The Source of Ore Fluids and Sm–Nd Age of Siderite from the Largest Bakal Deposit, Southern Urals

Abstract— Based on Sm–Nd data, a crustal source of iron-ore fluid was substantiated and the probability of age estimation for hydrothermal–metasomatic siderite of the Bakal Group, Southern Urals, was shown for the first time. The εNd (Т) values of siderite (from –13.4 to –17.6) plot in the field of Riphean shale and not the Precambrian rift gabbro and granite of this region. The obtained Sm–Nd age of the Bakal siderite is 970 ± 40 Ma, which is consistent with the Pb–Pb age of siderite from the major ore phase (~1000 Ma). The established age boundary coincides with tectonic restructuring, including the formation of a number of barite–polymetallic deposits, as well as ferruginous magnesite and fluorite in the Riphean deposits on the western slope of the Southern Urals.

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The Lower Precambrian in the structure of paleozoic in the Subpolar Urals

Доклады Академии наук ◽

10.31857/s0869-56524865572-576 ◽

2019 ◽

Vol 486 (5) ◽

pp. 572-576

Author(s):

Yu. I. Pystina ◽

A. M. Pystin ◽

V. B. Hubanov

Keyword(s):

Southern Urals ◽

Western Slope ◽

Geochronological Data ◽

The Urals ◽

The Southern Urals ◽

Early Precambrian ◽

Subpolar Urals ◽

Late Precambrian ◽

Lower Riphean ◽

First Time

In many polymetamorphic complexes of the Urals, rocks with Early Precambrian age marks have been established. But only with respect to the two polymetamorphic complexes located on the western slope of the Southern Urals: the Taratash and Aleksandrov, their indisputable belonging to the Archean-Paleoproterozoic section is recognized. They are framed by weakly metamorphosed Lower Riphean sediments and reliable geochronological data are obtained from them, which unambiguously indicate the Early Precambrian age of rock metamorphism. The available Early Precambrian age datings for other Ural polymetamorphic complexes (with the prevailing number of Late Precambrian and Paleozoic age values) are interpreted differently. Therefore, their attitude to the Lower Precambrian section has been disputed by many researchers. In the article, for the first time, based on the results of mass U-Pb dating of metamorphic zircons from the gneiss of the Nyrtin polymetamorphic complex of the Subpolar Urals, taking into account the available data, the Paleoproterozoic age of the earliest stage of rocks metamorphism (2127 ± 31 Ma) is substantiated. This gives grounds to assert that the complex under consideration, as well as the Taratash and Alexandrov complexes of the Southern Urals, belongs to the Lower Precambrian formations involved in the structure of Uralides.

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The first data on possible Mezozoic magmatism within the Western slope of the Southern Urals

Moscow University Bulletin. Series 4. Geology ◽

10.33623/0579-9406-2018-5-24-34 ◽

2018 ◽

pp. 24-34

Author(s):

A. O. Khotylev ◽

N. B. Devisheva ◽

Al. V. Tevelev ◽

V. M. Moseichuk

Keyword(s):

Southern Urals ◽

Western Slope ◽

Isotopic Age ◽

The Southern Urals ◽

Early Proterozoic ◽

Carbonate Formations ◽

Two Bodies

Within the Western slope of the Southern Urals, there are plenty of basite dyke complexes of Riphean to Vendian among Precambrian terrigenous-carbonate formations. In metamorphic formations of the Taratash complex (Archean to Early Proterozoic, the northern closure of the Bashkirian meganticlinorium) there was observed the andesitic dyke with isotopic age of 71±1 Ma (U-Pb SHRIMP II on zircons) and near Bakal two bodies of gabbroids with zircons of similar ages were found. These are the first evidence of possible Mezozoic magmatism in this region.

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ORDOVICIAN DEPOSITS ON THE WESTERN SLOPE OF THE SOUTHERN URALS AND THEIR CORRELATION BASED ON CONODONTS AND CHITINOZOANS

Геология и геофизика ◽

10.15372/gig20160204 ◽

2016 ◽

Vol 57 (02) ◽

Keyword(s):

Southern Urals ◽

Western Slope ◽

The Southern Urals

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The First Find of Cr2O3 Eskolaite Associated with Marble-Hosted Ruby in the Southern Urals and the Problem of Al and Cr Sources

Minerals ◽

10.3390/min10020101 ◽

2020 ◽

Vol 10 (2) ◽

pp. 101

Author(s):

Aleksander Kissin ◽

Irina Gottman ◽

Sergei Sustavov ◽

Valery Murzin ◽

Daria Kiseleva

Keyword(s):

Granite Gneiss ◽

Southern Urals ◽

X Ray Diffraction ◽

The Southern Urals ◽

Near Surface ◽

X Ray ◽

Gneiss Domes ◽

Electron Probe Microanalyzer ◽

Formation Zone ◽

First Time

The results of the study of eskolaite associated with marble-hosted ruby found for the first time in the Kuchinskoe occurrence (Southern Urals) are presented. Here, eskolaite was located on the surface and near-surface regions of ruby crystals. Eskolaite diagnostics was confirmed by powder X-ray diffraction (URS-55). The morphology and chemical composition of eskolaite and associated ruby was studied using a JSM-6390LV scanning electron microscope and a Cameca SX 100 electron probe microanalyzer. The eskolaite crystals were hexagonal and tabular, up to 0.2 mm in size. Ruby mineralization was formed during prograde and retrograde dynamothermal metamorphism. The eskolaite associated with the prograde stage ruby contained Al2O3 (9.1–23.62 wt %), TiO2 (0.52–9.66 wt %), V2O3 (0.53–1.54 wt %), FeO (0.03–0.1 wt %), MgO (0.05–0.24 wt %), and SiO2 (0.1–0.21 wt %). The eskolaite associated with the retrograde stage ruby was distinguished by a sharp depletion in Ti and contained Al2O3 (12.25–21.2 wt %), TiO2 (0.01–0.07 wt %), V2O3 (0.32–1.62 wt %), FeO (0.01–0.08 wt %), MgO (0.0–0.48 wt %), and SiO2 (0.01–0.1 wt %). The associated rubies contained almost equal amounts of Cr2O3 (2.36–2.69 wt %) and were almost free from admixtures. The identification of the eskolaite associated with the marble-hosted rubies from the Kuchinskoe occurrence is a new argument in favor of introduction of Al and Cr into the mineral formation zone. The mineralization was localized in the metamorphic frame of the granite gneiss domes and was formed synchronously with them.

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