Variations in the H2O Content and H2O/Ce Ratio of Mantle Pyroxenites: Implications for Enriched Components in the Mantle. Issue 7 (28th July 2018)

• Record Type: Journal Article
• Authors: Hao, Yan‐Tao; Li, Pei; Coltorti, Massimo; Xia, Qun‐Ke
• Is Part Of: Journal of geophysical research. Volume 123:Issue 7(2018)
• Page Start: 5628
• Page End: 5643
• Publication Date: 2018-07-28
• Subjects: H2O content -- H2O/Ce -- FTIR -- pyroxenite; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2018JB015854
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: Mantle pyroxenite xenoliths were collected from Hannuoba, East China, and investigated for their H2 O content and trace element contents, with particular regard to the H2 O/Ce ratio. The pyroxenites were divided into three groups: Cr‐pyroxenites, Al‐pyroxenites, and garnet pyroxenites. The H2 O contents and H2 O/Ce ratios of the pyroxenites in this study showed much wider ranges than those previously reported for the whole rock pyroxenites. The Cr‐pyroxenites had an H2 O content ranging from 23 to 339 ppm and an H2 O/Ce ratio between 32 and 212; the Al‐pyroxenites had an H2 O content ranging from 42 to 106 ppm and an H2 O/Ce ratio between 1 and 22, and the garnet pyroxenites had an H2 O content ranging from 37 to 69 ppm and an H2 O/Ce ratio between 5 and 54. These systematic variations in the H2 O contents and H2 O/Ce ratios for the Hannuoba pyroxenites are associated with their origins. Both the H2 O content and H2 O/Ce ratio of the Al‐pyroxenites were low compared to those of Hawaiian pyroxenite, enriched mantle, and depleted MORB mantle sources. The high H2 O content and H2 O/Ce ratio of the melt equilibrated with the Cr‐pyroxenites indicate that a water‐rich component was involved in its formation. Their large variations in the H2 O contents and H2 O/Ce ratios may indicate that pyroxenites are essential enriched components in the sources of continental basalts. Key Points: We report the H2 O content and H2 O/Ce ratio of pyroxenite xenoliths from Hannuoba The Al‐pyroxenites have both a low H2 O content and a low H2 O/Ce ratio A water‐rich component was involved in the source of the melt that formed the Cr‐pyroxenites