A combined petrological, geochemical and geochronological study of the magmatic rocks surrounding the Logatchev hydrothermal field.

在SPP的最后阶段，我们建议进行岩石学和火成岩地球化学（实验）联合研究项目，以研究Logatchev热液区岩浆岩。大量的样品可以获得或将被收集，我们可以用来研究岩浆（和能量）从地幔到地壳的运输，地壳的形成，以及岩浆岩和热液流体之间的相互作用。通过对Logatchev油田深部岩体和火山岩的岩石学、地球化学和同位素分析，确定它们之间的相互关系和结晶深度。为了实现这些目标，采用了不同的方法：(1)在αH2O和fD2的大范围内建立相平衡模型，包括平衡、分数和多压结晶计算；(2)研究了矿物中的玻璃包裹体，以了解挥发物在分化过程和上升过程中的行为和重要性；(3)研究了辉长岩对自然样品分异过程的深度和温度约束，并与理论模拟结果进行了对比。岩浆岩的岩石学和地球化学研究将揭示与热液流体的反应，这些反应可能导致地壳重熔和同化。铀系列定年法将得出火山作用的年龄估计，从而得出岩浆上升到地表作为可能热源的时间。因此，该项目将成为SPP内部地幔和地壳的岩浆过程与海底和浅层地壳的热液过程之间的重要联系。

For the last period of the SPP we suggest a joint research project of (experimental) petrology and igneous geochemistry in order to study the magmatic rocks in the region of the Logatchev hydrothermal field. A large number of samples is accessible or will be collected which we can use to study the transport of magmas (and energy) from the mantle to the crust, the formation of the crust, and the interaction between the magmatic rocks and hydrothermal fluids. Petrological, geochemical and isotopic analysis of plutonic and volcanic rocks from the Logatchev field will establish their relationship and depth of crystallization. To achieve these goals, different approaches are used: (1) phase equilibria are modeled in a wide range of αH2O and fD2 and include equilibrium, fractional, and polybaric crystallization calculations; (2) glass inclusions in minerals are investigated to understand the behavior and importance of volatiles in differentiation processes and during ascent; (3) gabbros are investigated to constrain depth and temperature of the differentiation process based on natural samples in comparison with the results from the theoretical simulations. Petrologic and geochemical studies of the magmatic rocks will reveal reactions with hydrothermal fluids, which may have led to crustal remelting and assimilation. Uranium series dating will yield age estimates of the volcanic processes and thus of the timing of magma ascent to the surface as possible heat sources. This project will thus represent an essential link within the SPP between the magmatic processes in the mantle and crust and the hydrothermal processes at the seafloor and the shallow crust.