Icelandia

Foulger, G. R.; Gernigon, Laurent; Geoffroy, Laurent

doi:10.1130/2021.2553(04)

Cited by 2 publications

(1 citation statement)

References 65 publications

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“…the MAR) episodically "jumped" and re-established as a new rift zone [Helgason 1984;Lawver and Muller 1994]. In this way, the currently active Kolbeinsey Ridge (KR) took over from the AEgir Ridge as the main active segment of the MAR in the North Atlantic around 30 Ma, separating the Jan Mayen Microcontinent from the Greenland continental crust (Figure 1) [Blischke et al 2016;Hjartarson et al 2017;Blischke 2020;Foulger et al 2022]. At around 30-25 Ma the Iceland plume likely started to intensify lava production on the rift segment that later became Iceland, thus creating an anomalously thick oceanic crust and elevating segments of the MAR above sea level [Torsvik et al 2001;2015;Steinberger et al 2019].…”

Section: Geological Settingmentioning

confidence: 99%

Geology of a Neogene caldera cluster in the Borgarfjörður eystri–Loðmundarfjörður area, Eastern Iceland

Burchardt

Óskarsson

Gustafsson³

et al. 2022

Volcanica

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The Borgarfjörður eystri–Loðmundarfjörður area in Eastern Iceland hosts several volcanic centres in a relatively small area. Large volumes of silicic, as well as an unusual amount of intermediate rocks, occur in this area, alongside other volcanic and sub-volcanic features that formed in the Miocene between 14 and 12:2 Ma. We compiled the first comprehensive geological map of the area and summarise the geology based on more than 40 years of fieldwork. We identify regionally extensive marker horizons that comprise intermediate (icelandite) and mafic (olivine basalt and porphyritic basalt) lavas. These marker horizons, along with new paleomagnetic data and some previous radiogenic dating, allow us to bracket a phase of magmatic activity that is one of the oldest in Eastern Iceland. We describe the prominent features of the volcanic centres, including remnants of collapse calderas in Njarðvík, Dyrfjöll, Breðuvík and other ignimbrite-producing vent structures in Kækjuskörð and Herfell. Notably, the area also contains extremely well exposed examples of volcanic vents, cone sheets, and unique caldera-lake sediments. We conclude with open questions to inspire future research on this understudied area.

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Section: Geological Settingmentioning

confidence: 99%

Geology of a Neogene caldera cluster in the Borgarfjörður eystri–Loðmundarfjörður area, Eastern Iceland

Burchardt

Óskarsson

Gustafsson³

et al. 2022

Volcanica

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Impact of sub-basalt thrust systems on the Faroe continental shelf for the late Paleoproterozoic–Cenozoic tectonic evolution of the margin.

Koehl,

Jolley,

Peace

et al. 2024

Open Res Europe

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Background The Faroe margin in the northeastern Atlantic is segmented by margin-orthogonal, WNW–ESE-striking lineaments extending several hundred kilometers out to the continent–ocean transition. Despite several earlier studies speculating that these features are the product of reactivation of pre-Cenozoic basement-seated structures at depth, the thick Cenozoic volcano-sedimentary sequences deposited along the margin mask the underburden, thus rendering the identification and interpretation of such structures and resolving the pre-Cenozoic history of the area challenging. The present study documents for the first time the existence of margin-orthogonal basement-seated thrust systems and describes their detailed geometry, kinematics, and tectonic evolution. Methods We interpreted basement-seated tectonic structures on seismic reflection data from TGS on the Faroe Platform and the Wyville–Thomson and Munkagrunnur ridges using a newly established methodology. Results The data show that the Wyville–Thomson Ridge, Munkagrunnur Ridge, and Faroe Platform are cored by WNW–ESE-striking thrust systems hundreds of kilometers long and 30–50 km wide, showing dominantly top-SSW kinematics. The thrust systems were reworked into NE–SW-striking folds during the Caledonian Orogeny and controlled the formation of Caledonian thrusts, which in turn controlled the formation of post-Caledonian normal faults. The pre-Caledonian nature of the WNW–ESE-striking shear zones and their geometry and kinematics suggest a relationship with late Paleoproterozoic Laxfordian shear zones onshore northern Scotland and the continuation of the coeval Nagssugtoqidian Orogen in southeastern Greenland, the Ammassalik Belt. In addition, the thrust systems align with the Tornquist Zone in eastern Europe and the southern North Sea, thus suggesting a genetic link between these structures, i.e., a possibly much longer (Paleoproterozoic?) tectonic history for the Tornquist Zone. Conclusions The Faroe Island margin is crosscut by late Paleoproterozoic Laxfordian–Nagssugtoqidian thrust systems, which controlled further tectonic development of the margin and may be related to the Tornquist Zone.

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Icelandia

Cited by 2 publications

References 65 publications

Geology of a Neogene caldera cluster in the Borgarfjörður eystri–Loðmundarfjörður area, Eastern Iceland

Geology of a Neogene caldera cluster in the Borgarfjörður eystri–Loðmundarfjörður area, Eastern Iceland

Impact of sub-basalt thrust systems on the Faroe continental shelf for the late Paleoproterozoic–Cenozoic tectonic evolution of the margin.

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