An ion microprobe U-Th-Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe, eastern Finland

Peltonen, P.; Mänttäri, Irmeli

doi:10.17741/bgsf/73.1-2.004

Cited by 28 publications

(5 citation statements)

References 24 publications

(27 reference statements)

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“…Etheridge et al, 1987;Rutland et al, 2001b). However, both the Svionian and younger extensional events may also have contributed to the underplating (e.g.a t1.8 Ga, Peltonen & Mänttäri, 2001).…”

Section: Concluding Commentmentioning

confidence: 99%

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: Concluding Commentmentioning

confidence: 99%

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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“…1.8 Ga comes from kimberlites and related rocks. Abundant ages around 1.8 Ga in zircon xenocrysts and zircons in lower crustal xenoliths from Palaeozoic kimberlites have shown that significant portions of the mafic lower crust, at least in east-central Finland formed around this age Peltonen and Mänttäri 2001;Peltonen et al 2006). This supports a connection between the small 1.8 Ga middle to upper crustal post-kinematic intrusions Downloaded by [McGill University Library] at 04:44 27 September 2012 and coeval widespread mafic underplating.…”

Section: Geodynamic Inferencesmentioning

confidence: 99%

1.8 Ga magmatism in southern Finland: strongly enriched mantle and juvenile crustal sources in a post-collisional setting

Rutanen

Andersson

Väisänen

et al. 2010

International Geology Review

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“…The latter idea is supported by the results of the Re-Os isotope investigation of sulfides from peridotite xenoliths in this pipe with estimation of their model age ranging from 2.9 to 3.1 Ga [13]. Investigation of zircon xenoc rysts from the Lakhtoika kimberlitic pipe in Eastern Finland with a similar task formulation revealed two concordant zircon populations of the lower crustal and/or upper mantle genesis with an age of 2.7 and 1.8 Ga [14]. Because of this, it is evident that Pale oproterozoic alteration of the lower crust and lithos pheric mantle was intense over the whole region.…”

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confidence: 62%

U-Pb Age and geochemistry of zircons from xenoliths of the V. Grib kimberlitic pipe, Arkhangelsk diamond province

et al. 2012

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An ion microprobe U-Th-Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe, eastern Finland

Cited by 28 publications

References 24 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

1.8 Ga magmatism in southern Finland: strongly enriched mantle and juvenile crustal sources in a post-collisional setting

U-Pb Age and geochemistry of zircons from xenoliths of the V. Grib kimberlitic pipe, Arkhangelsk diamond province

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