The Arizona LaserChron Center is an NSF multi-user facility that is designed to address problems in Earth Science through the generation of U-Th-Pb geochronologic data and complementary geochemical information by Laser Ablation ICP Mass Spectrometry. Our primary goals are as follows:
Generate U-Th-Pb ages, Hf isotope ratios, and trace element concentrations of the best precision, accuracy, and spatial resolution possible from LA-ICPMS.
Provide opportunities for researchers from around the world (and especially NSF-supported scientists) to use our instruments and expertise to address geologic problems.
Drive the development of new techniques and applications of geochronology, thermochronology, and petrochronology.
Build new cyberinfrastructure for data acquisition, analysis, and archiving.
Use every aspect of facility operation as an opportunity to enhance expertise and diversity among geochronologists and users of geochronology.
The main instruments utilized at the Arizona LaserChron Center include a Nu Plasma multicollector ICPMS, a Thermo Element2 single-collector ICPMS, two Photon Machines Analyte G2 excimer lasers, and a Hitachi 3400N SEM, all of which are dedicated to ALC research. These instruments were acquired with support from the University of Arizona, the National Science Foundation, and ExxonMobil Upstream Research.
Support for the Arizona LaserChron Center is provided by the NSF Instrumentation and Facilities Program. The center is a multi-user facility, available to all NSF-supported researchers and students as well as researchers from around the world. NSF funding allows us to significantly reduce the cost of NSF-supported research, with additional support available to subsidize research conducted by students. Additional information about NSF multi-user facilities is available at http://www.nsf.gov/geo/ear/if/facil.jsp.
Please contact George Gehrels (Director of the ALC; firstname.lastname@example.org) for general questions about the lab, or Mark Pecha (Manager of the ALC; email@example.com) for specific information about analytical methods, schedules, costs, letters of collaboration, etc.
We are continually adjusting how we operate in response to the evolving Covid-19 situation. As described in our Covid-19 video, we operated with only lab employees (no visitors) working on high-priority samples through the summer and early fall. We are now allowed to have external researchers conduct analyses in our labs, so long as stringent guidelines are followed. Please check out (and complete) our Re-Entry Form if interested. If you prefer to not travel, we are able to perform the analyses needed for your project, and you will be able to watch and participate in lab activities through live Zoom or TeamViewer sessions. Please contact Mark Pecha (firstname.lastname@example.org) or George Gehrels (email@example.com) to set up either of these arrangements and/or if you have questions or suggestions regarding ALC operation.
We have created a Researcher Info-Form to help us keep track of ALC projects and people, and to gather input on how the ALC operates. Please complete the form before, during, and/or after your visit! Note that all information is optional, and you should feel free to submit comments anonymously. Thanks for your input!
Please upload your data to Geochron.org!! We have streamlined the process such that it now takes just a couple of minutes per sample. Instructions are available from the Tools=>Geochron Uploading link to the right...
In an effort to enhance diversity/inclusion in geochronology, we are encouraging researchers to include one extra student from an under-represented minority in their visit to the ALC. We will cover all travel, lodging, and analysis costs for this student. Details available from the Analytical Costs link to the right.
We are developing new MATLAB-based software tools that can be used for analyzing and visualizing geochronologic and complementary geochemical data. These tools can be accessed from the Analysis Tools links to the right. Note that Kurt Sundell (ALC post-doc), Joel Saylor (Univ. British Columbia), and John Hartman (UofA Computer Science) are leading these programming efforts.
Check out the growing set of videos on the LaserChron YouTube Channel. Presentations so far focus on methods for preparing/analyzing samples and for maintaining our NU ICPMS, Element2 ICPMS, and Photon Machines G2 lasers. Martin Pepper (ALC resesrcher) is leading these efforts...
We have collected a large batch of FC-1 (Duluth Gabbro) from the original outcrop to serve as primary or secondary zircon standard for U-Pb geochronology by LA-ICPMS and SIMS. Please contact George Gehrels (firstname.lastname@example.org) if you would like a bucket!
A Short Course on "Detrital Zircon Geochronology: Best Practices for U-Pb Data Acquisition, Reduction, Analysis, and Archiving" was offered at the 2020 National GSA Meeting. The modules and video recordings for this course are available from the "Short Course" link to the right. You will also find modules from previous Short Courses that included information about Oxygen isotopes and Trace/REE geochemistry (with contributions from John Valley and Jay Chapman).
For users of Thermo Element instruments, note that we have developed a routine that extracts information from dat files. This provides access to the raw counts for each measurement, resulting in more reliable data reduction than is possible from FIN2 files. The decoding routine is posted on GitHub, and more information is available in a manuscript available from Archive.org. Thanks to John Hartman (UofAZ Computer Science) and Philip Wenig (OpenChrom) for cracking the code!
If you are working on an NSF proposal, note that the current NSF Grant Proposal Guide requires that letters of collaboration include only a statement about willingness to collaborate. Information about instruments and methods should be provided in your "Facilities, Equipment, and Other Resources" section. We are happy to provide a letter of collaboration. Information about our instruments, methods, and analyses is available from the Proposal Tools section (link to right). Financial information can be accessed from the Analytical Costs and Student Support links (to the right). We also have a Data Management Plan that can be modified for your project.
We continue to work on developing techniques that integrate U-Th-Pb geochronology, Trace and Rare Earth Element analysis, and Lu-Hf isotope geochemistry. We are able to conduct U-Th-Pb and T/REE analyses just using our Element2 (single-collector ICPMS) -- there is no need for split-stream analysis. U-Th-Pb, T/REE, and Lu-Hf can be done simultaneously in split-stream mode, by connecting the Element2 with our Nu multi-collector ICPMS. But it is much more efficient (and cost-effective) to do the analyses in two different sessions given that most studies require many more U-Pb ages than T/REE or Hf isotope analyses. We accordingly recommend doing large-n U-Th-Pb first (with the E2 or NU), and then selecting optimal grains for T/REE and Hf isotope analyses. Our methods for doing each type of analysis are described in the Analytical Methods section to the right.
We have developed a system for extracting zircons from fine-grained sediments (e.g., loess, siltstone), enabling analysis of zircons down to ~10 microns. The process relies on a series of ultrasonic baths for separating zircon from clay. Check out the recent application of this method for analysis of Chinese Loess.
Our Hitachi 3400N SEM (equipped with Gatan Chroma CL2 color/UV and Oxford EDS/EBSD detectors) is now fully integrated into the LaserChron facility. This instrument generates high-resolution BSE and/or color CL images that are necessary for characterizing grains and optimizing analysis locations. See the accompanying information about Imaging Options to determine which types of images are appropriate for your analyses, and for costs of imaging. Here are some examples of CL images and BSE images. Please contact Nicky Giesler (email@example.com), manager of the SEM lab, for more information.
Information about ongoing projects, samples, costs, correspondence, etc. can be found at our Current Projects page (link to right). Note that secure sites are available on request.
Having issues with high Hg content during laser ablation analyses in your lab? You might try installing a gold trap similar to this design. We can provide the glass ends (at no charge) -- contact firstname.lastname@example.org.
The "Working-Group for Geochronology by LA-ICPMS" (http://www.plasmage.org) continues to be active. Most recent is a paper by Horstwood and others (2016) that presents "best practices" for acquisition, reduction, and reporting of U-Th-Pb data by LA-ICPMS. We offered a workshop and short course at the 2018 Goldschmidt Meeting that presented results from a new interlab calibration study, the benefits of chemical abrasion & thermal annealing, U-Pb dating of minerals besides zircon, and a comparison of different methods of standardization, common-Pb correction, and uncertainty propagation. Prior sessions were held at 2015, 2014, 2013, 2011, and 2009 Goldschmidt/AGU meetings. Note that we are distributing sets of standards to other labs that would like to participate in this interlab calibration -- see Geochronology Standards link to the right.
We are participating in several efforts to build community and increase engagement in geochronology. Activities include (1) development of the "It's About Time" whitepaper which was prepared in response to NROES recommendations concerning geochronologic infrastructure, (2) participation in the CORES committee, which is gathering information from the community about future infrastructure needs, and (3) helping lead the Geochronology Division of Geological Society of America.
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