Institute of Geosciences, University of Potsdam, 14476 Potsdam, Germany.
Dipartimento di scienze Chimiche e Geologiche, University of Cagliari, 09042 Monserrato, Italy.
Sci Adv. 2023 Feb 10;9(6):eabp9482. doi: 10.1126/sciadv.abp9482.
Subduction is the main process that recycles surface material into the mantle. Fluids and melts derived by dehydration and partial melting reactions of subducted continental crust, a major reservoir of volatiles (i.e., HO and CO) and incompatible elements, can substantially metasomatize and refertilize the mantle. Here, we investigate glassy inclusions of silicate melt of continental origin found in Variscan ultrahigh-pressure eclogites to assess the continental crust contribution to mantle metasomatism and the journey of volatiles, carbon in particular, to the deep roots of mountain belts. We argue that the melt preserved in these inclusions is the agent responsible for mantle metasomatism and subsequent ultrapotassic magmatism in the Variscides. We propose that continental subduction can redistribute a substantial volume of carbon in the continental lithosphere, which is subsequently transferred to the continental crust during postcollisional magmatism and stored for a time length longer than that of the modern carbon cycle.
俯冲是将地表物质循环到地幔的主要过程。俯冲大陆地壳（挥发物和不相容元素的主要储层，即 HO 和 CO）脱水和部分熔融反应产生的流体和熔体可以极大地交代和再生地幔。在这里，我们研究了在华力西超高压榴辉岩中发现的源自大陆的硅酸盐熔体的玻璃质包裹体，以评估大陆地壳对地幔交代作用的贡献以及挥发性物质，特别是碳，向山脉深根迁移的过程。我们认为，这些包裹体中保存的熔体是负责地幔交代作用和随后在华力西地区超钾质岩浆作用的原因。我们提出，大陆俯冲可以在大陆岩石圈中重新分配大量的碳，随后在碰撞后岩浆作用过程中转移到大陆地壳中，并储存一段时间，比现代碳循环的时间还要长。
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