Ore component mobility, transport and mineralization at mid-oceanic ridges: A stable isotopes (Zn, Cu and Fe) study of the Rainbow massif (Mid-Atlantic Ridge 36°14′N)

Debret, Baptiste; Beunon, Hugues; Mattielli, Nadine; Andréani, M.; Costa, I.; Escartı́n, J.

doi:10.1016/j.epsl.2018.09.009

Cited by 32 publications

(31 citation statements)

References 60 publications

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“…Pons et al (2016) reported a progressive decrease of δ 66 Zn in subducted serpentinites with increasing metamorphic grade and degree of dehydration, from greenschist (δ 66 Zn = +0.32 ± 0.08‰) to eclogite (δ 66 Zn = +0.16 ± 0.06‰) P-T facies conditions. Similarly, Debret et al (2018a) showed the existence of abnormally low δ 66 Zn in decarbonated serpentinites (δ 66 Zn down to −0.56 ± 0.02‰) relative to C-bearing serpentinites (δ 66 Zn = +0.21-0.05‰) from blueschist terrains. Both observations clearly point towards the release of isotopically heavy-δ 66 Zn, S-and Cbearing dehydration fluids during serpentine breakdown and decarbonation of the serpentinized slab mantle.…”

Section: Subduction Zone Metamorphismmentioning

confidence: 91%

“…A growing number of studies advocates for the presence of Cbearing eclogites as possible source lithologies responsible for major elements enrichment in OIB (Jackson and Dasgupta, 2008;Dasgupta et al, 2010). Given the large offset of δ 66 Zn between unmetasomatized peridotites (δ 66 Zn = +0.18 ± 0.06‰) and more heterogeneous marine carbonates (δ 66 Zn = +0.91 ± 0.24‰, Pichat et al, 2003;+1.07 ± 0.14‰, Little et al, 2016;up to +0.79 and + 0.87 ± 0.14‰, Maréchal et al, 2000;Kunzmann et al, 2013), Zn isotopes are particularly well suited to track the carbon cycle at large scale (Liu et al, 2016;Liu and Li, 2019;Debret et al, 2018a). To our knowledge, Ravna et al (2017) present the only available dataset of Zn concentration and Sr-Nd isotopic composition of C-bearing eclogites from ultrahigh-pressure metamorphic terranes (n = 4).…”

Section: Carbon-bearing Oceanic Crust Recyclingmentioning

confidence: 99%

“…Among the FRTEs, Zn has been subject to a growing interest for tracing eclogite fragments in the mantle through Zn/Fe ratio systematics in oceanic basalts (Le Roux et al, 2010, 2011. In parallel, recent studies have also shown the great potential of some metal stable isotopes, including Zn, as sensitive tracers of the Deep Carbon Cycle (DCC) since carbonates and Bulk Silicate Earth display very distinct isotopic compositions (δ 66 Zn carbonates = +0.91 ± 0.24‰ and δ 66 Zn BSE = +0.16 ± 0.06‰ using the per mille deviation of 66 Zn/ 64 Zn from the JMC-Lyon standard, Liu et al, 2016;Pichat et al, 2003;Sossi et al, 2018;Liu and Li, 2019;Debret et al, 2018a). The concomitant use of Zn and δ 66 Zn offers some interesting possibilities to distinguish between MORB-eclogite and C-bearing eclogite contribution in the source of oceanic basalts.…”

Section: Introductionmentioning

confidence: 99%

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Mantle heterogeneity through Zn systematics in oceanic basalts: Evidence for a deep carbon cycling

Beunon

Mattielli

Doucet

et al. 2020

Earth-Science Reviews

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Subduction at convergent margins introduces a range of sedimentary and crustal materials into the mantle, providing the most dominant form of heterogeneity in the source of oceanic basalts. Yet, the relationship between geochemical variability and lithologic heterogeneities in the Earth's mantle remains controversial. In this paper, we comprehensively review Zn, δ 66 Zn and Sr-Nd isotope systematics in near-primary basalts erupted at mid-ocean ridges (MORB) and ocean islands (OIB) to help constrain the nature and proportion of the carbon (C) bearing slab-derived component in their mantle sources. We show that Zn elemental and isotopic composition of oceanic basalts differs according to their tectonic settings, increasing from MORB (Zn = 62 ± 10 to 73 ± 11 ppm; δ 66 Zn = +0.24 ± 0.01 to +0.31 ± 0.02‰) to OIB (Zn = 74 ± 9 to 124 ± 7 ppm; δ 66 Zn = +0.21 ± 0.07 to +0.40 ± 0.04‰). Unlike MORB, the high Zn and δ 66 Zn recorded in OIB cannot be explained by partial melting of a fertile peridotite mantle source only. Importantly, global correlations between Zn content and Sr-Nd isotopes in oceanic basalts suggest that the Zn enrichment in OIB is inherited from a recycled component in their mantle source rather than melting processes. We demonstrate that involvement of neither typical MORB-like oceanic crust nor subducted sediments can achieve the whole range of Zn composition in OIB. Instead, addition of ≤6% C-bearing oceanic crust to a fertile peridotite mantle fully resolves the Zn heterogeneity of OIB, both in terms of magnitude of Zn enrichment and global trends with Sr-Nd isotopes. Such scenario is corroborated by the elevated δ 66 Zn of OIB relative to MORB and mantle peridotites, reflecting the contribution of isotopically heavy C-bearing phases (δ 66 Zn = +0.91 ± 0.24‰) to the mantle source (δ 66 Zn = +0.16 ± 0.06‰). Our study thus emphasizes the use of Zn and δ 66 Zn systematics to track the nature and origin of mantle carbon, highlighting the role of subduction in the deep carbon cycle. Finally, the positive correlation between Zn content and temperature of magma generation of oceanic basalts suggests that hotter mantle plumes are more likely to carry a higher proportion of dense C-bearing eclogite. Zinc systematics therefore may provide evidence that the presence of heterogeneous domains in the source of OIB is, at least partly, linked to plume thermal buoyancy, bringing new insights into mantle dynamics.

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Section: Subduction Zone Metamorphismmentioning

confidence: 91%

Section: Carbon-bearing Oceanic Crust Recyclingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mantle heterogeneity through Zn systematics in oceanic basalts: Evidence for a deep carbon cycling

Beunon

Mattielli

Doucet

et al. 2020

Earth-Science Reviews

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“…This potentially relates to the inhomogeneity of this reference material, as suggested by the large range of d 60/58 60/58 Ni could suggest the potential of Ni isotope ratios to track ore component mobility and reaction pathways beneath hydrothermal elds as observed for Zn, Cu and Fe isotope ratios. 70 Although the method is demonstrated to work for igneous rocks, additional tests are needed before expanding it to geological matrices with lower Ni abundances and/or high organic contents (e.g., shales), or biological samples.…”

Section: Nickel Stable Isotope Composition Of Geological Reference Materialsmentioning

confidence: 99%

Innovative two-step isolation of Ni prior to stable isotope ratio measurements by MC-ICP-MS: application to igneous geological reference materials

Beunon

Chernonozhkin

Mattielli

et al. 2020

J. Anal. At. Spectrom.

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“…This observation suggests that the composition serpentinites recorded at depth can be partly overprinted by low-temperature reactions (b 250°C) during clast exhumation. However, the exact source of the added Zn is unclear as Zn can be mobile in fluids either at depth during serpentinite devolatilization , decarbonation processes (Debret et al, 2018a;Inglis et al, 2017) as well as near the seafloor through hydrothermal fluid circulation (Debret et al, 2018b) and microbial activity via sulfate reduction (Kelley et al, 2009).…”

Section: Evolution Of Forearc Mantle Wedge Composition During Subductionmentioning

confidence: 99%

Shallow forearc mantle dynamics and geochemistry: New insights from IODP Expedition 366

Debret

Albers

Walter

et al. 2019

Lithos

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The Mariana forearc is a unique setting on Earth where serpentinite mud volcanoes exhume clasts originating from depths of 15 km and more from the forearc mantle. These peridotite clasts are variably serpentinized by interaction with slab derived fluid, and provide a record of forearc mantle dynamics and changes in geochemistry with depth. During International Oceanic Discovery Program (IODP) Expedition 366, we recovered serpentinized ultramafic clasts contained within serpentinite muds of three different mud volcanoes located at increasing distance from the Mariana trench and at increasing depth to the slab/mantle interface: Yinazao (distance to the trench: 55 km / depth to the slab/mantle interface: 13 km), Fantangisña (62 km / 14 km) and Asùt Tesoru (72 km / 18 km). Four different types of ultramafic clasts were recovered: blue serpentinites, lizarditeserpentinites, antigorite/lizardite-and antigorite-serpentinites. Lizardite-serpentinites are primarily composed of orange serpentine, forming mesh and bastite textures. Raman and microprobe analyses revealed that these textures contain a mixture of Fe-rich brucite (XMg~0.84) and lizardite/chrysotile. Antigorite/lizardite-and antigorite-serpentinites record the progressive recrystallization of mesh and bastite textures to antigorite, magnetite and pure Fe-poor brucite (XMg~0.92). Oxygen isotope compositions of clasts and pore fluids showed that the transition from lizardite to antigorite is due to the increase in temperature from 200°C to about 400°C within the forearc area above the slab/mantle interface. Lizardite-, antigorite/lizardite-and antigorite-serpentinites displayed U-shaped chondrite normalized Rare Earth Element (REE) patterns and are characterized by high fluid mobile element concentrations (Cs, Li, Sr, As, Sb, B, Li) relative to abyssal peridotites and/or primitive mantle. The recrystallization of lizardite to antigorite is accompanied by a decrease in Cs, Li and Sr, and an increase in As and Sb concentrations in the bulk clasts, whereas B concentrations are relatively constant. Some clasts are overprinted by blue serpentine, often in association with sulfides. Most of these blue serpentinites were recovered at Yinazao and the uppermost units of Fantangisña and Asùt Tesoru suggesting alteration in the shallower portions of the forearc, possibly during exhumation of the clasts. This episode of alteration resulted in a flattening of REE spectra and an increase of Zn concentrations in serpentinites. Otherwise, no systematic changes of ultramafic clasts chemistry or mineralogy were observed with increasing depth to the slab. The samples document previously undescribed prograde metamorphic events in the shallow portions of the Mariana subduction zone, consistent with a continuous burial of the serpentinized forearc mantle during subduction. Similar processes, induced by the interaction with fluids released from the downgoing slab, likely occur in subduction zones worldwide. At greater depth, breakdown of brucite and antigorite will result in the massive...

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Ore component mobility, transport and mineralization at mid-oceanic ridges: A stable isotopes (Zn, Cu and Fe) study of the Rainbow massif (Mid-Atlantic Ridge 36°14′N)

Cited by 32 publications

References 60 publications

Mantle heterogeneity through Zn systematics in oceanic basalts: Evidence for a deep carbon cycling

Mantle heterogeneity through Zn systematics in oceanic basalts: Evidence for a deep carbon cycling

Innovative two-step isolation of Ni prior to stable isotope ratio measurements by MC-ICP-MS: application to igneous geological reference materials

Shallow forearc mantle dynamics and geochemistry: New insights from IODP Expedition 366

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