220A Pillsbury Hall
George and Orpha Gibson Chair of Earth and Planetary Sciences
PhD, 1992, University of Washington
I use high pressure/high temperature experiments together with analytical and theoretical tools to understand melting, mass transfer, and differentiation in planetary interiors. Areas of focus include the role of lithologic heterogeneity in basalt source regions, regions of possible stability of small-degree partial melts, such as the asthnenosphere and above the 410 km discontinuity, and deep Earth H2O and CO2 cycles.
Most recent and current research projects in my laboratory involve the role of volatiles in mantle melting. These include the role of volatiles in partial melting and their influence on the composition of oceanic basalts, storage of volatiles in the mantle, including the influence of oxygen fugacity on the stable form of carbon in the mantle, and partitioning between nominally volatile-free minerals and melts. Another area of interest is the role of magmatic volatiles on Mars, including their relationship to the composition of the atmosphere and the evolution of climate, as well as the influence of H2O and CO2 on magmagenesis. A related topic is the role of magma oceans on early volatile cycling on Earth and other terrestrial planets, including their influence on the composition and thickness of earliest atmospheres
Research employs solid media high pressure devices, including piston cylinder and multianvil apparatuses, for exploration of phase equilibria and transport properties of Earth materials up to ~15 GPa. Experiments are analyzed by a range of microbeam and spectroscopic techniques, including electron microprobe, FTIR, Raman spectroscopy, SIMS, XANES, Mossbauer spectroscopy, high resolution FEG-SEM, and LA-ICP-MS
Geo 1001/1101 Earth and its Environments
Geo 2302 Petrology
Geo 3006 Planets of the Solar System
Geo 5503 Advanced Petrology
Hirschmann, M.M. and Withers, A.C. (2008) Ventilation of CO2 from a reduced mantle and consequences for the early Martian greenhouse. Earth and Planetary Science Letters 270, 147-155.
Aubaud, C. Hirschmann, M.M., Withers, A.C., Hervig, R.L. (2008) Hydrogen partitioning between melt, clinopyroxene, and garnet at 3 GPa in a hydrous MORB with 6 wt.% H2O. Contributions to Mineralogy and Petrology. 156, 607-625.
Withers A.C. and Hirschmann M.M. (2008) Influence of temperature, composition, silica activity and oxygen fugacity on the H2O storage capacity of olivine at 8 GPa. Contributions to Mineralogy and Petrology. 156, 595-605.
Hirschmann, M.M. and Dasgupta, R. (2009) The H/C ratios of Earths near-surface and deep reservoirs, and consequences for deep Earth volatile cycles. Chemical Geology 262: 4-16.
Hirschmann, M.M., Tenner, T.J., Aubaud, C. Withers, A.C., (2009) Dehydration melting of nominally anhydrous mantle: The primacy of partitioning. Physics of the Earth and Planetary Interiors 176: 54-68.
Tenner, T.J., Hirschmann, M.M., Withers, A.C., Hervig, A.C. (2009) Hydrogen partitioning between nominally anhydrous upper mantle minerals and melt between 3 and 5 GPa. Chemical Geology: 262: 42-56.
Dasgupta, R., Hirschmann, M.M., McDonough, W.F., Spiegelman, M., Withers, A.C. (2009) Trace element partitioning between garnet peridotite and carbonatite at 6.6 and 8.6 GPa with applications to the geochemistry of the mantle and of mantle-derived melts. Chemical Geology 262: 57-77.
Hirschmann, M.M. (2010) Partial melt in the oceanic low velocity zone. Physics of the Earth and Planetary Interiors 179: 60-71.
Dasgupta, R. and Hirschmann, M.M. (2010) The deep carbon cycle and melting in Earth’s Interior. Earth and Planetary Science Letters 298: 1-13.
Recent Research Support
2011-2014 NASA –Mars Fundamental Research Program: Experimental study of volcanogenic methane and other C-O-H gases and their influence on ancient and modern Martian atmospheres and climates.
2010-2013 National Science Foundation – Earth Sciences: Near solidus partial melting of garnet peridotite and the origin of alkali olivine basalt. A.C. Withers, co-PI.
2008-2011 National Science Foundation –Cooperative Studies of Earths Deep Interior: CSEDI: Integrated Study of H2O in the Mantle: Processes and Signature; R. Wentzcovitch, PI, D.L. Kohlstedt, J. Revenaugh, co-PIs.
2008-2011 NASA –Mars Fundamental Research Program: Role of C-H-O volatiles in melting of the Martian mantle: Influence on crust formation, degassing, and volatile fluxes. A.C. Withers, co-PI.
2007-2010 National Science Foundation – Ocean Sciences: Influence of H2O and CO2 on deep melting beneath ridges. A.C. Withers, co-PI.
2009-2010 National Science Foundation – Instrumentation and Facilities: Acquisition of a new microFTIR spectrometer to aid experimental and analytical studies of C-H-O volatiles in the mantle, D.L. Kohlstedt, A.C. Withers co-PIs.
Recent Honors and Awards
Fellow, Mineralogical Society of America 2003
McKnight-Land Grant Professorship 1999-2001
NSF CAREER Award 1998
NSF Earth Sciences Post-Doctoral Fellowship 1993