TY - JOUR ID - 54647 TI - Constraining the Water Activity during Peak Metamorphism in a Thermal Aureole; a Mineral Equilibria Approach JO - Journal of Sciences, Islamic Republic of Iran JA - JSCIENCES LA - en SN - 1016-1104 AU - Moazzen, M. AD - Department of Earth Sciences, Faculty of Natural Sciences, University of Tabriz, 51664, Tabriz, Islamic Republic of Iran Y1 - 2015 PY - 2015 VL - 26 IS - 2 SP - 151 EP - 163 KW - Contact metamorphism KW - Water activity KW - Fluid-absent condition KW - Mineral equilibria DO - N2 - In order to assess the presence or absence of fluids under peak metamorphic conditions within the inner aureole of the Etive igneous complex in west Scotland, eight suitable metabasic hornfels samples and one suitable pelitic hornfels were used to calculate water activities using a mineral equilibria. Calculated activities for water are lower than unity in the pelitic sample and extremely low in the metabasic rocks. These low H2O activities due to dilution of water by other fluid species are unlikely, since no mineralogical evidence for the presence of other fluids were found in the studied rocks. As a consequence, the low H2O activities support fluid-absent conditions during the peak metamorphism of the inner aureole rocks. The findings from this study are in good agreement with calculated water activities using water contents of cordierite in the pelitic rocks for the same part of the aureole, suggesting that cordierite in metapelites retained its syn-metamorphic volatiles. UR - https://jsciences.ut.ac.ir/article_54647.html L1 - https://jsciences.ut.ac.ir/article_54647_1f14670dbc900860c3786985db2c739c.pdf ER -