Recent Exploration for Au-Cu in Central and North Sulawesi.

Symposium on : "Magmatic‐Fluid Activities and Ore Formation in the Island Arc and The Continental Margin"
Hokkaido University, Sapporo March 24, 2012

 

Recent Exploration for Au-Cu in Central and North Sulawesi
Mega F.Rosana
Faculty of Geology, Padjadjaran University
rosanamf@yahoo.com, mega_fr@unpad.ac.id
Abstract

Sulawesi island is located between three major plates (Indian-Australia; Philippine Sea; and
Eurasian) that converge and interact each other resulting the "K-shape" of the island with very
complex geology and diverse mineral resources. Geologically its simplified into (1) West-North arm
consist of volcano-magmatic of pre-Tertiary to Recent ages; (2) Central part is part of metamorphic
areas; (3) East arm composed mainly obducted ophiolitic nappes; and (4) Banggai-Sula terrain micro
continent consist of sedimentary-volcanic rocks of Mesozoic ages.
Mineral exploration and mining activity in Sulawesi is starting more than 150 years, but the
region remains underexplored by today's. Up to 1984, explorations are mainly focus on nickel laterite

and several small scale gold deposit. Since 1985 the exploration is shift to gold, copper, molybdenum,
lead and zinc, significant gold discoveries was made and developed (eg. Mesel). Exploration for
gold-copper is mainly in west-north arm of Sulawesi of volcanic terrain, although few gold
occurrence also discover in metamorphic host rock.
North Sulawesi is relatively well endowed mineral deposits and prospects. A number of
mineral styles have been recognized by intensive exploration, those are porphyry Cu-Au+Mo, highlow sulphidation epithermal Au-Ag, sediment-hosted Au, breccia-hosted base metal Au, intrusionrelated base metal Au veins, Fe+Au skarn, and Cu-Pb-Zn VMS.
Central-west Sulawesi appear to be less well mineralized than north Sulawesi. Mining
activities in this arm is very limited todate. Few porphyry Cu occurrences appear associated with
Neogene potassic alkaline intrusive or skarn mineralization. Small cluster of Pb-Zn-Cu kuroko-type,
intrusion-related Au vein in metasedimen-metamorphic terrain are occur. However the metallogeny of
central-west Sulawesi is poor development of typical epithermal-style gold mineralization.
Eastern Sulawesi mineral deposits mostly associated with large ophiolite host rocks. They
mainly of lateritic nickel, iron and chromite deposits. Small occurrence of Cu-bearing siliceous rock
associated with ophiolitic. Alluvial and primary gold are occur, most notably at Bombana district,
although the origin has not yet been established.
The exploration in Sulawesi are likely still continue in Brownfield region, due to many data
have been collected over 40 years exploration. Applying new concepts and revisiting certain areas to
collect additional data are also selected by several companies.. However, the new mining law and
forestry permit issues are important factor to be consider in the area selection for exploration in both
Greenfield or Brownfield area.