Chemical Characteristics of Ore-Bearing Intrusions and the Origin of PGE–Cu–Ni Mineralization in the Norilsk Area

Abstract

The composition of the parental magmas of Cu–Ni deposits is crucial for the elucidation of their genesis. In order to estimate the role of magma in ore formation, it is necessary to compare the compositions of silicate rock intrusions with different mineralization patterns, as observed in the Norilsk region. The rock geochemistry of two massifs located in the same Devonian carbonate rocks—the Kharaelakh intrusion, with its world-class platinum-group element (PGE)–Cu–Ni deposit, and the Pyasinsky–Vologochansky intrusion, with its large deposit—was studied. Along with these massifs, the Norilsk 2 massif with noneconomic mineralization intruded in the Ivakinskaya–Nadezhdinskaya basalts was studied as well. Their settings allow the estimation of the parental magma composition, taking into account the possible assimilation of host rocks. Analyses of 39 elements in 97 samples demonstrated the similarity of the intrusions in terms of their major components. The Pyasinsky–Vologochansky intrusion contains the highest trace element contents compared with the Kharaelakh and Norilsk 2 massifs, evidencing its crystallization from evolved parental magma. No influence of host rocks on the silicate rock compositions was found, except for narrow (1–2 m) endo-contact zones. There is no correlation between the mineralization volume and the rock compositions of the studied intrusions. It is assumed that the intrusions were formed from one magma crustal source irregularly rich in sulfur (S). This source inhomogeneity in terms of the sulfur distribution resulted in deposits of varying sizes. The magmas served as a transporting agent for sulfides from deep zones to the surface.

Geochemical Distribution of Platinum Metals, Gold and Silver in Intrusive Rocks of the Norilsk Region

“…The observed clear differences in morphostructural features, internal structure, composition, degree of differentiation and content of the ore component allowed distinguishing of the Talnakh (also known as Norilsk or Norilsk-Talnakh), Zubovsk, Kruglogorsk and Lower Talnakh types of intrusions within the Norilsk intrusive complex. The silicate composition of rocks of all the intrusions is quite similar, despite their different positions in the stratigraphic section and a different mineralization [5,6] (excepting the latter type).…”

Lithogeochemistry in exploration for intrusion-hosted magmatic Ni-Cu-Co deposits

“…Data sources for figures Song et al 2006;Tao et al 2008;Hanski et al 2010;Pang et al 2010;. Li et al Barnes and Kunilov 2000;Li et al 2003;Barnes et al 2019b;Schoneveld et al 2020a;Krivolutskaya et al 2021) …”

Abstracts from the early-career researchers virtual International Platinum Symposium, May 2022

“…Left panel – typical example of the ‘low-sulfide’ assemblage in the Noril'sk-1 intrusion (BSE-photo): dark grey matrix – silicates, light grey grains – chromite, white segregations – sulfides. Right panel – a generalised genetic scheme, assuming that a part of olivine and sulfide liquid are brough from a deep chamber as inferred by Krivolutskaya et al (2021). [3]…”