Mafic dyke swarms of the Baltica-Iapetus transition, Seve Nappe Complex of the Sarek Mts., Swedish Caledonides

Andréasson, Per-Gunnar; Svenningsen, Olaf; Johansson, Ingrid; Solyom, Zoltan; Tan, Xiaodan

doi:10.1080/11035899209453460

Cited by 24 publications

(23 citation statements)

References 46 publications

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“…In normalized multielement diagrams, samples of the Rohkunborri and Sarek dykes are close to typical E-MORB patterns. They show irregularities and enrichments for some of the most incompatible LIL elements (Rb, Ba, Th, K), which is attributed to local upper crustal contamination (Andréasson et al 1992;see also Fig. 6).…”

Section: Geochemical Signatures Of the Baltoscandian Swarmsmentioning

confidence: 95%

“…The main swarms are the Ottfjället Swarm in the Särv Nappe complex in Sweden ) and dykes in the equivalent Leksdal Nappe in Norway (Andréasson et al 1979), the Sarek swarm in the Sarektjåkkå Nappe (Seve Nappe complex; Andréasson et al 1992) and correlative dykes in Indre Troms (Rohkunborri Nappe; Stølen 1994) and dykes in the Corrovarre Nappe (Kalak Nappe complex; Roberts 1990). In the Seve Nappe complex, dyke swarms are locally voluminous and form sheeted dyke complexes representing more than 70% of outcrop surface, for example, the Sarek and Rohkunborri dykes.…”

Section: Swarms Of the Baltoscandian Marginmentioning

confidence: 99%

“…Major and trace element data on unaltered and unmetamorphosed fine-to medium-grained dykes are available for the Ottfjället Swarm (Solyom et al , 1985, the Corrovarre dykes (Roberts 1990), the Sarek Swarm (Andréasson et al 1992;Svenningsen 1994) and Rohkunborri dykes (Stølen 1994). These different groups have largely overlapping tholeiitic-subalkaline composition, with Mg# of 62-44, TiO 2 content of 1.1-2.4% and SiO 2 content of 47.1-52.3% (Fig.…”

Section: Geochemical Signatures Of the Baltoscandian Swarmsmentioning

confidence: 99%

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Geochemical signature of the Egersund basaltic dyke swarm, SW Norway, in the context of late-Neoproterozoic opening of the Iapetus Ocean

Bingen¹,

Demaiffe

1999

Norsk Geologisk Tidsskrift

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The Egersund basaltic dyke swarm is made up of 11 ESE-WNW-trending dykes in the Proterozoic crystalline basement of southwest Norway. Two types of dyke occur: porphyritic dykes with plagioclase phenocrysts and aphyric dykes. Limited magmatic differentiation occurred in the dykes during shallow level intrusion. The porphyritic dykes and one of the aphyric dykes have subalkaline to mildly alkaline compositions, whereas the other aphyric dykes have alkaline compositions. The most primitive magmas occur in the porphyritic dykes; they have Mg numbers of 56-61, TiO 2 contents of 2.0-2.1% and enriched incompatible trace element contents. Initial isotopic compositions, Sr i and e(Nd) i , are 0.7034-0.7039 and 2.0-3.1 respectively. The most evolved magmas in alkaline dykes are SiO 2 -poor (45-46%) ferrobasalts, very enriched in TiO 2 (3.2-3.4%), P 2 O 5 (2.0-2.5%) and incompatible trace elements. They have Sr i of 0.7058-0.7060 and e(Nd) i of 1.0. The compositions of the most primitive magmas and minerals suggest that the porphyritic dykes tapped a magma chamber situated at the crust-mantle boundary, at ca. 10 kbar. It is shown that one of the aphyric dykes is possibly related to the porphyritic dyke magma by a fractional crystallization process accompanied by limited crustal assimilation at this pressure. The alkaline dykes represent a distinct suite with a distinct mantle source. The 616 AE 3 Ma Egersund Swarm is placed in the geotectonic context of late-Neoproterozoic rifting leading to opening of the Iapetus Ocean. At the Baltoscandian passive margin of Baltica, there is a first order 'oceanwards' decrease in incompatible trace element contents and Sr i and an increase of e(Nd) i values of basaltic dyke swarms, from the Egersund Swarm in the continental basement, to the sheeted dyke complexes situated at the continent-ocean transition. This geochemical trend is interpreted as a change from high-pressure partial melting of garnet peridotite with residual garnet in a mildly depleted mantle, to lower-pressure partial melting of a depleted mantle. Norway, 7491 Trondheim, Norway (bernard.bingen@ngu.no); D. Demaiffe, Département des Sciences de la Terre et de l'Environnement, CP160/02, Université Libre de Bruxelles, 1050 Bruxelles, Belgium (ddemaif@ulb.ac.be). B. Bingen, Geological Survey of

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Section: Geochemical Signatures Of the Baltoscandian Swarmsmentioning

confidence: 95%

Section: Swarms Of the Baltoscandian Marginmentioning

confidence: 99%

Section: Geochemical Signatures Of the Baltoscandian Swarmsmentioning

confidence: 99%

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Geochemical signature of the Egersund basaltic dyke swarm, SW Norway, in the context of late-Neoproterozoic opening of the Iapetus Ocean

Bingen¹,

Demaiffe

1999

Norsk Geologisk Tidsskrift

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“…-In order to evaluate their regional significance, the KIC rocks are compared to correlative riftrelated igneous rocks occurring at the western margin of Baltica, either intruding the crystalline basement, or contained in the Middle Allochthon (Särv and Kalak Nappes) and the Upper Allochthon (Seve Nappes), respectively. These include (1 -Basement): the Egersund dykes (Bingen et al, 1998;Bingen and Demaiffe, 1999), and the Alnö Alkaline Complex (Vuorinen, 2005); (2 -Särv Nappes): the Ottfjället dykes (Solyom et al, 1979(Solyom et al, , 1985, the Sørli dykes (Beckholmen and Roberts, 1999); (3 -Kalak Nappes): the Corrovarre dykes (Roberts, 1990), the Seiland Igneous Province (Roberts, 2007;Roberts et al, 2010); (4 -Seve Nappes): the Tsäkokk basalts (Kullerud et al, 1990), the Sarek (Andréasson et al, 1992;Svenningsen, 1994) and Indre Troms dykes (Rohkunborri; Stølen, 1994), as well as mafic rocks from the Grapesvare Sun and McDonough (1989). Other Seve mafic rocks include values from Sarek (Andréasson et al, 1992;Svenningsen, 1994), Indre Troms (Stølen, 1994), Grapesvare (Andréasson and Albrecht, 1995) and Sylarna (Solyom et al, 1985;Pettersson, 2003).…”

Section: Geochemistrymentioning

confidence: 97%

Root zone of a continental rift: the Neoproterozoic Kebnekaise Intrusive Complex, northern Swedish Caledonides

Kirsch

Svenningsen²

2015

GFF

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Mafic magmatic rocks formed between ca. 615 and 560 Ma along the Neoproterozoic margins of Baltica and Laurentia are classically attributed to continental rifting heralding the opening of the Iapetus Ocean. We report new data for the Kebnekaise Intrusive Complex (KIC) exposed in the Seve Nappes in northern Sweden. The KIC consists of sheeted dolerite dykes and gabbroic bodies with mutually intrusive relations. Major and trace element data exhibit a transitional-to normal-mid-ocean-ridge basalt-type geochemical signature. Differentiation processes and late-stage liquid immiscibility of a tholeiitic melt are considered to account for the compositional range exhibited by the KIC igneous rocks. U/Pb SIMS geochronological data from zircon rims yield an emplacement age of 578^9 Ma. The KIC is thus younger and more depleted than coeval mafic rocks found in the Seve Nappe, and is interpreted to represent a highlevel magma plumbing system in a late-stage continental rift. The composition and volume of rift-related igneous rocks in the Seve Nappes are inconsistent with a mantle plume origin, but are thought to record progressive lithospheric thinning and increasing involvement of an asthenospheric mantle component.

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“…The sample (CKS10) collected from directly above the Akkajaure Nappe Complex is a mica schist from what Kirkland et al inferred is the Skarja Nappe, by some authors (Rehnström et al, 2002) treated as lower Seve, by other authors interpreted as equivalent to the Särv nappes (Andréasson et al, 1992;Svenningsen, 1994;Rehnström, 1998;Thelander, 2009). Kirkland et al (2011) obtained a unimodal Paleoproterozoic (c. 1800 Ma) detrital zircon population from the mica schist, i.e.…”

Section: Anomalous Data From the Akkjaure Profile Of Central Norrbottenmentioning

confidence: 98%

Detrital zircon signatures of the Baltoscandian margin along the Arctic Circle Caledonides in Sweden: The Sveconorwegian connection

Gee

Andréasson

Lorenz

et al. 2015

Precambrian Research

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Mafic dyke swarms of the Baltica-Iapetus transition, Seve Nappe Complex of the Sarek Mts., Swedish Caledonides

Cited by 24 publications

References 46 publications

Geochemical signature of the Egersund basaltic dyke swarm, SW Norway, in the context of late-Neoproterozoic opening of the Iapetus Ocean

Geochemical signature of the Egersund basaltic dyke swarm, SW Norway, in the context of late-Neoproterozoic opening of the Iapetus Ocean

Root zone of a continental rift: the Neoproterozoic Kebnekaise Intrusive Complex, northern Swedish Caledonides

Detrital zircon signatures of the Baltoscandian margin along the Arctic Circle Caledonides in Sweden: The Sveconorwegian connection

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