The Systematics of Chlorine, Lithium, and Boron andδ³⁷Cl,δ⁷Li, and δ¹¹B in the Hydrothermal System of the Yellowstone Plateau Volcanic Field

Abstract

Chlorine, lithium, and boron are trace elements in rhyolite but are enriched in groundwater flowing through rhyolite because they tend to partition into the fluid phase during high‐temperature fluid‐rock reactions. We present a large data set of major element and δ37Cl, δ7Li, and δ11B compositions of thermal water and rhyolite from Yellowstone Plateau Volcanic Field (YPVF). The Cl/B, Cl/Li, δ37Cl (−0.2‰ to +0.7‰), and δ11B (−6.2‰ to −5.9‰) values of alkaline‐chloride thermal waters reflect high‐temperature leaching of chlorine, lithium, and boron from rhyolite that has δ37Cl and δ11B values of +0.1‰ to +0.9‰ and −6.3‰ to −6.2‰, respectively. Chlorine and boron are not reactive, but lithium incorporation into hydrothermal alteration minerals result​s in a large range of Cl/Li, B/Li, and δ7Li (−1.2‰ to +3.8‰) values in thermal waters. The relatively large range in δ7Li values of thermal waters reflects a large range of values in rhyolite. Large volumes of rhyolite must be leached to account for the chloride, lithium and boron fluxes, implying deep groundwater flow through rhyolite flows and tuffs representing Yellowstone's three eruptive cycles (∼2.1 Ma). Lower Cl/B values in acid‐sulfate waters result from preferential partitioning of boron into the vapor phase and enrichment in the near‐surface water condensate. The Cl/B, Cl/Li, δ7Li (−0.3‰ to +2.1‰), and δ11B (−8.0‰ to −8.1‰) values of travertine depositing calcium‐carbonate thermal waters which discharge in the northern and southern YPVF suggest that chlorine, lithium, and boron are derived from Mesozoic siliciclastic sediments which contain detrital material from the underlying metamorphic basement.

Quantifying Non‐Thermal Silicate Weathering Using Ge/Si and Si Isotopes in Rivers Draining the Yellowstone Plateau Volcanic Field, USA

“…The relatively narrow range of δ 30 Si in thermal waters from UGB is comparable to that reported for rhyolite (−0.14 ± 0.19‰; Savage et al., 2011). This is consistent with recent laboratory and field observations that solutes in thermal springs in the geyser basins are derived from reactions between water and rhyolite at high temperature (Cullen et al., 2019, 2021). In these thermal waters emerging at near boiling temperature and undersaturated with respect to amorphous silica, the effect of opal precipitation on the δ 30 Si composition is limited.…”

“…A contribution from alkaline‐chloride waters to Snake River may contribute to a slightly higher Ge/Si. This more complex pattern in Gardner and Snake rivers is also reflected with other isotope systems (Cullen et al., 2021).…”

Cl, Br, B, Li, and noble gases isotopes to study the origin and evolution of deep groundwater in sedimentary basins: a review

“…For example, measurements of δ 11 B values (+ 8.7 to + 23.1‰) in geothermal reservoirs from the Jiangling Basin, South China, indicate that the hot brines are derived from high-temperature water-rock interactions involving basalt and clastic rocks and recharge of meteoric waters, consistent with the results of traditional δD, δ 18 O, and 87 Sr/ 86 Sr isotopes in explaining water-rock interaction processes (Yu et al 2021). The δ 37 Cl (−0.2 to + 0.7‰) and δ 11 B (−6.2 to −5.9‰) in alkaline-chloride thermal waters in Yellowstone plateau volcanic field show that the water is likely originated from high-temperature leaching of chlorine, lithium, and boron from rhyolite (δ 37 Cl and δ 11 B values of + 0.1 to + 0.9‰ and −6.3 to −6.2‰, respectively) (Cullen et al 2021). Moreover, the residual B in the liquid phase will be enriched in 11 B because of the adsorption effect of clay minerals or iron and aluminum oxides along groundwater flow at pH higher than 8, when the anion B(OH) 4 − becomes more enriched.…”

“…δ 37 Cl ‰ References to the data sources Shallow fresh groundwater −2.13 to 3.82 Bassett et al 1995;Chen et al 2014;Desaulniers et al 1986;Eastoe et al 1989;Eastoe, 2016;Gwynne et al 2013;Kaufmann et al 1984aKaufmann et al , 1993Khaska et al 2015;Lavastre et al 2005;Li et al 2012;Liu et al 1996;Liu et al 2016;Sie and Frape 2002;Véronique et al 2005;Xiao et al 1994a;Zhang et al 2007 Hydrothermal fluids or geothermal brines −1 to 4.32 Banks et al 2000aBanks et al , 2000bBernal et al 2014;Bonifacie et al 2005;Cullen et al 2015Cullen et al , 2021Kaufmann et al 1984a;Li et al 2015;Liu et al 1996;Pinti et al 2020;Stefánsson and Barnes 2016;Stefánsson et al 2017;Xiao et al 1994a, 2000Meteoric waters −3.5 to 5.86 Koehler and Wassenaar, 2010Xiao et al 1994a River water −0.4 to 3.07 Eastoe et al 2007;Eastoe 2016;Godon et al 2004;Kaufmann et al 1984a;Koehler and Wassenaar 2010;Liu et al 1996Liu et ...…”

“…This is related to a series of prolonged water-rock interactions or evaporation, dilution, and a mixture of different waters in deep sedimentary environments. For instance, δ 7 Li in thermal waters in Yellowstone plateau volcanic field ranges from −1.2 to + 3.8‰ because Li is incorporated into hydrothermal alteration minerals (Cullen et al 2021). Additionally, based on the values of δ 7 Li (−0.3 to + 2.1‰) and δ 11 B (−8.0 to −8.1‰), Cl, Li, and B in travertine depositing calcium-carbonate thermal waters which discharge in the northern and southern Yellowstone plateau volcanic field are found to be derived from Mesozoic siliciclastic sediments (Cullen et al 2021).…”