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| Titel |
Achaean TTG and high alimunia gneisses on Baltic Shield: Precise U-Pb (ID-TIMS) and SHRIMP-II ages on single zircon |
| VerfasserIn |
Tamara Bayanova, Ludmila Morozova, Felix Mitrofanov, Pavel Serov, Elena Nitkina, Dzorzh Fedotov, Alexander Larionov |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091184
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| Publikation (Nr.) |
 EGU/EGU2014-5460.pdf |
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| Zusammenfassung |
| New U-Pb (ID-TIMS) data on single zircon from high alimunia gneisses near Murmansk in the Central-Kola domain gave 3.17 Ga. Core from these zircon population has the age 3695±5 Ma by SHRIMP-II. Time of amphibolites metamorphism was dated with 2753±3 Ma.
Achaean gneisses in Monchegorsk ore region were firstly dated in the Central-Kola domain. Single zircon from gneisses in Monchegorsk region which are the basement for Paleoproterozoic PGE layered intrusions with U-Pb ages on zircon and baddeleyite from 2.4-to 2.5 Ga (Bayanova et all, 2009) has 3.16 Ga. Single zircon from gnneisses gave 2776±3 Ma and is considered as amphibolites metamorphism.
Voche-Lambina international polygon lies on the boundary between Belomorian mobile block and Central –Kola domain (Morozova et al, 2011). New neoarhaean U-Pb data on single zircon from TTG of polygon yielded 3158.2±8.2. Zircon are characterized by low concentration U and Pb, low U/Th ratio with 0.2. REE diagrams of grey gneisses reflect high fractionation La/Yb>30,encriched by light REE and depleted by heavy Yb<0.6 ppm. Model Sm-Ng ages on the rocks have protolith from with the ages 3.4 to 3.2 Ga, positive εNd from +1.29 to +3.3, ISr equals 0.702. Precise (ID-TIMS) age of amphibolites metamorphism has been dated on single zircon with 2704.3±5.9 Ma.
In the frame of the Central-Kola domain there is an Ingosersky TTG complex. Firstly U-Pb dating on single zircon from Bt-gneisses reflects 3149±49 Ma. Metamorphic alterations were in 2725.2±2.5 Ma and connected with origin of Amf-Bt gneisses and 2733.6±6.6 with Bt-Amf gneisses. (NItkina et al., 2012).
Therefore based on the new data on single zircon from TTG and high alimunia gneisses from Central-Kola domain leads to the long history of continental crust origin in the Baltic or Fennoscandian Shield from 3.16 to 3.7 Ga.
We thank to G. Wasserburg for 205 Pb artificial spike, J. Ludden for 91500 and Temora standards, F. Corfu, V. Todt and U. Poller for assistance in the establishing of the U-Pb method for single zircon and baddeleyite grains. The studes are contribution and supported by RFBR 13-05-00493, OFI-M 13-05-12055, Department of Earth Sciences RAS, programs 4, 6 and IGCP 599. |
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