Carbon recycling efficiency in subduction zones constrained by the effects of H2O-CO2 fluids on partial melt compositions in the mantle wedge
Carbon recycling efficiency in subduction zones constrained by the effects of H2O-CO2 fluids on partial melt compositions in the mantle wedge
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俯冲带碳循环效率受 H2O-CO2 流体对地幔楔部分熔体成分影响的限制
DOI：
10.1016/j.epsl.2022.117578
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发表时间：
2022
影响因子：
5.3
通讯作者：
Dasgupta, Rajdeep
中科院分区：
文献类型：
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作者：
Lara, Michael;Dasgupta, Rajdeep
二氧化碳从俯冲岩性向上覆地幔楔体的转移程度，特别是向弧岩浆源区的转移程度仍然存在争议。如果能结合观测到的原始弧岩浆组成来评价co2对地幔楔初级含水熔体组成的影响，就可以估计co2向亚弧地幔转移的极限。本文提出了一种新的活塞缸和多砧实验，使用au75pd25和Au胶囊在4种枯竭橄榄岩+ H2O±CO2起始成分（3.5 wt.% H2O和XCO2[=摩尔CO2/ (CO2+ H2O)]为0-0.17）上进行。实验在2-4 GPa和1200°C下进行，以约束板状衍生水溶液中可变co2的存在如何影响橄榄岩部分熔体的组成。所有实验均为低熔体（<10 wt.%），与橄榄石+正辉石±斜辉石平衡。当XCO2值为0 ~ 0.10时，熔体为玄武质；当XCO2值为0 ~ 0.10时，熔体变为贫sio2富cao。我们的实验部分熔体成分与全球最原始弧岩浆数据的比较表明，在2-4 GPa下，XCO2in流体诱导地幔楔块熔化的上限为~ 0.10。我们将这些新的约束应用到俯冲带的H2O和co2质量平衡模型中，并估计至少34-86%的co2进入俯冲带，绕过亚弧熔体生成带，由板块或直接在板块上方的地幔楔的下拉分支携带，并俯冲到对流地幔中。
The extent of CO2transfer from subducting lithologies to the overlying mantle wedge in general and to the arc magma source regions in particular remains debated. The limit of CO2transfer to the sub-arc mantle could be estimated if the effects of CO2on the primary hydrous melt compositions of mantle wedge can be assessed in relation to the observed compositions of primitive arc magmas. Here we present new piston cylinder and multi-anvil experiments using Au75Pd25and Au capsules on four depleted peridotite + H2O ± CO2starting compositions with 3.5 wt.% H2O and XCO2[= molar CO2/ (CO2+ H2O)] of 0–0.17. Experiments were performed at 2–4 GPa and 1200 °C to constrain how the presence of variable CO2in slab-derived aqueous fluids affects the composition of peridotite partial melts. All experiments consisted of low degree melts (<10 wt.%) in equilibrium with olivine + orthopyroxene ± clinopyroxene. Melts at 2–4 GPa are basaltic for XCO2of 0–0.10 and become SiO2-poor and CaO-rich at XCO2> 0.10. Comparison between our experimental partial melt compositions with a global dataset of the most primitive arc magmas suggests that the upper limit of XCO2in fluids inducing melting in mantle wedges is ∼0.10 at 2–4 GPa. We apply these new constrains to an H2O and CO2mass balance model for subduction zones and estimate that at least 34–86% of CO2entering subduction zones bypasses the sub-arc melt generation zone and is subducted to the convecting mantle, either carried by the slab or by the down-dragged limb of the mantle wedge directly above the slab.
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影响因子：
5.3
作者：
Grove, Timothy L.;Chatterjee, Nilanjan;Medard, Etienne
通讯作者：
Medard, Etienne
影响因子：
5
作者：
Lara, Michael;Dasgupta, Rajdeep
通讯作者：
Dasgupta, Rajdeep
高压高温下的 Fe-Ni-Cu-C-S 相关系 – 硫在上地幔中深层碳储存和金刚石稳定性中的作用
影响因子：
5.3
作者：
K. Tsuno;R. Dasgupta
通讯作者：
R. Dasgupta
影响因子：
5.3
作者：
Blundy, Jonathan;Cashman, Katharine V.;Witham, Fred
通讯作者：
Witham, Fred
1）3万个微卫星位置、PCR引物、多态性频率等信息数据库。
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