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

[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/cm, instead of the actual measured X-ray density of 3.180(3) g/cm. The measured X-ray density of 3.180(3) g/cm 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 Swave 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.