Correction to “Effects of hydration on the elastic properties of olivine”

Abstract

[1] In the paper “Effects of hydration on the elastic properties of olivine” by S. D. Jacobsen et al. (Geophysical Research Letters, 35, L14303, doi:10.1029/2008GL034398, 2008), the sample of hydrous olivine labeled hy-Fo97 with (001) orientation in the bottom plot of original Figure 1b has been subsequently identified by Raman spectroscopy as OH-chondrodite, (Mg,Fe)5Si2O8(OH)2 [e.g., Lin et al., 1999]. The OH-chondrodite co-existed with hydrous forsterite in the synthesis run, and all other samples in the study have been confirmed to be hydrous forsterite. Upon removing the OH-chondrodite platelet from the fit, we obtain a corrected set of elastic constants (Cij) and crystallographic orientations for hy-Fo97 using a two-plane fit, displayed in corrected Figure 1 and presented in corrected Table 1. The original Table 2 of anisotropy factors has been updated and presented here in corrected Table 2. Brillouin spectra from the two remaining orientations of hy-Fo97 determine eight of the nine Cij, leaving C12 unconstrained. As a result, C12 was fixed to the value obtained for hy-Fo100 and a large uncertainty of ±5 GPa in this parameter was assumed in calculating the aggregate bulk (KS0) and shear (G) moduli. [2] In addition, a minor correction to the elastic constants of hydrous forsterite (hy-Fo100) is presented in revised Table 1 because the original calculation used an earlier estimated density of 3.19 g/cm3, instead of the actual measured X-ray density of 3.180(3) g/cm3. The measured X-ray density of 3.180(3) g/cm3 was correctly reported in the original text, but not used in the calculation of Cij. The revised Cij of hydrous forsterite are affected by only 0.2–0.3% from the original calculation as a result of the error. [3] The revised values of elastic properties for hy-Fo100 and hy-Fo97 presented in the corrected Table 1 apply to the following statements in the text: [4] The last four sentences of paragraph [1] should read: The adiabatic bulk (KS0) and shear (G0) moduli of hy-Fo100 are 125.4(±0.2) GPa and 79.6(±0.1) GPa, respectively. For hy-Fo97, we obtain KS0 = 125.2(±0.8) GPa and G0 = 77.7(±0.3) GPa. Compared with anhydrous forsterite, the combined effects of 3 mol% Fe and 0.8 wt% H2O reduce bulk and shear moduli by 2.9(±0.6)% and 4.5(±0.4)% respectively, with greater reductions expected for more iron-rich Fo90 mantle compositions. Although lattice preferred orientation (LPO) studies have not been carried out under relevant conditions of water or pressure, analysis of idealized single-crystal anisotropy for various known LPO types predicts no more than 2% effect of hydration on S-wave splitting anisotropy in olivine. [5] The last sentence of paragraph [9] should read: We measured two platelets of hy-Fo97 with fitted orientations of (100) and (010), shown in the corrected Figure 1b. [6] The last two sentences of paragraph [10] should read: The addition of 0.89 wt% H2O to forsterite in our hy-Fo100 samples shows a reduction of all Cij by 1.8–4.3%, except C33, which is reduced by only 0.8%. For hy-Fo100, we obtain KS0 = 125.4(±0.2) GPa and G0 = 79.6(±0.1) GPa, which are about 2.7% and 2.2% lower than anhydrous forsterite, respectively. [7] The first two sentences of paragraph [11] should read: Comparing the Cij of hy-Fo97 with anhydrous Fo100 to ascertain the net effect of iron and hydration shows that there is a large reduction in Cij by 2.4–6.4%, except for C23, which increased by 2.1%. For hy-Fo97, we obtain KS0 = 125.2(±0.8) GPa and G0 = 77.7(±0.3) GPa, which are 2.9% and 4.5% lower than anhydrous forsterite. [8] The last sentence of paragraph [11] should read: The aggregate hy-Fo97 velocities Vp and Vs (with only 3 mol% Fe) are 2.1% and 2.4% lower, respectively, than anhydrous forsterite, suggesting that hydrous Fo90 olivine, closer to mantle composition, would exhibit even further reduced velocities. [9] The last sentence of paragraph [13] should read: Hydration of forsterite only slightly reduces the maximum P-wave anisotropy, expressed as [(Vmax − Vmin)/Vmean] × 100, from 25.0(±0.4)% to 24.1(±0.5)% for hy-Fo100, with moderate further reduction to 23.9(±0.4)% for hy-Fo97. [10] The third sentence of paragraph [15] should read: Under horizontal shear (used to reference VSH and VSV), the hy-Fo97 olivine shows no change in shear-wave splitting anisotropy for idealized LPO type-A and type-E compared with dry forsterite. [11] The fifth sentence of paragraph [15] should read: In both cases (type-B and type-C) there is moderate 1–2% change in S-wave splitting anisotropy with hydration (corrected Table 2). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.