Hydrogen in silicate melt inclusions in quartz from granite detected with Raman spectroscopy

By using Raman spectroscopy, hydrogen was detected, together with CH 4 , N 2 , H 2 O, disordered graphite, and possibly a (CH 4 ) n (H 2 ) m compound, in silicate melt inclusions (SMIs) in quartz from Jiajika granite in China. The occurrences of H 2 in fluid or melt inclusions are rarely reported because they are not commonly expected, and also the spectral window above 4000 cm −1 wavenumbers, where the dominant signals of H 2 located, is rarely covered in routine Raman analyses due to limited information of geological interest available in that spectral range. The mechanisms for the occurrence of H 2 in these SMIs are unknown. However, the retention of H 2 in these SMIs was most likely resulted from the low diffusion rate of H 2 in quartz at low temperatures and also the low H 2 gradient between SMIs and their environments surrounding the host minerals. More studies are needed to determine whether the occurrences of H 2 in inclusions in minerals are common in similar or other rock types, to formulate the mechanisms for its entrapment, and to investigate the associated geological processes. Copyright © 2015 John Wiley & Sons, Ltd.