Sulfide saturation in alkaline to peralkaline igneous rocks.

硫在硅酸盐熔体中的行为是一个广泛讨论的话题：它在火山爆发期间的释放影响全球气候，岩浆中的硫含量对岩浆-热液矿床的成因起着主要的控制作用。原生硫化物（主要是磁黄铁矿、黄铜矿和硫铁矿）等含硫矿物（主要是磷灰石和方钠石族矿物）在镁铁质、中间岩和花岗岩系统中的作用一直是最近许多研究的焦点，但在碱性-过碱性岩浆体系中，这一问题还没有进行过详细系统的研究。特征为碱性至过碱性深成岩体（摩洛哥的Tamazeght和格陵兰岛的Ilimaussaq）及其空间上相关和成因上相关的岩墙岩。待调查的岩石涵盖了大量的成分多样性，主要从辉长岩（碱性玄武岩）通过二长岩（红土）和正长岩（粗面岩）霞石正长岩（响岩）组成。因此，本研究的结果将具有普遍意义的行为，硫在碱性至过碱性岩浆系统。分析了各种硫化物的主、次、微量元素组成和硫同位素组成，以跟踪岩浆分异过程中硫化物的成分演化。这些数据将与其他含硫矿物（磷灰石和方钠石）中硫浓度的测定和共存的铁镁硅酸盐和铁钛氧化物的成分数据相结合，因为这提供了重要的限制，在其形成过程中占主导地位的氧和硫逸度。硫化物的硫同位素组成将对岩浆的硫同位素组成和不同硫化物组合的结晶温度提供约束。两个复合体内部和之间的变化有望揭示岩浆房过程的详细见解（例如，硫化物-硅酸盐熔体分离、分离结晶、岩浆补给、岩浆分层的形成），并将破译硫化物形成对碱性至过碱性岩浆地球化学演化的影响，并可能对此类系统的成矿潜力产生影响。深成岩和岩墙岩之间的比较将提供详细的洞察潜在的差异方面的保留和改变的主要化学和同位素组成的硫化物有关不同的冷却速率和强度的热液叠加。

The behavior of sulfur in silicate melts is a widely discussed topic: Its release during volcanic eruptions affects the global climate, and the sulfur content of magmas exerts a major control on the genesis of magmatic to hydrothermal ore deposits. Primary sulfides (mainly pyrrhotite, chalcopyrite and molybdenite) and other sulfur-bearing minerals (mainly apatite and sodalite group minerals) in mafic, intermediate and granitic systems have been the focus of many recent studies, but no detailed and systematic study on this topic in alkaline to peralkaline magmatic systems has been undertaken so far.The present proposal investigates and compares the primary sulfide inventory of two otherwise well-characterized alkaline to peralkaline plutonic complexes (Tamazeght in Morocco and Ilimaussaq in Greenland) and their spatially associated and genetically related dyke rocks. The rocks to be investigated cover a large compositional diversity ranging mainly from gabbroic (alkali basaltic) via monzonitic (latitic) and syenitic (trachytic) to nepheline syenitic (phonolitic) compositions. Therefore, the results of this study will have general implications for the behavior of sulfur in alkaline to peralkaline magmatic systems. The various sulfides will be analyzed for their major, minor and trace element composition and their sulfur isotopic composition in order to track their compositional evolution during magmatic differentiation. These data will be combined with determination of sulfur concentrations in other sulfur-bearing minerals (apatite and sodalite) and with compositional data on co-existing Fe-Mg silicates and Fe-Ti oxides, since this provides important constraints on prevailing oxygen and sulfur fugacity during their formation. The sulfur isotope composition of the sulfides will provide constraints on the sulfur isotope composition of the magmas and the temperature of crystallization of the different sulfide assemblages.The variability within and between the two complexes is expected to reveal detailed insights into magma chamber processes (e.g., sulfide-silicate melt separation, fractional crystallization, magma recharge, formation of magmatic layering) and will decipher the influence of sulfide formation on the geochemical evolution of alkaline to peralkaline magmas with possible implications for the ore potential of such systems. The comparison between plutonic rocks and dyke rocks will provide detailed insight into potential differences with respect to the retention and alteration of the primary chemical and isotopic compositions of sulfides related to different cooling rates and the intensity of hydrothermal overprint.