Сибирский федеральный университет

Тип публикации: доклад, тезисы доклада, статья из сборника материалов конференций

Конференция: Петрология магматических и метаморфических комплексов; Томск; Томск

Год издания: 2017

Аннотация: The new data on the composition of disseminated sulphide mineralization in the southern part of the Norilsk-1 deposit are obtained on the basis of the study of the PH-14 borehole. This borehole crosses all the rocks, alternating in a certain stratigraphic sequence which have been described earlier (Naldrett, 2003; Likhachev, 2006; Krivolutskaya, 2014). We studied samples of the upper horizon of the leucogabbro and the lower part of the intrusion, composed of picritic and olivine gabbrodolerites containing sulphide PGE-Cu-Ni mineralization. The changes of mineral parageneses and compositions of sulfides from picritic gabbrodolerite (821.2-902.0 m) and olivine gabbrodolerite (902.0-938.1) to massive veins on the contact with the host rocks have been studied. Absolute concentrations of Ni and Cu almost in the whole interval of the investigated section do not exceed of 0.5%, but there are single anomalies reaching 2-3%, which coincide with the presence of massive veins. Ni predominates over Cu (average Ni/Cu is 1.24) in picritic gabbrodolerite, but there are several horizons, where Ni/Cu <1, which coincide with Pt-Pd anamalies. In olivine gabbrodolerites, on the contrary, Cu prevails over Ni (the average Ni/Cu is 0.69). In general, Ni/Cu ratios vary considerably along section, gradually decreasing to contact with the host rocks and they are negatively correlated with Pd/Pt ratios. It is consistent with the evolution of sulphide melt and fractionation of ore elements during its deposition to the bottom of the magmatic chamber (Duran et al., 2017). The chalcopyrite-pentlandite-pyrrhotite assemblage with a predominance of pyrrhotite is characteristic of leucogabbro. Chrome spinels constitute a significant proportion of ore minerals. Arsenides and sulfoarsenides (nickeline, gersdorffite and hollingworthite) are also widely distributed in leucogabbro. A considerable variety of ore minerals are present in picritic gabbrodolerite: pyrrhotite, chalcopyrite, pentlandite, cubanite, talnakhite, chalcocite, bornite, native copper, millerite, magnetite and ilmenite, which are spread unevenly. It is noticed that the amount of pyrrhotite, chalcopyrite and pentlandite decreases with the increase of cubanite. The presence of Cu-rich minerals (talnakhite, bornite, chalcocite, native copper) are a typomorphic feature of the sulphide assemblage of picritic gabbrodolerites. Chrome spinels are distributed in the upper part of picritic gabbrodolerites - “chromite horizon”. In olivine gabbrodolerite sulfides are represented by a high-sulfur association composed of predominant chalcopyrite, pyrrhotite and pentanedite, as well as pyrite, which is distributed in the lower part of this interval. Chrome spinels and copper-rich minerals are absent in this interval. In olivine gabbrodolerites a positive correlation appears between amount of chalcopyrite and pentlandite and a negative correlation of both these minerals with amount of pyrrhotite, which also distinguishes picritic gabbrodolerites from olivine ones. PGM are the smallest single- and two-phase inclusions in all sulphides, silicates and on their contacts. Sperrylite is found in all types and horizons of rocks. For the upper horizons of picritic gabbrodolerite the compounds of Pd with Sn and Pb are characteristic [(PdJSn, (Pd,Pt)3(Sn,As,Sb), (Pd,Ag)5Pb3], which are changed by arsenides and As-containing PGM [RhAsS, PdNiAs, Pd(Sn,As)] on the lower horizons. In olivine gabbrodolerites, the michenerite (PdBiTe) of the upper horizon is changed by stannides and antimonides of PGE [(Pd,Pt)3Sn, Pd3(Sn,As), PdfSbJ, then Pd arsenides [PdNiAs, Pd3Ni-As, Pdfis и PdAsJ, and finally, by Pd tellurides [PdTe и Pd(Te,Bi)]. PGM in massive ores are represented by PtFe. The pentlandite is enriched in sulfur throughout the entire range of the rocks studied. The ratio of Me/S in it is 1.02 in picritic and 1.05 in olivine gabbrodolerite (1.12 in the sto

Журнал: Петрология магматических и метаморфических комплексов

Выпуск журнала: Выпуск 9

Номера страниц: 405-413

Место издания: Томск

Издатель: Томский центр научно-технической информации

• Толстых Н.Д. (Институт геологии и минералогии СО РАН)
• Шведов Г.И. (ООО «Геологические технологии»)
• Полонянкин А.А. (ООО «Русская платина»)
• Сильянов С.А. (Сибирский федеральный университет)
• Землянский С.А. (ООО «Новогео»)

• РИНЦ (eLIBRARY.RU)