MICHAEL J. HOLDAWAY
Ph.D., University of California, Berkeley
Professor

• Experimental Geology and Crystal Chemistry of Pelitic Minerals
• Metamorphic Petrology of Pelitic Schists in New England and New Mexico

An important project Mike is presently undertaking involves recalibration of the garnet-biotite geothermometer and the muscovite-almandine-biotite-sillimanite (MABS) geobarometer. Until now available experimetnal, calorimetric, and natural data have not been utilized to the fullest. Mike, with his former post-doc Mukhopadhyay, have been able to significantly improve on the various Margules parameters and the calibration of the biotite-garnet exchange equilibrium. Among observations they have made are (1) Fe3+ content of biotite and garnet must be accounted for, (2) the Fe-Mg Margules parameters of both garnet and biotite are larger than suggested by the most widely cited recent study, (2) Al content in biotite is an important factor, (4) a data base of pelitic rocks from west-central Maine provides an excellent opportunity to test their temperature and pressure results and compare them with previous calibrations. More accurate and precise measurements of metamorphic conditions are especially useful in studying the behavior of metamorphic fluids and in deducing pressure-temperature-time paths.

In attempting to calibrate the MABS geobarometer agains the garnet-Al silicate-plagioclase (GASP) geobarometer Mike has discovered some problems with GASP. Two different plagioclase activity models give significantly different results. He is attempting to resolve the problems with GASP before finalizing the calibration of MABS.

Selected Publications
Holdaway, M.J., Stability of andalusite and the aluminum silicate phase diagram: American Journal of Science, 271, 97-131, 1971.

Holdaway, M.J., B.L. Dutrow, and P. Shore, A model for the crystal chemistry of staurolite. American Mineralogist, 71, 1142-1159, 1986.

Holdaway, M.J., B.L. Dutrow, and R.W. Hinton, Devonian and Carboniferous metamorphism in west-central Maine: the muscovite-almandine geobarometer; the staurolite problem revisited. American Mineralogist, 73, 20-47, 1988.

Dutrow, B.L. and M.J. Holdaway, Experimental determination of the upper thermal stability of Fe-staurolite + quartz at medium pressures. Journal of Petrology, 30, 229-248, 1989.

Holdaway, M.J. and J.W. Goodge, Rock pressure vs. fluid pressure as as controlling influence on mineral stability: An example from New Mexico. American Mineralogist, 75, 1043-1058, 1990.

Mukhopadhyay, B., B. Sabyasachi, and M.J. Holdaway, A review of Margules-type fromulations for multicomponent solutions with a generalized approach. Geochimica et Cosmochimica Acta, 57, 277-283, 1993.

Holdaway, M.J. and B. Mukhopadhyay, A reevaluation of the stability relations of andalusite; Thermochemical data and phrase diagram for the aluminum silicates. American Mineralogist, 78, 298-315, 1993.

Mukhopadhyay, B. and M.J. Holdaway, Cordierite-garnet-sillimanite-quartz equilibrium: I. New experimental calibration in th system FeO-Al2O3-SiO2-H2O and certain P-T-X(H2O) relations. Contributions to Mineralogy and Petrology, 116, 462-472, 1994.

Holdaway, M.J. and B. Mukhopadhyay, Thermodynamic Properties of Stoichiometric Staurolites H2Fe4Al18Si8O48 and H6Fe2Al18Si8O48. American Mineralogist, 80, 520-533, 1995.

Mukhopadhyay, B., M.J. Holdaway, and A.M. Koziol, A statistical model of thermodynamic mixing properties of Ca-Mg-Fe2+ garnets. American Mineralogist, 82, 165-181, 1997.

Holdaway, M.J., B. Mukhopadhyay, M.D. Dyar, C.V. Guidotti, and B.L. Dutrow, Garnet-biotite geothermometry revised: New Margules parameters and a natural specimen data set from Maine. American Mineralogist, 82, 582-595, 1997.