Genesis of Guatemala jadeitite and related fluid characteristics: Insight from zircon

Zircon U–Pb dating of jadeitite from the Syum-Keu ultramafic complex, Polar Urals, Russia: Constraints for subduction initiation

“…Most of the zircons have very low Th/U ratios (<0.1), similar to those of zircons from high-pressure metamorphic veins (Rubatto and Hermann, 2003;Glodny et al, 2004) and zircons from Guatemala jadeitite (Yui et al, 2010). These low Th/U ratios are significantly different from those of zircons from other jadeitites, e.g., the huge zircons in jadeitite of the Osayama serpentinite, southwestern Japan, crystallized from fluids with Th/U ratios over 0.2 (0.2-0.76) (Tsujimori et al, 2005).…”

“…U contents of the zircons range from 27 to 158 ppm and Th contents are low from 1 to 20 ppm. Most of the zircons have very low Th/U ratios below 0.1 (0.03-0.09), compatible with precipitation from an aqueous fluid (Yui et al, 2010); only four grains have Th/U ratios over 0.1(0.1 to 0.21). Eleven concordant analyses yielded a weighted average 206 Pb/ 238 U age of 404 ± 7 Ma (MSWD = 0.70) (Fig.…”

A revisit to the Yorii jadeite–quartz rock, the Kanto Mountains, central Japan: Implications for petrogenesis

“…It generally occurs as blocks, in association with high-pres sure/low-temperature rocks, within serpentinite (cf., Tsujimori and Harlow, 2012). Its genesis has attracted much attention recently (Tsujimori et al, 2005;Bröcker and Keasling, 2006;Shi et al, 2008Shi et al, , 2009Qiu et al, 2009;Fu et al, 2010Fu et al, , 2012Yui et al, 2010Yui et al, , 2012Yui et al, , 2013Meng et al, 2011;Mori et al, 2011;Cárdenas-Párraga et al, 2012;Schertl et al, 2012;Flores et al, 2013;Fukuyama et al, 2013). Two formation mechanisms have been proposed: the wholesale metasomatic replacement and the vein precipitation (Harlow et al, 2007(Harlow et al, , 2014(Harlow et al, , 2015Yui et al, 2010;Tsujimori and Harlow, 2012).…”

Spherules with pure iron cores from Myanmar jadeitite: Type-I deep-sea spherules?

“…Methane (CH 4 ) bearing fluid inclusions found in jadeites from the Myanmar jadeitite confirm a fluid-related origin and suggest a reduced environment (Shi et al, 2005b;Sorensen et al, 2006). Studies on zircons in jadeitite from Myanmar and elsewhere suggest that their derivation can be from rapid reworking of juvenile oceanic crust, which was hydrated during its formation as revealed from highly positive depleted-mantle eHf (t) values (Qiu et al, 2008;Shi et al, 2009a), although aqueous solutions possibly related to serpentinization are suggested by low Th/U and fluid inclusions (Yui et al, 2010), and zircons in jadeitite can have multiple origins (Fu et al, 2010).…”