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Lehrstuhl für Geologie und Lagerstättenlehre

Mineral characteristics in low sulphidation epithermal deposits in South Celebes, Indonesia

Andy Yahya Al Hakim
Exploration Camp
The open pit of Gosowong

Andy Yahya Al Hakim

 

Introduction

The magmatic arc system in Indonesia is the result of a complex history of tectonic events, including the plate subduction and the arc magmatism. Many potentials ore deposits has not been studied and observed well, that become more interesting to elaborate deeper by the researcher in the future.  Unknown information about characteristics of ore deposits might be result in the problems of environment, such as problems in acid mine drainage and also the contamination of heavy mineral.

Awak Mas is located in a mountainous area in the Luwu Regency of South Sulawesi Province, Indonesia. The drilling in Awak Mas area is done since early 1990 until 2012, and resulted in 3 main prospects, Awak Mas, Sallu Bullo and Great Tarra. Mineralization at Awak Mas is associated with quartz veining, brecciation, and silicification within foliated meta-sediments and within fault zones. Albite-silica-pyrite ± carbonate alteration generally accompanies and envelopes quartz-bearing rocks. Gold mineralization is associated with fine grained pyrite within alteration zones. Two main styles of mineralization are evident including that within: 1) steeply dipping, structurally controlled quartz veins and stockworks with attendant brecciation and silica flooding, and 2) foliation parallel zones of quartz veins and stockworks. Some zones of quartz enrichment are barren of mineralization. The steeply dipping zones likely developed along pre-mineral faults that served as conduits to hydrothermal fluids from which gold precipitated. The second style formed in an upper level, nearer surface environment where hydrothermal fluids migrated laterally into permeable beds or foliated (bedding parallel) zones under decreased lithostatic confining pressures.

The basic study in ore deposits, such as the study of ore deposits genesis and mineral, characteristics of ore mineralization,  geochemical study, micro thermometry that correlate with the characteristics of fluids, are tends to be the interested to be studied to reveal the characteristics in many epithermal deposits in Indonesia, related with environmental aspects.

The mineral paragenesis, formation condition, alteration group minerals, gangue and ore minerals observed, are used not only for the purpose of ore deposition and the characteristics of minerals, that gives us information about the past and the forming of deposits; but also gives us information about the environmental study, that occur as a product of geological and mining activity, in correlations with the mineralogy. The important role of minerals in mining environmental problems makes today a very exciting time for mineralogy.

Aims

Basically, the research study will examine exploration and mining development data, with the aims:

(1)    to understand the mineralogical aspects that formed in gold deposits with the type of epithermal low sulphidation, in Awak Mas, Sallu Bullo Deposits, South Celebes, based on analytical study, mineralogical study, qualitative and quantitative study with several experimental study using SEM-EDS method, element mapping, age dating, and fluid inclusion analysis;

(2)   to identify the ore formation condition in prospect area and determine the period of mineralization in Awak Mas Deposits, South Celebes;

(3)   to characterize the alteration and mineralization in several prospect in the area of study;

(4)   determine the presence of mineral in the area of  research.

The scope of this dissertation entails a detailed investigations of the geology, mineralogy, geochemistry, of epithermal low sulphidation deposits, in South Celebes, Indonesia. The ultimate goal is to construct a model that will describe the genetic of deposit, and the implications to the environment. Based on the results of this investigations, recommendations will be made on where to focus attention in attempts to predict and define additional ore shoots