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A New Jadeitite Jade Locality (Sierra Del Convento, Cuba): first Report and Some Petrological and Archeological Implications

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A New Jadeitite Jade Locality (Sierra Del Convento, Cuba): first Report and Some Petrological and Archeological Implications Contrib Mineral Petrol DOI 10.1007/s00410-008-0367-0 ORIGINAL PAPER A new jadeitite jade locality (Sierra del Convento, Cuba): first report and some petrological and archeological implications Antonio Garcı´a-Casco Æ A. Rodrı´guez Vega Æ J. Ca´rdenas Pa´rraga Æ M. A. Iturralde-Vinent Æ C. La´zaro Æ I. Blanco Quintero Æ Y. Rojas Agramonte Æ A. Kro¨ner Æ K. Nu´n˜ez Cambra Æ G. Milla´n Æ R. L. Torres-Rolda´n Æ S. Carrasquilla Received: 19 July 2008 / Accepted: 24 November 2008 Ó Springer-Verlag 2008 Abstract A new jadeitite jade locality has been discov- P–T evolution. Field relationships are obscure, but some ered in the serpentinite-matrix subduction me´lange of the samples made almost exclusively of jadeite show evidence Sierra del Convento (eastern Cuba) in a context associated of crystallization from fluid in veins. In one of these with tectonic blocks of garnet-epidote amphibolite, tona- samples studied in detail jadeite shows complex textural litic–trondhjemitic epidote gneiss, and blueschist. The and chemical characteristics (including oscillatory zoning) mineral assemblages of jadeitite jade and jadeite rocks are that denote growth in a changing chemical medium. It is varied and include combinations of jadeite, omphacite, proposed that interaction of an Al–Na rich fluid with albite, paragonite, analcime, clinozoisite-epidote, apatite, ultramafic rocks produced Al–Na–Mg–Ca fluids of varying phlogopite, phengite, chlorite, glaucophane, titanite, rutile, composition. Episodic infiltration of these fluids, as a result zircon, and quartz formed during various stages in their of episodic opening of the veins, developed oscillatory zoning by direct precipitation from fluid and after reaction of fluid with pre-existing jadeite. The latest infiltrating Communicated by H. Keppler. fluids were richer in Mg–Ca, favouring the formation of A. Garcı´a-Casco (&) omphacite and Mg–Ca rich jadeite in open voids and the Departamento de Mineralogı´a y Petrologı´a, Universidad de replacement of earlier jadeite by fine-grained ompha- Granada, and Instituto Andaluz de Ciencias de la Tierra, cite ? jadeite at 550–560°C. This new occurrence of CSIC-Universidad de Granada, Avda Fuentenueva sn, jadeite in Cuba opens important perspectives for archeo- 18002 Granada, Spain e-mail: [email protected] logical studies of pre-Columbian jade artifacts in the Caribbean region. A. Rodrı´guez Vega Á Y. Rojas Agramonte ´ Departamento de Geologıa, Instituto Superior Minero- Keywords Jadeitite jade High pressure Fluids Metalu´rgico, Las Coloradas s/n., Moa 83329, Holguı´n, Cuba Á Á Á Subduction Á Caribbean Á Eastern Cuba J. Ca´rdenas Pa´rraga Á C. La´zaro Á I. Blanco Quintero Á R. L. Torres-Rolda´n Á S. Carrasquilla Departamento de Mineralogı´a y Petrologı´a, Universidad de Introduction Granada, Avda Fuentenueva sn, 18002 Granada, Spain M. A. Iturralde-Vinent Jade is a gemological term embracing actinolite–tremolite Museo Nacional de Historia Natural, Obispo no. 61, Plaza de amphibolitite rocks (termed nephrite jade) and jadeite Armas, 10100 La Habana, Cuba pyroxenite rocks or jadeitite (jadeite jade). Nephrite jade is Y. Rojas Agramonte Á A. Kro¨ner a metasomatic rock that forms in a variety of petrologic– Institut fu¨r Geowissenschaften, Universita¨t Mainz, 55099 Mainz, geologic settings, including the replacement of dolomitic Germany marble by Si-rich fluids associated with magmatic rocks in contact aureoles and the replacement of meta-ultramafic K. Nu´n˜ez Cambra Á G. Milla´n Instituto de Geologı´a y Paleontologı´a, Via Blanca y Carretera rocks (serpentinite) by Ca-rich fluids in (tectonic) inter- Central, San Miguel del Padro´n, 11000 Ciudad Habana, Cuba faces between serpentinite and Si-rich rocks such as 123 Contrib Mineral Petrol plagiogranite, graywacke, argillite or chert (Harlow and origin. A variety of jadeitite and jadeite-bearing rocks have Sorensen 2005). Jadeite jade, in turn, is found almost been recently discovered in the Cretaceous subduction exclusively associated with serpentinite, generally within me´lange of Rı´o San Juan, Dominican Republic (Schertl serpentinite-matrix tectonic me´langes containing exotic et al. 2007a, b; Baese et al. 2007; Krebs et al. 2008). The blocks formed in high-pressure subduction environments available information suggests complex processes includ- (Harlow and Sorensen 2005). The temperature of crystal- ing direct precipitation from fluid. The high-pressure lization of jadeite jade is generally relatively low (250– Escambray complex and Rio San Juan me´lange may be 550°C), as documented by in situ jadeitite deposits where geologically correlated to Cretaceous high pressure com- antigoritite forms the wall rock of jade bodies. Harlow and plexes of central Guatemala (Motagua Valley region), Sorensen (2005) noted the scarcity of jadeitite in high- where jadeitite is abundant and varied in terms of P–T pressure complexes, citing only 12 localities in Myanmar, conditions of formation (Harlow 1994; Harlow et al. 2003). Guatemala, Russia, Kazakhstan, Japan, California, Italian In this paper, we document for the first time the occur- Alps, and Turkey. Sorensen et al. (2006) cited only eight rence of jadeite jade in eastern Cuba. The new locality is in ‘‘well documented, primary, hard-rock occurrences’’ of the subduction me´lange of Sierra del Convento (Fig. 1), jade. Recently, new jadeitite localities have been docu- which correlates with the Rio San Juan me´lange (Garcı´a- mented in Iran (Oberha¨nsli et al. 2007) and Dominican Casco et al. 2008;La´zaro et al. 2008). These me´langes and Republic (Schertl et al. 2007a, b; Baese et al. 2007). Har- the Escambray complex may have formed in the same low and Sorensen (2005) indicated that, in spite of probable subduction zone, but the latter mostly records late fairly common formation of jadeitite in subduction envi- Cretaceous subduction-accretion of margin-like sediments ronments, complex sequences of tectonic of events/ (Garcı´a-Casco et al. 2008) while the former record mid-late conditions should concur in order to exhume serpentinite- subduction of oceanic material. Our goal is not to offer a full matrix me´langes bearing jadeitite. description of the variety of jadeitite and related rocks in the Metasomatism of blocks of trondhjemite, plagiogranite, me´lange, but to give notice of the finding and to provide (meta)granitoid, leucogabbro, eclogite, metapelite, and some insight into the origin of jadeitite and jadeitite- metagraywacke has been classically considered the main forming fluids. This is relevant because the Sierra del jadeitite-forming process (see review by Harlow and Convento me´lange shows abundant evidence for fluid cir- Sorensen 2005 for complete list of references). However, culation in the subduction environment. In particular, fluid these authors have noted a number of problems with this infiltration triggered metasomatism and partial melting of interpretation, including the common lack of protoliths and subducted ocean crust (Garcı´a-Casco et al. 2008;La´zaro protolith replacement textures, severe mass-balance prob- and Garcı´a-Casco 2008), a process hardly ever seen in other lems, and the common occurrence of idiomorphic worldwide occurrences of oceanic subduction complexes oscillatory zoning of jadeite. After reviewing worldwide exhumed to the Earth’s surface (e.g., Sorensen and Barton jadeitite occurrences (Harlow and Sorensen 2005, see also 1987; Sorensen 1988). Partial melts crystallized in the Sorensen et al. 2006) emphasized that jadeite precipitates subduction environment (Garcı´a-Casco 2007; Garcı´a-Casco directly from fluids evolved at depth. This conclusion et al. 2008) and evolved fluids that formed pegmatitic and makes this type of rock of interest for the direct charac- hydrothermal rocks that may have had to do with jadeite terization of fluids and fluid-assisted processes in the formation. Also, the me´lange contains a high quantity of subduction environment, including processes of mass pure rock crystal quartz in hydrothermal veins and blocks transfer from the downgoing slab to the upper plate which prospected for electronic applications (Kulachkov and may ultimately lead to the formation of arc magmas. Leyva 1990; Leyva 1996). Jadeitite and jadeite-bearing rocks are scarce in the The new finding, together with other old and recent Caribbean region. Rare river pebbles of jadeitite of findings of jadeitite in the Caribbean region, opens new unknown in situ location were found in the Cretaceous archeological perspectives for the source of pre-Columbian subduction complex of Escambray, central Cuba, by Milla´n jade artifacts found in the Antilles (e.g., Harlow et al. 2006, and Somin (1981). This ‘‘old’’ finding has reached only Fig. 1a). limited audience due to editorial and language problems. However, only a brief petrographic description was made available by Milla´n and Somin (1981), who indicate radial Geologic and petrologic settings aggregates of jadeite and isolated grains of clinozoisite, lawsonite and albite. Rare relictic presumably magmatic The Sierra del Convento me´lange represents an oceanic clinopyroxene partly replaced by fine-grained jadeite led subduction channel related to subduction of Proto-Caribbean these authors to suggest formation of jadeitite by replace- lithosphere below the Caribbean plate during the Cretaceous ment of basic intrusive bodies, implying metasomatic (Garcı´a-Casco et al. 2006, 2008; Garcı´a-Casco 2007;La´zaro 123 Contrib Mineral Petrol Fig. 1 a Plate tectonic scheme of the Caribbean region, with important geological features including ophiolitic bodies and location of geological jadeitite source regions (Milla´n and Somin 1981; Harlow 1994; Harlow and Sorensen 2005; Schertl et al. 2007a; Schertl et al. 2007b; Baese et al. 2007, this paper) and of archeological locations of Antillean jade artifacts (Calvache 1944; Soto Gonza´lez 1981; Keegan 1991; Aarons 1990; Rodriguez 1991; Harlow et al. 2006; Garcı´a Padilla et al. 2006; Wilson 2007). b Geological sketch map of Cuba (after Iturralde-Vinent 1998) showing location of the study area. c Geologic map of the Sierra del Convento me´lange (Kulachkov and Leyva 1990) showing jade locality and Garcı´a-Casco 2008, and La´zaro et al.
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