Geochemical Soil Survey for Au Exploration in the Uluwai Village in Toraja, South Sulawesi

Abstract

A Geochemical soil survey was carried out over an area of approximately 25 km2 in Uluwai Village, Toraja Regency, South Sulawesi in order to select the promising areas for gold occurrences. The survey area is situated in the southern part of Toraja near the border with Enrekang Regency, about 340 km north of Makassar, the capital of South Sulawesi Province. The survey area is underlain within the Latimojong Complex, composed of metasedimentary sequence (upper Cretaceous) surrounded by Tertiary sedimentary rocks (Eocene to Miocene) of Toraja and Makale Formation. During the detailed survey, a total of 40 soil samples were taken using the grid pattern of 100 m by 50m. All samples were analyzed for Au, Ag, As and other metals (Cu, Zn, Bi, Co, Mo, Pb and U) using Atomic Absorption Spectrometer method after aqua regia digestion. The result shows that three Au and As anomalous sample were detected and the areas show similar directional patterns with the NW direction of the main regional fractures. From the detailed soil survey, two Au anomalous areas were finally proposed as promising prospects for the next Au exploration stage (geophysical investigation and drilling process).