Three-D Mineralogical Mapping of the Kovdor Phoscorite-Carbonatite Complex, NW Russia: II. Sulfides

Abstract

Abstract:The world largest phoscorite-carbonatite complexes of the Kovdor (Russia) and Palabora (South Africa) alkaline-ultrabasic massifs have comparable composition, structure and metallogenic specialization, and can be considered close relatives. Distribution of rock-forming sulfides within the Kovdor phoscorite-carbonatite complex reflects gradual concentric zonation of the pipe: pyrrhotite with exsolution inclusions of pentlandite in marginal (apatite)-forsterite phoscorite, pyrrhotite with exsolution inclusions of cobaltpentlandite in intermediate low-carbonate magnetite-rich phoscorite and chalcopyrite (±pyrrhotite with exsolution inclusions of cobaltpentlandite) in axial carbonate-rich phoscorite and phoscorite-related carbonatite. Chalcopyrite (with relicts of earlier bornite and exsolution inclusions of cubanite and mackinawite) predominates in the axial carbonate-bearing phoscorite and carbonatite, where it crystallizes around grains of pyrrhotite (with inclusions of pentlandite-cobaltpentlandite and pyrite), and both of these minerals contain exsolution inclusions of sphalerite. In natural sequence of the Kovdor rocks, iron content in pyrrhotite gradually increases from Fe 7 S 8 (pyrrhotite-4C, Imm2) to Fe 9 S 10 (pyrrhotite-5C, C2 and P2 1 ) and Fe 11 S 12 (pyrrhotite-6C) due to gradual decrease of crystallization temperature and oxygen fugacity. Low-temperature pyrrhotite 2C (troilite) occurs as lens-like exsolition inclusions in grains of pyrrhotite-4C (in marginal phoscorite) and pyrrhotite-5C (in axial phoscorite-related carbonatite). Within the phoscorite-carbonatite complex, Co content in pyrrhotite gradually increases from host silicate rocks and marginal forsterite-dominant phoscorite to axial carbonate-rich phoscorite and carbonatite at the expense of Ni and Fe. Probably, this dependence reflects a gradually decreasing temperature of the primary monosulfide solid solutions crystallization from the pipe margin toward its axis. The Kovdor and Loolekop phoscorite-carbonatite pipes in the Palabora massif have similar sequences of sulfide formation, and the copper specialization of the Palabora massif can be caused by higher water content in its initial melt allowing it to dissolve much larger amounts of sulfur and, correspondingly, chalcophile metals.

Neoproterozoic Lysan Alkaline–Ultramafic Complex in the Eastern Sayan, Southern Siberia, Russia: Mineralogical Constraints of Carbonate Rocks and Albitite for Petrogenesis

“…The Sallanlatvi and Ozernaya Varaka Massifs are good examples of this [13,60]. While the carbonatites of the Kovdor [68][69][70][71], Vuorijärvi [72], and Ozernaya Varaka [73] massifs have been extensively studied, the origin of the carbonate veins in the Lesnaya Varaka Massif remains unclear [60,74].…”

Sulfide mineralization of phoscorites and carbonatites of the guli massif (Polar Siberia) and potential of these rocks on noble metals

“…L -расплав. Эти минералы были описаны в зонах замещения ранних сульфидов карбонатитов и фоскоритов Палаборы, ЮАР, и Ковдора, Кольский п-ов, а также в поздних доломит-кальцитовых и анкеритовых карбонатитах массивов Вуориярви, Хибины, Кандагубский, Кольский п-ов (Шпаченко, Савченко, 2004;Шпаченко, 2012Шпаченко, , Pilipiuk et al, 2001Rudashevsky et al, 2004;Petrov et al, 2018;Ivanyuk et al, 2018). Пределы температур кристаллизации благороднометальных фаз оцениваются для Палаборы в 80−480°С (Рудашевский, 2001), Ковдора -470-500°С (Рудашевский, 1995), Вуориярви -105−300°С (Шпаченко, Савченко, 2004), что в принципе согласуется с полученными нами данными для сульфидов Гулинского массива -500-150°С и ниже.…”

Mineralogy and petrology of alkaline rocks and carbonatites: Celebrating the life and work of Gregory Yu. Ivanyuk (1966–2019)

“…Ivanyuk and Goryainov's ‘self-organisation’ team published two books on this expansive subject (Goryainov and Ivanyuk, 2001; Bazai et al , 2009), which were highly appraised by the Nobel laureate and one of the fathers of non-equilibrium thermodynamics Ilya Prigogine, who even wrote a letter to the Russian Foundation for Fundamental Research, urging them to provide additional financial support to Ivanyuk and Goryainov's efforts. It is noteworthy here that Gregory's interests in Kola rocks were not purely theoretical and he made a lasting contribution to our understanding of mineral deposits as diverse as iron formations, phoscorites and apatite ores, particularly in his latter years and in collaboration with his younger colleagues (Ivanyuk et al , 2016, 2018a, b; Kalashnikov et al , 2016, 2017; Mikhailova et al , 2016, 2017, 2018).…”