Acquisition of a Laser Ablation System in Support of (U-Th)He and UPb Multidating of Accessory Minerals

Project: Research project

Description

Acquisition of a Laser Ablation System for (U-Th)/He and U/Pb Multidating of Accessory Minerals (U-Th)/He thermochronology has become a valuable tool for Earth scientists who explore the coevolution of climate and landscapes in tectonic settings, and increasingly for those who wish to better understand short-timescale thermal processes related to meteorite impact and volcanism. Although many research problems are adequately served by conventional (U-Th)/He analytical protocols that focus on bulk single crystal dating of mechanically separated accessory minerals, many others require resolution of the intracrystalline distribution of parent and daughter products or a way to date grains in petrographic context. In addition, for detrital mineral studies, the capacity to apply additional isotopic chronometers to the same grains (e.g., U/Pb), the ability to reduce the possibility of sampling bias, and high sample throughput are all desirable but are presently difficult or impossible to achieve using conventional protocols. As a consequence, the PI and his research groups at the Massachusetts Institute of Technology and, more recently, at Arizona State University have focused considerable attention on developing a new approach to (U-Th)/He analysis that involves laser microanalysis. This technique is now sufficiently mature to propose the establishment of an automated laser microprobe facility that will serve internal ASU and external users in the Earth sciences community. Most components of this facility have been acquired through investments by Arizona State University without National Science Foundation support. This proposal is a request for NSF funds to procure the last important instrument necessary for the facility: an ultraviolet laser ablation system that will be used for both helium extraction for magnetic sector mass spectrometry and trace element and isotopic measurements by inductively coupled, plasmasource quadrupole mass spectrometry. Notably, the quadrupole instrument also permits simultaneous U/Pb geochronology of the same grains and we thus refer to the entire instrument as a Laser Microprobe Multidating System (LaMMS). Broader Impacts This project will result in the establishment of a geoscience community resource for integrated laser ablation (U-Th)/He thermochronology and reconnaissance U-Pb geochronology of zircons, particularly detrital zircon samples. The PIs research laboratories at MIT and ASU have always been open to external users from around the world, but the new facilities at ASU in which LaMMS will be housed permits the accommodation of an even larger cadre of users. In addition, this complex instrument that requires the integration of multiple subsystems, each a complex instrument in its own right, is ideal for teaching undergraduates the principles of analytical systems engineering. We will take advantage of this to develop an online analytical systems engineering (ASE) subject as part of its the School of Earth and Space Explorations B.S. degree program in exploration systems design.
StatusFinished
Effective start/end date9/1/138/31/15

Funding

  • National Science Foundation (NSF): $216,000.00

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accessory mineral
ablation
laser
thermochronology
geochronology
zircon
mass spectrometry
engineering
sampling bias
coevolution
Earth science
tectonic setting
meteorite
helium
teaching
volcanism
trace element
crystal
timescale
climate