Zircon U–Pb age for the Orkney lamprophyre dyke swarm, Scotland, and relations to Permo-Carboniferous magmatism in northwestern Europe

Lundmark, Anders Mattias; Gabrielsen, Roy H.; Brown, J. F.

doi:10.1144/0016-76492011-017

Cited by 8 publications

(3 citation statements)

References 29 publications

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“…The c. 267 Ma age proposed for Group 3 structures by Dichiarante et al (2016) lies almost within error of the K-Ar age of 252 ± 10 Ma obtained for lamprophyre dykes in the Thurso area (Baxter and Mitchell 1984). Lundmark et al (2011) more recently obtained a U-Pb zircon age for a lamprophyre dyke in Orkney of 313 ± 4 Ma, which is 20-60 Ma older than the previously obtained K-Ar ages for Scottish lamprophyres. These researchers suggested that the previously obtained K-Ar ages could have been partially reset by later alteration processes and are possibly not reliable.…”

Section: Structural Relationships Associated With Ene-wsw Faults and supporting

confidence: 79%

Outcrop-scale manifestations of reactivation during multiple superimposed rifting and basin inversion events: the Devonian Orcadian Basin, northern Scotland

Dichiarante

Holdsworth

Dempsey

et al. 2020

JGS

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The Devonian Orcadian Basin in Scotland hosts extensional fault systems assumed to be related to the initial formation of the basin, with only limited post-Devonian inversion and reactivation. However, a recent detailed structural study across Caithness, underpinned by published Re–Os geochronology, shows that three phases of deformation are present. North–south- and NW–SE-trending Group 1 faults are related to Devonian ENE–WSW transtension associated with sinistral shear along the Great Glen Fault during the formation of the Orcadian Basin. Metre- to kilometre-scale north–south-trending Group 2 folds and thrusts are developed close to earlier sub-basin-bounding faults and reflect late Carboniferous–early Permian east–west inversion associated with dextral reactivation of the Great Glen Fault. The dominant Group 3 structures are dextral oblique NE–SW-trending and sinistral east–west-trending faults with widespread syndeformational carbonate mineralization (± pyrite and bitumen) and are dated using Re–Os geochronology as Permian (c. 267 Ma). Regional Permian NW–SE extension related to the development of the offshore West Orkney Basin was superimposed over pre-existing fault networks, leading to local oblique reactivation of Group 1 faults in complex localized zones of transtensional folding, faulting and inversion. The structural complexity in surface outcrops onshore therefore reflects both the local reactivation of pre-existing faults and the superimposition of obliquely oriented rifting episodes during basin development in the adjacent offshore areas.Supplementary material: Stereographic projections of compiled structural data from individual fieldwork localities are available at https://doi.org/10.6084/m9.figshare.c.5115228

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Section: Structural Relationships Associated With Ene-wsw Faults and supporting

confidence: 79%

Outcrop-scale manifestations of reactivation during multiple superimposed rifting and basin inversion events: the Devonian Orcadian Basin, northern Scotland

Dichiarante

Holdsworth

Dempsey

et al. 2020

JGS

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“…Near the base of the UORS are extrusive volcanic rocks (lavas), with associated volcanic vents (Halliday et al 1977). All of these rocks are cross-cut by an igneous dyke swarm dated as Permian (Lundmark et al 2011). The UORS sandstones are especially well exposed and accessible at Brough (pronounced 'broch').…”

Section: Geological Settingmentioning

confidence: 99%

Oil charge and biodegradation history in an exhumed fractured reservoir, Devonian, UK

Baba

Parnell

Muirhead

et al. 2019

Marine and Petroleum Geology

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The distribution of oil residues in fractured Upper Devonian reservoir sandstones of Caithness help us to understand relationships between oil charge and episodes of fracturing. The sandstones are cut by an extensive set of tightly cemented deformation bands in the vicinity of the Brough Fault, and calcite-mineralized open fractures. The deformation bands compartmentalized the reservoir, which subsequently was charged by oil to varying extent in different compartments. Petrographic and biomarker data distinguish two charges of oil. The first charge of oil was unaltered. The later mineralized fractures introduced a heavier biodegraded oil that spread into the sandstone pores and displaced/overprinted the earlier oil. Two distinct oil charges are also evident from two generations of oil fluid inclusions, firstly in overgrowths on quartz grains, and secondly in the calcite veins, exhibiting distinct fluorescence characteristics. Migration and trapping of oil depended on the combination of two fracturing episodes of different character, in which the first episode created sealed compartments which were then filled by oil introduced by the second episode.

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“…The late Carboniferous alkaline dikes have been proposed to reflect incipient rifting signaling the start of the intense Stephanianearly Permian magmatism in north-western Europe (e.g. Lundmark et al, 2011). In northern Britain and the North Sea the Stephanianearly Permian magmatism is manifested in numerous sub-alkaline 308-290 Ma quartz-dolerite dikes and sills (Monaghan and Pringle, 2004;Monaghan and Parrish, 2006).…”

Section: Geological Settingmentioning

confidence: 99%

Repeated post-Caledonian intra-cratonic rifting in the central North Sea: Evidence from the volcanic record in the Embla oil field

Lundmark

Gabrielsen

Strand³

et al. 2018

Marine and Petroleum Geology

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Intrusive and extrusive mafic igneous rocks in the Embla oil field, central North Sea, testify to repeated post-Caledonian magmatism on the northern flank of the Mid North Sea High. The igneous rocks are highly clay-and carbonate-altered, but retain their High Field Strength element signatures on the sample scale. These signatures are used to group, classify and investigate the tectonic significance of the rocks. Three magmatic events are identified. Late Devonian transitional basalts are interpreted as part of a bimodal volcanic assemblage that includes ca. 375 Ma alkali rhyolites, suggested to record rifting in a proto-Central Graben. Early Permian volcanic and hypabyssal alkaline rocks in the Embla oil field display lamprophyric traits and represent low degree melts. They likely correlate either to ca. 300 Ma lamprophyre magmatism leading up to, or 298-292 Ma alkaline magmatism in the Midland Valley-Southern Uplands coeval with the northwest European magmatic flare-up at the Permo-Carboniferous boundary. Kimmeridgian-Tithonian submarine tholeiitic basalts in the Embla oil field postdate the alkaline continental mid Jurassic magmatism associated with doming and initial rifting in the North Sea, and are suggested to represent a hitherto unknown volcanic expression of the late Jurassic main rift phase in the Central Graben.

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Zircon U–Pb age for the Orkney lamprophyre dyke swarm, Scotland, and relations to Permo-Carboniferous magmatism in northwestern Europe

Cited by 8 publications

References 29 publications

Outcrop-scale manifestations of reactivation during multiple superimposed rifting and basin inversion events: the Devonian Orcadian Basin, northern Scotland

Outcrop-scale manifestations of reactivation during multiple superimposed rifting and basin inversion events: the Devonian Orcadian Basin, northern Scotland

Oil charge and biodegradation history in an exhumed fractured reservoir, Devonian, UK

Repeated post-Caledonian intra-cratonic rifting in the central North Sea: Evidence from the volcanic record in the Embla oil field

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