Decoupling of inorganic and organic carbon during slab mantle devolatilisation.
Decoupling of inorganic and organic carbon during slab mantle devolatilisation.
复制标题
板片地幔脱挥发分过程中无机碳和有机碳的解耦。
DOI：
10.1038/s41467-022-27970-0
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发表时间：
2022-01-14
影响因子：
16.6
通讯作者：
Burton KW
中科院分区：
文献类型：
--
作者：
Bouilhol P;Debret B;Inglis EC;Warembourg M;Grocolas T;Rigaudier T;Villeneuve J;Burton KW
蛇纹岩是无机碳和有机碳的重要汇，其在俯冲过程中的行为被认为在全球碳循环中起着重要作用。在这里，我们表明，流体衍生的静脉保存在Zermart-Saas超高压蛇纹岩提供的关键证据，碳酸盐流动性蛇纹岩脱挥发分。我们通过对脉矿物和寄主蛇纹岩的O、C和Sr同位素分析表明，约90%的变蛇纹岩无机碳在板状脱挥发分过程中被再活化。相比之下，类石墨含碳化合物仍然被困在寄主岩石内的变质橄榄石内的夹杂物，而大量的有机碳的元素和同位素组成保持相对不变，在俯冲过程中。这表明在俯冲带蛇纹岩脱水过程中碳的退耦行为。因此，这一过程将促进无机碳向地幔楔的转移和有机碳向深部地幔的优先板状封存。水化地幔岩石储存了大量的有机和无机碳，影响了地质循环。在俯冲过程中，碳酸盐回到上层板块，而有机碳仍然被困在地球深处进行再循环。
Serpentinites are an important sink for both inorganic and organic carbon, and their behavior during subduction is thought to play a fundamental role in the global cycling of carbon. Here we show that fluid-derived veins are preserved within the Zermatt-Saas ultra-high pressure serpentinites providing key evidence for carbonate mobility during serpentinite devolatilisation. We show through the O, C, and Sr isotope analyses of vein minerals and the host serpentinites that about 90% of the meta-serpentinite inorganic carbon is remobilized during slab devolatilisation. In contrast, graphite-like carbonaceous compounds remain trapped within the host rock as inclusions within metamorphic olivine while the bulk elemental and isotope composition of organic carbon remains relatively unchanged during the subduction process. This shows a decoupling behavior of carbon during serpentinite dehydration in subduction zones. This process will therefore facilitate the transfer of inorganic carbon to the mantle wedge and the preferential slab sequestration of organic carbon en route to the deep mantle. Hydrated mantle rocks store a significant amount of organic and inorganic carbon, impacting the geological cycle. During subduction the carbonate return to the upper plate while organic carbon remains trapped to be recycled in the deep earth.