A GIS APPROACH ON PROSPECT EVALUATION AND MINERAL TARGETING IN BATU HIJAU AREA OF INTEREST

PROCEEDINGS PIT IAGI RIAU 2006
The 35^th IAGI Annual Convention and Exhibition
Pekanbaru – Riau, 21 – 22 November 2006

A GIS APPROACH ON PROSPECT EVALUATION AND MINERAL TARGETING IN
BATU HIJAU AREA OF INTEREST

Dibiansyah Hamid & Elang Soeriaatmadja
PT Newmont Nusa Tenggara, Batu Hijau Mine, West Sumbawa, NTB
ABSTRACT

Series of intensive and extensive exploration works, in various phases, have been carried out within the PT Newmont Nusa Tenggara Contract of Work since the early CoW application in 1986. These include the data set that has led to the discovery of the world class Batu Hijau porphyry copper-gold mine in May 1990, with ore reserve of 1,197 metric tonnes grading 0.43% copper and 0.33 g/t gold. The exploration data consisted of packages of geological, geochemical and geophysical data set which were taken in various exploration stages from early regional reconnaissance, prospect definition to deposit delineation stages. Prior to the construction of copper and gold mine in Batu Hijau in 1997, the exploration work in the area surrounding, Batu Hijau Areas of Interest (AoI) had also been intensely carried out but with a different goal namely to search ‘additional reserves’ within the current mine project.

Following digital map data conversion into GIS Map-Info format of all exploration mapping data, a fully GIS-based digitally processed area rating has been applied to rank the prospect in term of main target ‘porphyry Cu-Au’ type of deposit and based on basic concept exposed ‘classical porphyry’ analogue to Batu Hijau mine. The method is mainly based on the compilation of all geological, geochemical and geophysical datasets which were converted into eight ‘digital’ ‘exploration aspects’ as rating criteria.

Weighting as the most important process in the rating were defined for each polygon clusters within each layers based on the basic concept and target that already been set up. The layer of polygon, representing each aspect, then will be overlaid each other, and the total weight of the combined polygons will be digitally calculated using map-info based GIS operation.

The rating has produced final prospectivity image for porphyry copper and gold target that showing the rank of exploration target based on the total weight and it is confirmed to be still referred and analogue to Batu Hijau mine in where the highest total weight and rank outline is located. It also successfully drives the area of Naga Emas, Arung Ara and West Nangka in northwest of Batu Hijau as the high priority targets. The high total weight has also occurred at Katala Prospect, east of Batu Hijau, eventhough the area is closed to Batu Hijau mine facility – Katala east dam.

This area rating method is conclusively highly applicable in ranking and defining priority target in areas or block that data collection has been performed in a similar proportion. Best practices can be applied to do the same process in rating the similar area using a different basic concept and/or target. In this case, weighting will be the critical aspect to produce accurate rate and rank.