Water in enstatite from Mid-Atlantic Ridge peridotite: Evidence for the water content of suboceanic mantle?

Water contents of the Cenozoic lithospheric mantle beneath the western part of the North China Craton: Peridotite xenolith constraints

“…Rare opx grains have a band at 3100 cm − 1 . The positions of the absorption bands are similar to those reported in previous studies on both natural and experimental minerals and interpreted as the vibration of structural OH (Skogby and Rossman, 1989;Skogby et al, 1990;Bell and Rossman, 1992;Ingrin and Skogby, 2000;Peslier et al, 2002;Grant et al, 2007;Li et al, 2008;Yang et al, 2008;Bonadiman et al, 2009;Gose et al, 2009;Green et al, 2010;Xia et al, 2010;Hao et al, 2011;Sundvall and Stalder, 2011). The relative absorbance of these bands varies among grains in a given sample due to variable orientation of grains with respect to the IR beam direction.…”

Water disequilibrium in olivines from Hawaiian peridotites: Recent metasomatism, H diffusion and magma ascent rates

“…Hydrogen is located in defects of the olivine lattice (Libowitzky and Beran, 1995;Rossman, 1996). Quantitative estimates of the amounts of H in olivine are typically reported in ppm weight H 2 O and the term "water" is therefore often used as equivalent to H. Numerous studies have measured water in continental peridotites, mainly xenoliths, but water measurements on oceanic peridotites are rare (Gose et al, 2009;Peslier, 2010;Schmädicke et al, 2011;Warren and Hauri, 2014). Moreover, pyroxenes are more often studied for water in natural peridotites because of their higher water contents and of the hydrothermal alteration of olivine in the case of abyssal peridotites.…”

On water in nominally anhydrous minerals from mantle peridotites and magmatic rocks

“…In addition, the fast hydrogen diffusion in olivine may be due to charge compensation by a flux of electron (Kohlstedt and Mackwell, 1998), while the hydrogen diffusion in pyroxene is rate limited by the coupled exchanges of Al 3+ and H + for Si 4+ (or 2Mg 2+ ), or exchange reaction governed by Fe content (Hercule and Ingrin, 1999;Woods et al, 2000;Warren and Hauri, 2014). Nevertheless, it is generally believed that pyroxene might not have exchanged water with its host magma, in contrast to the significant H loss of olivine during magma ascent (e.g., Peslier et al, 2002;Gose et al, 2009;Warren and Hauri, 2014).…”

“…Therefore, pyroxene water contents typically represent the mantle values. (e.g., Peslier et al, 2002;Gose et al, 2009;Xia et al, 2013a;Warren and Hauri, 2014;Hui et al, 2015;. In addition, covariation between water contents of pyroxene and those of cations with low diffusivity, such as pyroxene Al concentrations, could also be used as evidence that pyroxene may have preserved mantle water content (e.g., .…”