Iron and lithium isotope systematics of the Hekla volcano, Iceland — Evidence for Fe isotope fractionation during magma differentiation

Schuessler, Jan A.; Schoenberg, Ronny; Sigmarsson, Olgeir

doi:10.1016/j.chemgeo.2008.06.021

Cited by 258 publications

(150 citation statements)

References 66 publications

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“…First, there is a striking range of ~2 ‰ towards heavy d 51 V with progressive differentiation in both suites of lavas, which is an order of magnitude larger than Fe isotope variations in fractionating magmas (e.g., Schuessler et al, 2009;Sossi et al, 2012). Second, basaltic lavas from the Marianas, Iceland and MORB have overlapping d 51 V.…”

Section: Resultsmentioning

confidence: 99%

Stable vanadium isotopes as a redox proxy in magmatic systems?

Prytulak¹,

Sossi²,

Halliday³

et al. 2016

Geochem. Persp. Let.

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Recycling pathways of multivalent elements, that impact our understanding of diverse geological processes from ore formation to the rise of atmospheric oxygen, depend critically on the spatial and temporal variation of oxygen fugacity ( fO 2 ) in the Earth's interior. Despite its importance, there is currently no consensus on the relative fO 2 of the mantle source of mid-ocean ridge basalts compared to the sub-arc mantle, regions central to the mediation of crust-mantle mass balances. Here we present the first stable vanadium isotope measurements of arc lavas, complemented by non-arc lavas and two co-genetic suites of fractionating magmas, to explore the potential of V isotopes as a redox proxy. Vanadium isotopic compositions of arc and non-arc magmas with similar MgO overlap with one another. However, V isotopes display strikingly large, systematic variations of ~2 ‰ during magmatic differentiation in both arc and non-arc settings. Calculated bulk V Rayleigh fractionation factors (1000 lna min-melt of -0.4 to -0.5 ‰) are similar regardless of the oxidation state of the evolving magmatic system, which implies that V isotope fractionation is most influenced by differences in bonding environment between minerals and melt rather than changes in redox conditions. Thus, although subtle fO 2 effects may be present, V isotopes are not a direct proxy for oxygen fugacity in magmatic systems.

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Section: Resultsmentioning

confidence: 99%

Stable vanadium isotopes as a redox proxy in magmatic systems?

Prytulak¹,

Sossi²,

Halliday³

et al. 2016

Geochem. Persp. Let.

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“…Basaltic lavas are thought to represent about 10% melting of the mantle source, based on U and Th (Sigmarsson et al, 1992). The ascent of basaltic liquid is proposed to heat and initiate melting of metabasalts and metagabbros in the Icelandic crust, producing dacites; rhyolites are then generated by crystal fractionation of dacitic magma (Chekol et al, 2011;Schuessler et al, 2009;Sigmarsson et al, 1992) (Table 1). Since crystal fractionation is responsible for the evolution from basalt to basaltic andesite, relative incompatibilities of the elements can be assessed.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

“…where C l is the concentration in the liquid (basaltic andesite), C o is the concentration in the source (basalts), F is the amount of liquid remaining, and D is the bulk partition (e.g., Schuessler et al, 2009;Sigmarsson et al 1992).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Thallium elemental behavior and stable isotope fractionation during magmatic processes

et al. 2017

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Please cite this article as: Prytulak, J., Brett, A., Webb, M., Plank, T., Rehkämper, M., Savage, P.S., Woodhead, J., Thallium elemental behavior and stable isotope fractionation during magmatic processes, Chemical Geology (2016), doi: 10.1016/j.chemgeo. 2016.11.007 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractStable thallium (Tl) isotopes are an extremely sensitive tracer for the addition of small amounts of sediments or materials altered at low temperatures to the source(s) of mantle-derived melts. The ability of Tl to trace such materials is due to the large concentration contrast between the mantle (Tl < 2ng/g) and possible exotic inputs (Tl ~100ng/g to >g/g), which also often display fractionated Tl isotope compositions.However, the magnitude of Tl isotope fractionation induced by igneous processes alone has not been systematically assessed. Here, two suites of co-genetic magmas, spanning a large range of differentiation, from Hekla, Iceland, and Anatahan, in the Mariana arc, are used to assess the behavior of thallium and its stable isotope variations during magmatic processes. Thallium behaves as a near-perfectly incompatible lithophile element throughout magmatic evolution, mirroring elements such as Rb, Cs, and K. Lavas from Hekla have restricted Cs/Tl ratios and stable Tl isotope compositions, which overlap with mantle estimates. Lavas from subductionrelated Anatahan volcano also have a restricted range in Tl isotope composition, which overlaps with Hekla and MORB, demonstrating that fractional crystallisation and partial melting does not fractionate stable Tl isotopes. Subduction environments display variable Cs/Tl, indicating that the subduction process commonly fractionates these two elements. The immunity of thallium stable isotopes to fractionation by magmatic processes coupled with its extreme sensitivity for tracing pelagic sediments, FeMn crusts and low temperature altered oceanic crust highlight its value in elucidating the nature of mantle sources of both oceanic basalts and arc lavas.Critically, meaningful interpretation of thallium isotope compositions need not be restricted to primitive lavas.

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“…In contrast to this hypothesis, laboratory experiments at temperatures and pressures applicable to differentiation of parent bodies to achondrites have shown no iron isotope fractionation between metal and silicate minerals (Poitrasson et al, 2009;Hin et al, 2010). (3) Crust formation: It has been widely observed that iron isotopes could be fractionated during various magmatic differentiation processes of the terrestrial crust, such as partial melting, mineral fractionation and fluids exsolution (Williams et al, 2004;Poitrasson and Freydier, 2005;Weyer and Ionov, 2007;Teng et al, 2008;Schuessler et al, 2009). Island arc basalts also show iron isotope fractionation that may be related to the degree of partial melting (Dauphas et al, 2009a).…”

Section: Introductionmentioning

confidence: 99%

Iron isotope fractionation in planetary crusts

Wang

Moynier

Dauphas

et al. 2012

Geochimica et Cosmochimica Acta

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We present new high precision iron isotope data (d 56 Fe vs. IRMM-014 in per mil) for four groups of achondrites: one lunar meteorite, 11 martian meteorites, 32 howardite-eucrite-diogenite meteorites (HEDs), and eight angrites. Angrite meteorites are the only planetary materials, other than Earth/Moon system, significantly enriched in the heavy isotopes of Fe compared to chondrites (by an average of +0.12& in d 56 Fe). While the reason for such fractionation is not completely understood, it might be related to isotopic fractionation by volatilization during accretion or more likely magmatic differentiation in the angrite parent-body. We also report precise data on martian and HED meteorites, yielding an average d 56 Fe of 0.00 ± 0.01&. Stannern-trend eucrites are isotopically heavier by +0.05& in d 56 Fe than other eucrites. We show that this difference can be ascribed to the enrichment of heavy iron isotopes in ilmenite during igneous differentiation. Preferential dissolution of isotopically heavy ilmenite during remelting of eucritic crust could have generated the heavy iron isotope composition of Stannern-trend eucrites. This supports the view that Stannern-trend eucrites are derived from main-group eucrite source magma by assimilation of previously formed asteroidal crust.These new results show that iron isotopes are not only fractionated in terrestrial and lunar basalts, but also in two other differentiated planetary crusts. We suggest that igneous processes might be responsible for the iron isotope variations documented in planetary crusts.

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Iron and lithium isotope systematics of the Hekla volcano, Iceland — Evidence for Fe isotope fractionation during magma differentiation

Cited by 258 publications

References 66 publications

Stable vanadium isotopes as a redox proxy in magmatic systems?

Stable vanadium isotopes as a redox proxy in magmatic systems?

Thallium elemental behavior and stable isotope fractionation during magmatic processes

Iron isotope fractionation in planetary crusts

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