Characterization and Reconstruction of Deposit Facies of Mallawa Coal Formation of South Sulawesi Based on Proximate and Petrography Analysis

Abstract

This study has purpose to analysis the characteristic of Mallawa coal Formation, reconstruct facies deposit, and determine the rank of Mallawa coal Formation based on maseral content and reflectance of vitrinite.The data were collected from the field survey and were analysed by means of proximate measure and petrography analysis in the laboratory. The proximate analysis reveals that Doi-Doi and Massenrengpulu coals have higher calorie values (4900.47 kal/gram-6700.75kal/gram) but also possessing higher sulfur content (0.9%-4.63%). The petrography analysis of both areas indicates uniform contents of maceral consisting of vitrinite (57.4%-83.2%), inertinite (2.8%-17.8%), and liptinite (0.8%-3.0%). In addition, there are also other minerals such us pyrite (3.8%-15.4%) and clay (3.8%-18.4%). Reflectance value of Doi-Doi coal vitrinite is 0.31%-0.44% (peat sub bituminous C), and reflectance value of Massenrengpulu coal vitrinite is 0.38%-0.56% (lignite sub-bituminous B). Plotting result of TPI and GI values at Diessel diagram along with GWI and VI at Calder diagram indicates that coals of Doi-Doi and Massenrengpulu were deposited at back barrier in area condition of limnic-marsh. Environment facies of the coals in both areas were expansion from peat swamp with low moor in eutrophy condition to high moor in mesotrophy-oligotrophy condition when the top of coal seam was formed.