Distribution of gold in different size fractions of stream sediments as a guide to bedrock gold mineralisation along the Shyok Suture Zone and adjacent areas of the Kohistan Island Arc, Pakistan

摘要

This paper describes a new exploration methodology using stream sediments in remote and glaciated regions of northern Pakistan. Gold concentrations in 268 samples from grain size fractions collected in 10 catchments were studied to detect possible mineralisation in the area. The 10 catchments were identified as anomalous from the spatial analysis of gold data in a regional stream sediment dataset. The multi-size fraction approach successfully identified known gold prospects as well as new areas of gold mineralisation. The previously unknown catchments were ranked in terms of their prospectivity for gold, with the most prospective catchments (decreasing in rank) being: Teru, Asheriat and Pakora. The studied catchments, the coarse (< 1.68 mm-400 mu m) and fine size (< 75 mu m) fractions of the stream sediments were found to give the most reliable indication of gold prospectivity. It is therefore advised that exploration programs carried out in high-altitude terrains, similar to those in northern Pakistan, utilise the approach of multiple-sediment size fractions to locate prospective areas for mineralisation.