National-scale distribution of Cobalt in Papua New Guinea and its significance for mineralization potential

Abstract

The concentrations, variations, distribution and anomaly of cobalt values in stream sediments from Papua New Guinea (PNG) were studied based on the results of the Papua New Guinea National-Scale Geochemical Baseline (PNG-NGB) project (2015–2018). The data were studied to understand the spatial distribution of cobalt and its prospecting potential in PNG. 1399 samples were collected covering approximately 128,000 km² with sample density of approximately 1.1 site/100 km². The analytical results show that the cobalt values in stream sediments of PNG ranged from 1.8 μg/g to 446 μg/g with a baseline (median) value of 27.8 μg/g which is significantly higher than the upper crustal abundance of cobalt. Parent rocks especially ultramafic–mafic rocks, are the major factor that governing the spatial distribution of cobalt values in stream sediments, while cobalt mineralization is also important for the distribution of cobalt anomalies based on their close spatial correlation. Regional cobalt geochemical anomaly correlated with the national scale geochemical anomaly as well, which suggest that the national scale geochemical anomaly can be an indicator for further prospecting. 11 Cobalt geochemical provinces and 21 cobalt geochemical anomalies are delineated for further prospecting.