Jadeitite Jade and Related Rocks from the Sierra del Convento Subduction Mélange (Eastern Cuba)
Abstract
The geological and gemological term “Jade” includes two different types of (quasi-) monomineralic rocks. One is amphibole jade, termed nephrite, a tremolite-actinolite rock with a felted, microcrystalline habit. The other is, pyroxene jade, termed jadeitite, a jadeite rock which varies from micro- to macro- crystalline textures. Jadeite jade is scarcer and more valuable than nephritic jade. Jadeitite is formed in high-pressure subduction environments as a rare constituent within serpentinite-matrix tectonic mélanges. It is formed by fluid flow in veins over a wide range of pressure and temperature (P-T) conditions, from blueschist facies to eclogite facies (Harlow, 1994; Harlow and Sorensen, 2005; Sorensen et al., 2006; Harlow et al., 2008). Therefore, the study of jadeitites provides first hand insights into the chemical signature of released fluid and the role of slab dehydration, water-rock interactions and geochemical recycling in subduction zones, (Morishita et al., 2007; Sorensen et al., 2010). Sorensen et al. (2010) cited eight localities where the geology of jadeitite bodies in serpentinite has been documented, however new jadeitite occurrences have been discovered recently in the Sierra del Convento Mélange, Cuba (García-Casco et al., 2009), Iran (Oberhänsli et al., 2007) and Río San Juan mélange, Dominican Republic (Schertl et al., 2007; Baese et al., 2007). Jadeitite jade outcrops from Sierra del Convento mélange are described by Cárdenas-Párraga et al. (2010) and were interpreted as formed during subduction of Protocaribbean (García-Casco et al., 2009). In this paper, we present a description of the petrographic and geochemical characteristics of the different varieties of jadeite jade and related rocks found in the Sierra del Convento mélange.
Keywords: Jadeitite Jade; High Pressure; Subduction Fluids; Caribbean; Eastern Cuba
----------------------------------------------------------------------------------------------------------
To Cite this article: Cárdenas-Párraga, J., García-Casco, A. (2010): Jadeitite Jade and Related Rocks from the Sierra del Convento Subduction Mélange (Eastern Cuba). Macla, 13, 59-60. http://www.ehu.es/sem/macla_pdf/macla13/Macla13_059.pdf
