An oceanic volcano in an island arc setting – Seatura Volcano, Fiji

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Abstract
Seatura is a Pliocene caldera-type, shield volcano situated in SW Vanua Levu, Fiji. Shield-building basaltic lavas are predominantly subaerial though there is a shoreline facies of fossiliferous sediment, pillow lava and hyaloclastite. Late-stage events include the intrusion of a dyke swarm in and around the caldera, and deposition of laharic conglomerates. Chemically the rocks are intermediate between tholeiite and alkali basalt and have intraoceanic levels of TiO2. Late-stage derivatives include benmoreite, trachyte, and propylitically altered rocks. The parent magmas are thought to have been partial melts of undepleted mantle at relatively deep levels. Tapping of these deep levels may have been facilitated by extensional plate tectonic conditions existing in the Fiji area during the development of Seatura Volcano.