New data on origin and age (U-Pb, SHRIMP-II) of zircons from khondalites of the Lapland granulite belt (Baltic Shield)

Мыскова, Т. А.; Глебовицкий, В. А.; Mil’kevich, R. I.; Berezhnaya, N. G.; Скублов, С. Г.; Presnyakov, S. L.; Shuleshko, I. K.; Lvov, P. A.

doi:10.1134/s1028334x08080254

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“…The thickness of the tectonostratigraphic succession amounts to 7-8 km. In the history of the belt, there were three metamorphic events, (1) 2.79-2.71 Ga, (2) 2.66-2.64 Ga, and (3) 2.58-2.55 Ga [Bibikova, 1989;Avakyan, 1992;Glebovitsky, 2005;Petrovskaya et al, 2007;Myskova, Milkevich, 2005;Levchenkov et al, 1995;Myskova et al, 2008;Bayanova, 2004].…”

Section: The First Prominent Superplume Event Recognizable Worldwide mentioning

confidence: 99%

Age and isotopic geochemical characteristics of Archean carbonatites and alkaline rocks of the Baltic shield

2007

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Paradoxically, the lists of "proxies" of both plate-and plume-related settings are devoid of even a mention of the high-grade metamorphic rocks (granulite, amphibolite and high-temperature eclogite facies). However, the granulite-gneiss belts and areas which contain these rocks, have a regional distribution in both the Precambrian and the Phanerozoic records. The origin and evolution of the granulite-gneiss belts correspond to the activity of plumes expressed in vigorous heating of the continental crust; intraplate magmatism; formation of rift depressions filled with sediments, juvenile lavas, and pyroclastic flow deposits; and metamorphism of lower and middle crustal complexes under conditions of granulite and high-temperature amphibolite facies that spreads over the fill of rift depressions also. Granulite-gneiss complexes of the East European Craton form one of the main components of the large oval intracontinental tectonic terranes of regional or continental rank. Inclusion of the granulite-gneiss complexes from Eastern Europe, North and South America, Africa, India, China and Australia in discussion of the problem indicated in the title to this paper, suggests consideration of a significant change in existing views on the relations between the plate-and plume-tectonic processes in geological history, as well as in supercontinent assembly and decay. The East European and North American cratons are fragments of the long-lived supercontinent Lauroscandia. After its appearance at ~2.8 Ga, the crust of this supercontinent evolved under the influence of the sequence of powerful mantle plumes (superplumes) up to ~0.85 Ga. During this time Lauroscandia was subjected to rifting, partial breakup and the following reconstruction of the continent. The processes of plate-tectonic type (rifting with the transition to spreading and closing of the short-lived ocean with subduction) within Lauroscandia were controlled by the superplumes. Revision of the nature of the granulite-gneiss complexes has led to a fundamental new understanding of: a more important role than envisaged previously for mantle-plume processes in the juvenile additions to the continental crust, especially during the Neoarchaean-Proterozoic; the existence of the supercontinent Lauroscandia from ~2.80 to 0.85 Ga; the leading role of mantle plumes in the interaction of plate-and plume-tectonics in the Neoarchaean-Proterozoic history of Lauroscandia and perhaps of the continental crust as a whole. We propose that the evolution of the geodynamic settings of the Earth's crust origin can be represented as a spiral sequence: the interaction of mantle-plume processes and embryonic microplate tectonics during the Palaeo-Mezoarchaean (~3.8-2.8 Ga) → plume-tectonics and local plume-driven plate-tectonics (~2.80-0.55 Ga) → Phanerozoic plate tectonics along with a reduced role of mantle plumes.Key words: Precambrian; plate-tectonics; plume-tectonics; granulite-gneiss belts; supercontinent; intracontinent oval orogenRecommended by E.V. Sklyarov Аннотация: Ка...

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Section: The First Prominent Superplume Event Recognizable Worldwide mentioning

confidence: 99%

Age and isotopic geochemical characteristics of Archean carbonatites and alkaline rocks of the Baltic shield

2007

View full text Add to dashboard Cite

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New data on origin and age (U-Pb, SHRIMP-II) of zircons from khondalites of the Lapland granulite belt (Baltic Shield)

Cited by 1 publication

References 6 publications

Age and isotopic geochemical characteristics of Archean carbonatites and alkaline rocks of the Baltic shield

Age and isotopic geochemical characteristics of Archean carbonatites and alkaline rocks of the Baltic shield

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