Trace element concentrations and clumped isotope compositions of calcite veins pervading the Western Pacific Izu-Bonin forearc and rear arc crust'

The drill cores revealed that the forearc is composed of forearc basalts (FAB) and boninites, and the rear arc consists of FAB-like rocks. These rocks are pervaded by calcite veins, which document extensive fluid circulation and secondary mineralization.

Here we present two data sets with rare earth element and yttrium (REE+Y) concentrations and clumped isotopic (Δ47) compositions. Clumped isotopes reveal precipitation temperatures < 100 °C. REE+Y characteristics and clumped isotopic compositions indicate varying parental fluid compositions ranging from pristine seawater to variably modified seawater. The most pristine seawater signatures are recorded by FAB-hosted low-T (< 30 °C) vein calcites with seawater-like REE+Y distribution patterns and parental fluid δ18O values within the range of seawater (-2 to +2 ‰ VSMOW).