J. R. O’Neil P.F. Dobson 1987 <div id="abstracts" class="Abstracts u-font-serif text-s"><div id="ab1" class="abstract author" lang="en"><div id="aep-abstract-sec-id3"><p>Measurements of stable isotope compositions and water contents of boninite series volcanic rocks from the island of Chichi-jima, Bonin Islands, Japan, confirm that a large amount (1.6–2.4 wt.%) of primary water was present in these unusual magmas. An enrichment of 0.6‰ in¹⁸O during differentiation is explained by crystallization of¹⁸O-depleted mafic phases. Silicic glasses have elevated<span>&nbsp;</span><i>δ¹⁸O</i><span>&nbsp;</span>values and relatively low<span>&nbsp;</span><i>δD</i><span>&nbsp;</span>values indicating that they were modified by low-temperature alteration and hydration processes. Mafic glasses, on the other hand, have for the most part retained their primary isotopic signatures since Eocene time. Primary<span>&nbsp;</span><i>δD</i><span>&nbsp;</span>values of −53 for boninite glasses are higher than those of MORB and suggest that the water was derived from subducted oceanic lithosphere.</p></div></div></div> application/pdf 10.1016/0012-821X(87)90108-7 en Elsevier Stable isotope compositions and water contents of boninite series volcanic rocks from Chichi-jima, Bonin Islands, Japan article