Statement_of_Work_1.pdf
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- apatite and zircon grains from rock samples Federal contract opportunity
- Solicitation number
- 140G0324Q0026
About this file
This statement of work outlines requirements for (U-Th)/He thermochronometry analyses of rock samples to support the US Geological Survey Alaska Science Center's research efforts. The USGS requires (U-Th)/He analyses of 35 apatite samples and 35 zircon samples to elucidate the geologic context of Alaska's mineral resources by determining rock exhumation histories. The contractor must have experience performing (U-Th)/He thermochronometry using laser extraction, quadrupole mass spectrometry, clean lab preparation, and inductively coupled plasma mass spectrometry methods. The contractor shall provide analytical results and interpreted data in an Excel spreadsheet report, including raw data, methods documentation, and standards analysis. The period of performance spans from February 1, 2024 to March 31, 2025.
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US Geological Survey Alaska Science Center
Statement of Work
1.0 INTRODUCTION
The USGS needs to acquire (U-Th)/He thermochronometry analyses of apatite and zircon grains from rock samples.
2.0 BACKGROUND
The USGS conducts research on regional geology related to energy, minerals, and hazards.
This involves making geologic maps of the area being investigated, and reconstructing the tectonic, exhumation, and erosion history. (U-Th)/He thermochronometry is a key laboratory technique for determining exhumation histories, in particular rock cooling through 40-80°C (apatite U-Th/He) and 150-200°C (zircon U-Th/He). The samples submitted for thermochronometry analyses will help us elucidate the geologic context of mineral resources in Alaska.
3.0 SCOPE
(U-Th)/He thermochronometry requires access to and expertise in the use of a quadropole mass spectrometer (QMS) with a laser heating cell for Helium extraction and measurement, a clean lab for grain digestion with nitric acid or hot hydrofluoric acid, and an inductivity coupled plasma mass spectrometry (ICPMS) for Uranium, Thorium, and Samarium measurements. The exhumation age of each analyzed apatite or zircon grain is calculated from the analytical data, which come in Excel Spreadsheet format.
(U-Th)/He analyses of zircon- ZHe (qty 35) apatite samples-AHe (qty 35)
4.0 APPLICABLE DOCUMENTS
Publications documenting state-of-the-art analytical methods for collection and interpretation of AHe and ZHe data.
Farley, K.A. and Stockli, D.F., 2002, (U-Th)/He Dating of Phosphates: Apatite, Monazite, and Xenotime. In: Kohn, M., Rakovan, J., and Hughes, J.M. (eds.), Phosphates. Reviews in Mineralogy and Geochemistry, v. 15, p. 559-578.
Flowers, R. M., Ketcham, R. A., Shuster, D. L., & Farley, K. A. (2009). Apatite (U–Th)/He thermochronometry using a radiation damage accumulation and annealing model. Geochimica et Cosmochimica Acta, 73(8), 2347-2365.
Guenthner, W. R., Reiners, P. W., Ketcham, R. A., Nasdala, L., & Giester, G. (2013). Helium diffusion in natural zircon: Radiation damage, anisotropy, and the interpretation of zircon (U-Th)/He thermochronology. American Journal of Science, 313(3), 145-198.
Reiners, P. W. (2005). Zircon (U-Th)/He thermochronometry. Reviews in Mineralogy and
Geochemistry, 58(1), 151-179.
5.0 TECHNICAL REQUIREMENTS
The contractor shall have experience in all aspects of (U-Th)/He thermochronometry using laser extraction and QMS, clean lab, and ICPMS methods.
6.0 DELIVERABLES
The contractor shall provide deliverables in a report in Excel spreadsheet format, with both the raw and interpreted data included. The report shall include analysis of standards and a write-up of analytical methods shall be available (in digital form, as a Word document to USGS on request.
7.0 PERIOD OF PERFORMANCE
02/01/2024 to March 31, 2025
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