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

Jadeitite formed during subduction: In situ zircon geochronology constraints from two different tectonic events within the Guatemala Suture Zone

“…A contrasting example to the complexes described above is the Syum-Keu and Marun-Keu belts of the Polar Urals (Russia) wherein zircon ages from jadeitite of the first unit are only 38 −28 Ma older than the Sm-Nd, U-Pb and Rb-Sr mineral ages from eclogites of the second complex ( Fig. 6d; Shatsky et al, 2000;Glodny et al, 2003Glodny et al, , 2004Meng et al, 2011). A similar example comes from HP-LT rocks from the Río San Juan Complex, where a 115 Ma U-Pb age from zircon cores on the quartz-free jadeitite is 11 Ma older than the 104 Ma metamorphic peak given by Lu-Hf on eclogite, and, the younger 93 Ma age from zircon rims on jadeitites is also older than the 75−73 Ma exhumation age (see Fig.…”

“…(d) 600-650 1C and 1.4-1.7 GPa 1 Glodny et al (2003Glodny et al ( , 2004, Meng et al (2011), Molina et al (2002), Shatsky et al (2000), Udovkina (1985) Age range groups 414-368 (n¼ 13) (b) 357.3 7 6.6 to 353.373.1 (Rb-Sr in eclogite and eclogite-facies vein); 357.9 7 3.7 to 3537 6 (Rb-Sr in retrograde amphibolite) 1 Th/U 0.03-0.21 (n¼ 13 Tsujimori 2002, Tsujimori and Matsumoto (2006), Tsujimori et al (2001), Kunugiza and Goto (2010) Goffé et al (2002), Qiu et al (2009); Oberhänsli et al (2007), Shi et al (2001Shi et al ( , 2003Shi et al ( , 2008 Mean 153.7 7 3.5 (n¼8); 158 7 4.6(n ¼10); and 129.7 7 4.3(n¼7) (a) 143.9 7 9 and 132.17 6.5 (Sm-Nd in Lws-eclogite) Harlow et al (2004Harlow et al ( , 2011, Tsujimori et al (2006aTsujimori et al ( , 2006b; This paper Age range groups 160-134 (n¼ 9); and 172-120 (n ¼17) Mean 95.0 7 3.5 (n¼17); 94.17 3.9 (n¼ 13); and 02.9 7 4.6 (n ¼3) (a) 130.7 7 6.3 and 1257 7.8 (Sm-Nd in eclogite); 777 13 (Sm-Nd in eclogite-facies bands and boudins) 5 ; and 75.5 7 2 (Zrn U-Pb in eclogite-facies bands and boudins) 5…”

Jadeitites and Plate Tectonics

“…By comparison, both primary and secondary fluid inclusions in eclogite and garnet amphibolite samples from the Franciscan complex and Catalina schist, California, and the Samaná Peninsula, Dominican Republic, preserve seawater-like salinities (Sorensen & Barton 1987, Giaramita & Sorensen 1994. Meng et al (2011), in their research on jadeitite from Syum-Keu, have reported both H 2 O-rich and CH 4 -rich fluid inclusions, which they describe as one-phase but are clearly imaged as two-phase; no interpretation was made about these inclusions other than their consistency with prior research on jadeitite. For Osayama quartz-free jadeitite, T h for two-phase aqueous fluid inclusions led Shoji & Kobayashi (1988) to estimate a minimum jadeite crystallization T of ∼345 • C.…”

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

“…6 as discussed above. In addition to these cases, jadeitites from Polar Urals (Russia), Osayama (Japan), the South Motagua Mélange (Guatemala), the Rio San Juan Complex (Dominica Republic), the Sierra del Convento Mélange (Cuba) and the Cycladic blueschist belt (Greece) have also been studied recently (Tsujimori et al, 2005;Bröcker and Keasling, 2006;Meng et al, 2011;Cárdenas-Párraga et al, 2012;Schertl et al, 2012;Flores et al, 2013). With a few exceptions, most zircons in these studies contain mineral inclusions of metasomatic origin and were suggested to be newly-formed.…”

“…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).…”