Petrology of Al- and Cr-rich ophiolitic chromitites from the Muğla, SW Turkey: implications from composition of chromite, solid inclusions of platinum-group mineral, silicate, and base-metal mineral, and Os-isotope geochemistry

Platinum-Group Minerals and Other Accessory Phases in Chromite Deposits of the Alapaevsk Ophiolite, Central Urals, Russia

“…In contrast, the majority of the supra-Moho chromitites are Al-rich and characterized by a variable content of TiO 2 (0.15 wt % to 0.8 wt %). Confirming the previous work by [8,[14][15][16][17]21], the composition of the Alapevsky chromite indicates the coexistence of the Al-rich and Cr-rich chromitites, a common feature of many ophiolitic belts worldwide [22,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50].…”

“…Chromite is widely accepted to be an important petrogenetic indicator and it can be used to define the geodynamic setting in which chromitites and their host rocks formed [29][30][31][32][33][34][35][36][37][38][39]. According to the morphology of the ore body and the chromite composition, chromitites belong to two main groups: (1) stratiform chromitites that form layers of massive chromite associated with mafic-ultramafic cumulates in the lower part of continental layered intrusions and supra-Moho cumulate sequences of ophiolites and (2) podiform chromitites that consist of lenses, pods, and schlieren, mainly occurring in the mantle section of ophiolites, orogenic lherzolites, and in the dunitic portion of Ural-Alaskan complexes [6,[29][30][31][32][33][34][35][36].…”

“…According to the morphology of the ore body and the chromite composition, chromitites belong to two main groups: (1) stratiform chromitites that form layers of massive chromite associated with mafic-ultramafic cumulates in the lower part of continental layered intrusions and supra-Moho cumulate sequences of ophiolites and (2) podiform chromitites that consist of lenses, pods, and schlieren, mainly occurring in the mantle section of ophiolites, orogenic lherzolites, and in the dunitic portion of Ural-Alaskan complexes [6,[29][30][31][32][33][34][35][36]. In the ophiolites of the Urals, both the mantle-hosted podiform chromitites as well as the supra-Moho stratiform chromitites have been described ( [6] and references therein).…”

Platinoid Microinclusions of Native Osmium Group in Ancient Gold Artifacts From Siberia and Urals as a Source of Geoarchaeological Information

“…Рутениевый (Ru) распола-гается в центре, имея субвертикальное положение от основания (Os-Ir) к рутениевой вершине; ириди-ево-осмиевый (Ir-Os) -в правой части и ориентиро-ван в направлении от иридиевой к осмиевой вершине параллельно основанию (Os-Ir). Эти два тренда объ-единяют большинство фигуративных точек и отве-чают составам минералов осмия из месторождений платиноидов, генетически связанных с гипербазитами [Tolstykh et al, 2002;Uysal et al, 2009;Агафонов и Иридиево-рутениевый тренд в правой части диа-граммы характерен для наноразмерных частиц (1-3 мкм и менее), которые окружают более крупные микро-включения. В них зафиксировано уменьшение количе-ства осмия и возрастание содержания иридия и руте-ния.…”

Native osmium from the Guli Massif, Northern Siberia, Russia

“…To avoid confusion with osmium as an element, we will refer to the mineral grains as native osmium. Native osmium has been described in situ from ophiolites (Dmitrenko et al 1985;Legendre and Augé 1986;Augé and Johan 1988;Ohnenstetter et al 1991;Ohnenstetter 1992;Melcher et al 1997;Augé et al 1998;Garuti et al 1999;Melcher 2000;Zaccarini et al 2005;Ahmed 2007;Shi et al 2007;El Ghorfi et al 2008;Kapsiotis et al 2009;Uysal et al 2009;Gonzalez-Jimenez et al 2010 and references cited therein) layered intrusions (Cabri and Laflamme 1988;Balabonin et al 1994;Merkle 1998), and predominantly from placer deposits all over the world (Feather 1976;Cabri et al 1996;Malitch 1996;Krstid and Tarkian 1997;Nakagawa and Franko 1997;Gornostayev et al 1999;Weiser and Bachmann 1999;Weiser 2002;Malitch and Merkle 2004;Barkov et al 2005;Tolstykh et al 2005Tolstykh et al , 2009 among many others). For many placers, the location and type of the source rocks (e.g.…”