Petrology of Nickeliferous Mafic–Ultramafic Bodies of the Southeastern Aldan-Stanovoy Shield

Abstract

Consideration is given to the nature of mafic–ultramafic bodies in the southeastern part of the Aldan-Stanovoi Shield using the Kun-Manie ore field as an example. These bodies played an important role in the formation of the Kun-Manie sulfide copper–nickel deposit as conduits of sulfide-bearing magmas. A detailed mineralogical and geochemical study with interval sampling was carried out on core samples from the drilling of two intrusive bodies, Treugolnik and Iken, using drill holes 21 and 25. The drill–core data present evidence for their origin from a single parent magma. The Treugolnik and Iken minor intrusions were emplaced in magmatic chambers at different depths during the cotectic crystallization of dark minerals from the primary picrite (Treugolnik body) and intermediate picrobasalt (Iken body) magmas. A comparative study of petrogeochemical and mineralogical data suggests that the Treugolnik intrusion formed as a closed system with magma emplaced in a single, relatively rapid injection and crystallized without losses; the Iken sill formed as an open system as a result of magma emplacement in several pulses with time intervals between injections. These magma bodies, together with the host metamorphic rocks, were involved in tectonic deformations after they crystallized.