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The spatial distribution and statistics of indium in stream sediments from Papua New Guinea (PNG) were studied based on the results of Papua New Guinea National-Scale Geochemical Baseline (PNG-NGB) project (2015–2018). 1399 samples were collected covering approximately 128,000 km2 with sample density of approximately 1.1 site/100 km2. Indium concentration in the stream sediments of PNG ranged from 0.003 μg/g to 0.24 μg/g with a baseline (median) value of 0.067 μg/g, a value of slightly higher than the upper crustal abundance of indium and Europe, North America, Australia and China. 64 indium anomalies are decided by cumulative – frequency method and contrast value, 39 anomalies are associated with porphyry, VMS, skarn, bauxite, and epithermal deposits and occurrences while porphyry and VMS mineralization is the most important type for indium prospecting and exploration. Parent rock type is also an important factor that controls the geochemical pattern of the indium distribution in stream sediments of PNG. • Indium geochemical baseline of Papua New Guinea is 0.067 μg/g. • 64 indium anomalies are decided by cumulative – frequency and contrast value method • 39 indium anomalies shows potential for further prospecting and exploration. [ABSTRACT FROM AUTHOR]

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. • Cobalt geochemical baseline of Papua New Guinea is 27.8 μg/g. • National-scale geochemical survey is more effective for cobalt prospecting. • 11 cobalt geochemical provinces which holds prospecting potential are delineated. [ABSTRACT FROM AUTHOR]