Porphyry deposits host various trace elements in economic amounts, but the hydrothermal processes causing their fractionation and enrichment are still not fully understood, but vital to target the most prospective mineralisation. We present the first micro-analytical study on the trace element composition of pyrite from the Koloula Cu-Au porphyry in the young and thin (<25 km) Solomon Island arc. A statistical evaluation of the trace element data of pyrite indicates that mineral inclusions obscure the chemical signature of the mineralisation processes. The filtered pyrite data, from which the inclusions were excluded, correlate with variations in temperature and salinity, as defined by fluid inclusions from several alteration zones. Trace element ratios in pyrite show systematic variations with fluid temperature and salinity (Co/Ni), phase separation (Co/Ni, Co/As) and mixing of magmatic fluids and meteoric waters (Se/Ge, Se/Te). The mineralisation in the potassic alteration zone was controlled by the formation of a hypersaline liquid (Co/As>1, Co/Ni>50) from a magma-derived fluid (Se/Ge<100) at lithostatic pressure conditions and temperatures of up to 700°C (Se/Te>50). This was followed by a transition to hydrostatic pressure conditions due to open-fracture continuity towards the paleo-surface, marking the onset of boiling in the chlorite-sericite to sericitic alteration zone (Co/As<1), where minor proportions of meteoric water were involved (Se/Ge<100). The shallowest part of the mineralisation is controlled by lower temperature (<300°C, Se/Te<50) vapour-rich fluids (Co/As<1) that condensed into meteoric waters in an epithermal transition zone (Co/Ni<50, Se/Ge<100). Trace element systematics in pyrite from progressive alteration zones therefore preserve the time-space evolution of porphyry(-epithermal) systems in young and thin oceanic island arcs.

斑岩矿床含有经济量的各种微量元素，但导致其分馏和富集的热液过程仍未完全了解，但对于瞄准最具前景的矿化至关重要。我们首次对年轻而薄（<25 km）所罗门岛弧中 Koloula Cu-Au 斑岩中黄铁矿的微量元素组成进行了微量分析研究。对黄铁矿微量元素数据的统计评估表明，矿物包裹体掩盖了矿化过程的化学特征。过滤后的黄铁矿数据（其中排除了包裹体）与温度和盐度的变化相关，正如来自几个蚀变带的流体包裹体所定义的那样。黄铁矿中的微量元素比率显示出随流体温度和盐度 (Co/Ni) 的系统变化，相分离（Co/Ni、Co/As）以及岩浆流体和大气水（Se/Ge、Se/Te）的混合。钾蚀变带的矿化是由岩浆衍生流体（Se/Ge<100）在静岩压力条件和温度高达至 700°C (Se/Te>50)。随后由于向古地表的开放裂缝连续性转变为静水压力条件，标志着在绿泥石-绢云母到绢云母蚀变带 (Co/As<1) 开始沸腾，其中少量的大气水参与（Se / Ge <100）。矿化的最浅部分受低温（<300°C，Se/Te<50）富蒸汽流体（Co/As< 1）在超热液过渡带（Co/Ni<50，Se/Ge<100）凝结成大气水。因此，来自渐进蚀变带的黄铁矿中的微量元素系统保留了年轻和薄海洋岛弧中斑岩（浅热）系统的时空演化。