The department has outstanding facilities to support geochemical research. In house light stable isotope ratio mass spectrometers (IRMS) include Fisons Optima and Finnigan MAT 251 mass spectrometers with automated capabilities for analyzing carbon and oxygen isotope ratios on very small carbonate samples, carbon and nitrogen isotope ratios on organic matter, and oxygen and hydrogen isotope ratios on waters. A third continuous flow IsoPrime IRMS is available for sulfur, carbon and nitrogen isotope analyses. Off line isotopic separation facilities include vacuum lines for carbonates, organic carbon, SCO2 in water, hydrogen and oxygen in silicates, and sulfur in sulfides and sulfates. Additional departmental equipment includes: a cathodoluminescence microscope, an epi-fluorescence reflected light microscope, and petrographic microscopes; cooled CCD camera with video and digital image capture systems for use with the microscopes; and a pH-stat system for mineral precipitation/dissolution experiments at constant pH. The department also houses a fully automated CAMECA electron microprobe, and the Davis campus has recently installed a state of the art multi-collector ICP-MS (Nu Plasma HR) and two quadrupole ICP-MS (Agilent Technologies 7500a and 7500c) and a laser ablation system (New Wave Research UP-213) for trace element and radiogenic isotope measurements.
William Casey. Interest is in the reactions between water, rock and minerals. Many weathering phenomena involve reactions with water on mineral surfaces, something which can be mimicked in the laboratory by studying the aqueous chemistry of metal aquo clusters by heteronuclear NMR and MS. Other interests include crystal growth, general cluster chemistry, bio-inorganic chemistry, and chemistry from an environmental aspect.
Kari Cooper. Isotope geochemistry of volcanic rocks; dynamics of magma reservoir systems including magma storage, crystallization/differentiation, and interaction with wallrocks, with emphasis on crystal ages from uranium-series disequilibria measured in minerals and coexisting liquids; origin and distribution of chemical heterogeneity in the mantle with emphasis on stable-isotope tracers of recycled crustal material, including oxygen isotope variations in fresh MORB and lithium isotopic composition of altered oceanic crust. Current and recent projects include timing of magma mixing and assimilation of wallrocks beneath Icelandic volcanoes; magma storage and differentiation timescales at Mount St Helens; crystal and magma residence times at Kilauea and Mauna Loa, Hawaii; oxygen-isotope records of crustal recycling in the upper mantle beneath the Mid-Atlantic Ridge and the Australian-Antarctic Discordance; timescales and mechanisms of hydrothermal alteration of oceanic crust using U-series disequilibria and lithium isotopic composition.
Tessa Hill. Research areas include marine micropaleontology, geological oceanography, and paleoceanography utilizing geochemistry of marine sediment and coral records. Tessa is also involved in interdisciplinary research to investigate the impacts of ocean acidification on coastal California environments. Research in her laboratory includes
- Culturing of key species in the laboratory under controlled environmental conditions
- Monitoring modern pH variability on the Northern California coast using pH sensors and oceanographic transects
- Reconstructing climate variability utilizing geochemical proxies in foraminifera, corals, and other carbonates
- Investigating coastal environments to understand potential for carbon storage
Charles Lesher. Experimental igneous petrology and geochemistry; phase equilibria and kinetics of silicate systems at elevated pressure and temperature; physical, transport and thermodynamic properties of silicate melts. Recent projects include (a) Laboratory: low to high pressure phase equilibria studies of basaltic systems; trace element partitioning; chemical and self diffusion studies of silicate melts; solution properties of silicate liquids from thermal diffusion. (b) Field: magmatic evolution of the North Atlantic Ocean basin and the evolution of the Iceland hot spot; petrologic studies of early Tertiary volcanic and plutonic rocks of East Greenland.
Isabel Montañez. Research interests are in the sedimentary record of coupled physical and chemical variation in paleo-oceans, global biogeochemical cycling in marine and terrestrial records, and carbonate fluid-rock interaction in sedimentary basins using stratigraphy, petrography and geochemistry, including stable and radiogenic isotopes and trace elements. Research in the laboratory broadly focuses on development of quantitative paleoclimate proxies, and their application to intervals of time characterized by major and/or abrupt climate change including past periods of icehouse-to-greenhouse transitions through to the last deglaciation.
Sujoy Mukhopadhyay. Early terrestrial atmospheres, magma oceans and the early volatile history of Earth, chemical evolution of the mantle-crust-atmosphere system, application of surface exposure dating to understanding land surface evolution, novel techniques for reconstructing mineral dust emission from continents and climatic effects of mineral dust, sediment mass accumulation rates from extraterrestrial helium-3.
Alexandra Navrotsky. Research interests have centered about relating microscopic features of structure and bonding to macroscopic thermodynamic behavior in minerals, ceramics, and other complex materials. She has made contributions to mineral thermodynamics; mantle mineralogy and high pressure phase transitions; silicate melt and glass thermodynamics; order-disorder in spinels; framework silicates; and other oxides; ceramic processing; oxide superconductors; and the general problem of structure-energy-property systematics. The main technical area of her laboratory is high temperature reaction calorimetry.
Howard Spero. Research focuses on the biological and environmental parameters that affect the stable isotope and trace metal geochemistry of the shells of recent and fossil organisms; marine micropaleontology, paleoclimatology, and paleoceanography. An ongoing multi-year field research program involving graduate and undergraduate students has been studying living planktonic foraminifera in the Southern California Borderland and the Caribbean. The results of this study are being used to interpret fossil foraminifera stable isotope data from Indian and Atlantic Ocean deep sea cores in order to reconstruct paleoenvironmental sea surface temperatures, nutrient levels and CO2 concentrations during the Pleistocene.
Dawn Sumner. My research uses stratigraphic, petrographic, and low temperature geochemical techniques to address the biological and abiotic influences on carbonate precipitation with the intent to understand ancient ocean chemistry and the interactions between microbial communities and their environment. I also work with the Mars Science Laboratory team to constrain sediment provenance, chemical sedimentation, diagenesis and weathering of rocks in Gale Crater, Mars.
Please see http://mygeologypage.ucdavis.edu/sumner for ongoing projects.
Qing-zhu Yin. Using extinct radioactivity and general isotopic anomalies in the early solar system recorded in primitive meteorites as a tool to study the time scales and site of nucleosynthesis, the time of formation of the solar system and planetary differentiation. Isotope and trace element geochemistry with applications to crust-mantle evolution. Heavy metal stable isotope fractionation in low temperature environments on planetary surfaces or in biological systems using newly emerging high precision mass spectrometry techniques. The development of associated experimental techniques involving high precision mass spectrometry and ultra-clean sample processing in Class-100 clean laboratories for isotope analyses.
Robert Zierenberg. Aqueous geochemistry; stable isotope geochemistry; economic geology. Research has focused on water/rock interaction in active and ancient hydrothermal systems, including the "black smokers" on the mid-ocean ridges. Recent work includes investigation of seafloor hydrothermal systems on sediment-covered portions of the northern Juan de Fuca Ridge and southern Gorda Ridge during Leg 169 of the Ocean Drilling Program. Ancient analogs of seafloor hydrothermal systems investigated include the Turner-Albright massive sulfide deposit in the Josephine Ophiolite, OR, and the Red Dog Pb-Zn-Ag deposit in the Brooks Range, AK. Other interests include the environmental effects of mining, particularly the generation of acid mine drainage, mercury contamination in Clear Lake related to the abandoned Sulphur Bank Hg mine, and the geochemical and biological cycling of sulfur.
Scientists & Academic Federation Emeriti
Sarah Lambart. Visiting Assistant Professor. I'm an experimental petrologist. My primary research is focused on the understanding of mantle melting and basalt genesis processes. This part of my research is articulated on the role of mantle heterogeneities and magma-rock interactions in the genesis of basalt. I discuss this topic via an experimental approach coupled to thermodynamical modeling. I also work on fluid-rock interactions to constrain the conditions for witch reactive-cracking can occur. Reaction-driven cracking could be important in geological capture and storage of CO2 as it is essential for in situ mineral carbonation methods to maintain or enhance permeability and reactive surface area.
Ian MacGregor. Research interests focus on understanding mineralogy, petrology and geochemistry of upper mantle using field and experimental approaches. Recent research includes development of geothermometers and geobarometers for mantle samples in the spinel peridotite stability field. Currently working in science education as science consultant to National Science Resources Center, Smithsonian Institution on development of K-12 science curricula.