caa a22 4500 445390107 CHVBK 20180317143044.0 cr unu---uuuuu 170323e20110301xx s 000 0 eng 10.1007/s00710-011-0146-x doi (NATIONALLICENCE)springer-10.1007/s00710-011-0146-x Ruiz Cruz Maria Facultad de Ciencias, Campus de Teatinos, 29071, Málaga, Spain aut NH4-bearing micas in poly-metamorphic Alpujárride micaschists and gneisses from the central zone of the Betic Cordillera (Spain): tectono-metamorphic and crystal-chemical constraints [Elektronische Daten] [Maria Ruiz Cruz] The content and distribution of NH4-bearing micas in micaschists and paragneisses of the Alpujárride complex (Betic Cordillera, Spain) are interpreted on the basis of textures, metamorphic history and crystal-chemical constraints. NH4 is present in important amounts in early micas, recording their older diagenetic-to-metamorphic history. NH4 was inherited by micas formed in successive metamorphic events. At similar metamorphic grade, annite is enriched in NH4 relative to muscovite with a fractionation of 4:1. Maximum NH4 contents were estimated in golden annite from medium-grade schists and in retrogressive annite-chlorite mixed-layers (~1.0wt.%). A Ti-NH4 avoidance gives rise to associated chemical changes, such as the enrichment in Mg and in VIAl. These data suggest that NH4 can be a decisive factor in chemical equilibrium and element partitioning between coexisting phases, thus affecting to the commonly used thermobarometers. Estimation of the P-T conditions from texturally different muscovite-annite pairs reveals the superposition of several stages of mica growth, under different geothermal gradients. Springer-Verlag, 2011 Mineralogy and Petrology Springer Vienna 101/3-4(2011-03-01), 225-244 0930-0708 101:3-4<225 2011 101 710 https://doi.org/10.1007/s00710-011-0146-x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00710-011-0146-x text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Ruiz Cruz Maria Facultad de Ciencias, Campus de Teatinos, 29071, Málaga, Spain aut NATIONALLICENCE 773 0- Mineralogy and Petrology Springer Vienna 101/3-4(2011-03-01), 225-244 0930-0708 101:3-4<225 2011 101 710 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer