Stratigraphies and depositional ages of Svecofennian, Palaeoproterozoic metavolcanic rocks in E. Svealand and Bergslagen, south central Sweden

Lundström, Ingmar; Allen, Rodney L.; Persson, Per‐Olof; Ripa, Magnus

doi:10.1080/11035899809453225

Cited by 39 publications

(14 citation statements)

References 16 publications

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“…Lindroos & Ehlers, 1994, Fig. 1;Lundström et al, 1998). This has been confirmed in the Orijarvi area, where IDTIMS U-Pb zircon analyses from the bottom and top of the felsic succession yielded ages of 1895.3±2.4 Ma and 1878.2±3.4 Ma respectively (Väisänen & Mänttäri, 2002).…”

Section: Evidence For Pre-191 Ga Structures In the Cfgc And Lsgmsupporting

confidence: 53%

Pre-1.91 Ga deformation and metamorphism in the Palaeoproterozoic Vammala Migmatite Belt, southern Finland, and implications for Svecofennian tectonics

Rutland¹,

Williams²,

Korsman³

2004

Bull Geol Soc Finland

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A metamorphic event in the Vammala Migmatite Belt (VMB) at ~1.92 Ga, revealed by SHRIMP U-Pb analyses of both zircon overgrowths and monazite,is interpreted as post-depositional and is correlated with the development of the early high-grade schistosity.Neither this Early Svecofennian deformation and metamorphism, nor the associated complex folding, is present in the overlying Ta mpere Schist Belt (TSB) sequence, consistent with the VMB being part of a pre-1.91 Ga basement complex. The ~1.92 Ga event provides a maximum deposition age for the TSB,confirming earlier age estimates. Earlier stratigraphic correlations between parts of the VMB and TSB,and associated tectonic interpretations, can no longer be sustained.The crustal thickening seen in the VMB,and previously attributed to arc accretion at ~1.89 Ga, is now attributed to accretion of a large Svionian marginal basin during the 'Early Svecofennian' orogenic phase at ~1.92 Ga.This is of similar age to the deformation and metamorphism associated with collision in the Lapland-Kola Orogen to the north of the Karelian Province. The well-known post-TSB orogenic phase was also identified in the VMB by a monazite age of 1881±6 Ma. A granitoid intrusion gave an emplacement age of 1888±5 Ma, comparable to the age of granitoid clasts in the upper part of the TSB succession.The detrital zircon data are interpreted to suggest that deposition of the precursor VMB sediments probably took place soon after an earlier pre-depositional metamorphism at ~1.98 Ga, which affected igneous source complexes dated at ~1.99 Ga and ~2.01 Ga. Mafic rocks in the southern part of the VMB,and probably also the Haveri basalts, represent a renewed episode of extensional magmatism, which might correlate with the 1.96-1.95 Ga Jormua and Outokumpu ophiolites. A pre-1.96 Ga older stage basin has an expression in Sweden and complexes of similar age occur in the concealed Palaeoproterozoic basement south of the Gulf of Finland. Similar rocks, deformed and metamorphosed before ~1.96 Ga, might be present beneath the Central Finland granitoid complex and the late Svecofennian granite-migmatite zone,and were possibly more local sources for both the younger stage Svionian basin sediments and the post-1.91 Ga Bothnian Basin sediments.The TSB and other post-accretionary volcanic sequences, and the associated plutonism, are interpreted to reflect a ~40 m.y.extensional period, inboard of the contemporaneous active margin, between orogenic phases at ~1.92 Ga and ~1.88 Ga.This interpretation provides a more satisfactory explanation of the major heat input to the crust over a very wide area than does the arc accretion hypothesis.The tectonic evolution of the Svecofennian Province has strong similarities to that of the Palaeozoic Lachlan Fold Belt in eastern Australia.

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Section: Evidence For Pre-191 Ga Structures In the Cfgc And Lsgmsupporting

confidence: 53%

Pre-1.91 Ga deformation and metamorphism in the Palaeoproterozoic Vammala Migmatite Belt, southern Finland, and implications for Svecofennian tectonics

Rutland¹,

Williams²,

Korsman³

2004

Bull Geol Soc Finland

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“…The U -Th-total Pb monazite age of 1911^16 Ma (sample Volc-2) overlaps the range of U -Pb ages of magmatic zircon from 1909 to 1882 Ma in the Svecofennian volcanic rocks of the Bergslagen area (Kumpulainen et al 1996;Lundström et al 1998;Andersson et al 2006;Stephens et al 2009). The age supports the idea that Mg-alteration occurred during a relatively early stage before c. 1.87 -1.8 Ga Svecokarelian orogeny (Stephens et al 2009).…”

Section: Discussionmentioning

confidence: 87%

An epigenetic magnesite deposit in the Bergslagen area, central Sweden

Högmalm

Hellingwerf

Cornell

et al. 2012

GFF

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A Palaeoproterozoic magnesite deposit in the Bergslagen ore province in Sweden is characterized in terms of petrography and major element, trace element and stable isotope compositions. The magnesite horizons are situated at the contact between a metamorphosed gabbro intrusion and felsic metavolcanic rocks, in association with iron-oxide mineralizations and intense Mg-metasomatism. The alteration of the surrounding rocks is used to explain the formation of the magnesite, and chemical dating of hydrothermal monazite constrains the timing of Mg-alteration to a pre-metamorphic age of 1911^16 Ma (2s). High Y contents in hydrothermal monazite in both metavolcanic and magnesite samples indicate a temperature of . 4008C for the hydrothermal alteration. C and O isotopic composition of the magnesite points to interaction with seawater at 200-2508C. We conclude that the magnesite was formed by replacement of a carbonate precursor through hydrothermal alteration, induced by the emplacement of the gabbro intrusion.

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“…Evolving geochronology has demonstrated large-scale Svecofennian growth in the 1.91-1.86 Ga interval (Lahtinen & Huhma 1997;Lundström et al 1998) and that migmatisation occurred prior to emplacement of the ~1.85 Ga Askersund suite. These rocks, along with the 1.83-1.82 Ga OJB intrusions, demonstrate southwestward-stepping growth along the Svecofennian crust in southern Sweden.…”

Section: Svecofennian Constraintsmentioning

confidence: 98%

Transitioning from Svecofennian to Transcandinavian Igneous Belt (TIB) magmatism in SE Sweden: Implications from the 1.82 Ga Eksjö tonalite

Åhäll¹,

Connelly

Brewer

2002

GFF

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Stratigraphies and depositional ages of Svecofennian, Palaeoproterozoic metavolcanic rocks in E. Svealand and Bergslagen, south central Sweden

Cited by 39 publications

References 16 publications

Pre-1.91 Ga deformation and metamorphism in the Palaeoproterozoic Vammala Migmatite Belt, southern Finland, and implications for Svecofennian tectonics

Pre-1.91 Ga deformation and metamorphism in the Palaeoproterozoic Vammala Migmatite Belt, southern Finland, and implications for Svecofennian tectonics

An epigenetic magnesite deposit in the Bergslagen area, central Sweden

Transitioning from Svecofennian to Transcandinavian Igneous Belt (TIB) magmatism in SE Sweden: Implications from the 1.82 Ga Eksjö tonalite

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