The Uralide Orogen is one of the main Paleozoic belts formed during the assembly of Pangea. The present-day Urals (Uralian Mountains, N-S-trending through northern Eurasia) expose the relics of this Paleozoic orogen. The Voykar Massif, located at the Polar Urals, is an ophiolite assemblage composed mainly of mantle tectonite, gabbroic to ultramafic plutonic sequence and sheeted dikes with a MORB-type source. Geochronological data for this region show a wide range of ages and are mainly based on U-Pb zircon data, although some Rb-Sr and Sm-Nd are available. We present high-resolution U-Pb (LA-ICP-MS) analyses performed on zircon crystals extracted from a plagiogranite vein associated with a porphyritic dolerite dike. Magmatic zircon grains yielded a U-Pb age of 428.1±7.4 Ma, corresponding to the Wenlock Period (middle Silurian). This age suggests a late stage of oceanic crust generation in the Voykar basin. Different ages from plagiogranite and gabbroic bodies suggest that oceanic spreading lasted from ca. 490 to 425 Ma, i.e., at least 65 Ma or even longer, in the Voykar basin.

Massif

Dike

Porphyritic

Ultramafic rock

10.4454/ofioliti.v41i2.443

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U–Pb-(SHRIMP-II)-age of zircon from granites of Bolshoy Tyuters Island (Gulf of Finland, Russia) and the problem of the Ediacaran thermal event in the region

Доклады РОССИЙСКОЙ АКАДЕМИИ НАУК Науки о Земле (2024)

С. Г. Скублов E. N. Terekhov Н. Б. Кузнецов A. B. Makeyev Л. И. Салимгараева

New data on the U–Pb age (SHRIMP-II) and trace element composition (SIMS) of zircons from granites of Bolshoy Tyuters Island (Outer Islands of the Gulf of Finland) are presented. The upper intersection of the discordia (1825±11 Ma) is taken as the age of crystallization of granites cutting through secondary quartzites, and thereby determines their youngest age. Subconcordant zircons located in the upper part of the discordia has growth oscillatory zoning and geochemical characteristics of zircons of magmatic origin. The age of the lower intersection of discordia and concordia is about 570 Ma, supported by the independent generation of zircons, represented by black in the CL domains and rims in magmatic zircons, which are characterized by increased contents of non-formula elements (light REE, Ca, P, Ti, Nb, etc. ), up to anomalous values. The most probable interpretation of the age of the lower intersection of discordia and concordia can be considered the Timan (Ediacaran) or Finnmark (Early Caledonian) thermal activation of the Fennoscandian Shield, previously established based on zircons from gneisses of the Kola series.

10.31857/s2686739724070104

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The First Results of U–Pb Isotope Dating of Detrital Zircons from the Upper Mesoproterozoic Gulliksenfellet Quartzite (Southern Part of Wedel Jarlsberg Land, Southwest Spitsbergen)

Doklady Earth Sciences (2018)

Н. Б. Кузнецов Т. V. Romanyuk Елена Белоусова

10.1134/s1028334x18030194

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First results of U–Pb dating of detrital zircons from the Upper Ordovician sandstones of the Bashkir uplift (Southern Urals)

Doklady Earth Sciences (2016)

Н. Б. Кузнецов Елена Белоусова К. Е. Degtyarev E. S. Pyzhova А. В. Маслов