Resumen de Enclaves tonalíticos en la dacita neógena del Hoyazo de Níjar (Almería): hipótesis petrogenética
A. Piqué, Pere Enrique Gisbert, Gemma Alías López
The Neogene dacite of El Hoyazo (SE Spain) contains a large amount of AI rich metapelitic (restltlc) and igneous enclaves. The presence of these metapelitic enclaves strongly suggests an important contribution of crustal anatectic magmas on the dacite genesis. This study gives new information about igneous enclaves, which were previously described as quartz diorites, quartz gabbros and basaltoids.
The enclaves sampled fall within the tonalité field according to the IUGS classification, although plagioclases have anortite contents greater than 50%, showing a gabbroic afinity. Their origin could be related to the crystallization of magmas under plutonio conditions or represent restitic compositions from the partial melting of pre-existing intermediate to basic plutonio or metamorphic rocks. Calcic-rich plagioclase (up to An82) with glass filled cavities together with inverse zoning and the presence of intergranular glass suggest a restitic origin for these tonalité rocks. In that case the liquids (l-type) resulting from their partial melting could have been added to the melts generated by anatexis of pelitic rocks (Stype) and would be involved in the genesis of El Hoyazo dacite.
