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Boninitic melt percolation makes depleted mantle wedges rich in silica

Chen Ming, Zheng Jianping, Dai Hongkun, Xiong Qing, Sun Min, Mikhail M. Buslov, Zhou Xiang and Liu Jingao
Boninitic melt percolation makes depleted mantle wedges rich in silica
Geology (Boulder) (August 2023) 51 (8): 791-795


Global fore- and sub-arc peridotites show paradoxically highly melt-depleted yet silica-enriched (as excess orthopyroxene) compositions, which have been attributed to either silica-enriched mantle sources or metasomatic overprints by silica-rich fluids/melts. Here, we present robust mineralogical evidence from an ophiolitic peridotite suite and thermodynamic modeling suggesting that boninitic melt percolation is a viable manner to induce silica enrichment and keep the ultra-depleted signature in a nascent lithospheric mantle wedge. The co-occurrence of resorbed olivines and euhedral high-Crpinels with a boninitic origin enclosed by porphyroblastic orthopyroxenes in these peridotites documents that the primary olivines were partially melted or dissolved along with precipitation of the euhedral spinels and growth of the orthopyroxene through reactions between the depleted peridotites and boninitic melts. Such metasomatism modulates the geochemistry of mantle wedges and can explain the compositional variations observed in the majority of global fore- and sub-arc peridotites and supra-subduction zone ophiolitic counterparts. Lateral assembly of these mantle domains by accretionary orogenesis may contribute to the growth of continental lithosphere and accounts for the existence of melt-depleted yet silica-enriched mantle domains beneath orogens.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 51
Serial Issue: 8
Title: Boninitic melt percolation makes depleted mantle wedges rich in silica
Affiliation: China University of Geosciences, School of Earth Sciences, State Key Laboratory of Geological Processes and Mineral Resources, Wuhan, China
Pages: 791-795
Published: 202308
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 2023-053910
Categories: Solid-earth geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus.
Secondary Affiliation: University of Hong Kong, CHN, ChinaRussian Academy of Sciences, Siberian Branch, RUS, Russian Federation
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2023, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 2023
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