The alteration of platinum group minerals (PGM) of eluval, proximal, and distal placers associated with the Ural-Alaskan type clinopyroxenite-dunite massifs were studied. The Isovsko-Turinskaya placer system is unique regarding its size, and was chosen as research object as it is PGM-bearing for more than 70 km from its lode source, the Ural-Alaskan type Svetloborsky massif, Middle Urals. Lode chromite-platinum ore zones located in the Southern part of the dunite “core” of the Svetloborsky massif are considered as the PGM lode source. For the studies, PGM concentrates were prepared from the heavy concentrates which were sampled at different distances from the lode source. Eluvial placers are situated directly above the ore zones, and the PGM transport distance does not exceed 10 m. Travyanistyi proximal placer is considered as an example of alluvial ravine placer with the PGM transport distance from 0.5 to 2.5 km. The Glubokinskoe distal placer located in the vicinity of the Is settlement are chosen as the object with the longest PGM transport distance (30–35 km from the lode source). Pt-Fe alloys, and in particular, isoferroplatinum prevail in the lode ores and placers with different PGM transport distance. In some cases, isoferroplatinum is substituted by tetraferroplatinum and tulameenite in the grain marginal parts. Os-Ir-(Ru) alloys, erlichmanite, laurite, kashinite, bowieite, and Ir-Rh thiospinels are found as inclusions in Pt-Fe minerals. As a result of the study, it was found that the greatest contribution to the formation of the placer objects is made by the erosion of chromite-platinum mineralized zones in dunites. At a distance of more than 10 km, the degree of PGM mechanical attrition becomes significant, and the morphological features, characteristic of lode platinum, are practically not preserved. One of the signs of the significant PGM transport distance in the placers is the absence of rims composed of the tetraferroplatinum group minerals around primary Pt-Fez alloys. The sie of the nuggets decreases with the increasing transport distance. The composition of isoferroplatinum from the placers and lode chromite-platinum ore zones are geochemically similar.

This work presents the results of the first comprehensive study of PGE mineralization from massive chromitites of the Iov dunite body (Northern Urals). The chromitites are composed of...

The article reports the preliminary research results of a multilayer site, which comprises the cultural layers dating from the Middle Ages, Kuro-Araks culture, Eneolithic, Neolithic and Epipaleolithic. Of particular interest are the Neolithic layers dating from ca. 8.2 ka BP or 6.300 BC to 7.5–6.7 ka BP or 5.700–4.800 BC. The site shows not only the earliest evidence of the Ceramic Neolithic in the North Caucasus and also provides the authors an opportunity to study the transformation of the Neolithic culture over time. There is no ceramics in the lower layer. Lithic assemblage from this layer is dated to 9.5 ka BP and shows many similarities in the materials of the Epipaleolithic sites of the Elbrus region. A hunter-gatherer camp from the beginning of the Holocene, which existed during the Pereslavl cold stage (ca. 10–9 ka BP), has been preserved in the layer.

The results of U–Pb isotope dating of perovskites from silicate–calcite vein rocks spatially associated with the Kusa–Kopan gabbro intrusion are presented. At present, the genesis of these silicate–carbonate rocks remains controversial. The obtained U–Pb ages are 497.0 ± 4 Ma for perovskite from the Perovskite mines and 468 ± 6.4 Ma for that from the Zelentsovskaya mine. The obtained ages are significantly different from the age of the Kusa–Kopan gabbro intrusion (1379 ± 8 Ma). Furthermore, the REE distribution trend (LA–ICP–MS) in the perovskites studied is similar to that in perovskites from carbonatites and kimberlites. Together with the geochronological data, this suggests that the carbonate–silicate rocks studied originated from a carbonatite origin. Additional confirmation of the manifestation of Early Paleozoic diastrophism in the region studied is the U–Pb age of zircons from volcanics of the Bashkir anticlinorium obtained earlier by various methods.

This study presents the first comprehensive investigation of perovskite from its type locality (Mineral Mines of Southern Urals, Russia), where this mineral was first described by Gustav Rose in 1839. The new data includes results from precise chemical analyses (electron-probe microanalyzer, LA-ICP-MS) and U-Pb ages (SHRIMP-II) of perovskite. Perovskite occurs in silicate-carbonate veins that transect the marginal parts of the Middle Riphaean Kusinsko-Kopanskaya layered intrusion, previously thought to be skarns. The perovskite crystals range from micrometer-scale grains to up to 11 cm in size. Chemical investigations revealed a low content of trace elements (rare earth elements, Y, Nd, U, Th) compared to perovskites from alkaline ultramafic rocks, silica-undersaturated basic rocks, carbonatites, and kimberlites. The determined age of the perovskite, 535 ± 43 Ma, significantly differs from the 1379 ± 8 Ma age of the Kusinsko-Kopanskaya intrusion, challenging the skarn-origin hypothesis for perovskite. Instead, the findings suggest a carbonatite origin for the perovskite mineralization. This timing indicates a previously unknown stage of endogenic activity on the Western Slope of the Southern Urals.