Catchment basin analysis of regional geochemical gold data in Queensland

This study incorporates background correction and dilution correction methods for delineating Au geochemical anomalies using data of catchment outlet sediments from two horizons: top outlet sediments (TOS, 0–10 cm) and bottom outlet sediments (BOS, 60–90 cm), collected across the entire Queensland region as part of the National Geochemical Survey of Australia (NGSA) project. The dataset comprises Au concentrations from catchments covering numerous lithological units, which were merged into seven dominant lithologies for analysis. Multiple regression analysis was applied to estimate background Au values owing to lithology, enabling separation of background signals from mineralisation-related anomalies. Results show that dilution-corrected Au residuals improve anomaly detection, with BOS samples outperforming TOS in spatial alignment with 26 of 30 known gold deposit clusters, compared with 14 clusters identified by raw TOS data. The BOS horizon benefits from enrichment in fine sediment fractions (<75 µm) and reduced effects of surface weathering, providing a more stable and representative geochemical signal. Elevated Au levels associated with dominant lithologies may mask true anomalies, underscoring the importance of background correction.

Australian Journal of Earth Sciences

Australian Journal of Earth Sciences

73

1440-0952

N/A

3

10