naa a22 4500 510736459 CHVBK 20180411083011.0 cr unu---uuuuu 180411e20131201xx s 000 0 eng 10.1134/S1075701513080035 doi (NATIONALLICENCE)springer-10.1134/S1075701513080035 Gulbin Yu St. Petersburg State Mining University, 21-aya liniya 2, St. Petersburg, 199106, St. Petersburg, Russia aut Modeling of zoning patterns in garnet: Thermodynamic and kinetic aspects [Elektronische Daten] [Yu. Gulbin] Results from the modeling of compositional zoning patterns in garnet porphyroblasts from the medium-grade metapelitic schist of northern Ladoga area are considered. The P-T pseudosections in the model KMnFMASH system were calculated for this purpose using THERMOCALC software (Powell et al., 1998). Particular emphasis is placed upon the effect of garnet growth kinetics on the model zoning profiles for Mn (Gulbin, 2013). They fit the observed profiles if intergranular diffusion-controlled growth is assumed for porphyroblasts. Additionally, a model of metamorphic fractional crystallization is used to characterize the oscillations in both the garnet core and rim. Starting from the assumption that a reservoir, where garnet grows, consists of chlorite, and that this mineral is intensely replaced with biotite and staurolite at the onset of crystallization, a partial release of Mn from the chlorite structure and the concentration of this component in intergranular space is inferred. In terms of the model under consideration, the coefficient of the Mn partition between garnet and reservoir temporarily increases at the early stage of garnet growth, giving rise to the enrichment of the intermediate zone of porphyroblasts in Mn. In addition to the modeling of garnet growth zoning, its subsequent diffusion modification is estimated on the basis of intracrystalline diffusion profile simulation. The reverse zoned, Mn-rich and Mg-poor garnet rims are related to retrograde growth of garnet at the late stage of porphyroblast formation. The data obtained are used to constrain metamorphic evolution and the P-T-t path of staurolite-bearing rocks in the northern domain of the studied area. Pleiades Publishing, Ltd., 2013 Geology of Ore Deposits Springer US; http://www.springer-ny.com 55/8(2013-12-01), 625-636 1075-7015 55:8<625 2013 55 11477 https://doi.org/10.1134/S1075701513080035 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1134/S1075701513080035 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Gulbin Yu St. Petersburg State Mining University, 21-aya liniya 2, St. Petersburg, 199106, St. Petersburg, Russia aut NATIONALLICENCE 773 0- Geology of Ore Deposits Springer US; http://www.springer-ny.com 55/8(2013-12-01), 625-636 1075-7015 55:8<625 2013 55 11477 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer