Late Neoproterozoic extended continental margin development recorded by the Seve Nappe Complex of the northern Scandinavian Caledonides

Walczak, Katarzyna; Ziemniak, Grzegorz; Barnes, Christopher J.; Callegari, Riccardo; Bukała, Michał; Kielman‐Schmitt, Melanie; Zagórska, Anna; Majka, Jarosław

doi:10.1016/j.lithos.2022.106640

Cited by 7 publications

(4 citation statements)

References 56 publications

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“…2; Petrík et al 2019;Bukała et al 2020;Barnes et al 2022;Walczak et al 2022b). The pressures for diamond stability exceed the pressure realized in the northern SNC (up to 3.2 GPa) at c. 480 Ma, suggesting that also the southern Seve crust was subducting in the late Cambrian, with PT conditions decreasing from south to north (Walczak et al 2022a). The c. 470-455 Ma (U)HP event recorded in the southern SNC indicates a second subduction-exhumation cycle, which is not recorded in the northern SNC (Barnes et al 2022).…”

Section: Arc-continent Collision Followed By Morb-type and Ultrapotas...mentioning

confidence: 87%

“…The dates record cooling and exhumation of the unit at c. 459 Ma, and renewed deformation and fluid infiltration at c. 434 Ma. The upper gneiss unit shows amphibolite facies peak metamorphic conditions, and zircon and monazite ages indicate that this represents a Neoproterozoic (c. 600 Ma) metamorphic event (Walczak et al 2022a). The PT conditions of this unit during the early HP Seve metamorphism (at c. 490-480 Ma) are therefore unknown and interpreted to have been at or below amphibolite facies conditions, possibly reflecting oblique subduction along-strike of the subducting units with decreasing PT conditions from south to north (Barnes et al 2023).…”

Section: Arc-continent Collision Followed By Morb-type and Ultrapotas...mentioning

confidence: 98%

“…These studies showed that dyke emplacement was preceded by partial melting of the metasedimentary host rock at c. 612-610 Ma (continuing until at least 599 Ma, e.g. Walczak et al 2022a), followed by intense mafic magmatism peaking at 608-596 Ma, and therewith representing the onset of the rift-drift transition within the allochthonous rocks. Magmatism was most probably the result of the melting of multiple mantle plume sources, which were upwelling into the thinning continental lithosphere, assisting in the final break-up (Buiter and Torsvik 2014;Tegner et al 2019).…”

Section: Magma-rich Margin Sections and The Central Iapetus Magmatic ...mentioning

confidence: 99%

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A review of the Caledonian Wilson cycle from a North Atlantic perspective

Gasser,

Majka,

Jakob

et al. 2024

JGS

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The opening and closure of the Paleozoic Iapetus Ocean, leading to the collision of Laurentia and Baltica forming the Caledonian orogen, is one of the prime examples of a Wilson Cycle. In this perspective article, we summarize and discuss the content of 10 new research articles within a 5-stage framework of the Caledonian Wilson cycle from a North Atlantic perspective. Stage 1 covers Neoproterozoic rifting of both the Laurentian and Baltican margins, where the plate tectonic configurations and the timing for the onset of rifting are far from resolved; Stage 2 covers the onset of sea-floor spreading within Iapetus, with several different oceanic basins opening at different times, and with variable geometries of the rifted margins; Stage 3 covers the narrowing of the Iapetus basins along several subduction zones, the number, location and orientation of which are debated; Stage 4 covers the main continent-continent collision, documenting advances in our understanding of (U)HP metamorphism within the Western Gneiss Region; Stage 5 covers post-orogenic extension, transitioning into stage 1 of the subsequent Atlantic Wilson cycle. We review the evolution of the Caledonian Wilson cycle in the light of the recent literature from the past decade and highlight open questions and unresolved issues. Thematic collection: This article is part of the Caledonian Wilson cycle collection available at: https://www.lyellcollection.org/topic/collections/the-caledonian-wilson-cycle

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Section: Arc-continent Collision Followed By Morb-type and Ultrapotas...mentioning

confidence: 87%

Section: Arc-continent Collision Followed By Morb-type and Ultrapotas...mentioning

confidence: 98%

Section: Magma-rich Margin Sections and The Central Iapetus Magmatic ...mentioning

confidence: 99%

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A review of the Caledonian Wilson cycle from a North Atlantic perspective

Gasser,

Majka,

Jakob

et al. 2024

JGS

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“…The Seve nappes host voluminous rift‐related mafic dykes that intruded the outermost passive margin of Baltica during the initial opening of Iapetus between 616 and 595 Ma (Gee et al, 2017; Kjøll et al, 2019; Svenningsen, 2001). Besides abundant mafic rocks, the Seve Nappe Complex also contains schist and paragneiss, migmatite, leucogranite and peridotite lenses, which formed the outer part of the continental shelf of Baltica (Andréasson, 1994; Andréasson et al, 1998, 2018; Brueckner et al, 2004; Gilio et al, 2015; Kjøll et al, 2019; Walczak et al, 2022). The subduction‐related UHP metamorphic events that produced the Seve eclogites (e.g., Bukała et al, 2018; Klonowska et al, 2016) predated the Scandian continental collision and are dated by U–Pb zircon, Sm–Nd and Lu–Hf at 490–460 Ma (e.g., Brueckner & van Roermund, 2004, 2007; Fassmer et al, 2017, 2021; Root & Corfu, 2012).…”

Section: Discussionmentioning

confidence: 99%

An Iapetus origin for a layered eclogite complex in the northern Western Gneiss Region, Scandinavian Caledonides

Möller,

Cai,

Brueckner

et al. 2024

Journal Metamorphic Geology

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The Western Gneiss Region (WGR) is a Precambrian basement domain in the Scandinavian Caledonides and one of the world's largest high‐ and ultrahigh‐pressure terranes. The south–central WGR underwent regional eclogite facies metamorphism 415–400 Ma ago when Baltica subducted beneath Laurentia, during the Scandian orogeny. Eclogites in the WGR group into two traditional types: (1) Precambrian mafic intrusions metamorphosed in situ during Scandian continental subduction and (2) eclogites, garnet peridotites and garnet pyroxenites within ultramafic complexes derived from the subcontinental mantle beneath Laurentia. We document, using field relations, petrography, whole‐rock geochemistry and secondary ion mass spectrometry (SIMS) zircon geochronology, a hitherto unrecognized third type of eclogite in the WGR that places new constraints on its tectonic architecture: an eclogitized fragment of oceanic crust from the Iapetus Ocean. The Kråkfjord eclogite complex is a km2‐sized body with an interior consisting of kyanite eclogite (meta‐troctolite) and subordinate layers and lenses of garnet peridotite, garnet websterite and kyanite–garnet leucotonalite. This interior is capped by Fe–Ti‐rich eclogite, which locally contains subordinate pockets of migmatitic aluminous gneiss. The elemental abundances and isotopic compositions of the Fe–Ti‐rich eclogites resemble those of mid‐ocean ridge basalt (MORB). In contrast, the interior kyanite eclogites, peridotites and pyroxenites have compositions similar to the gabbroic cumulates in the lower oceanic crust of slow‐spreading ridges. U–Pb SIMS dating of igneous zircon cores from a leucotonalite pod in the interior of the Kråkfjord complex yields Cambro‐Ordovician igneous ages of 500–440 Ma, with the ~500 Ma age interpreted as the isotopically undisturbed age. This age matches those of Iapetan oceanic rocks exposed elsewhere in the mountain belt. Metamorphic zircon from an Fe–Ti‐rich eclogite in the carapace of the Kråkfjord complex dates the eclogite facies metamorphism at 421.9 ± 2.2 Ma, synchronous with the continental collision. Zircon from a leucosome in Fe–Ti‐rich retro‐eclogite indicates an age of 408.5 ± 2 Ma for the crystallization of partial melt following the decompression. Detrital zircon core ages from a pocket of aluminous migmatitic gneiss in the carapace indicate derivation of sediment from the Baltic crust. Collectively, the data show that the eclogite complex (1) originated at an Iapetus spreading centre near the continent Baltica, (2) subducted to eclogite conditions during Scandian continental collision and (3) was tectonically intercalated with the Precambrian Baltica basement of the WGR.

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Garnet–Quartz Inclusion Thermobarometry and Lu–Hf Chronology Detail the Pre-Ultra-High Pressure Metamorphic History of the Grapesvare Nappe, Scandinavian Caledonides

Barnes,

Gilio,

Bukała

et al. 2023

Journal of Petrology

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The subduction–exhumation history of the Grapesvare nappe in the northern Seve Nappe Complex (Scandinavian Caledonides) is recorded by late Cambrian/Early Ordovician ultra-high pressure (UHP) and subsequent amphibolite facies metamorphic events. Records of these events obscured earlier metamorphic episodes that are important for understanding the tectonics of the orogen. To extract the pre–UHP metamorphic records, garnet Lu–Hf geochronology, Titanium-in-Quartz thermobarometry, and Quartz-in-Garnet elastic thermobarometry were applied to garnet porphyroblasts in metasedimentary rocks and eclogite. Metasedimentary rocks contain chemically homogeneous garnet (Grt-M1) with shape-matured quartz inclusions. In some rocks, these garnets are overgrown by garnet with bell-shaped Mn-zoning (Grt-M2) containing irregularly-shaped quartz inclusions. This evolution is interpreted as partial dissolution of Grt-M1 and subsequent growth of Grt-M2. Garnet in the eclogite is volumetrically dominated by eclogite-facies garnet (Grt-E1) that envelope remnants of an older, chemically distinct generation (Grt-E0) with highly irregular and diffuse boundaries. Shape-matured quartz inclusions are present within both garnet generations and define a zoning pattern that is not reflective of the chemical zoning. Collectively, these characteristics are interpreted as replacement of Grt-E0 by Grt-E1 via interface-coupled dissolution–reprecipitation, with the latter inheriting the shape-matured quartz inclusions of the former. Pressure–temperature (P–T) conditions extracted from the quartz inclusions in Grt-M1 and Grt-E0/E1 are 1.08 to 1.21 GPa at 645°C to 695°C and 0.94 to 1.03 GPa at 605°C to 640°C, respectively. These conditions are interpreted as cooling of the rocks from a high temperature metamorphic history, altogether preceding subduction of the Grapesvare nappe. The quartz inclusions in Grt-M2 record 1.04 to 1.21 GPa at 620°C to 675°C, interpreted as prograde metamorphic growth of Grt-M2 during subduction at 495.7 ± 3.2 Ma. Subsequent eclogite-facies metamorphism was responsible for the formation of Grt-E1 at the expense of Grt-E0. The collective results indicate a prolonged polymetamorphic history of the Grapesvare nappe prior to UHP metamorphism that has not been recognized previously.

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Late Neoproterozoic extended continental margin development recorded by the Seve Nappe Complex of the northern Scandinavian Caledonides

Cited by 7 publications

References 56 publications

A review of the Caledonian Wilson cycle from a North Atlantic perspective

A review of the Caledonian Wilson cycle from a North Atlantic perspective

An Iapetus origin for a layered eclogite complex in the northern Western Gneiss Region, Scandinavian Caledonides

Garnet–Quartz Inclusion Thermobarometry and Lu–Hf Chronology Detail the Pre-Ultra-High Pressure Metamorphic History of the Grapesvare Nappe, Scandinavian Caledonides

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