The Palaeoproterozoic Gallujavri Ultramafic Intrusion, Karasjok Greenstone Belt; Petrogenesis of a Trans-Crustal Magma System

Abstract The modern concepts of magmatic plumbing systems have evolved from simple models melt-dominated crustal magma chambers to that span the continental crust. geochemistry these is challenging model numerically because a complex polybaric and multiphase evolution, which not well described by mathematic end-member formulas. We propose recent modelling tool, Magma Chamber Simulator (MCS), can reveal part petrological complexities such systems. MCS phase equilibria, mineral chemistry major trace elements in multicomponent–multiphase finding extremes appropriate state functions. This study presents new petrographical geochemical data Palaeoproterozoic Gallujavri ultramafic intrusion Karasjok Greenstone Belt, Arctic Norway. Our indicate (1) affected assimilation, (2) equilibria require crystallisation (3) spinel compositions are similar sub-volcanic intrusions flood basalt provinces. utilise simulate petrogenesis test comparing it against our reported data. shows parental consistent with coeval Karasjok-type komatiites observed at various places throughout greenstone belt. First, komatiitic primary intruded Archaean lower crust (c. 700 MPa), where fractionation assimilation resulted hybrid melt. Second, melt migrated accumulated mid-crustal chamber 400 continued fractionate assimilate while remaining open recharge mantle-derived melts, forming intrusion. interpret as trans-crustal system, many similarities other Fennoscandian ultramafic-mafic layered intrusions.