GeochemAnalyses_Statement_of_Work_0044001216_1.pdf

PERFORMANCE-BASED WORK STATEMENT

I. GENERAL INFORMATION

A. Introduction. The laboratory will provide chemical analyses of rock samples by the X-ray fluorescence method for scientists of the USGS Geology, Minerals, Energy and Geophysics (GMEG) Science Center.

B. Background. address unresolved problems from the past). Geochemical properties of volcanic rocks are important criteria for distinguishing distinct stratigraphic units or rocks from different eruptions. This is particularly the case for rocks of the Miocene Columbia River Basalt Group of the Pacific Northwest. This widespread sequence of flood basalts underlays more than 200,000 km2 of the region. Separating individual formations, members, and flows is important for defining the regional geologic history, structural deformation (including faulting and folding), and extent of important aquifers. Distinguishing CRBG flow units requires precise geochemical assessment of field-collected samples. And because CRBG geochemical distinctions can be very subtle, it is critical that the analyses are both (1) precise and (2) consistent with the long history of previous analyses of these lava flows. For this reason, nearly all CRBG analyses for USGS mapping efforts have been made by a very few laboratories, all with substantial experience in CRBG geochemical analysis.

C. Definitions/Applicable Documents.

• Columbia River Basalt Group (CRBG). The CRBG is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over 210,000 km2 of mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada.

• X-Ray Fluorescence (XRF). XRF is a measurement technique that uses x-rays, an energetic portion of the electromagnetic spectrum that includes microwaves and visible light, to determine the elemental makeup of materials ranging from rocks to minerals to soil.

• Loss on Ignition (LOI). LOI is the percent weight change upon heating above about 950° C, for sufficient time for sample weight to stabilize.

• Technical details on underlying principles of XRF spectrometry are summarized by Bruker AXS at the following link: https://my.bruker.com/acton/attachment/2655/f- 08f9/0/-/-/-/-/Introduction%2520to%2520XRF.pdf

D. Scope.

• The laboratory will provide chemical analyses of 200 rock samples submitted in calendar year 2025 by the X-ray fluorescence method for USGS GMEG scientists (with the option of 100 additional samples in 2026). Each sample analysis will determine and report the weight concentrations of at least 29 major and trace elements (Si, Al, Ti, Fe, Mn, Ca, Mg, K, Na, P, Sc, V, Ni, Cr, Ba, Sr, Zr, Y, Rb, Nb, Ga, Cu, Zn, Pb, La, Ce, Th, Nd, U). Major element concentrations will be reported as oxides:

SiO2, TiO2, Al2O3, total Fe as either FeO or Fe2O3, MnO, MgO, CaO, Na2O, K2O, P2O5. Concentrations of the remaining elements are to be reported as weight parts per million (ppm).

• Samples will be analyzed for loss on ignition (LOI: percent weight change upon heating above about 950° C, for sufficient time for sample weight to stabilize), with

LOI results included along with major element concentrations.

• Results will be reported to individual USGS requestors upon completion of each batch of submitted samples, within a typical turnaround time of 8-12 weeks.

II. WORK REQUIREMENTS

A. Technical Requirements.

• The laboratory will provide chemical analyses of 200 rock samples submitted in calendar year 2025 by the X-ray fluorescence method for USGS GMEG scientists (with the option of 100 additional samples in 2026). Each sample analysis will determine and report the weight concentrations of at least 29 major and trace elements (Si, Al, Ti, Fe, Mn, Ca, Mg, K, Na, P, Sc, V, Ni, Cr, Ba, Sr, Zr, Y, Rb, Nb, Ga, Cu, Zn, Pb, La, Ce, Th, Nd, U). Major element concentrations will be reported as oxides: SiO2, TiO2, Al2O3, total Fe as either FeO or Fe2O3, MnO, MgO, CaO, Na2O, K2O, P2O5. Concentrations of the remaining elements are to be reported as weight parts per million (ppm).

• Industry standard calibration and validation techniques should be applied, preferably using the BCR-1and BCR-2 reference standards when appropriate.

• As requested, samples will be analyzed for loss on ignition (LOI: percent weight change upon heating above about 950° C, for sufficient time for sample weight to stabilize), with LOI results included along with major element concentrations.

• Samples can be submitted by USGS scientists as hand samples, picked chips, or ground powders for no difference in price and will be ground by contract lab personnel (if necessary). The lab will provide the following options of materials for material grinding: agate, tungsten carbide, hardened steel, or alumina (99.5 wt%) to be specified by the requestor. Processing must not fractionate the samples, and equipment and environment must be cleaned thoroughly between samples to ensure no cross-contamination. Excess sample will be returned to the submitting scientists.

• Results will be reported to individual USGS requestors upon completion of each batch of submitted samples, within a typical turnaround time of 8 weeks for batches of 50 samples.

1. Criteria for acceptance of Product or Service.

• Samples are analyzed for major and trace element concentrations by an X-ray fluorescence spectrometer yielding consistent research-grade precision and accuracy (precision of ca. 1% relative for major oxides, ca. 5-10% relative for trace elements).

• Analytical results must be of high enough accuracy and precision to be comparable to decades of internally scrutinized analyses of USGS standards.

B. Deliverables.

a) Once contract is awarded, all analytical results produced by the laboratory will be sent to the individual submitters in Excel spreadsheet form via email.

b) The laboratory will maintain records of standardization results establishing analytical accuracy and precision, including international rock standards analyzed as unknowns, and will provide tabular summaries of such results to the USGS annually.

1. Delivery dates for work/product to be completed and point of delivery.

a) Samples will be provided for analysis in fiscal year 2025 but with the option of continuing sample submittals in fiscal year 2026.

b) Results will be reported to individual USGS requestors upon completion of each batch of submitted samples, within a typical turnaround time of 3-8 weeks for batches of 50 samples.

III. SUPPORTING INFORMATION

A. Place of Performance -Vendors location

B. Period of Performance (estimated) 01/01/2025 – 12/31/2026

C. Government Furnished Property (GFP): list property and its value. Not applicable.

D. Special Considerations.

1. Key personnel qualifications Not applicable.

2. Data Rights, Safety, Environment Not applicable.

3. Security/Privacy issues Not applicable.