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Pease, Victria; Vernikovsky, Valerij (2000): Tab. 2: U-Pb ion-microprobe ages from Taymyr peninsula. doi:10.1594/PANGAEA.759565, Supplement to: Pease, V; Vernikovsky, V (2000): The tectono-magmatic evolution of the Taimyr Peninsula: further constraints from new ion-microprobe data. Polarforschung, 68, 171-178, hdl:10013/epic.29804.d001

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Abstract:
We present the initial results of a U-Th-Pb zircon ion-microprobe investigation on samples from the Central Belt of Taimyr, in order to constrain its tectono-magmatic evolution. The zircon samples are from a deformed twomica granite (Faddey Massif), deformed metamorphosed gabbroic dike entrained as pods and lenses within metamorphosed tholeiitic basalts of the Kunar-Mod volcanic suite (Klyaz'ma River region), a metamorphosed rhyolite of the same volcanic suite overlying the basic metavolcanic rocks, as well as an undeformed dolerite dike which intrudes the metamorphosed Kunar-Mod basic volcanic rocks.
Preliminary results on zircons from the two-mica granite suggest a crystallization age of ~630 Ma for this rock, with inheritance from assimilated crust 840 Ma to 1.1 Ga in age. In the Klyaz'ma River region, zircons from the meta-rhyolite yield a concordant age of -630 Ma. Zircons from the entrained metagabbroic dikes have so far yielded an age of -615 Ma (1 grain), as well as Archean ages (5 grains, concordant at 2.6-2.8 Ga). It seems likely that the Archean grains represent assimilation of older crustal material. Zircons from the post-tectonic dolerite dike have a bimodal age distribution. A well-defined younger age of 281 ±9 Ma is interpreted to represent the crystallization age of the dike, while older, concordant ages of 2.6-2.9 Ga likely represent assimilation of Archean crust (Siberian craton at depth).
Several important conclusions can be drawn from the data. (1) The mafic and felsic lithologies of the Kunar-Mod volcanic suite are genetically related and should be the same age. Ages of-630 Ma (meta-rhyolite) and -615 Ma (metagabbroic dikes representing the latest stage of mafic magmatism associated the Kunar-Mod suite) suggest that these lithologies may be the same age, but more data are required to confirm this hypothesis. (2) The 630 Ma two-mica granite is similar in age to the time of high-grade metamorphism, suggesting that syntectonic granite emplacement accompanied obduction of the accretionary Central Belt to the Siberian craton. (3) An Early Permian age is well defined for the undeformed dolerite dike. Dolerite dikes occur across the whole of Taimyr, but are deformed to the south. If related, this single magmatic event pre-dates Permo-Triassic Siberian trap magmatism. Furthermore, it suggests that deformation was localized to southeastern Taimyr.
Coverage:
Median Latitude: 77.142020 * Median Longitude: 104.194000 * South-bound Latitude: 76.916700 * West-bound Longitude: 103.180000 * North-bound Latitude: 77.240000 * East-bound Longitude: 107.100000
Event(s):
510tay (510) * Latitude: 77.166700 * Longitude: 103.750000 * Location: Taymyr * Device: Geological sample (GEOS)
512tay (512) * Latitude: 77.170000 * Longitude: 103.700000 * Location: Taymyr * Device: Geological sample (GEOS)
514tay (514) * Latitude: 77.216700 * Longitude: 103.180000 * Location: Taymyr * Device: Geological sample (GEOS)
Comment:
Position of sites digitized from map.
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethodComment
1Optional event labelEvent 2
2Rock typeRockPease, Victria
3Sample code/labelSample labelPease, Victriagrain.spot; c=core, m=rim
4UraniumUmg/kgPease, Victria
5LeadPbmg/kgPease, Victria
6ThoriumThmg/kgPease, Victria
7Thorium/Uranium ratioTh/UPease, Victria
8--Pease, Victriaf 206 [%]
9Lead 207/Lead 206 ratio207Pb/206PbPease, Victria
10Lead 207/Lead 206, standard error207Pb/206Pb std e±Pease, Victria1 sigma
11Lead 206/Uranium 238206Pb/238UPease, Victria
12Lead 206/Uranium 238, error206Pb/238U e±Pease, Victria1 sigma
13Age, datedAge datedkaPease, VictriaAge, 206Pb/207Pb Lead-Lead
14Age, dated standard deviationAge std dev±Pease, VictriaAge, 206Pb/207Pb Lead-Lead
15Age, datedAge datedkaPease, VictriaAge, 238U/206Pb Uranium-Lead
16Age, dated standard deviationAge std dev±Pease, VictriaAge, 238U/206Pb Uranium-Lead
17DiscordanceD%Pease, Victriarefers to the degree of discordance at the 2 sigma error limit between 207Pb/206Pb and 206Pb/238U ages
18Age, commentCommPease, Victria* = values are not included in mean age determinations
Size:
564 data points

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