Monte Carlo simulation results of zircon depletion effects on Hf isotopic compositions of dust, supplement to: Ujvari, Gabor; Wegner, Wencke; Klötzli, Urs; Horschinegg, Monika; Hippler, Dorothee (2018): Sr-Nd-Hf Isotopic Analysis of <10 mg Dust Samples: Implications for Ice Core Dust Source Fingerprinting. Geochemistry, Geophysics, Geosystems, 19(1), 60-72

• Main Authors: Ujvari, Gabor, Wegner, Wencke, Klötzli, Urs, Horschinegg, Monika, Hippler, Dorothee
• Format: Dataset
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2017
• Subjects: Greenland; Greenland ice cores; ice core
• Online Access: https://dx.doi.org/10.1594/pangaea.884461; https://doi.pangaea.de/10.1594/PANGAEA.884461

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. : Monte Carlo simulation were done in MATLAB to model zircon depletion effects on the Hf isotopic composition of hypothetical 5 mg amount of dust (<10 and <2 micron fractions). All simulation parameters as defined in the original publication.