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Title: The petrogenesis of sodic island arc magmas at Savo volcano, Solomon Islands
Authors: Smith, Daniel J.
Petterson, MG
Saunders, AD
Jenkin, GRT
Petterson, MG
Naden, J
Cook, JM
Millar, IL
Toba, T
First Published: 2009
Publisher: Springer Verlag
Citation: CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, 2009, 158 (6), pp. 785-801
Abstract: Savo, Solomon Islands, is a historically active volcano dominated by sodic, alkaline lavas, and pyroclastic rocks with up to 7.5 wt% Na2O, and high Sr, arc-like trace element chemistry. The suite is dominated by mugearites (plagioclase–clinopyroxene–magnetite ± amphibole ± olivine) and trachytes (plagioclase–amphibole–magnetite ± biotite). The presence of hydrous minerals (amphibole, biotite) indicates relatively wet magmas. In such melts, plagioclase is relatively unstable relative to iron oxides and ferromagnesian silicates; it is the latter minerals (particularly hornblende) that dominate cumulate nodules at Savo and drive the chemical differentiation of the suite, with a limited role for plagioclase. This is potentially occurring in a crustal “hot zone”, with major chemical differentiation occurring at depth. Batches of magma ascend periodically, where they are subject to decompression, water saturation and further cooling, resulting in closed-system crystallisation of plagioclase, and ultimately the production of sodic, crystal and feldspar-rich, high-Sr rocks. The sodic and hydrous nature of the parental magmas is interpreted to be the result of partial melting of metasomatised mantle, but radiogenic isotope data (Pb, Sr, Nd) cannot uniquely identify the source of the metasomatic agent.
DOI Link: 10.1007/s00410-009-0410-9
ISSN: 0010-7999
Type: Journal Article
Rights: The final publication is available at Springer via
Appears in Collections:Published Articles, Dept. of Geology

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