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：火山喷发期间硫的释放影响着全球气候，岩浆中的硫含量对岩浆-热液矿床的成因起着重要的控制作用。镁铁质、中质和花岗岩系中的原生硫化物(主要是磁黄铁矿、黄铜矿和辉钼矿)和其他含硫矿物(主要是磷灰石和方钠石族矿物)是最近许多研究的焦点，但到目前为止，还没有人在碱性-过碱性岩浆系统中对这一问题进行详细和系统的研究。本提案调查和比较了两个特征良好的碱性-过碱性深成杂岩(摩洛哥的塔马塞赫特和格陵兰的伊利马萨克)的原生硫化物清单及其空间相关和成因相关的脉岩。要研究的岩石的成分多样性很大，主要从辉长岩(碱性玄武岩)到二长岩(宽长岩)和正长岩(粗面岩)再到霞石正长岩(声橄榄岩)。因此，这一研究结果将对硫在碱性-过碱性岩浆体系中的行为具有普遍意义。将分析各种硫化物的主、次、痕量元素组成和硫同位素组成，以追踪其在岩浆分异过程中的成分演化。这些数据将与其他含硫矿物(磷灰石和方钠石)中硫浓度的测定以及共存的铁-镁硅酸盐和铁-钛氧化物的成分数据结合起来，因为这对它们形成过程中的主要氧和硫逸度提供了重要的限制。硫化物的硫同位素组成将制约岩浆的硫同位素组成和不同硫化物组合的结晶温度。两个杂岩内部和之间的差异有望揭示岩浆室过程的详细信息(例如，硫化物-硅酸盐熔体分离、分离结晶、岩浆补给、岩浆分层形成)，并将破译硫化物形成对碱性至过碱性岩浆的地球化学演化的影响，可能对此类系统的找矿具有重要意义。深成岩和脉岩的对比将提供详细的洞察，了解与不同冷却速度和热液叠加强度有关的硫化物原生化学和同位素组成的保留和变化的潜在差异。

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.