ALBERT

Description: Combined Sr-Nd-Hf isotopic data of two reference materials (AGV-1/BCR2) and 50, 10 and 5 mg aliquots of carbonate-free fine grain (〈10 µm) separates of three loess samples (Central Europe/NUS, China/BEI, USA/JUD) are presented. Good agreement between measured and reference Sr-Nd-Hf isotopic compositions (ICs) demonstrate that robust isotopic ratios can be obtained from 5-10 mg size rock samples using the ion exchange/mass spectrometry techniques applied. While 87Sr/86Sr ratios of dust aluminosilicate fractions are affected by even small changes in pretreatments, Nd isotopic ratios are found to be insensitive to acid leaching, grain-size or weathering effects. However, the Nd isotopic tracer is sometimes inconclusive in dust source fingerprinting (BEI and NUS both close to epsilon-Nd(0) -10). Hafnium isotopic values (〈10 µm fractions) are homogenous for NUS, while highly variable for BEI. This heterogeneity and vertical arrays of Hf isotopic data suggest zircon depletion effects towards the clay fractions (〈2 µm). Monte Carlo simulations demonstrate that the Hf IC of the dust 〈10 µm fraction is influenced by both the abundance of zircons present and maturity of crustal rocks supplying this heavy mineral, while the 〈2 µm fraction is almost unaffected. Thus, epsilon-Hf(0) variations in the clay fraction are largely controlled by the Hf IC of clays/heavy minerals having high Lu/Hf and radiogenic 176Hf/177Hf IC. Future work should be focused on Hf IC of both the 〈10 and 〈2 µm fractions of dust from potential source areas to gain more insight into the origin of last glacial dust in Greenland ice cores.

Description: Volcanic rocks from the Izu-Bonin-Mariana forearc and rear arc, which were recovered during the International Ocean Discovery Program (IODP) Expeditions 352 and 351, are pervaded by calcite veins. The trace element concentrations of these calcite veins were determined using a laser ablation inductively-coupled plasma mass spectrometer.

Description: Calcite veins pervading the pillow lava section of the Troodos ophiolite document fracturing and fluid flow through the oceanic crust. Their δ¹⁸O, δ¹³C, Δ₄₇ (clumped) and ⁸⁷Sr/⁸⁶Sr isotopic compositions, and trace element concentratios (laser ablation) provide insights into the fluid composition from which they precipitated and the precipitation temperature.

Description: International Ocean Discovery Program Expeditions 352 and 351 drilled into the Western Pacific Izu-Bonin forearc and rear arc. 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). As a result of weak fluid-rock interaction and precipitation from modified seawater, boninite-hosted low-T (〈 30 °C) vein calcites show reduced Y/Ho ratios (〈 36) and less pronounced negative Ce anomalies relative to seawater. In the rear arc, intense low-T host rock alteration produced fluids with significantly depleted δ18O compositions (up to -9.7 ‰ VSMOW) and reduced Y/Ho ratios (〈 36). Vein calcites precipitated at temperatures up to 74 ± 12 °C.

Description: The data are related to an ammonium-bifluoride-based rock digestion procedure. Table S1/S2 describe ion exchange chemistry procedures for hafnium, strontium and neodymium separations and purifications using micro-columns filled with AG-50W-X8 (Sr) and Ln (Hf-Nd) resins. Table S4/S4 provide information on a procedure of amplifier gain calibrations using a combination of 10(13) Ohm amplifiers for masses 172-176, as applied on the JMC-475 hafnium isotopic standard, and calculated gain factors for each measurement cycle. Table S5 lists data of calculated blank contributions for 5 USGS geological rock reference materials (GRMs), including AGV-2, BCR-2, GSP-2, RGM-2 and STM-2, based on measured total chemistry blanks and elemental concentrations of the GRMs.