Phillip D. Ihinger, Ph.D.

• Earth Resources
• Global Environmental Change
• Mineralogy &Petrology I, II, &III
• Physical Geology

My research agenda focuses on three programs: (1) the theoretical and analytical study of hot-spot magmas in the oceanic and continental environment, (2) the experimental and analytical study of the role of volatiles in magmatic processes, and (3) the role of water in nominally anhydrous minerals, with emphasis on hydrous impurities in quartz crystals and how they can be used to study the process of crystal growth from hydrothermal solutions. Here, I briefly introduce these programs and provide a summary of their accomplishments.

I. Theoretical and analytical studies of hot-spot magmas: This program is devoted to understanding mantle plumes and interpreting the physical and chemical constraints that hot spots provide regarding the structure and evolution of the mantle. This work has resulted in a new model for the evolution of hot spot magmatism. My model is based on previously unexplained observations of Hawaiian volcanism, including the segregation of the hot-spot track into well-defined volcano lineaments. Individual chains of volcanoes along the Hawaiian track show faster age progression within each chain compared to the average propagation rate of the Pacific plate. Additionally, the two youngest chains (each with well-sampled volcanoes) show age-progressive trends in their geochemistry. The new model invokes the segregation of the upwelling plume into discrete blobs that arise from shear created by flow in the mantle. The model is substantiated by numerous experimental and theoretical studies in the earth science literature, and if it is correct, it requires that we change our paradigm regarding the nature of mantle convection, the driving force of plate tectonics, and the chemical evolution of the mantle.

To test this model, I have undertaken comprehensive studies of plume-related magmatism within the continental setting, where sampling between and within individual lineaments is possible. I have selected two field areas for geochemical characterization;the Cretaceous New England Lamprophyre Suite, and the Eocene Montana Alkaline Province. The New England Suite is a part of an elongate alkaline magmatic province that trends in time and space from the interior of the Canadian craton across the mid-Atlantic ridge. In the oceanic setting, the volcanic lineament is known as the New England Seamount Chain, which tracks across the floor of the Atlantic Ocean to the active Great Meteor Hotspot. Within the continental setting in New England, three distinct east-west lineaments are discernable. Our study has characterized the geochemical fingerprint of this continental alkaline lamprophyre province and matches it with the geochemical signature of the seamounts. Linking the continental alkaline magmatism to hot-spot origins has profound new implications for our understanding of the origin of intraplate alkaline lamprophyres and their cousins, the kimberlites and carbonatites. We are continuing the study of these rocks in order to compare the chemical and age progressions along each of the three magmatic lineaments within the New England province with the observations along the Hawaiian volcano trends.

Not all alkaline igneous provinces are associated with age-progressive lineations. Since coming to UW-Eau Claire, my students and I have begun to characterize the nature and chemistry of the Eocene high-K magmatic province in central Montana. No simple theory for the origin of these peculiar rocks can explain the vast production of mantle-derived material under the North American craton at that time. In collaboration with UW-Eau Claire students Luke Beranek, Jesse Bernhardt, Benjamin Paulson, and James Watkins, we hope to compare and contrast these two seemingly disparate magmatic provinces with the aim of furthering our understanding of melt production under an otherwise tectonically-stable craton.

II. Experimental and analytical studies on the role of volatiles in magmatic processes: The second program in my research agenda involves the experimental and analytical study of volatiles in minerals and melts. This topic is important to every aspect of earth science, as it is central to the understanding of the origin and evolution of the Earth's oceans and atmosphere, as well as global change on both the shortest time scales (e.g., the immediate effect of volcanic eruptions on the Earth's temperature) and on the longest time scales (e.g., the dependence of volcanic input on the global cycles of H, C, and S). The volatile contents of natural magmas show tremendous variability throughout magmatic evolution. As such, volatile content variability is the most important control on source melting temperature, on magma rheology during transport through the crust, on the kinetics of crystallization, and on the explosivity of eruption. Simply put, volatiles control the origin, the evolution, and the fate of every natural magma and thus control the chemical differentiation of the Earth.

Some of the contributions of this aspect of my program to date include:

1. The first experimental study to determine quantitatively the effect of water on the kinetics of homogeneous crystal nucleation in silicate melt, and the discovery that this effect exhibits universal behavior such that we can accurately predict the number of crystals that will nucleate after any prescribed time from a melt of any prescribed hydroxyl content.
2. The discovery that crystals can nucleate on bubbles in silicate melt, with implications for the development of groundmass texture in shallow intrusive rocks. This study resulted in a patent for the development of ceramics with prescribed crystallinities with potentially lucrative industrial applications.
3. The determination of the effect of cooling rate on homogeneous crystal nucleation in silicate melt. This study allows us to explore the degree of crystallinity expected for silicate magmas as they rise through the crust and erupt on the earth's surface.
4. The first determination of the effect of water on the time scales required for the relaxation of silicate melt to its equilibrium structural configuration. This study gives insights into melt behavior and allows us to measure the time scales associated with magmatic processes that occur during intrusion and eruption.
5. The first observation of correlated carbon isotopic composition and CO₂concentration in a natural suite of igneous rocks (the Cretaceous New England lamprophyres). This study depicts the degassing history of the alkaline magmatic system and constrains the fractionation factor that governs melt-vapor carbon isotope partitioning in the CO₂-saturated magmatic system.
6. The first measurement of the hydrogen isotopic composition of water-bearing nominally anhydrous minerals from the mantle. These results offer a new view into the nature and evolution of global hydrogen reservoirs.

These contributions represent collaborative efforts with my students: (1) - (4) represent the dissertation and post-doctoral work of Mark Davis (Yale PhD, 97);and (5) - (6) represent the dissertation work of Shona Smith (Yale PhD, 00), and collaborations with undergraduate students Ken Andersen (Yale 95), and Matt Jackson (Yale 00).

III. Water in nominally anhydrous minerals and crystal growth kinetics of hydrothermal quartz: In collaboration with undergraduate students Steve Zink (Yale, 96) and An-Lin Bardin (Yale, 97), we have undertaken a detailed study of the distribution and abundance of hydrous impurities in natural quartz crystals. We have discovered that the molecular water concentration incorporated in a growing crystal face serves as a growth speedometer by recording the relative growth rates in the quartz crystal. Remarkably, we have seen that two crystal faces that grew from the same fluid at the same time on the same crystal actually grew at order-of-magnitude differences in rates. This phenomenon leads to what is commonly termed "sector zoning". Our study quantifies the growth rates experienced by individual growth faces. In addition, we discovered that our IR measurements on Li-OH and Al-OH concentrations in these quartz crystals enable us to follow the changing Al and Li concentration in the fluids from which they grew, and additionally constrain the post-crystallization thermal histories that our natural samples had experienced. Our work was recently featured on the cover of Nature:

Ihinger, P. D., and Zink, S. I. (2000) Determination of relative growth rates of natural quartz crystals, Nature, 404, p. 865-869.

With recently acquired NSF funding, we will calibrate our "water speedometer" by measuring the water contents of crystals grown in controlled environments at known rates. UW -Eau Claire students Jacob Chmielowiec and Ryan Prechel will analyze synthetic quartz samples (provided by Thermo Dynamics, Inc. of Merriam, Kansas) with precisely known growth rates. We will additionally perform diffusion experiments to constrain the parameters that control H-OH, Li-OH, and Al-OH mobility within the crystals after they have grown in order to constrain the thermal histories of quartz crystals in the natural environment that show measured diffusion profiles.

Publications

Ihinger, P. D., and Stolper, E. M. (1986) The color of meteoritic hibonite: An indicator of oxygen fugacity. Earth and Planetary Science Letters, v. 78, p. 68-79.

Silver, L. A., Ihinger, P. D., and Stolper, E. M. (1989) The influence of bulk composition on the speciation of water in silicate glasses. Contribution to Mineralogy and Petrology, v. 104, p. 142-162.

Ihinger, P. D., Hervig, R. L., and McMillan, P. F. (1994) Analytical methods for volatiles in glasses. Reviews in Mineralogy, v. 30, p. 67-121.

Bell, D., Ihinger, P. D., and Rossman, G. (1995) Quantitative Analyses of Trace Hydroxyl in Garnet and Pyroxenes. American Mineralogist, v. 80, p. 465-474.

Zhang, Y., Stolper, E. M., and Ihinger, P. D. (1995) Kinetics of reaction H2O + O = 2OH in rhyolitic glasses: Preliminary results. American Mineralogist, v. 80, p. 593-612.

Ihinger, P. D. (1995) Mantle flow beneath the Pacific plate: Evidence from seamount segments in the Hawaiian-Emperor chain. American Journal of Science, v. 295, p. 1035-1057.

Davis, M. J., Ihinger, P. D., and Lasaga, A. C. (1997), The influence of water on nucleation kinetics in silicate melt, Journal of Non-Crystalline Solids, v. 219, p. 62-69.

Zhang, Y., Belcher, R., Ihinger, P. D., Wang, L., Xu, Z., and Newman, S. (1997), New calibration of infrared measurement of dissolved water in rhyolitic glasses, Geochimica et Cosmochimica Acta, v. 61, p. 3089-3100.

Davis, M. J., and Ihinger, P. D. (1998), Heterogeneous crystal nucleation on bubbles in silicate melt: American Mineralogist, v. 83, p. 1008-1015.

Davis, M. J., and Ihinger, P. D. (1999), New controlled rapid quench technique in a 1-atm infrared image furnace: American Mineralogist, v. 84, p. 48-54.

Davis, M. J., and Ihinger, P. D., (1999), Influence of hydroxyl on glass transformation kinetics in lithium disilicate silicate melt and a re-evaluation of structural relaxation in NBS 710 and 711, Journal of Non-Crystalline Solids, v. 244, p. 1-15.

Ihinger, P. D., Zhang, Y., and Stolper, E. M. (1999) The speciation of dissolved water in rhyolitic melt. Geochimica et Cosmochimica Acta, v. 63, p. 3567-3578.

Smith, S. C., and Ihinger, P. D., (1999) Origin and evolution of mafic alkaline magmas: constraints from the mineral chemistry of the New England lamprophyre suite, in The P.H. Nixon Volume, eds. Gurney, J. J., Gurney, J. L., Pascoe, M.D., and Richardson, S. H., p. 795-807.

Bell, D.R., and Ihinger, P.D. (2000) The isotopic composition of hydrogen in nominally anhydrous minerals. Geochimica Cosmochimica et Acta, v. 64, p. 2109-2118.

Ihinger, P.D., and Zink, S. (2000) Determination of relative growth rates of natural quartz crystals. Nature, v. 404, p. 865-869.

Ihinger, P.D., and Zink S. (2001) Control of defect concentrations in single crystals: insights from natural hydrothermal quartz crystals, in Inorganic Optical Materials III, A. J. Marker III, M. J. Davis, eds., Proceedings of SPIE, Vol. 4452, p. 7-16.

Davis, M. J., and Ihinger, P. D. (2002) Effect of thermal history on crystal nucleation in silicate melt I. Experimental results, Journal of Geophysical Research, in press.

Abstracts

Ihinger, P. D., Stolper, E. M., and Epstein, S. (1990) Hydrogen isotope fractionation between rhyolitic melt and hydrous vapor at 850°C. In V.M. Goldschmidt Conf Program and Abstracts II, p. 55.

Zhang, Y., Stolper, E. M., and Ihinger, P. D. (1990) Reaction Kinetics of H2O + O = 2OH and its equilibrium, revisited. In V.M. Goldschmidt Conf Program and Abstracts II, p. 94.

Ihinger, P. D., and Bell, D. R. (1991) Isotopic composition of hydrogen in nominally anhydrous mantle minerals, EOS Trans. AGU, Fall Meeting Suppl., p. 537.

Bell, D. R., Rossman, G. R., and Ihinger, P. D. (1991) Hydroxyl in upper mantle minerals, EOS Trans. AGU, Fall Meeting Suppl., p. 537.

Watson L. L., Ihinger P. D., Epstein S., and Stolper E. M. (1991) Hydrogen, carbon, and oxygen isotopic composition of volatiles in Nakhla, Lunar and Planet. Sci. XXII, Lunar and Planetary Institute, Houston, p.1473-1474.

Ihinger, P. D. (1992) Evolution of global hydrogen reservoirs: Isotopic constraints from water-bearing, nominally anhydrous mantle minerals, EOS Trans. AGU, Spring Meeting Suppl., p. 141.

Ihinger, P. D. (1993) Mantle flow beneath the oceanic lithosphere: Evidence from individual en echelon seamount segments along hot-spot tracks, EOS Trans. AGU, Spring Meeting Suppl., p. 598.

Ihinger, P. D. (1993) Mantle flow beneath the Pacific Plate: Evidence from seamount segments in the Hawaiian-Emperor Chain, GSA Annual Mtg. Suppl, Abstracts with Programs, Vol. 25, No. 6, p. A-197.

Newman, S., Blouke, K., Bashir, N., Ihinger, P. D., and Stolper, E. (1993) Cooling of rhyolitic volcanics-evidence from melt inclusions, GSA Annual Mtg. Suppl, Abstracts with Programs, Vol. 25, No. 6, p. A-43.

Davis, M. J., Lasaga, A. C., and Ihinger, P. D. (1993) Significant T-t hysteresis of the nucleation rate of lithium disilicate--melt speciation kinetics? EOS Trans. AGU, Fall Meeting Suppl., p. 630.

Ihinger, P. D. (1994) A "plumelet" model for the generation of en echelon patterns along hot-spot tracks, EOS Trans. AGU, Fall Meeting Suppl., p. 726.

Davis, M. J., and Ihinger, P. D. (1994) The effect of thermal history on homogeneous nucleation in silicate melt. EOS Trans. AGU, Fall Meeting Suppl., p. 702.

Ihinger, P. D., and Andersen, K. M. (1995) A "plumelet" model for the generation of New England lamprophyres. NEGSA Annual Mtg. Suppl, Abstracts with Programs, Vol. 27, No. 1, p. A-57.

Zhang, Y., Belcher, R., and Ihinger, P. D., (1995) Calibration of IR measurement of water in glasses: Absorptivities, EOS Trans. AGU, Spring Meeting Suppl., p. F650.

Davis, M. J., and Ihinger, P. D. (1995) The effect of water on crystal nucleation in lithium disilicate melt, EOS Trans. AGU, Fall Meeting Suppl.

Davis, M. J. and Ihinger, P. D. (1996) Crystal nucleation on bubbles in hydrous silicate melt, EOS Trans. AGU, 77(46), Fall Meeting Suppl., p F819.

Bonneville, A., Davaille, A., and Ihinger, P. D. (1997) Viscous Fingering and Double Hotspots. EUG Abstracts with Programs.

Davis, M. J. and Ihinger, P. D. (1997) The influence of water on crystal growth rates in silicate melt, EOS Trans. AGU, 78(46), Fall Meeting Suppl., p F834.

Smith, S. and Ihinger, P. D. (1997) Volatile evolution in mafic alkaline rocks: A stable isotopic study of the New England Lamprophyre suite, EOS Trans. AGU, 78(46), Fall Meeting Suppl., p F813.

Zink, S., and Ihinger, P. D. (1997) Microscopic IR investigation of water in gemmy quartz crystals: growth histories revealed, GSA Abstracts with Programs, p. A91.

Smith, S. C., and Ihinger, P. D., (1998) Geochemical evolution of the New England lamprophyre suite: a hotspot signature preserved in the continental crust?, Abstracts of the VII International Kimberlite Conference, V. 7, p. 820-822.

Ihinger, P. D., and Smith, S. C. (1998) Deuteric processes in mafic alkaline rocks: distinguishing mantle from crustal-derived volatiles in the New England Lamprophyre Suite, EOS Trans. AGU, 79(46), Fall Meeting Suppl., p. F979.

Davis, M. J., Ihinger, P. D., (1998), Influence of water on glass transformation kinetics in lithium disilicate melt, submitted EOS Trans. AGU, 79(46), Fall Meeting Suppl., p. F1017.

Gazis, C., and Ihinger, P. D., (1999), Stable isotopic compositions and H2O concentrations of rhyolitic glasses from the Chegem Caldera (Caucuses Mountains, Russia), GSA Annual Mtg. Suppl, Abstracts with Programs.

Ihinger, P. D., and Smith, S. C. (1999) The role of volatiles in the origin and evolution of mafic alkaline rocks, EOS Trans. AGU, 80(46), Fall Meeting Suppl, p. F1133.

Ihinger, P. D., Woglom, E., &Skorina, L., (2000) Experimental Results Bearing on Hydroxyl Sub-Speciation in Low-Pressure Silicate Melts, EOS.

Jackson, M. G., and Ihinger, P.D. (2000) Carbonatite expulsion from a lamprophyre: an integrated geochemical study of dike-wall rock interactions, GSA Abstracts with Programs, V. 32, no. 7, p. A436.

Ihinger, P. D., Chamberlin, S., and Smith, S. C. (2002) INORGANIC TERRESTRIAL ANALOG FOR CARBONATE-MAGNETITE-PYRITE ASSEMBLAGE IN ALH-84001, Lunar and Planet. Sci. XXXIII, Lunar and Planetary Institute, Houston, in press.