| Autor: |
Sobolev, I. D., Novikova, A. S., Vikentyev, I. V., Sheshukov, V. S., Dubensky, A. S., Travin, A. V., Varlamov, D. A., Bortnikov, N. S. |
| Předmět: |
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| Zdroj: |
Doklady Earth Sciences; 2022Suppl, Vol. 507, pS357-S364, 8p |
| Abstrakt: |
In the Polar Urals, there are a few small granitoid intrusions (Yarkeu, Yajyu, and Pogurei complexes), which are usually associated with the Urals collision. Their Carboniferous–Early Permian age is generally based on methodologically obsolete K/Ar dates and is assumed from the field geological relationships. We have studied the monzonitoids of the Yarkeu petrotypical pluton, one of the largest intrusions, and for the first time we obtained the Late Precambrian U–Pb LA-ICP-MS (zircon) and 40Ar/39Ar (amphibole) dates of 687 ± 3 Ma and 669 ± 8 Ma, respectively. The water-saturated fluid regime (the presence of magmatic amphibole with a high water content of 4.5–5.6 wt %), hypabyssal formation conditions (P = 2.1–3.5 kbar, T = 871–960°C), and specific features of the chemical composition of monzonitoids (low contents of TiO2 (0.6–0.8 wt %) and CaO (3.6–6.3 wt %), high contents of Al2O3 (16.6–18.0 wt %) and K2O (1.7–4.6 wt %), enrichment in large-ion lithophile elements relatively to high field strength and rare earth elements, and the Ta–Nb minimum and Pb maximum), as well as metallogenic specialization in Cu and Mo (±Pb, Hg, Au), indicate the formation of the rocks of the Yarkeu complex in the supra-subduction setting in the relatively thick continental crust. The isotopic clocks in these monzonitoids imprinted two stages of the assembly of the Pangea supercontinent: the earliest stage in the Late Precambrian, when monzonitoids were formed on the active Bolshezemel margin of Arctida, and one of the final stages in the Middle–Late Carboniferous, when rocks were affected by metamorphism due to the closure of the Uralian paleo-ocean and the beginning of collision between Arct-Laurussia and Siberia. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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