@article { author = {Izadyar, J. and Mojab, S. and Kuroshi, O. and Zare, M.}, title = {An unusual assemblage of talc-phengite-chlorite-K-feldspar in quartz schists from the Nahavand area, Sanandaj-Sirjan zone, Iran}, journal = {Iranian Journal of Science}, volume = {38}, number = {3}, pages = {243-252}, year = {2014}, publisher = {Springer}, issn = {2731-8095}, eissn = {2731-8109}, doi = {10.22099/ijsts.2014.2267}, abstract = {For the first time, an unusual assemblage of talc-phengite-chlorite-K-feldspar was found in quartz schists from the Sanandaj-Sirjan zone in the Nahavand area in western Iran. The talc-bearing quartz schists occur as small bodies or lenses within pelitic schist layers and contain talc, phengite, chlorite, K-feldspar and quartz as major mineral constituents with subordinate amounts of calcite and graphite. Textural analysis revealed that talc, phengite, chlorite and K-feldspar are in sharp contact and no reaction rims between them were observed. Constructed petrogenetic gird in the K   2O-FeO-MgO-Al2O3-SiO2-H2O (KFMASH) model system containing talc, phengite, chlorite, K-feldspar, phlogopite and kyanite with excess quartz and H   2O shows that divariant assemblage of talcphengite- chlorite-K-feldspar is stable over a wide P-T range defined by the following two univariant reactions: phengite + talc + quartz = chlorite + K-feldspar + kyanite + H   2O and chlorite + phlogopite + quartz = talc + phengite + K-feldspar + H   2O. Constructed Al2O3-KAlO2-MgO+FeO (AKM) compatibility diagrams predict that phengite (X   Ph = 0.280, YPh = 0.860), chlorite (XChl = 0.570, YChl = 0.640), talc (XTlc = 0.160, YTlc = 0.02) and Kfeldspar are stable at P = 11 kbar and T = 400°C. This relatively high-pressure assemblage could be formed during the subduction of the Neo-Tethys oceanic plate under Iranian microcontinent.}, keywords = {High-pressure metamorphism,Nahavand,Sanandaj-Sirjan zone,Talc-phengite-K-felds parassemblage}, url = {https://ijsts.shirazu.ac.ir/article_2267.html}, eprint = {https://ijsts.shirazu.ac.ir/article_2267_097a52546c1e1a651e40284e47493b80.pdf} }