at the outer limit of the Iceland Plume influence
Authors: Breivik, Asbjorn Johan Browse this author
Faleide, Jan Inge Browse this author
Mjelde, Rolf Browse this author
Flueh, Ernst R. Browse this author
Murai, Yoshio Browse this author →KAKEN DB
Keywords: Ocean bottom seismometers
Large igneous provinces
Marine magnetics
Continental breakup
Issue Date: 30-Oct-2017
Publisher: Elsevier
Journal Title: Tectonophysics
Volume: 718
Start Page: 25
End Page: 44
Publisher DOI: 10.1016/j.tecto.2017.07.002
Abstract: The Early Eocene continental breakup was magma-rich and formed part of the North Atlantic Igneous Province. Extrusive and intrusive magmatism was abundant on the continental side, and a thick oceanic crust was produced up to a few m.y. after breakup. However, the extensive magmatism at the Voring Plateau off mid-Norway died down rapidly northeastwards towards the Lofoten/Vesteralen Margin. In 2003 an Ocean Bottom Seismometer profile was collected from mainland Norway, across Lofoten, and into the deep ocean. Forward/inverse velocity modeling by raytracing reveals a continental margin transitional between magma-rich and magma-poor rifting. For the first time a distinct lower-crustal body typical for volcanic margins has been identified at this outer margin segment, up to 3.5 km thick and similar to 50 km wide. On the other hand, expected extrusive magmatism could not be clearly identified here. Strong reflections earlier interpreted as the top of extensive lavas may at least partly represent high-velocity sediments derived from the shelf, and/or fault surfaces. Early post-breakup oceanic crust is moderately thickened (similar to 8 km), but is reduced to 6 km after 1 m.y. The adjacent continental crystalline crust is extended down to a minimum of 4.5 km thickness. Early plate spreading rates derived from the Norway Basin and the northern Voring Plateau were used to calculate synthetic magnetic seafloor anomalies, and compared to our ship magnetic profile. It appears that continental breakup took place at similar to 53.1 Ma, similar to 1 m.y. later than on the Voring Plateau, consistent with late strong crustal extension. The low interaction between extension and magmatism indicates that mantle plume material was not present at the Lofoten Margin during initial rifting, and that the observed excess magmatism was created by late lateral transport from a nearby pool of plume material into the lithospheric rift zone at breakup time. (C) 2017 Elsevier B.V. All rights reserved.
Rights: © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
http://creativecommons.org/licenses/by-nc-nd/4.0/
Type: article (author version)
URI: http://hdl.handle.net/2115/74897
Appears in Collections:理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 村井 芳夫

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