Magmatic and hydrothermal prerequisites for porphyry-epithermal mineralisation in continental volcanic arcs, Thrace, NE Greece

为绿色过渡提供关键和能源关键要素是一项日益严峻的挑战。这些金属和类金属中的许多都有很强的副产品依赖性，因此它们的供应取决于主要目标商品。这些因素对欧洲联盟能源和经济部门的强烈影响使其具有战略重要性。因此，必须减少对中国这样的采矿业国家的依赖，以确保未来的原材料供应，因为它们从这些国家的进口可能面临风险，因为政治紧张局势导致供应链瓶颈。在这方面，需要重新探索欧洲大陆，以限制富含关键和能源关键要素的经济区。希腊东北部色雷斯的矿床就是这样一个例子，在欧洲成矿化的陆弧背景下，金属和类金属(如铜、镓、锗、硒、钼、锑、碲、稀土、金和铋)的高密度带出现在不同的地壳深度。这包括直接靠近岩浆室的斑岩环境，以及较浅的浅表热液系统，其中一些甚至可能保存了表面表达。矿床矿物学已观察到区域差异，但斑岩-浅成热液矿床的成矿过程仍缺乏从微量元素角度的约束。导致这种矿化弧系形成的岩浆和热液先决条件也仍然存在争议，但对于发现大陆地壳中关键和能源关键元素的正异常是必不可少的。伴生的深成岩和火山岩/次火山岩的痕量金属和类金属成分将提供有关地壳深部岩浆作用的新结果，以及这些元素在岩浆上升到地表时的潜在损失；进入可能为上覆斑岩-浅成热液系统提供补给的区域。这使得能够研究岩浆脱气以及硫化物饱和和分离在中下地壳形成预浓缩的影响，作为弧形矿化的可能岩浆先决条件。黄铁矿和磁铁矿赋存于上覆热液系统中大多数含金属矿脉中。对这些矿物的高分辨率微量元素分析将从三维角度，即在地层和区域背景下，提供对成矿过程的洞察。热液黄铁矿的(原位)S同位素组成有助于更好地了解岩浆与热液系统的相互作用过程。因此，岩浆和热液作用的联合研究使这一方法变得独特，并将有助于发展关于S和金属来源、分馏和降水的新基本概念，最终确定欧洲大陆火山弧成矿和能量关键元素富集的岩浆和热液先决条件。

Supplying critical and energy critical elements for the green transition is a growing challenge. Many of these metals and metalloids have a strong by-product dependency and their supply therefore depends on the primary target commodities. The strong impact of these elements on the energy and economy sector of the European Union gives them a strategic importance. Thus, the dependency on mining countries like China must be reduced to secure the future supply of raw materials, since their import from these countries may be at risk because of political tensions leading to bottlenecks in the supply-chain. In this respect, the European continent needs to be re-explored to constrain economic zones enriched in critical and energy critical elements. The deposits of Thrace, NE Greece, represent such an example, where zones with high metal and metalloid concentrations (e.g., Cu, Ga, Ge, Se, Mo, Sb, Te, Re, Au and Bi) occur at variable crustal depth in a mineralized continental arc setting in Europe. This includes the porphyry environment in the direct vicinity of a magma chamber, as well as shallower epithermal systems with some that may even preserve a surface expression. Regional variations in deposit mineralogy have been observed, but the ore-forming processes of the porphyry-epithermal deposits are still poorly constrained from a trace element perspective. The magmatic and hydrothermal prerequisites that lead to the formation of such a mineralised arc system are also still controversial, but essential to discover positive anomalies of critical and energy critical elements in the continental crust. The trace metal and metalloid composition of associated plutonic and volcanic/sub-volcanic rocks will provide new results on the magmatic processes in the deeper crust and the potential loss of these elements during magma ascent towards the surface; into regions where they may feed an overlying porphyry-epithermal system. This allows to investigate the effect of magma degassing, as well as sulphide saturation and segregation to form a pre-concentrate in the mid- to lower crust, as possible magmatic prerequisites for arc mineralisation. Pyrite and magnetite occur in most metal-bearing veins in the overlying hydrothermal system. High-resolution trace element analyses on these minerals will provide insights into the processes of ore-formation from a 3D perspective, i.e. in a stratigraphic and regional context. The (in situ) S isotope composition of hydrothermal pyrite will help to better understand the interaction processes between the magmatic and hydrothermal system. Hence, the combined investigation of magmatic and hydrothermal processes makes this approach unique and will help to develop new fundamental concepts with respect to S and metal sourcing, fractionation and precipitation, which ultimately defines the magmatic and hydrothermal prerequisites for continental volcanic arc mineralisation and energy critical element enrichment in Europe.