Lithium and Li-isotopes in young altered upper oceanic crust from the East Pacific Rise

Brant, C.; Coogan, L. A.; Gillis, K. M.; Seyfried, William E.; Pester, Nicholas J.; Spence, Jody

doi:10.1016/j.gca.2012.08.025

Cited by 50 publications

(22 citation statements)

References 101 publications

(136 reference statements)

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“…The Li isotope compositions of basalts BCR‐2 and BHVO‐2 have been reported to be homogeneous with a δ 7 Li variation of < 1‰ (Figure a). The mean δ 7 Li values of BCR‐2 and BHVO‐2 determined here were 2.64 ± 0.10‰ ( n = 5) and 4.39 ± 0.23‰ ( n = 3), consistent with reported values of 2.6–3.5‰ and 4.1–5.5‰, respectively (Zack et al , Jeffcoate et al , Kasemann et al , Magna et al , b, , Marschall et al , Rosner et al , Huang et al , Pogge von Strandmann et al , , Vlastélic et al , Gao and Casey , Brant et al , Penniston‐Dorland et al , Genske et al , Ryu et al , Lin et al , Bohlin et al ). Regarding AGV‐2, several researchers thought it heterogeneous in terms of Li isotopic composition (Tian et al .…”

Section: Resultssupporting

confidence: 89%

A Revisited Purification of Li for ‘Na Breakthrough’ and its Isotopic Determination by MC‐ICP‐MS

Luo

Wen

2020

Geostandard Geoanalytic Res

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The accurate and precise determination of Li isotopic composition by MC‐ICP‐MS suffers from the poor performance of traditional column chromatography. Previously established chromatographic processes cannot completely remove Na in complex geological samples, which is currently interpreted to be a result of Na breakthrough. In this study, Na breakthrough during single‐column purification was found to differ between simply artificial Na‐containing sample solutions, where a little Na residue was found, and silicate rocks, where a large amount of breakthrough occurred. A revised two‐step column purification for Li using 0.5 and 0.3 mol l−1 HCl as eluents was designed to remove the Na. This modified method achieves high‐efficiency Li purification from Na and consequently avoiding high Na/Li ratio interference for subsequent MC‐ICP‐MS analyses. The proposed method was validated by the analysis of a series of reference materials, including Li2CO3 (IRMM‐016, ‐0.10‰), basalt (BCR‐2: 2.68‰; BHVO‐2: 4.39‰), andesite (AGV‐2: 6.46‰; RGM‐2: 2.59‰), granodiorite (GSP‐2: −0.87‰) and seawater (CASS‐5, 30.88‰). This work reports early Na appearance prior to the elution curves in chromatography and emphasises its influence for subsequent Li isotope measurement. Based on the findings, the established two‐step method would be more secure than single‐column chemistry for Li purification.

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Section: Resultssupporting

confidence: 89%

A Revisited Purification of Li for ‘Na Breakthrough’ and its Isotopic Determination by MC‐ICP‐MS

Luo

Wen

2020

Geostandard Geoanalytic Res

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“…An extraction efficiency of less than 100%, however, would result in lower values, as is typically the case for Li. For example, both basalt alteration experiments and data from exposed dikes at Hess Deep exhibit only 50-70% Li removal from the rock (Seyfried et al, 1984;Seewald and Seyfried, 1990;James et al, 2003;Brant et al, 2012). Assuming similar Li solubility constraints for Lost City, associated fluid/rock ratios are lower (2.5-3.5), and therefore consistent with the range of values predicted by Sr isotopes.…”

Section: Trace Elementsmentioning

confidence: 62%

The Lost City hydrothermal system: Constraints imposed by vent fluid chemistry and reaction path models on subseafloor heat and mass transfer processes

Seyfried

Pester

Tutolo

et al. 2015

Geochimica et Cosmochimica Acta

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123

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Since the first reported discovery of the Lost City hydrothermal system in 2001, it was recognized that seawater alteration of ultramafic rocks plays a key role in the composition of the coexisting vent fluids. The unusually high pH and high concentrations of H 2 and CH 4 provide compelling evidence for this. Here we report the chemistry of hydrothermal fluids sampled from two vent structures (Beehive: $90-116°C, and M6: $75°C) at Lost City in 2008 during cruise KNOX18RR using ROV Jason 2 and R/V Revelle assets. The vent fluid chemistry at both sites reveals considerable overlap in concentrations of dissolved gases (H 2 , CH 4 ), trace elements (Cs, Rb, Li, B and Sr), and major elements (SO 4 , Ca, K, Na, Cl), including a surprising decrease in dissolved Cl, suggesting a common source fluid is feeding both sites. The absence of Mg and relatively high concentrations of Ca and sulfate suggest solubility control by serpentine-diopside-anhydrite, while trace alkali concentrations, especially Rb and Cs, are high, assuming a depleted mantle protolith. In both cases, but especially for Beehive vent fluid, the silica concentrations are well in excess of those expected for peridotite alteration and the coexistence of serpentine-brucite at all reasonable temperatures. However, both the measured pH and silica values are in better agreement with serpentine-diop side-tremolite-equilibria. Geochemical modeling demonstrates that reaction of plagioclase with serpentinized peridotite can shift the chemical system away from brucite and into the tremolite stability field. This is consistent with the complex intermingling of peridotite and gabbroic bodies commonly observed within the Atlantis Massif. We speculate the existence of such plagioclase bearing peridotite may also account for the highly enriched trace alkali (Cs, Rb) concentrations in the Lost City vent fluids. Additionally, reactive transport modeling taking explicit account of temperature dependent rates of mineral dissolution and precipitation clarifies the feedback between permeability, heat loss, and changes in the dissolved Si of the vent fluids. Assuming both the Beehive and M6 vent fluids were sourced at similar subseafloor conditions (tremolite buffered at 200°C), model results indicate loss of approximately 30% Si upon cooling to $150°C during upflow. However, Si concentrations remained largely conservative with continued cooling to lower temperatures owing to unfavorable reaction kinetics. While consistent with the Beehive endmember composition, these results fail to explain the relative Si depletion in the lower temperature M6 fluids. Thus, it may be that more robust kinetic models for silicates are needed to accurately account for the mechanism and rate of silica removal in the unusually high pH of the Lost City vent fluids.

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“…Lithium is incorporated as a trace element in most primary minerals in basalts, namely, olivines, clinopyroxenes, and Ca‐plagioclase feldspars, where Li abundance varies in the order of 0.2–12 ppm [see, e.g., Chan et al ., ; Teng et al ., ; Wimpenny et al ., ; Brant et al ., ]. Within this interval, there is little variation between coexisting minerals in the average Li content and their isotopic signatures.…”

Section: Methodsmentioning

confidence: 99%

“…Lithium (Li) isotope geochemistry investigations provide important information about the balance between silicate‐bearing minerals in source rocks and the geochemical processes associated with the weathering of primary silicates in aqueous environments [see, e.g., Chan et al ., ; Hathorne and James , ; Decarreau et al ., ; Ryu et al ., ]. Usually Li can be found, in the range of ppm, in almost all primary minerals present in basalt because of its small ionic radius, similar to Mg [ Seitz and Woodland , ; Seitz et al ., ; Tang et al ., ; Brant et al ., ].…”

Section: Introductionmentioning

confidence: 99%

Tracking the weathering of basalts on Mars using lithium isotope fractionation models

Fairén

Losa-Adams

Gil-Lozano

et al. 2015

Geochem Geophys Geosyst

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Lithium (Li), the lightest of the alkali elements, has geochemical properties that include high aqueous solubility (Li is the most fluid mobile element) and high relative abundance in basalt‐forming minerals (values ranking between 0.2 and 12 ppm). Li isotopes are particularly subject to fractionation because the two stable isotopes of lithium—7Li and 6Li—have a large relative mass difference (∼15%) that results in significant fractionation between water and solid phases. The extent of Li isotope fractionation during aqueous alteration of basalt depends on the dissolution rate of primary minerals—the source of Li—and on the precipitation kinetics, leading to formation of secondary phases. Consequently, a detailed analysis of Li isotopic ratios in both solution and secondary mineral lattices could provide clues about past Martian weathering conditions, including weathering extent, temperature, pH, supersaturation, and evaporation rate of the initial solutions in contact with basalt rocks. In this paper, we discuss ways in which Martian aqueous processes could have lead to Li isotope fractionation. We show that Li isotopic data obtained by future exploration of Mars could be relevant to highlighting different processes of Li isotopic fractionation in the past, and therefore to understanding basalt weathering and environmental conditions early in the planet's history.

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Lithium and Li-isotopes in young altered upper oceanic crust from the East Pacific Rise

Cited by 50 publications

References 101 publications

A Revisited Purification of Li for ‘Na Breakthrough’ and its Isotopic Determination by MC‐ICP‐MS

A Revisited Purification of Li for ‘Na Breakthrough’ and its Isotopic Determination by MC‐ICP‐MS

The Lost City hydrothermal system: Constraints imposed by vent fluid chemistry and reaction path models on subseafloor heat and mass transfer processes

Tracking the weathering of basalts on Mars using lithium isotope fractionation models

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