Supplementary data for "Age, Geochemistry and Radiogenic Heat Production of Felsic Intrusive Rocks from the Eastern Athabasca Basin, Saskatchewan" GSC Open FIle
Description
This research builds on a recent study from the southwestern Athabasca Basin, which identified a large pluton linked to the 1.85–1.80 Ga high heat-producing Hudsonian granitoid suite as a key component of the local uranium ore system. Here, we test a similar hypothesis in the eastern Athabasca Basin, where uranium deposits are proposed to coincide with a zone of elevated heat production near the boundary between the Wollaston and Mudjatik domains of the Hearne craton. To investigate, we collected samples of felsic intrusive rocks from uranium deposits and discoveries along a transect across the Wollaston–Mudjatik Transition Zone (WMTZ), and assessed their age, geochemistry, and radiogenic heat production capacity to evaluate affinities with the Hudsonian suite. Although a single syn-orogenic granite sample south of the present-day basin margin yielded an age of 1826 ± 3 Ma and may represent a typical Hudsonian intrusion, other samples assumed to be Hudsonian were determined to be older Paleoproterozoic granites (ca. 1.875 Ga) or metamorphosed Neoarchean granites (2.58–2.67 Ga). Radiogenic heat production values mostly fall within global averages for granite and upper continental crust (1.6 – 3.5 µWm-3), although pegmatitic samples are elevated relative to nearby granites. Whereas the data are equivocal in defining a high heat-producing corridor within the WMTZ, new metamorphic ages from zircon rims (ca. 1.83, 1.81, 1.77 Ga) decrease from southeast to northwest across the zone, and highlight its role as a long-lived thermotectonic and structural boundary. This data repository includes the geochemistry (Table S1) and SHRIMP zircon U-Pb (Table S2) data for the corresponding Geological Survey of Canada Open File report
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A suite of 34 rock samples and additional blind certified reference materials were submitted for whole-rock geochemical analysis at Activation Laboratories in Ancaster, Ontario. Drill core sections were crushed in a mild steel mill, and then pulverized in an agate mill. Sample preparation was by lithium metaborate/tetraborate fusion followed by analysis by inductively coupled plasma-optical emission spectrometry (ICP-OES) for major elements and inductively coupled plasma-mass spectrometry (ICP-MS) fortrace elements using their Code 4 Lithoresearch package. Ferrous/ferric iron concentrations were determined by titration. Fluorine contents were determined by LiBO2 fusion followed by ion-selective electrode (ISE) analysis. SHRIMP analytical procedures followed those described by Stern (1997). Fragments of the GSC zircon primary reference material (RM) 6266 (206Pb/238U age = 559±02 Ma; Stern and Amelin, 2003) and secondary zircon RM 1242 (207Pb/206Pb age = 2679.7±0.2 Ma; Davis et al., 2019) were analyzed on the same mount and under the same conditions as the unknowns. Analyses were conducted using an O− primary beam, with a spot size of ~20 µm at a beam current of ∼0.4 nA. The count rates of 11 isotopes of Yb, Hf, U, Th, and Pb were sequentially measured over six scans with a single electron multiplier. Off-line data processing was accomplished using Squid3 software (Bodorkos et al., 2020). The decay constants used follow the recommendations of Steiger and Jäger (1977). The 1σ external errors of 206Pb/238U ratios reported in the data table (Table S1)incorporate a ±1.0 % error in calibrating the primary RM (see Stern and Amelin, 2003). Analyses of a secondary zircon RM 1242 were interspersed between the sample analyses to assess the requirement of an isotopic mass fractionation correction for the 207Pb/206Pb age. Common Pb correction utilized the Pb isotope composition of the surface blank (Stern, 1997). IsoplotR software (Vermeesch, 2018) was used to generate concordia plots and calculate weighted means. The error ellipses on the concordia diagrams, and the weighted mean errors in the text are reported at 2σ. Errors reported in the data table (Tables S2) are given at the 1σ confidence interval.
Institutions
- Natural Resources Canada