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Variations in the H 2 O Content and H 2 O/Ce Ratio of Mantle Pyroxenites: Implications for Enriched Components in the Mantle
Author(s) -
Hao YanTao,
Li Pei,
Coltorti Massimo,
Xia QunKe
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb015854
Subject(s) - mantle (geology) , geochemistry , geology , chemistry , analytical chemistry (journal) , mineralogy , environmental chemistry
Mantle pyroxenite xenoliths were collected from Hannuoba, East China, and investigated for their H 2 O content and trace element contents, with particular regard to the H 2 O/Ce ratio. The pyroxenites were divided into three groups: Cr‐pyroxenites, Al‐pyroxenites, and garnet pyroxenites. The H 2 O contents and H 2 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 H 2 O content ranging from 23 to 339 ppm and an H 2 O/Ce ratio between 32 and 212; the Al‐pyroxenites had an H 2 O content ranging from 42 to 106 ppm and an H 2 O/Ce ratio between 1 and 22, and the garnet pyroxenites had an H 2 O content ranging from 37 to 69 ppm and an H 2 O/Ce ratio between 5 and 54. These systematic variations in the H 2 O contents and H 2 O/Ce ratios for the Hannuoba pyroxenites are associated with their origins. Both the H 2 O content and H 2 O/Ce ratio of the Al‐pyroxenites were low compared to those of Hawaiian pyroxenite, enriched mantle, and depleted MORB mantle sources. The high H 2 O content and H 2 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 H 2 O contents and H 2 O/Ce ratios may indicate that pyroxenites are essential enriched components in the sources of continental basalts.