To researchers and students of solid-earth geochemistry, the past two decades have been a time of many exciting developments. Perhaps foremost among these is the realization that the Earth's crust and upper mantle are highly complex, heterogeneous chemical systems that have evolved continuously (or perhaps sporadically) since the formation of the earth 4.6 billion years ago.
To a great extent, our present knowledge of the chemistry and petrology of the Earth's interior has developed through analysis of rock samples brought to the surface by volcanoes, tectonic processes and erosion. However, it is laboratory experimentation at deep-Earth conditions that provides the interpretational framework for the analytical and geologic data. Accordingly, the goal of experimental geochemistry at Rensselaer is to learn about the behavior of earth materials and synthetic analogs at the pressure-temperature conditions of the deep crust and upper mantle. The results of our investigations help us form clearer pictures of deep-earth systems and more accurate models of their evolution over geologic time.
Our work includes experimental studies of both equilibrium and disequilibrium phenomena, with primary focus on (1) the kinetics of geochemical and petrological processes, including diffusion of cations in molten silicates and supercritical fluids, infiltration of solid rock by melts and fluids, grain boundary transport in the presence (and absence) of fluids, permeability of rocks to flow of fluids and melts, and textural aspects of fluid-bearing and partially-molten rocks; (2) the equilibrium partitioning behavior of trace elements among rock-forming minerals, melts and fluids at high pressures and temperatures; and (3) the stabilities, kinetic properties and textural aspects of accessory phases that concentrate trace elements (such as the lanthanides) and radioactive or radiogenic isotopes. In conjunction with experimental studies, we use simple numerical modeling approaches to guide the design of specific experiments and demonstrate the implications of our results for natural systems.
Numerous experimental and analytical techniques are brought to bear at RPI on problems in solid-Earth geochemistry. High P-T conditions are achieved mainly with solid-media, piston-cylinder apparati (up to 4 GPa and 1800oC) as well as with internally- and externally-heated gas-medium pressure vessels (up to 300 MPa and 1300oC). Analytical methods include SEM and electron-microprobe analysis, scanning confocal microscopy, vibrational and electronic spectroscopy (including cathodoluminescence), beta-track autoradiography, gamma-ray spectroscopy, Rutherford backscattering spectroscopy (RBS) and nuclear reaction analysis (NRA). These last two methods involve the use of the Dynamitron linear accelerator at the State University of New York at Albany; they have been perfected at RPI for analysis of high pressure-temperature run products by Daniele Cherniak, a physicist-turned-geochemist who works in our research group.
The unifying goal of our wide-ranging research is an understanding of the processes that redistribute the chemical elements and their isotopes in the solid Earth at scales ranging from micrometers to kilometers (with emphasis on the region extending from the mid-crust to the upper mantle). Our work is supported by the National Science Foundation and by the Office of Basic Energy Sciences of the U.S. Department of Energy.
For more information about ongoing projects, current collaborators and published results from the RPI experimental geochemistry lab, try the following...current research projects at RPI
research collaborators at RPI
EB Watson publications, 1976-present