Temperature-pressure-composition model for melt viscosity in the Di-An-Ab system
department or school: Science, Faculty of
department or school: Earth, Ocean and Atmospheric Sciences, Department of
data provider: DSpace
degree campus: UBCV
creator: Li, Mu
issued: 2020-09-01T17:09:29Z
issued: 2020
related degree: Master of Science - MSc
degree grantor: University of British Columbia
description: A model for the viscosity (η) of melts in the system CaMgSi₂O₆-CaAl₂Si₂O₈-NaAlSi₃O₈ (Di-An-Ab) based on data compiled from the literature is presented. The model is calibrated on 560 measurements of melt viscosity at 1 bar pressure on 40 individual melt compositions and 303 measurements obtained at high pressures on 18 melt compositions. The model uses the Tammann-Vogel- Fulcher equation for temperature (T)- dependence and accounts for variations in melt composition (X) and pressure (P). At ambient pressures, the model spans 15 orders of magnitude of η, a T range of 933-2450 K, and reproduces the datasets well (RMSE = 0.26). The high-P model is calibrated over a T range of 970-2470 K and P range of 50 to 13100 MPa and reproduces the high-pressure data sets to within (larger) experimental uncertainties (RMSE = 0.35). The T-P-X model predicts the glass transition temperatures (Tg), melt fragilities (m) and activation energies (Ea) across the ternary with increasing P. Used in conjunction with chemical proxies for melt structural organization (i.e. SM and NBO/T), the model informs on changes in melt polymerization as functions of T, X, and P. Di-An-Ab melts with SM values > 25 have positive pressure coefficients and show a minimal to substantial increase in viscosity with increasing P. Melts with SM less than 25 show negative P-coefficients indicating a decrease in viscosity with increasing P. The P-effect might be correlated with the degree of polymerization and explained by the increasing coordination numbers of silicate and aluminum cations at elevated pressures. Model values of Tg for Di-An-Ab melts range between 930 K and 1130 K at ambient conditions; whilst at elevated pressures, Tg values are depressed for highly polymerized melts by as much as 150K at 5000 MPa but are higher for more depolymerized melts (i.e. SM > 25). A comparison of the liquidus surface topology for the ternary system to the corresponding isokoms of viscosity shows the relative effects of X a…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/75812
note: Temperature-Pressure-Composition Model for Melt Viscosity inthe Di-An-Ab SystembyMu LiB.Sc., The University of Waterloo, 2018B.Sc., China University of Geosciences (Beijing), 2018A THESIS SUBMITTED IN PARTIAL FULFILLMENTOF THE REQUIREMENTS FOR THE DEGREE OFMASTER OF SCIENCEinTHE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES(Geological Sciences)The University of British Columbia(Vancouver)August 2020c©Mu Li, 2020The following individuals certify that they have read, and recommend to the Faculty of Graduateand Postdoctoral Studies for acceptance, the thesis entitled:Temperature-Pressure-Composition Model for Melt Viscosity in the Di-An-Ab Systemsubmitted by Mu Li in partial fulfillment of the requirements for the degree of MASTER OFSCIENCE in Geological Sciences.Examining Committee:James Kelly Russell; Earth, Ocean and Atmospheric SciencesSupervisorLori Kennedy; Earth, Ocean and Atmospheric SciencesSupervisory Committee MemberJames Scoates; Earth, Ocean and Atmospheric SciencesSupervisory Committee MemberLee Groat; Earth, Ocean and Atmospheric SciencesExternal ExamineriiAbstractA model for the viscosity (η) of melts in the system CaMgSi2O6-CaAl2Si2O8-NaAlSi3O8(Di-An-Ab) based on data compiled from the literature is presented. The model is calibrated on560 measurements of melt viscosity at 1 bar pressure on 40 individual melt compositions and 303measurements obtained at high pressures on 18 melt compositions. The model uses the Tammann-Vogel- Fulcher equation for temperature (T)- dependence and accounts for variations in melt com-position (X) and pressure (P). At ambient pressures, the model spans 15 orders of magnitude ofη , a T range of 933-2450 K, and reproduces the datasets well (RMSE = 0.26). The high-P modelis calibrated over a T range of 970-2470 K and P range of 50 to 13100 MPa and reproduces thehigh-pressure data sets to within (larger) experimental uncertainties (RMSE = 0.35). The T-P-Xmodel predicts the glass transition temperatures (Tg), melt fragilities (m)…
has type: Thesis/Dissertation
date issued: 2020-11
is shown at: 10.14288/1.0394144
language: eng
degree discipline: Geological Sciences
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/75812