Contrasting platinum-group mineral assemblages from chromitites of the Nizhny Tagil and Guli massifs (Russia): Implications for composition, sources and age

U–Pb geochronology of calcite carbonatites and jacupirangite from the Guli alkaline complex, Polar Siberia, Russia

“…Yegorov, 1991, p. 30). However, this interpretation is inconsistent with the much older age of dunites reported by Malich et al (2011), who interpreted these rocks as ophiolite-type blocks of Ediacaran age juxtaposed by alkaline–ultramafic magmas.…”

“…This interpretation is supported by their low negative εNd and high initial 87 Sr/ 86 Sr values (Kogarko and Zartman, 2007). It is also noteworthy that the dunites are viewed by some researchers as much older rocks unrelated to the Permian–Triassic event (Malitch et al , 2011).…”

Native osmium from the Guli Massif, Northern Siberia, Russia

“…If it would be assumed that the Guli Massif represents an Uralian-Alaskan type intrusion, and if Uralian-Alaskan type intrusions are the product of arc volcanism (Murray 1972), then derivation of native osmium from the core-mantle boundary region becomes an unlikely scenario. On the other hand, if the Guli Massif is considered as Aldantype complex, which may have a translithospheric mantle origin (e.g., Kondyor; Burg et al 2009), these massifs could be well corresponded according to osmium isotope studies (Malitch 1998;Malitch and Kostoyanov 1999;Malitch et al 2005Malitch et al , 2007. These studies indicated a near-to-chondritic source with no obvious crustal contamination and are therefore in accordance with a deep mantle source of the native osmium.…”

“…Wehrlite and magnetite-rich clinopyroxenite form dikes, stockworks, and lenticular bodies within the dunite. A restricted number of bedrock-hosted platinum-group minerals (PGM) in dunite and chromitite have been described by Balmasova et al (1992); Malitch and Rudashevsky (1994); Malitch (1999) and Malitch et al (2003Malitch et al ( , 2005Malitch et al ( , 2011.…”

Petrogenesis of the Platinum-Group Minerals

“…CI-chondrite (Naldrett and Duke 1980) normalized patterns of different rock types from CUAAC. Data plotted in the top three graphs correspond to rocks from the Nizhny Tagil zoned complex in the Urals (Augé et al 2005a;Malitch et al 2011c). Average PGE concentration data for chromitites and dunites from other CUAAC are presented as follows: the Kytlym, Uktus Flekistovsky and Kyrlyn complexes of the Urals (Garuti et al , 2003Zaccarini et al 2011), Serpentinite Hill in Tasmania (Brown et al 1998), Tulameen in British Columbia, Canada ) and Viravira and Condoto in Colombia (Tistl 1994).…”