Sveconorwegian vs. Caledonian orogenesis in the eastern Øygarden Complex, SW Norway – Geochronology, structural constraints and tectonic implications

Wiest, Johannes; Jacobs, Joachim; Ksienzyk, Anna K.; Fossen, Haakon

doi:10.1016/j.precamres.2017.11.020

Cited by 14 publications

(11 citation statements)

References 213 publications

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“…In our study we recorded mafic magmatism at 1031 ± 5, 1025 ± 13 and 990 ± 12 Ma; along with earlier studies (Jensen and Corfu, 2016;Vander Auwera et al, 2011;Wiest et al, 2018), this suggests geographically widespread mafic magmatism during Sveconorwegian orogenesis.…”

Section: Slagstad Et Al |supporting

confidence: 88%

“…Most studies on the mechanisms of long-lived UHT metamorphism invoke mantle-derived heat in the form of mafic magmatism resulting from extensional and/or compressional tectonics in arc and/or backarc settings (e.g., Brown, 2006;Currie and Hyndman, 2006;Walsh et al, 2015), similar to the tectonic-switching model of Collins (2002). Emerging evidence from the Sveconorwegian Province, including this study and that of Wiest et al (2018) near Bergen, and Jensen and Corfu (2016) at Finse, show that the Sveconorwegian orogeny was accompanied by geographically widespread mafic magmatism. A marked increase in Ti-in-zircon temperatures ca.…”

Section: Smb High-grade Metamorphism As a Results Of Repeated Basalticmentioning

confidence: 54%

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Magma-driven, high-grade metamorphism in the Sveconorwegian Province, southwest Norway, during the terminal stages of Fennoscandian Shield evolution

et al. 2018

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Recently it has been argued that the Sveconorwegian orogeny in southwest Fennoscandia comprised a series of accretionary events between 1140 and 920 Ma, behind a long-lived, active continental margin characterized by voluminous magmatism and high-grade metamorphism. Voluminous magnesian granitic magmatism is recorded between 1070 and 1010 Ma (Sirdal Magmatic Belt, SMB), with an apparent drop in activity ca. 1010-1000 Ma. Granitic magmatism resumed ca. 1000-990 Ma, but with more ferroan (A type) compositions (hornblende-biotite granites). This ferroan granitic magmatism was continuous until 920 Ma, and included emplacement of an AMCG (anorthosite-mangerite-charnockite-granite) complex (Rogaland Igneous Complex). Mafic rocks with ages corresponding to the spatially associated granites suggest that heat from underplated mafic magma was the main driving force for lower crustal melting and long-lived granitic magmatism. The change from magnesian to ferroan compositions may reflect an increasingly depleted and dehydrated lower crustal source. High-grade metamorphic rocks more than ~20 km away from the Rogaland Igneous Complex yield meta morphic ages of 1070-1015 Ma, corresponding to SMB magmatism, whereas similar rocks closer to the Rogaland Igneous Complex yield ages between 1100 and 920 Ma, with an apparent age peak ca. 1000 Ma. Ti-in-zircon temperatures from these rocks increase from ~760 to 820 °C ca. 970 Ma, well before the inferred emplacement age of the Rogaland Igneous Complex (930 Ma), suggesting that long-lived, high-grade metamorphism was not directly linked to the emplacement of the latter, but rather to the same mafic underplating that was driving lower crustal melting. Structural data suggest that the present-day regional distribution of high-and low-grade rocks reflects late-stage orogenic doming.

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Section: Slagstad Et Al |supporting

confidence: 88%

Section: Smb High-grade Metamorphism As a Results Of Repeated Basalticmentioning

confidence: 54%

Magma-driven, high-grade metamorphism in the Sveconorwegian Province, southwest Norway, during the terminal stages of Fennoscandian Shield evolution

et al. 2018

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“…The crystalline basement beneath the northern North Sea rift is exposed onshore in Norway, the Shetland Islands and in northern Scotland. The basement initially formed during the Proterozoic Sveconorwegian orogeny (Roffeis & Corfu, ; Slagstad et al, ), before being reworked during the Ordovician‐Devonian Caledonian orogeny (Coward, ; McKerrow et al, ; Milnes et al, ; Roberts, ; Wiest et al, ). The Scandian phase of the Caledonian orogeny involved the collision of Baltica and Laurentia and the closure of the Iapetus Ocean (Gee et al, ), with the further collision of Avalonia to the south (McKerrow et al, ).…”

Section: Regional Setting and Evolution Of The North Seamentioning

confidence: 99%

The Influence of Structural Inheritance and Multiphase Extension on Rift Development, the NorthernNorth Sea

et al. 2019

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The northern North Sea rift evolved through multiple rift phases within a highly heterogeneous crystalline basement. The geometry and evolution of syn-rift depocenters during this multiphase evolution and the mechanisms and extent to which they were influenced by preexisting structural heterogeneities remain elusive, particularly at the regional scale. Using an extensive database of borehole-constrained 2D seismic reflection data, we examine how the physiography of the northern North Sea rift evolved throughout late Permian-Early Triassic (RP1) and Late Jurassic-Early Cretaceous (RP2) rift phases, and assess the influence of basement structures related to the Caledonian orogeny and subsequent Devonian extension. During RP1, the location of major depocenters, the Stord and East Shetland basins, was controlled by favorably oriented Devonian shear zones. RP2 shows a diminished influence from structural heterogeneities, activity localizes along the Viking-Sogn graben system and the East Shetland Basin, with negligible activity in the Stord Basin and Horda Platform. The Utsira High and the Devonian Lomre Shear Zone form the eastern barrier to rift activity during RP2. Toward the end of RP2, rift activity migrated northward as extension related to opening of the proto-North Atlantic becomes the dominant regional stress as rift activity in the northern North Sea decreases. Through documenting the evolving syn-rift depocenters of the northern North Sea rift, we show how structural heterogeneities and prior rift phases influence regional rift physiography and kinematics, controlling the segmentation of depocenters, as well as the locations, styles, and magnitude of fault activity and reactivation during subsequent events.

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“…The description of the Gulen MCC by Wiest et al (2019) provides the onshore part of this study, complemented by observations from the detachment footwall exposed in the Øygarden Complex (Wiest et al, 2018, 10.1029/2020TC006178 Tectonics 2020). The Gulen MCC is a westward plunging antiform consisting of a high-grade metamorphic core with subvertical foliations flanked by detachment shear zones (Figure 1).…”

Section: Field Observationsmentioning

confidence: 99%

From Caledonian Collapse to North Sea Rift: The Extended History of a Metamorphic Core Complex

et al. 2020

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Extensional systems evolve through different stages due to changes in the rheological state of the lithosphere. It is crucial to distinguish ductile structures formed before and during rifting, as both cases have important but contrasting bearings on the structural evolution. To address this issue, we present the illustrative ductile-to-brittle structural history of a metamorphic core complex (MCC) onshore and offshore western Norway. Combining geological field mapping with newly acquired 3-D seismic reflection data, we correlate two distinct onshore basement units (BU1 and BU2) to corresponding offshore basement seismic facies (SF1 and SF2). Our interpretation reveals two 40 km wide domes (one onshore and one offshore), which both show characteristic kilometer-scale, westward plunging upright folds. The gneiss domes fill antiformal culminations in the footwall of a >100 km long, shallowly west dipping, extensional detachment. Overlying Caledonian nappes and Devonian supradetachment basins occupy saddles of the hyperbolic detachment surface. Devonian collapse of the Caledonian orogen formed dome and detachment geometries. During North Sea rifting, brittle reactivation of the MCC resulted in complex fault patterns deviating from N-S strike dominant at the eastern margin of the rift. Around 61°N, only minor N-S faults (<100 m throw) cut through the core of the MCC. Major rift faults (≤5 km throw), on the other hand, reactivated the detachment and follow the steep flanks of the MCC. This highlights that inherited ductile structures can locally alter the orientation of brittle faults formed during rifting. Plain Language Summary The mechanical behavior of the lithosphere largely determines the style of crustal deformation. Therefore, many areas go successively through different modes of extension. In the case of a thick and warm crust, extension can form ductile domes below low-angle normal faults, so-called metamorphic core complexes (MCCs). Onshore West Norway, we observe a MCC formed during Devonian collapse of the Caledonian orogen. Offshore, new 3-D seismic data reveal a second dome underneath rift basins in the northern North Sea. Both domes are connected through a 100 km long extensional high strain zone, which formed during Caledonian collapse. The combination of ductile and brittle processes formed a deformation zone with nonplanar geometry, which consists of a series of domes and saddles. About 140 Myr later, Permian-Triassic rifting formed large normal faults, which exploited the inherited weakness of the deformation zone. This brittle reactivation resulted in strongly deviating rift fault orientations around 61°N.

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Sveconorwegian vs. Caledonian orogenesis in the eastern Øygarden Complex, SW Norway – Geochronology, structural constraints and tectonic implications

Abstract: Paper 1: Sveconorwegian vs. Caledonian orogenesis in the eastern Øygarden Complex, SW Norway -Geochronology, structural constraints and tectonic implications.

Cited by 14 publications

References 213 publications

Magma-driven, high-grade metamorphism in the Sveconorwegian Province, southwest Norway, during the terminal stages of Fennoscandian Shield evolution

Magma-driven, high-grade metamorphism in the Sveconorwegian Province, southwest Norway, during the terminal stages of Fennoscandian Shield evolution

The Influence of Structural Inheritance and Multiphase Extension on Rift Development, the NorthernNorth Sea

From Caledonian Collapse to North Sea Rift: The Extended History of a Metamorphic Core Complex

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