Petrogenetic relationships between jadeitite and associated high-pressure and low-temperature metamorphic rocks in worldwide jadeitite localities: a review TATSUKI TSUJIMORI 1, * and GEORGE E. HARLOW 2 1 Pheasant Memorial Laboratory, Institute for Study of the Earth’s Interior, Okayama University, Misasa, Tottori-ken, Japan *Corresponding author, e-mail: tatsukix@misasa.okayama-u.ac.jp 2 Department of Earth and Planetary Sciences, American Museum of Natural History, New York, NY, USA Abstract: Jadeitite-bearing serpentinite-matrix me ´lange is distributed in the Caribbean (Guatemala, Cuba, and Dominican Republic), circum-Pacific (Japan, Western USA, and Papua New Guinea), Alpine-Himalayan (Italy, Iran, Greece, and Myanmar), and Caledonian (Russia and Kazakhstan) orogenic belts, and always contains high-pressure, low-temperature (HP-LT) metamorphic rocks. There are also jadeitite xenoliths in kimberlitic pipes in the Colorado Plateau (USA). The oldest occurrences of jadeitite are Early Paleozoic in Japan, Russia, and Kazakhstan, suggesting subduction-zone thermal structures evolved the necessary high pressure/temperature conditions for jadeitite formation since Early Paleozoic; the youngest occurrence is a xenolith from the Colorado Plateau. Major occurrences consist principally of fluid precipitates (P-type) that infiltrated the mantle wedge; fewer occurrences document metasomatic replacement (R-type) of plagiogranite, metagabbro and eclogite, and both types may be possible in the same occurrence or system. The P-T conditions for jadeitite formation can be extended beyond the previously argued limits of blueschist-facies conditions. Some jadeitite formed at epidote amphibolite and others at eclogite facies conditions. Available geochronological data of both jadeitite and associated HP-LT rock show temporal discrepancies between jadeitite formation and HP-LT metamorphism at some localities. The close association between older jadeitite and younger HP-LT rock in a single me ´lange complex implies different histories for the subduction channel and jadeitite-bearing me ´lange. Jadeitite-bearing serpentinite me ´lange can stay at the mantle wedge for a considerable time and, as a result, experience multiple fluid-infiltration events. The subduction channel can occasionally incorporate overlying serpentinized mantle wedge material due to tectonic erosion. With time, the disrupted mantle wedge containing jadeitite veins is mixed with younger blueschists, exhumed eclogites and various fragments of suprasub- duction-zone lithologies. Consequently, recrystallization and re-precipitation of jadeitite are reactivated along a slab–mantle wedge interface. All these possible scenarios and their combinations yield a complicated petrological record in jadeitite. With further investigation, the rock association of jadeitite–HP-LT metamorphic rocks–serpentinite has the potential to yield a greater under- standing of subduction channels and overlying mantle wedge. Key-words: jadeitite, blueschist, eclogite, HP-LT metamorphism, serpentinite me ´lange, fluid precipitation, metasomatic replacement. 1. Introduction Jadeitite is an uncommon, nearly monomineralic rock that has been interpreted to have crystallized directly from sub- duction-zone Na-Al-Si-rich hydrous fluids or formed through almost complete metasomatic replacement of pre- cursor-rocks by subduction-zone fluid–serpentinite interac- tion (cf. Harlow & Sorensen, 2005; Sorensen et al., 2006; Harlow et al., 2007). In either formation process, fluid that can be saturated with jadeite (Manning, 1998, 2004) is an essential component in the subduction zones. Since the polymerized Na-Al-Si-rich hydrous fluids at HP-LT condi- tions can behave as an agent of mass transfer, the petrolo- gical record within the jadeitites offers a proxy for the fluid- related mass transfer within a subduction zone. Moreover, fluids released from subducting slabs enhance serpentiniza- tion of mantle wedge peridotites and, consequently, control a variety of processes relating to the subduction channel as an interface between the subducting plate and an overlying serpentinizing mantle wedge. So far, the subduction-related origin of jadeitite has been documented in various localities in close spatial association with high-pressure and low- temperature (HP-LT) metamorphic rocks, such as blueschist and eclogite. In particular, a jadeitite-bearing HP-LT com- plex with a large quantity of ultramafic rocks (typically a me ´lange) can be regarded as a fossil serpentinite-dominant subduction channel, in which a buoyancy-driven return flow necessary to exhume deeply subducted materials is estab- lished (e.g., Cowan & Silling, 1978; Cloos, 1982; Guillot et al., 2001; Gerya et al., 2002; Tsujimori et al., 2006a; Jadeitite: new occurrences, new data, new interpretations 0935-1221/12/0024-2193 $ 9.00 DOI: 10.1127/0935-1221/2012/0024-2193 # 2012 E. Schweizerbart’sche Verlagsbuchhandlung, D-70176 Stuttgart Eur. J. Mineral. 2012, 24, 371–390 Published online January 2012