@article {634700,
	title = {Vanadium isotope compositions of mid-ocean ridge lavas and altered oceanic crust},
	journal = {Earth and Planetary Science Letters},
	volume = {493},
	year = {2018},
	pages = {128-139},
	abstract = {Vanadium isotope compositions of igneous rocks have the potential to constrain variations of physico-chemical conditions such as oxidation states during magmatism. Here, we present V isotope data for 27 fresh lavas (ranging from basaltic to dacitic compositions) from mid-ocean ridges, 31 altered basalts and gabbros from IODP site 1256 near the East Pacific Rise (EPR), and 2 back arc basin basalts (BABB). Our analyses of fresh mid-ocean ridge basalt (MORB) provide new constraints on the V isotope composition of MORBs, i.e.\&nbsp;{\textperthousand}δ51V=-0.84{\textpm}0.02{\textperthousand}\&nbsp;(2SE,\&nbsp;n=22). In addition, the mean\&nbsp;δ51V\&nbsp;of MORBs from individual segments is correlated with the mean ridge depth and Na8.0\&nbsp;of the segment, which might reflect the effect of melting extent on V isotope fractionation during mantle melting.The mafic profile of intact altered oceanic crust (AOC) from the IODP site 1256 has\&nbsp;δ51V ranging from -1.01 to\&nbsp;{\textperthousand}-0.77{\textperthousand}, similar to that of fresh MORBs, suggesting that V isotope fractionation is limited during alteration of oceanic crust. These results also indicate the V isotopic homogeneity of the bulk oceanic crust with average\&nbsp;δ51V of\&nbsp;{\textperthousand}-0.85{\textpm}0.02{\textperthousand}\&nbsp;(2SE,\&nbsp;n=53), which is unaffected by ocean water and hydrothermal fluid alteration. Our results provide a guideline for application of V isotopes into studies of low and high temperature geochemical processes.The evolved lavas (basaltic andesites, andesites, and dacites) from the East Pacific Rise (EPR) show apparent shifts towards heavy\&nbsp;δ51V values with increasing degree of differentiation, which can be explained by the crystal{\textendash}liquid fractionation during crystallization with an inferred isotope fractionation factor of\&nbsp;Δ51Vmineral-melt=-0.15{\texttimes}106/T2. The enrichment of\&nbsp;51V with increasing differentiation degree for the 9{\textdegree}N Overlapping Spreading Center (OSC) lavas is consistent with direction of the isotope shift observed in lavas from Anatahan Island (Northern Mariana Arc) and Hekla Volcano (Iceland), but the magnitude (0.3{\textperthousand}) is much smaller than that (2{\textperthousand}) reported in\&nbsp;Prytulak et al. (2017). Modeling of V isotope fractionation between mineral and melt shows that variations in redox condition are important for controlling V isotope fractionation, but insufficient to explain the dramatically different\&nbsp;Δ51Vmineral-melt\&nbsp;between 9{\textdegree}N OSC lavas and Anatahan/Hekla suites. More studies are necessary for better understanding of mechanisms of V isotope fractionation during magmatism.},
	url = {https://www.sciencedirect.com/science/article/pii/S0012821X18302048},
	author = {Wu, F and Qi, Y and Perfit, MR and Gao, Y and Langmuir, C.H. and Wanless, VD and Yu, H and Huang, F}
}
