The influence of near-surface winds on the Sr isotope composition of aeolian sediments: a wind tunnel experiment

We used wind tunnel experiments to simulate the effect of near-surface wind velocity on the silicate strontium (Sr) isotopic compositions of the fractions <10 mu m in windblown dust using intact surface samples obtained from a potential dust source area in arid northern China. Our results showed that the Sr-87/Sr-86 ratios of the silicate fractions in the windblown dust varied with near-surface wind speed and with the total amount of the fraction <10 mu m. For the five samples that we analyzed, the variances of the Sr-87/Sr-86 ratio under a range of wind velocities were 0.00014, 0.00004, 0.00052, 0.00151, and 0.00012. In addition, although most samples were collected at the same site and were treated in the same way, there were still differences in the Sr-87/Sr-86 ratios, with an intersample variance of up to 0.00409. These observations suggest that although using the Sr-87/Sr-86 ratios of aeolian sediments to reconstruct climate change or as fingerprints for aeolian materials transported from dust source areas remains a valid technique, the effects of the near-surface wind on the Sr-87/Sr-86 ratios in the dust source regions must be carefully considered. (C) 2012 Elsevier B.V. All rights reserved.