Calcium Stable Isotopes of Tonga and Mariana Arc Lavas: Implications for Slab Fluid‐Mediated Carbonate Transfer in Cold Subduction Zones

Wang, Xia; Wang, Zaicong; Liu, Yongsheng; Park, Jung‐Woo; Kim, Jonguk; Li, Ming; Zou, Zongqi

doi:10.1029/2020jb020207

Cited by 12 publications

(14 citation statements)

References 122 publications

(325 reference statements)

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“…The estimated endmember δ 44/40 Ca value of AMMF falls in the Ca isotopic range of BSE, suggesting the metasomatism by slab-derived fluids may not significantly modify the Ca isotopic characteristics. This result is consistent with previous works demonstrating the Ca isotopic characteristics are rarely affected by carbonates released from AOC (Wang et al, 2021;Kang et al, 2021). After the metasomatism by slab-derived fluids, either the metasomatism by sediment melts or crustal contamination, or a combination of both, decreased the δ 44/40 Ca of Lutao arc magmas from BSE-like to MORB-like.…”

Section: Subduction-related Metasomatismsupporting

confidence: 94%

“…These results are consistent with previous works, demonstrating magma differentiation would produce negligible influence on the Ca isotopes of igneous rocks (Zhang et al, 2018;Chen et al, 2019;Zhu et al, 2020a;Wang et al, 2021). The Ca isotopic fractionation factor between Cpx and basaltic melt (αCpx-melt) at magmatic temperatures is close to 1 (Chen et al, 2019(Chen et al, , 2020a, and the residual melt would be only slightly affected by the accumulation of Cpx.…”

Section: Fractional Crystallizationsupporting

confidence: 92%

“…2). Furthermore, the Lutao arc magmas show similar ranges with that previously reported arc magmas from Tonga, Mariana, Central America, Southern Lesser Antilles, and Central-eastern Aleutian arcs (Wang et al, 2021;Kang et al, 2021).…”

Section: Isotopic Compositionssupporting

confidence: 86%

“…The δ 44/40 Ca of Lutao volcanics decreases significantly with subduction indicators, suggesting the metasomatism by sediment melts did affect the Ca isotopes of arc magmas. Such an effect, however, was absent in the reported BABBs and arc magmas (Zhu et al, 2020a;Wang et al, 2021;Kang et al, 2021 sediments (Plank and Langmuir, 1998;Zhu et al, 2020a), or the survival of subducted carbonate during plate subduction (Plank and Langmuir, 1993;Shen et al, 2018;Kang et al, 2021). The arc magmas from these studies present Sr-Nd isotopes and subduction indicators (e.g., Ba/Nb and Nb/La) close to DMM ranges, further supporting the relatively low influence of subducting sediment (Zhu et al, 2020a;Wang et al, 2021;Kang et al, 2021).…”

Section: Implications For Carbonate Recycling In Subduction Zonesmentioning

confidence: 94%

“…The carbonate solubility could reach up to 5000 ppm at sub-arc depth in the slab-derived fluids (Kelemen and Manning, 2015). Several works suggested the prograde metamorphism dehydration and the alteration of oceanic crust may not significantly modify the δ 44/40 Ca values (Ionov et al, 2019;Lu et al, 2020;Wang et al, 2021). However, hydrothermal or seawater altered rock samples generally show higher δ 44/40 Ca values than the less-altered counterparts, despite the large δ 44/40 Ca ranges of AOC (Blättler and Higgins, 2017;Chen et al, 2020a).…”

Section: Subduction-related Metasomatismmentioning

confidence: 99%

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Recycling of Marine Carbonate Induced Calcium Isotope Heterogeneity of Arc Magmas in Subduction Zones

Chen¹,

Wu²,

Gao³

et al. 2021

Preprint

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Calcium (Ca) is an essential element constituting sedimentary carbonate in subducting sediments. Ca isotopic characteristics of subduction-related rocks could provide insight into the behavior and budget of carbonate and carbon cycles in subduction zones, due to the distinctive δ44/40Ca ranges of sedimentary carbonate with respect to the mantle. Here, we studied the Ca isotopic compositions of arc magmas from the Northern Luzon arc (NLA), which are evolved from a depleted mantle metasomatized by slab-derived fluids and sediment melts. The δ44/40Ca values range from 0.76 ± 0.04&permil; to 1.01 ± 0.03&permil; and cover the typical ranges for bulk silica earth (BSE, ~ 0.94&permil;) and fresh mid-ocean ridge basalt (MORB, ~ 0.83&permil;). The Ca isotopes of NLA volcanics are not dominantly determined by the effects of mantle partial melting or fractional crystallization, nor significantly modified by secondary alteration. Instead, the δ44/40Ca values of NLA volcanics are controlled by the subduction-related metasomatism. The metasomatism by slab-derived fluids (mainly expelled from altered oceanic crust, AOC) dramatically elevated the contents of fluid-mobile elements (e.g., Ba and Pb) with respect to fluid-immobile elements (e.g., Ce). This process, however, rarely modified the Ca isotopes, possibly ascribed to the δ44/40Ca similarity between AOC and the depleted mantle. The δ44/40Ca values significantly correlated with subduction indicators (e.g., Sr-Nd isotopes, Ba/Nb, Ce/Pb, and Nb/La), demonstrating the Ca isotopes of NLA volcanics are mainly controlled by the metasomatism of sediment melts subducting from the South China Sea (SCS). Based on the thermal structures and chemical compositions of sediments subducting into global trenches, we propose that carbonate Ca isotopic signals can only be observed in the arcs with high sedimentary Ca fluxes and temperature-pressure conditions well beyond the solidus of H2O-saturated sediment melting, e.g., NLA, Nicaragua, Guatemala, Colombia, Peru, South Chile, North Vanuatu, New Zealand, and Kermadec. The absence of such signals in other arcs suggests either limited sedimentary fluxes or much of the subducting sedimentary carbonate has been survived during plate subduction to enter the deep mantle.

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Section: Subduction-related Metasomatismsupporting

confidence: 94%