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Ultramafic and mafic rock types from Choiseul, Santa Isabel and santa Jorge (Northeastern Solomon Islands): origins and significance

Abstract : The Solomon Islands are a double chain of islands in the Pacific Ocean (Noth-east of Australia) resulting from the recent collision (<10 Ma) of the world's largest oceanic plateau Ontong Java (OJP) with the Solomon arc. In response of this collision, thin fault slices of peridotites, pyroxenites, gabbros and basalts are now exposed on the islands of Santa Isabel, san Jorge and Choiseul (Northeastern Solomons). Although some pillow basalts are OJP-related, the origins of the most of the mafic and ultramafic rocks remain uncertain.
The Choiseul peridotites are interpreted to have two stage origins: 1-residual harzburgites formed beneath an ocean ridge; 2) infiltration of a reactive metasomatic agent released from the slab. Similar but more complex metasomatic process results in the formation of the pyroxenites from San Jorge and Santa Isabel. This metasomatic agent released from the slab is likely to represent an hydrous granitic melt derived from the subducted sediments. The mafic rocks (including the basalts and gabbros) are interpreted as portions of an arc-backarc crust. As a result, the formation and the exhumation of the ultramafic and mafic rocks from the Solomon Islands are directly related to the OJP-arc collision.
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https://tel.archives-ouvertes.fr/tel-00012073
Contributor : Thomas Berly <>
Submitted on : Sunday, April 2, 2006 - 12:10:59 PM
Last modification on : Thursday, November 19, 2020 - 3:54:26 PM
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Thomas Berly. Ultramafic and mafic rock types from Choiseul, Santa Isabel and santa Jorge (Northeastern Solomon Islands): origins and significance. Geochemistry. Université Joseph-Fourier - Grenoble I, 2005. English. ⟨tel-00012073⟩

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