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Petrology

At the Geophysical Laboratory the contributions to our understanding of these processes are experimental determination of properties of rock-forming materials and how to apply the property information to characterize rock-forming processes at the pressures and temperatures in the crust, the mantle, and the core of the Earth and terrestrial planets.

The rock-forming materials include all crystalline and molten silicates and oxides (minerals and magmatic liquids) as well as volatile-rich fluids. Experimentally determined properties include mineral, melt, and fluid structure, transport and volume properties (viscosity, diffusivity, conductivity, density, compressibility, and expansivity) at high temperature and pressure, and assessment of the mechanisms, on the atomic scale, the relate properties to structure. These experimental data are obtained with equipment capable of covering the pressure and temperature range of essentially the entire Earth. Some experiments (structure and related properties) are conducted while the sample is at appropriate temperature and pressure, whereas others rely on examination of experimentally produced materials after quenching to ambient pressure and temperature. Evaluation of the quenching path on property and structure behavior is an integral part of all experimental endeavors.

Major, minor, and trace element distribution among these phases is central to our understanding for the formation and evolution of the Earth. The necessary experimental element partitioning and isotope fractionation data are obtained in the laboratory throughout the pressure and temperature range. The partitioning behavior is also characterized in terms of thermodynamics of mineral, melt, and fluid solutions and its relationship to structure in order to provide a basis for modeling partitioning and fractionation under conditions not readily attainable in the laboratory. These experimental data are employed to extract past and present rock-forming processes, and often combined with experimental mineral physics information (equation-of-state) and geophysical data to characterize major boundaries within terrestrial planetary bodies. There are major efforts that focus on the formation and evolution of early magma oceans and core separation, and with the formation and evolution of chemistry and physics associated with major discontinuities in the Earth.Volatile-rich fluids in the system C-H-O-N-S serve as major transport agents in the Earth’s interior throughout its history. The C-H-O-N-S S components are, furthermore, of great interest because understanding of their behavior in pressure, temperature, composition space provides the basis for characterization of degassing processes, formation evolution of atmospheres and oceans, and provide a natural link to the organic world and characterization of processes relevant to the emergence of life. To this end, high-pressure/-temperature experimental programs are aimed at determination of solubility of volatiles in silicate melts and crystalline materials, as well as of silicates in volatile-rich fluids. The solution mechanisms (speciation) and their implication for mineral, melt, and fluid properties as well as element and C-H-O-N-S isotope distribution represent a major experimental effort at the Geophysical Laboratory. Integrated studies, using experimental data from the laboratory, together with natural observations and theoretical modeling, guide petrology at the Geophysical Laboratory. Ultimately, this information coupled with data from other observational and experimental endeavors at the Geophysical Laboratory and elsewhere, will provide the quantitative data needed to describe the formation and evolution of the Earth and terrestrial planets in our solar system and perhaps elsewhere.

 

 

Brief description of instruments

  • 3 solid-media, high-pressure apparatus
  • 2 multi-anvil, high-pressure apparatus
  • 7 cold-seal, externally heated apparatus
  • 1 internally heated, gas-media apparatus
  • Bell-Mao type internally and externally heated diamond anvil cells
  • Bassett type Hydrothermal diamond anvil cells
  • Externally heated, diamond-windowed cell for in-situ, high-pressure and high-temperature fluid studies
  • 6 1-atm vertical quench furnaces (to 1700˚C), 3 equipped for gas mixing; 1 1-atm vertical quench furnace (2000˚C)
  • High-temperature cells, for in-situ studies of melt and crystal structure at temperature and ambient pressure
  • Micro-FTIR spectroscopy
  • Micro-Raman spectroscopy
  • MAS NMR spectroscopy
  • Mossbauer spectroscopy 



 

 

 

 

 

 

 

 

 Selected Publications

Cody, G. D., Mysen, B. O., and Lee, S. K. (2005) Structure vs. composition:  a solid-state 1H and 29Si NMR study of quenched glasses along the Na2O-SiO2-H2O join. Geochim. Cosmochim. Acta, 69, 2373-2384.  

Fei, Y. and C. M. Bertka, The interior of Mars, Science 308, 1120-1121, (2005).

Fei, Y., C. M. Bertka, and L. W. Finger, High-pressure iron-sulfur compound, Fe3S2, and melting relations in the system Fe-FeS at high pressure, Science 275, 1621-1623, (1997).

Hirose, K., Y. Fei, Y. Ma, and H. K. Mao, Fate of subducted basaltic crust in the lower mantle, Nature, 397, 53-56, (1999).

Lee, S. K, Cody, G. D., Fei, Y., Mysen, B. O. (2008). Oxygen-17 Nuclear Magnetic Resonance Study of the Structure of Mixed Cation Calcium−Sodium Silicate Glasses at High Pressure: Implications for Molecular Link to Element Partitioning between Silicate Liquids and Crystals. J. Phys. Chem. B, 112, 11756-11761.

Lee, S. K., Cody, G. D., and Mysen, B. O. (2005) Structure and the extent of disorder in quaternary (Ca-Mg and Ca-Na) aluminosilicate glasses and melts. Am. Mineral., 90, 1393-1401.

Lee, S. K., Cody, G. D., Fei, Y., and Mysen, B. O. (2006) The effect of Na/Si on the structure of sodium silicate and aluminosilicate glasses quenched from melts at high pressure:  A multi-nuclear (Al-27, Na-23, O-17) 1D and 2D solid-state NMR study. Chem. Geol., 229, 162-172.

Lee, S. K., Mibe, K., Fei, Y., Cody, G. D., and Mysen, B. O. (2005) Structure of B2O3 glass at high pressure:  a 11B solid-state NMR study.. Phys. Rev. Lett., 94, 165507.

Mysen, B. O. (2006) Redox equilibria and melt structure: Implications for olivine/melt element partitioning. Geochim. Cosmochim. Acta. 70, 3121-3138

Mysen, B. O. (2006) The structural behavior of ferric and ferrous iron in aluminosilicate glass near meta-aluminosilicate joins. Geochim. Cosmochim. Acta, 70, 2337-2353. 

Mysen, B. O. (2007) The solution behavior of H2O in peralkaline aluminosilicate melts at high pressure with implications for properties of hydrous melts. Geochim. Cosmochim. Acta, 71, 1820-1834.

Mysen, B. O. (2007). Olivine/melt transition metal partitioning, melt composition, and melt structure – Influence of Si4+Al3+ substitution in the tetrahedral network. Geochim. Cosmochim. Acta. 71, 5500-5513.

Mysen, B. O. (2008) Olivine/melt transition metal partitioning, melt composition, and melt structure – Melt polymerization and Qn-speciation in alkaline earth silicate systems. Geochim. Cosmochim. Acta. 72, 4796-4813

Mysen, B. O. and Cody, G. D. (2005) Solution mechanisms of H2Oin depolymerized peralkaline melts. Geochim. Cosmochim. Acta, 69, 5557-5566. 

Mysen, B. O. and Shang, J. (2005) Evidence from olivine/melt element partitioning that nonbridging oxygen in silicate melts are not equivalent. Geochim. Cosmochim. Acta, 69, 2861-2875.

Mysen, B. O. Shigeru Yamashita, S., and Chertkova, N. (2008). Solubility and Solution Mechanisms of NOH Volatiles in Silicate Melts at high Pressure and Temperature - Amine Groups and Hydrogen Fugacity. Amer. Mineral. 93, 1760-1770.

Mysen, B. O., Cody, G. D., and Morrill, P. L. (2009) Solution behavior of reduced C-O-H volatiles in silicate melts at high pressure and temperature. Geochim. Cosmochim. Acta, 73, 1696-1710

Rama Murthy, V., W. van Westrenen, and Y. Fei, Experimental evidence that potassium is a substantial radioactive heat source in planetary cores, Nature, 423, 163-165, (2003).

Roskosz, M., Luais, B., Watson, H. C., Toplis, M. J., Alexander, C. O., and Mysen, B. O. (2006) Experimental quantification of the fractionation of Fe isotopes during metal segregation from a silicate melt. Earth Planet. Sci. Lett. 248, 851-867.

Roskosz, M., Mysen, B. O., and Cody, G. D. (2006) Dual speciation of nitrogen in silicate melts at high pressure and temperature: An experimental study. Geochim. Cosmochim. Acta. 70, 2902-2918.