Systematic variations in magmatic sulphide chemistry from mid-ocean ridges, back-arc basins and island arcs

摘要: Abstract Immiscible sulphide liquids preserved as magmatic globules are hosted in igneous rocks of highly variable composition formed during processes at different tectonic settings. Here we report on compositional situ data sulphides from mid-ocean ridge, back-arc and island arc systems. Iron-Ni-rich monosulphide solid solutions (mss) that mainly consist pyrrhotite pentlandite the dominant phases globules. In subduction-related magmas mss most abundant relatively evolved melts characterised by low Ni high Fe contents, well Ni/Cu ratios (  1). Thus, chemistry varies systematically lavas settings terms their Fe-Ni distribution ratio. The observed mineralogical chemical variations between reflect early S saturation accompanied olivine fractionation along ridges compared to later stage systems associated with Fe-Ti oxide fractionation. These systematics probably related oxidised character subduction zone opposed more reduced ridge melts. Large same locality individual samples suggest is a multistage or continuous process leading inclusions represent stages ascending magma.