Transport of oxygen in silicate glasses

Origin of retrograde fluid in ultrahigh-pressure metamorphic rocks: Constraints from mineral hydrogen isotope and water content changes in eclogite–gneiss transitions in the Sulu orogen

“…The similar H 2 O-dD negative correlation was also found in clinopyroxene megacryst and ascribed to diffusive H loss during magma ascent to the surface (e.g., Newman et al, 1988). While in principle the H-rich fluid diffuses much faster than the Drich fluid, it is more possible that molecular H 2 O diffuses faster than the structural OH (e.g., Zhang et al, 1991;Doremus, 2004). Thus, the observed H isotope variations in the two CCSD-MH core segments may be principally caused by the preferential loss of molecular H 2 O from garnet and omphacite during the exhumation of deeply subducted continental crust.…”

Diffusion and reactions of interstitial oxygen species in amorphous SiO2: A review

“…This observation indicates that there are two types of mobile oxygen species whose properties are largely different. The 18 O-rich layer near the outer surface has been believed to be formed by the diffusion of the network oxygen; however, recent reports have indicated the importance of residual water in determining the 18 O profile [5,30]. In contrast, the oxygen flow that forms the interface 18 O-rich layer has been attributed to interstitial oxygen species, which migrate thorough interstitial voids without extensive interactions with the Si-O network [6,[30][31][32].…”

Oxygen-excess amorphous SiO2 with 18O-labeled interstitial oxygen molecules

“…The diffusion of interstitial O 2 in a-SiO 2 can be regarded basically as permeation [3][4][5][6][7][8][9][10], however, exchange between interstitial O 2 and oxygen atoms in the a-SiO 2 network also takes place, particularly at high temperatures [11][12][13][14][15]. The activation energy for the oxygen exchange is~2 eV [13][14][15] and is much larger than that of the permeation (diffusion) of interstitial O 2 (~0.8-1.2 eV [3,8,9,[16][17][18]).…”