Fluids in the evolution of granitic magmas: Consequences of finite CO2 solubility

Research Article| October 01, 1976 Fluids in the evolution of granitic magmas: Consequences of finite CO2 solubility JOHN R. HOLLOWAY JOHN R. HOLLOWAY 1Division of Geochemistry, Department of Chemistry, Arizona State University, Tempe, Arizona 85281 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1976) 87 (10): 1513–1518. https://doi.org/10.1130/0016-7606(1976)87<1513:FITEOG>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation JOHN R. HOLLOWAY; Fluids in the evolution of granitic magmas: Consequences of finite CO2 solubility. GSA Bulletin 1976;; 87 (10): 1513–1518. doi: https://doi.org/10.1130/0016-7606(1976)87<1513:FITEOG>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The small but finite solubility of CO2 in granitic magmas under crustal conditions, together with the common occurrence of CO2 in likely magma source materials, suggests that granitic magmas will often be accompanied by a CO2-H2O fluid phase during their ascent in the crust.Polybaric and isobaric calculations have been made for model systems with varying total volatile content, initial CO2/H2O ratios, crystallization rates, and closed-system or open-system conditions. The calculations demonstrate that the presence of CO2 in an evolving magma system can result in greatly differing values of H2O activity (and hence H2O content, phase equilibria, and physical properties of the magma). Specifically, if the mass ratio CO2/H2O is ≥0.4 and the initial mass ratio of total volatiles to silicate magma is ≥0.05, then, if little or no loss of the fluid phase occurs during magma evolution, the activity of H2O will remain nearly constant. This is in strong contrast to all other possible cases in which the activity of H2O increases rapidly with decreasing pressure and (or) anhydrous phase crystallization, invariably reaching a value of unity.It is also demonstrated that if CO2 is present in a fluid phase in the magma source region, then there will be a fluid present throughout the evolutionary history of the magma. The presence of fluid bubbles in the magma should considerably alter many properties of the magma system such as heat transfer, mass transfer, and viscosity. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.