Petrology and Geochemistry of Boninite-Series Volcanic Rocks, Chichi-Jima, Bonin Islands, Japan

Abstract

An Eocene submarine boninite series volcanic center is exposed on the island of Chichi-jima, Bonin Islands, Japan. Five rock types, boninite, bronzite andesite, dacite, quartz dacite, and rhyolite, were distinguished within the boninite volcanic sequence on the basis of petrographic and geochemical observations. Boninite lavas contain high magnesium, nickel, and chromium contents indicative of primitive melts, but have high silica contents relative to other mantlederived magmas. All boninite series lavas contain very low incompatible element concentrations, and concentrations of high-field strength elements in primitive boninite lavas are less than half of those found in depleted mid-ocean ridge basalts. Abundances of large-ion lithophile elements are relatively high in boninite series lavas, similar to the enrichments observed in many island arc lavas. Trends for both major and trace element data suggest that the more evolved lavas of the boninite magma series were derived primarily through high-level fractional crystallization of boninite. Textural features, such as resorption and glomeroporphyrocrysts, and reverse chemical zonations suggest that magma mixing contributed to the development of the quartz dacite lavas.

Boninite and boninite-series volcanics in northern Zambales ophiolite: doubly vergent subduction initiation along Philippine Sea plate margins

“…Reproducibility is better than 2 % for REEs and better than 3 % for the rest of the trace elements except for Ta (6.5 %) and Be (3.6 %). Mean percent error is generally within 5 to 10 % relative to the preferred values of Jochum et al (2016) and Dulski (2001).…”

The Narooma Terrane offshore: a new model for the southeastern Lachlan Orogen using data from rocks dredged from the New South Wales continental slope

“…(b) Geotectonic classification Pearce and Norry (1979). Boninite field has been added using data from Crawford (1988), Meijer (1980), Dobson et al (2006) and Konig et al (2010). Victorian Howqua and Heathcote basalts from Crawford (1988) plot in the mid-ocean ridge field.…”

Identification, classification, and interpretation of boninites from Anthropocene to Eoarchean using Si-Mg-Ti systematics

“…1B), the boundary is drawn as a tie line to an olivine composition, because MORB, arc basalts, and boninites with MgO > 8 wt% are typically dominated by olivine crystallization. The olivine composition chosen is MgO = 50 wt%, SiO 2 = 41 wt%, corresponding closely to olivines in equilibrium with inferred primary magmas from the Troodos Massif (e.g., Cameron, 1985) and Chichijima (e.g., Dobson et al, 2006).…”

“…Boninite is one of a small number of rock types (adakite is another obvious example) that are commonly linked to a particular present-day tectonic environment but (1) have more than one potential mode of origin and can therefore be generated in more than one tectonic setting, and (2) have likely, but unclear, significance for early Earth. Boninite is most commonly linked to embryonic arc volcanism following intraoceanic subduction initiation, i.e., the inferred setting of its type area, Chichijima, once known as Bonin Island, in the western Pacific (e.g., Kuroda et al, 1978;Taylor et al, 1994;Dobson et al, 2006). For this reason, the presence of boninites in Archean terranes has been cited as key evidence that subduction, and hence plate tectonics, operated during the Archean (e.g., Kerrich et al, 1998;Polat et al, 2002;Turner et al, 2014).…”