Noble gas isotopes, although present in trace amounts, are generally more reliable and less ambiguous recorders of their source than the major volatile species. In volcanic settings in particular, this advantage derives from their chemical inertness, as noble gas isotopic and elemental fractionations are strongly coupled to their source and modified only by physical processes during magma ascent and eruption. The Neogene volcano El Hoyazo (Betic Cordillera, SE Spain) is a highly favourable natural laboratory to study the links between partial crustal melting processes occurring at depth and the eruptive products at the surface, because partially melted crustal xenoliths are preserved in silicic lavas. Comparing the noble gas isotopic compositions of xenoliths and lavas has the potential to yield new insights into volatile behaviour during melting processes at inaccessible depths in the crust.

At El Hoyazo, noble gases trapped in lava glasses, and the fluid/melt inclusions within xeno- and phenocrysts, provide novel information on: (i) their response to the crustal melting process including mechanisms such as magma mixing (and crustal assimilation) of two endmembers: i.e. the extracted felsic melt from the country metapelitic crust, and the basic-intermediate magma from the underplating in the region. The results reveal significant modification of magmatic noble gases by the interaction with the partially melted crust; (ii) noble gas variations during degassing and magma ascent, showing higher atmospheric influence in the lava samples from shallower depths than in the deeper lavas and minerals; and (iii) higher magmatic influence in crystals of garnet from deeper lava than in both shallower crystals of amphibole, and garnet crystals within the crustal xenoliths. In addition, we find that noble gases in melt inclusions are also likely accumulating in their shrinkage bubbles, and not only remaining dissolved in the melt.

稀有气体同位素虽然以痕量存在，但通常比主要挥发性物质更可靠、更不模糊。特别是在火山环境中，这种优势源于它们的化学惰性，因为惰性气体同位素和元素分馏与其来源强烈耦合，并且仅在岩浆上升和喷发期间通过物理过程进行修改。新近纪火山 El Hoyazo（贝蒂科迪勒拉，西班牙东南部）是一个非常有利的自然实验室，用于研究发生在深处的部分地壳熔化过程与地表喷发产物之间的联系，因为部分熔化的地壳捕虏体保存在硅质熔岩中。

在 El Hoyazo，熔岩玻璃中捕获的惰性气体以及异种和斑晶中的流体/熔体包裹体提供了以下新信息：（i）它们对地壳熔化过程的反应，包括岩浆混合（和地壳同化）等机制两个端元：即从该地区变泥质地壳中提取的长英质熔体，以及来自该地区底床的碱性-中级岩浆。结果表明，岩浆稀有气体通过与部分熔融地壳的相互作用发生了显着变化；(ii) 脱气和岩浆上升过程中的惰性气体变化，表明较深的熔岩和矿物对来自较浅深度的熔岩样本的大气影响更大；(iii) 来自较深熔岩的石榴石晶体比角闪石的较浅晶体具有更高的岩浆影响，和地壳捕虏体中的石榴石晶体。此外，我们发现熔体包裹体中的惰性气体也可能在其收缩气泡中积聚，而不仅仅是溶解在熔体中。