Magnesium isotopic systematics of mafic rocks during continental subduction

Wang, Shui‐Jiong; Teng, Fang‐Zhen; Li, Shuguang; Jian, Huang

doi:10.1016/j.gca.2014.03.029

Cited by 89 publications

(42 citation statements)

References 71 publications

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“…2) suggest an inheritance of protolith isotopic composition. This is consistent with previous conclusions that metamorphism, up to eclogite facies, has little effect on the Mg isotopic composition of mafic rocks Wang et al 2014). The causes for the outlier Mg isotopic compositions of some eclogites are unclear and beyond the scope of this study.…”

Section: Discussionsupporting

confidence: 93%

Empirical calibration of the clinopyroxene–garnet magnesium isotope geothermometer and implications

Teng

Xiao

et al. 2016

Contrib Mineral Petrol

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between clinopyroxene and garnet. The equilibrium Δ 26 Mg clinopyroxene-garnet and corresponding temperature data obtained in this study, together with those available so far in literatures for natural eclogites, are used to calibrate the clinopyroxene-garnet Mg isotope thermometer. This yields a function of Δ 26 Mg clinopyroxene-garnet = (0.99 ± 0.06) × 10 6 /T 2 , where T is temperature in Kelvin. The refined function not only provides the best empirically calibrated clinopyroxene-garnet Mg isotope thermometer for precise constraints of temperatures of clinopyroxene-and garnet-bearing rocks, but also has potential applications in high-temperature Mg isotope geochemistry.

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Section: Discussionsupporting

confidence: 93%

Empirical calibration of the clinopyroxene–garnet magnesium isotope geothermometer and implications

Teng

Xiao

et al. 2016

Contrib Mineral Petrol

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“…Equivalent sediments in arc crust through which the Martinique lavas erupted could provide such a source, as well, if they were assimilated into the lavas. Furthermore, due to the lack of Mg isotope fractionation during prograde metamorphism (31,33,34), the metamorphic counterparts of the subducting sediments should preserve their original Mg isotopic signature. Previous isotopic studies of Martinique lavas show that the sedimentary input increases with age from old to intermediate lavas whereas it is much more variable in the recent lavas (4).…”

Section: Significancementioning

confidence: 99%

Magnesium isotope geochemistry in arc volcanism

Teng

Chauvel

2016

Proc. Natl. Acad. Sci. U.S.A.

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Incorporation of subducted slab in arc volcanism plays an important role in producing the geochemical and isotopic variations in arc lavas. The mechanism and process by which the slab materials are incorporated, however, are still uncertain. Here, we report, to our knowledge, the first set of Mg isotopic data for a suite of arc lava samples from Martinique Island in the Lesser Antilles arc, which displays one of the most extreme geochemical and isotopic ranges, although the origin of this variability is still highly debated. We find the δ 26 Mg of the Martinique Island lavas varies from −0.25 to −0.10, in contrast to the narrow range that characterizes the mantle (−0.25 ± 0.04, 2 SD). These high δ 26 Mg values suggest the incorporation of isotopically heavy Mg from the subducted slab. The large contrast in MgO content between peridotite, basalt, and sediment makes direct mixing between sediment and peridotite, or assimilation by arc crust sediment, unlikely to be the main mechanism to modify Mg isotopes. Instead, the heavy Mg isotopic signature of the Martinique arc lavas requires that the overall composition of the mantle wedge is buffered and modified by the preferential addition of heavy Mg isotopes from fluids released from the altered subducted slab during fluid−mantle interaction. This, in turn, suggests transfer of a large amount of fluidmobile elements from the subducting slab to the mantle wedge and makes Mg isotopes an excellent tracer of deep fluid migration. magnesium isotopes | arc magmatism | mantle wedge | Lesser Antilles arc | Martinique Island

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“…Therefore, Mg isotopes have also been used in attempts to trace recycled crustal materials in the mantle Shen et al, 2009;Xiao et al, 2013;Yang et al, 2012). Since metamorphic dehydration and high-temperature partial melting only result in limited Mg isotope fractionation (e.g., Li et al, , 2014Liu et al, 2010;Telus et al, 2012;Teng et al, 2007;2010b;Wang et al, 2014a), it is expected that the recycled materials will preserve their original Mg isotopic signatures through subduction zone processes. Thus, the similarity in Mg isotopic compositions of the carbonate-barren AOC and that of the mantle that we demonstrate in this study implies that recycling of such AOC is unlikely to result in heterogeneous Mg isotopic compositions of the mantle at a global scale.…”

Section: Implications For Tracing Recycled Crustal Materials Using Mgmentioning

confidence: 99%

Magnesium isotopic compositions of altered oceanic basalts and gabbros from IODP site 1256 at the East Pacific Rise

Huang

Gao

et al. 2015

Lithos

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Magnesium isotopic systematics of mafic rocks during continental subduction

Cited by 89 publications

References 71 publications

Empirical calibration of the clinopyroxene–garnet magnesium isotope geothermometer and implications

Empirical calibration of the clinopyroxene–garnet magnesium isotope geothermometer and implications

Magnesium isotope geochemistry in arc volcanism

Magnesium isotopic compositions of altered oceanic basalts and gabbros from IODP site 1256 at the East Pacific Rise

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