Major element composition of phenocrysts from the volcanic basement of ODP Hole 125-786B, Izu forearc region, Philippine Sea


Early arc volcanism during Eocene to Oligocene in the Izu forearc region was investigated during ODP Legs 125 and 126 in 1989, and effusive and intrusive volcanics were recovered from Leg 125 Site 786. These rocks were all classified into boninites and associated rocks by Leg 125 Shipboard Scientific Party, and they concluded that boninitic volcanism had occurred before 40 Ma, and arc tholeiitic volcanism began after 40 Ma. In this study, lava flows and breccias that classified into boninite series are divided into two groups, tholeiite and boninite, based on petrographical and petrological properties. Both series are also distinguished by bulk rock composition. It is considered that the sources of both rock types have similar depleted compositions because of their similar, very low bulk HFSE concentrations. We suggest that boninitic and tholeiitic volcanism occurred closely in time and space, and reflected different temperature and water condition.

Supplement to: Haraguchi, Satoru; Ishii, Teruaki (2007): Simultaneous boninitic and arc-tholeiitic volcanisms in the Izu forearc region during early arc volcanism, based on ODP Leg 125 Site 786. Contributions to Mineralogy and Petrology, 153, 509-531

Related Identifier
Metadata Access
Creator Haraguchi, Satoru ORCID logo; Ishii, Teruaki
Publisher PANGAEA
Publication Year 2007
Rights Creative Commons Attribution 3.0 Unported;
OpenAccess true
Resource Type Supplementary Publication Series of Datasets; Collection
Format application/zip
Size 9 datasets
Discipline Earth System Research
Spatial Coverage (141.226 LON, 31.874 LAT); North Pacific Ocean
Temporal Coverage Begin 1989-04-04T12:00:00Z
Temporal Coverage End 1989-04-16T17:00:00Z