Laurie Leshin - US grants

0120247
Leshin

This grant provides support for the 3rd Biennial Geochemical SIMS (Secondary Ion Mass Spectrometry) Workshop to be held at The Buttes Hotel and Conference Center in Tempe, AZ, October 12-14, 2001. The third in a series of biennial workshops, this meeting will bring together the bulk of U.S. geoscientists who either manage, maintain and/or utilize secondary ion mass spectrometry for microspatial trace element and isotopic analyses of natural and man made materials. The workshop will focus on presentations from the community that address developing new SIMS techniques for geological and cosmochemical applications, providing improved service to the community through NSF-sponsored SIMS facilities (i.e. WHOI; EAR-0115433 and UCLA; EAR-0113563) and the sharing and development of laboratory standards. The PI, Laurie Leshin, currently oversees a newly established (EAR-9871270) CAMECA 6f SIMS facility at Arizona State University and has included a list of invitees from the preeminent SIMS labs in U.S. academia and government labs. Additional attendees will include representatives from the manufactures of SIMS instrument (CAMECA and Australian Scientific Instruments) and should ensure that the analytical needs of U.S. geoscientists who use SIMS will be effectively transmitted to the private sector capable of facilitating instrumental improvements.

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This project is a collaboration between experimental petrologists at
U. Minnesota and analytical geochemists at Arizona State to address
two of the chief goals of the CSEDI initiative: (1) to understand
the Earth's deep water cycle and (2) to understand the influence of
H2O on melting, phase transitions, and physical properties of the
mantle. Experiments to determine the H2O storage capacity of
peridotite under upper mantle, transition zone, and lower mantle
conditions will be performed using high temperature high pressure
devices at the University of Minnesota. The storage capacity is the
maximum H2O that can be retained in solid peridotite at a given
temperature and pressure. Storage capacities constrain possible
regions of H2O-rich mantle reservoirs and possible loci of hydrous
melting. Owing to the large effect of H2O on mantle properties such
as creep strength, elasticity, and conductivity, they also provide
critical constraints on mantle dynamics. Experimental products will
be analyzed at Arizona State for trace quantities of H2O using
newly-developed low-blank secondary ion mass spectrometry techniques.
Four related experimental problems will be addressed: (1) To
investigate recent indications that the upper mantle has a larger
storage capacity than previously appreciated, experiments at 3-13
Gigapascals will determine peridotite H2O storage capacities. (2) To
determine the influence of H2O on deep melting beneath oceanic ridges
and oceanic islands and the consequences for dehydration of the upper
mantle, mineral/melt H2O partitioning will be determined at 3-8 GPa.
(3) To better understand transport of H2O across the 410 km
discontinuity, including the effect of H2O on melting and phase
transitions, inter-mineral partitioning of H2O and the storage
capacity will be determined at 13-15 GPa over a range of
temperatures. (4) To help resolve controversy about the storage
capacity of the lower mantle, experiments will be performed at 22-25
GPa, pressures relevant to in the region of the 670 km discontinuity.

EAR-0520648
Anbar

This proposal will fund an ICP-MS technical specialist to support innovative research in the newly renovated and equipped W.M. Keck Foundation Laboratory for Environmental Biogeochemistry at Arizona State University (ASU). The goal of this laboratory is to promote research at the intersection of the geosciences, the life sciences and chemistry by capitalizing on recent advances in mass spectrometry. The new position will therefore support the development and application of novel analytical methods. A special focus of this position will be new types of isotopic analyses made possible by the development of multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Examples of planned work include: the use of Mo isotope measurements in ancient sediments to reconstruct changes in the amount of oxygen in the atmosphere and oceans; the measurement of Fe isotopes to better understand the environmental chemistry of this biologically essential element, and exploration of Cr isotopes to trace toxic pollutants. In addition to supporting specific research projects, this award will enhance the development of a vibrant new program in isotope biogeochemistry at ASU that brings together researchers in several departments, schools, centers and institutes spanning a number of disciplines. The award will make it possible for us to effectively fold our new instruments into integrative graduate and undergraduate training as part of this program. It will also enhance the ability of ASU faculty to mentor post-Ph.D., non-tenure-track staff scientists, several of whom are involved in the planned research efforts.