Abstract

Eleven partial extraction methods were assessed for their exploration utility on 15 soil samples from a one-kilometre transect over the Palaeoproterozoic Talbot VMS occurrence that is hosted by metamorphic sequences of the Flin Flon-Snow Lake terrane and overlain by 100 m of Palaeozoic dolomites and up to 2 m of Quaternary glacial sediments. Student’s t-test statistics and t-distribution probabilities (Pt) were calculated to evaluate the magnitude and spatial accuracy of anomalies in each dataset. In the surface soil that was analysed, Zn anomalies have the greatest contrast by most methods, followed by P and Cd, albeit mostly restricted to a strong anomaly at a fault zone that is laterally offset c. 100 m from the projection of mineralization. Extraction methods with significant anomaly contrast in decreasing order of exploration utility are Enzyme Leach, deionized water, sodium pyrophosphate, MMI, and ammonium acetate at pH 7. Weaker leaches generate anomalies with greater contrast than stronger acid digests of the soils, which tend to dissolve the sample matrix and overwhelm the secondary signal from adsorbed species of ore indicator elements. Aqua regia digestions on the clay fraction extracted from the soil also have greater contrast than most soil digestions for ore-indicator elements. Continuous-leach ICP-MS analysis of the Talbot soil provides detailed phase relationships that indicate the presence of labile Zn present as organic complexes in anomalous soil over the fault, and the absence of such secondary Zn species in background soil, in which most Zn is released from carbonate dissolution.

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