Geochronology of Precambrian formations of the north of the Urals

Abstract

The paper summarizes results of work on the geochronological confirmation of the age of metamorphic structures occurring at the base of the Precambrian of the north of the Urals and the age of overlying Upper Precambrian basal sediments. It is shown that the occurrences of early stages of metamorphism of rocks of metamorphic (polymetamorphic) complexes date back to about 2.1 Ga. Their substrate is unambiguously related to the Lower Precambrian. We determined that Mesoproterozoic strata are absent Upper Precambrian sections of the north of the Urals, in contrast to more southern regions of the Urals. The basal strata in the Lyapin and Kharbey-Marunkeu anticlinoria, according to the data obtained, are dated to the Middle Neoproterozoic (cryogenian). The established fact of the absence of deposits of a huge age interval (Mesoproterozoic — at least 600 Ma) in the north of the Urals can be explained by a high standing of the territory of the northeast (in modern coordinates) of the Baltic craton, a fragment of which at that time was the Timan-Northern Ural lithospheric segment, and the location in the interiors of the Columbia (Nuna) supercontinent.

The Gold–Palladium Ozernoe Occurrence (Polar Urals, Russia): Mineralogy, Conditions of Formation, Sources of Ore Matter and Fluid

“…The geologic setting of the Ozernoe occurrence at the Dzelyatyshor massif, petrographic and petrochemical characteristics, and mineralogic-geochemical features of rocks and gold-palladium mineralization were reported in previous studies [8][9][10][11]. In this study, we conducted a detailed analysis of the mineral composition and mineral parageneses of gold-palladium ores from the Ozernoe occurrence and obtained the first data on the deposition temperature of noble metal minerals, using the chlorite geothermometer, studied the sulfur isotopic composition of sulfides, determined the sources of ore matter and fluid, and revealed the features of the distribution of Pd and Cu in native gold.…”

“…Clinopyroxenite bodies hosting gold-palladium mineralization of the Ozernoe occurrence were initially attributed to the Karshor complex. In terms of the most modern concepts [10], these clinopyroxenites are identified in the Dzelyatyshor wehrliteclinopyroxenite massif which is isolated from the Karshor complex. In the petrochemical characteristics, the Dzelyatyshor massif is similar to the wehrlite-clinopyroxenite series of the Platinum-bearing Belt of the Urals and possesses the features of layering displayed in the replacement of olivine by non-olivine rocks from bottom to top.…”

“…Its contacts with hosting gabbroids of the Karshor complex are tectonic. The Dzelyatyshor massif is composed of a continuous layered series of rocks-non-olivine clinopyroxenite-olivine clinopyroxenite wehrlite [10]. Mineralization belongs to the poor sulfide stratiform type and tends to sheet-like bodies of olivine clinopyroxenites in the upper part of the massif.…”

“…Mineralization belongs to the poor sulfide stratiform type and tends to sheet-like bodies of olivine clinopyroxenites in the upper part of the massif. The bodies consist of 13 ore bodies from 2 to 30 m in thickness [10]. The content of metals in the ores, determined using atomic absorption spectrometry, are: 1.5 wt.% Cu, 2.9 ppm Au, 3.7 ppm Pd, and 1.0 ppm Pt [9,10].…”

“…The bodies consist of 13 ore bodies from 2 to 30 m in thickness [10]. The content of metals in the ores, determined using atomic absorption spectrometry, are: 1.5 wt.% Cu, 2.9 ppm Au, 3.7 ppm Pd, and 1.0 ppm Pt [9,10].…”