Tab. 2: U-Pb ion-microprobe ages from Taymyr peninsula

• Main Authors: Pease, Victria, Vernikovsky, Valerij
• Format: Dataset
• Language: English
• Published: PANGAEA 2000
• Subjects: -; 510; 510tay; 512; 512tay; 514; 514tay; 520; 520tay; 5562; 5562tay; Age; 206Pb/207Pb Lead-Lead; 238U/206Pb Uranium-Lead; comment; dated; dated standard deviation; Discordance; Geological sample; GEOS; Lead; Lead-206/Uranium-238; error; Lead-206/Uranium-238 ratio; Lead-207/Lead-206; standard error; Lead-207/Lead-206 ratio; Optional event label; Rock type; Sample code/label; Taymyr; Thorium; Thorium/Uranium ratio; Uranium; Kunar; Polarforschung; Taimyr; Taymyr Peninsula
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.759565; https://doi.org/10.1594/PANGAEA.759565

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 ...