J_A_0044048484_1.pdf
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- Solicitation number
- 140GG027Q0015
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Sole-Source Determination for U-Pb Zircon Geochronology Services
This document is a Sole-Source Determination justification for an acquisition under the Simplified Acquisition Threshold (SAT) for a commercial product or service, issued by the USGS Geology, Energy, and Minerals Science Center (Reference: PR # 0044048484). The contracting agency restricts this acquisition exclusively to the University of Arizona LaserChron Lab in Tucson, Arizona. The required services involve laser ablation analysis of rock samples to determine uranium-lead (U-Pb) zircon geochronology and age dating coupled with chemical characterization. This analysis supports reconstruction of tectonic and depositional histories for critical depositional systems in the United States that host petroleum and mineral deposits. The contractor will provide U-Th-Pb data from submitted samples and furnish Lu/Hf and trace + REE analytical results via spreadsheet. The estimated total potential value of the requirement is redacted in the document.
The justification for sole-source procurement emphasizes that data turnaround time, quality, and continuity are essential for geochronological analyses, requiring that U-Pb samples be prepared and analyzed at the same laboratory on the same instrument to ensure direct comparability. The USGS has utilized Arizona LaserChron for U-Pb dating from 2021-2026, completing analyses valued in the redacted amount for Alaska and Gulf Coast projects. Arizona LaserChron Lab is identified as the only reasonably available source meeting government requirements due to its designation as an NSF National Facility for geochronology since 2005; its complete service offerings including zircon extraction, SEM imaging, Raman analysis, and isotopic analysis; its use of four ICPMS coupled to three excimer lasers for rapid turnaround; its measurement of 204Pb for common Pb correction; its proprietary in-house data reduction protocols (AgeCalcML and AgeCalcN3); and its full-service model where staff manage all phases from sample processing through data reduction. Market research confirmed no other laboratory offers equivalent full-service capabilities without introducing variables that prevent data set comparison.
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| Attachment_-_Statement_of_work_1.pdf |
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Data turnaround time, quality and continuity are essential for these geochronological analyses.
U-Pb samples must be prepared (mineral separates made) and analyzed at the same lab on the same instrument. Previous experience utilizing different labs for data sets that are to be a part of the same study has shown lab-based differences in the number of discordant grains, adding new variables to data and preventing data sets from being directly comparable.
The USGS has utilized the Arizona LaserChron lab for U/Pb dating from 2021-2026. During this time, Arizona Laserchron completed over worth of analyses for Alaska and Gulf Coast projects at the USGS. The data produced from analyses included in this PR would be a continuation of that effort, and this data needs to be directly compared to our existing data set.
Additionally, ALC offers several services not available from other labs:
ALC has been an NSF National Facility for geochronology since 2005, and the offers a complete service including zircon extraction, mounting, polishing, SEM imaging (backscatter and cathodoluminescence), Raman analysis, U-Pb, T/REE, and Hf isotopic analysis.
ALC has 4 ICPMS coupled to 3 excimer lasers to ensure rapid turnaround times. The lab exclusively uses excimer lasers for the ablation of zircon whereas many labs use less effective lasers (effectiveness is due to light coupling characteristics between the light wavelength and zircon crystals).
ALC measures 204Pb during each U-Pb measurement so each analysis can be corrected for common Pb.
ALC U-Pb data is reduced using in-house data reduction protocols (AgeCalcML (LA-SC-
ICPMS) or AgeCalcN3 (LA-MC-ICPMS)). This is highly desirable to ensure data reductions are completed appropriately/similarily for ALL samples, including those we have run to date. Many other labs use Iolite which allows users an extremely high degree of subjectivity when reducing datasets, which is highly undesireable.
ALC is a full-service lab where ALC staff not only separate and process samples but accurately select spots for laser ablation, analyze samples and collect data, and reduce data down to best collected in this way, it is imperative that future data analysis and processing be conducted using the exact same methods.
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