Tracking halogen recycling and volatile loss in kimberlite magmatism from Greenland: Evidence from combined F-Cl-Br and δ37Cl systematics

Bromine Isotope Variations in Magmatic and Hydrothermal Sodalite and Tugtupite and the Estimation of Br Isotope Fractionation between Melt and Sodalite

“…It is assumed that Br concentrates in the final melt from which SGMs (in principle sodalite proper) crystallise, as it is generally assumed that little Br is removed from the melt before sodalite crystallises. Still, changes in Br contents and isotope composition will reflect processes such as melt extraction, interaction with asthenosphere melts, interaction with subducted materials, and degassing [17,[25][26][27]. The average δ 81 Br in the magmatic sodalite samples is +0.23‰.…”

“…Although the melt from which sodalite crystallised is sourced from the lithospheric mantle, the composition of the residual melt may have been changed considerable before the first sodalite crystallises from this melt. Furthermore, considering the related element Cl, it is shown [17] that not only do the δ 37 Cl of the various mantle reservoirs show large variations, but also that variations within individual reservoirs can be significant. As a result, a single datapoint cannot be used to define the (average) value of the (lithospheric) mantle.…”

“…For Cl, this value is higher than previous estimations based on measurements of Cl isotopes in Mid Oceanic Ridge Basalt (MORB) samples. The older data suggested that δ 37 Cl values of the depleted mantle can vary between −3 and +0.5‰ [12][13][14][15][16][17], although the generally accepted value for the depleted mantle is −0.2 ± 0.3‰ [13]. Cl isotope data from other mantle reservoirs, for example, sampled at Ocean Island Basalts, suggest that Cl isotope values can be as high as +3‰ [16].…”

Heavy halogen compositions of lamprophyres derived from metasomatized lithospheric mantle beneath eastern North China Craton

“…The consistency of Cl concentrations in glass and melt inclusions of Tonga arc rear lavas (dredged below water depths of 1300 to 1900 m) indicates the negligible effect of halogen degassing during the submarine eruption (Park et al, 2015). Under continental crust conditions, experiments show that the CO 2 vapor phase begins to release from kimberlite melts at shallow depths of < 3 km in the upper crust (Hoare et al, 2021; Moussallam et al, 2015).…”

“…Kimberlites (Gaffney et al, 2007;Hoare et al, 2021;Toyama et al, 2012;Toyama et al, 2021); Glass inclusions in olivine of lamprophyres from Mexico (Maria and Luhr, 2008). Notes: Errors are standard deviation of repeated analyses (n = 3).…”