Innovations in experimental methods and instrumentation are revolutionizing the acquisition and application of geochronologic information in Earth Science research. Some of the most exciting advances are being driven by Laser-Ablation Multicollector ICP Mass Spectrometry (LA-MC-ICPMS), allowing one to determine U-Th-Pb ages with micron-scale spatial resolution. This technique is fundamentally changing the way that geochronologic information is utilized, with impacts that cover the span of structural geology, tectonics, stratigraphy, paleontology, petrology, economic geology, and geochemistry.
The Arizona LaserChron Center (ALC) is a multi-user facility that utilizes LA-MC-ICPMS to provide the NSF-supported Earth Science community with U-Th-Pb geochronologic information and training. Primary goals of the ALC are to (1) generate high quality/low cost U-Th-Pb geochronologic information for NSF-supported researchers, (2) use every aspect of facility operation as an opportunity to train student and faculty researchers in geochronologic theory and methodology, and (3) drive the development of new techniques and applications that take advantage of the strengths of LA-MC-ICPMS.
The funding will provide support for ALC staff members to assist NSF-supported researchers in acquiring geochronologic information and to drive the development of new analytical techniques, for maintenance and modernization of instrumentation, and for students to be able to conduct research in the laboratory. This support will enable the ALC to provide geochronologic information NSF-EAR awardees. This collaborative research will drive important new developments in studies of the growth of continents, processes of mountain building, generation and dispersal of sediment through space and time, formation of mineral and hydrocarbon resources, history of evolutionary changes, chronology of early hominids, and genetic linkages between climate and tectonics.
This award supported operation of the Arizona LaserChron Center (ALC), an NSF Multi-User Facility, from February 2011 through January 2014. The primary outcomes from ALC activities during this 3-year period are as follows: Outcome #1 has been to provide geochronologic training and educational opportunities for a large number of students and faculty researchers. This has been accomplished largely by encouraging researchers to visit the ALC in order to become familiar with all aspects of sample preparation, data generation, and synthesis of results. An average of 255 researchers (101 faculty members, 97 graduate students, and 57 undergraduate students) visited the lab per year. We have also developed extensive web-based resources that have been of significant benfit to the broader Earth Science community. These resources include detailed descriptions of all analytical methods used, software to make plots and analyze data, and short courses on geochronologic methods and applications that can be used for individual instruction or in a classroom setting. One-day short courses have been taught at all three National GSA Meetings during the award period. Outcome #2 has been to generate geochronologic data that are used to address a wide range of critical problems in Earth Science. Research conducted at the ALC has been fundamental to our understanding of processes such as the growth of continents, formation of mountain systems, generation and transport of sediments, formation of essential mineral and hydrocarbon resources, and linkages between climate and tectonics. We have also explored applications of geochronology to other fields, such as the timing of early hominid evolution, chronology of evolutionary changes, archaeological sourcing of artifacts (e.g., mano stones and temper sands), chronology of mineral evolution as a record of bio-, atmo-, and hydro-sphere evolution, and chronology of meteorites and Mars. During the award period, over 236K U-Pb and Hf analyses were generated in support of an average of 86 different EAR awards per year. 212 peer-reviewed journal articles or book chapters containing data from the ALC were published during 2011-2013. Outcome #3 has been to develop and report analytical methods that take advantage of the spatial resolution and efficiency of Laser-Ablation ICP Mass Spectrometry (LA-ICPMS). The ALC has been very active in improving the precision, accuracy, efficiency, and spatial resolution of U-Pb analyses of zircon by LA-ICPMS. These improvements resulted from our in-house research, from collaborations with academic researchers at other institutions, and from interactions with engineers at companies that manufacture mass spectrometers and laser ablation systems. We have also invested considerable effort in acquiring and developing new instrumentation and analytical methods to be able to determine U-Pb ages on a variety of other phases (e.g., titanite, baddeleyite, monazite, and apatite) and to measure isotope ratios of Hf and Li as well as U, Th, and Pb. New instrumentation acquired during the award period includes a single-collector ICPMS (funded as a gift from ExxonMobil), as well as a second excimer laser and an automated CL image acquisition system (funded in part by the University of Arizona). Outcome #4 has been the enhancement of human resources in the Earth Sciences. We strive to involve students in all aspects of facility operation, and strongly encourage involvement of members of underrepresented minorities. We also encourage faculty researchers from other institutions to bring students to the lab when conducting analyses. Travel costs for student researchers are subsidized using NSF Participant Support funds ($90K allocated during the award period), and this has been very effective at increasing the number of undergraduate and graduate students involved in research. We have also co-hosted international workshops in 2011 and 2013 to share the results of our research with students and faculty researchers from around the world.
