COMPARATIVE PETROGRAPHY OF OMBILIN AND BAYAH COALS RELATED TO THEIR ORIGIN
DOI:
https://doi.org/10.30556/imj.Vol10.No3.2007.608Keywords:
Ombilin, Bayah, comparative petrography, coalAbstract
Two coalfields have been contrasted and compared on the basis of qualitative and quantitative stud- ies of macerals and minerals. Petrological comparison of the coals indicates that vitrinite and liptinite contents within Ombilin coal are higher than those of the Bayah coal. The inertinite content of both coals is somewhat similar. Mineral matter of Bayah coal is higher than that of Ombilin coal. The vitrinite reflectance and rank of the Ombilin coal is higher and thus, its coal rank (sub-bituminous to anthracite) is better than that of the Bayah coal (sub-bituminous to medium volatile bituminous). A clear distinction between the Ombilin and Bayah coals is not possible with petrographic methods alone, and other geological parameters have to be considered. The maceral compositions of the Ombilin and Bayah coals are slightly different from each other due to intrusion effect. In the thermally affected coals from both areas, liptinite generally cannot be distinguished from vitrinite and therefore it appears to contain high proportion of vitrinite (>90 %). However, thermally unaffected coals from both coalfields contain <90 % of vitrinite. Liptinite maceral is common in coals unaffected by contact alteration with some samples containing up to 10 %. In contrast, thermally affected coals have trace amounts of liptinite. Both thermally affected and affected coals contain rare inertinite with some samples containing up to 7 %. In some cases, coals with high inertinite content have a relatively high amount of mineral matter. The Ombilin and Bayah coals show variable vitrinite reflectances, due to igneous intrusion factor. Coal of lower rank has been metamorphosed to bituminous or anthracitic ranks. The extent of rank increase depends primarily on distance from the intruding igneous rock, but it may also be related to size and temperature of the intrusion. As the vitrinite reflectance (Rvmax) values of the Ombilin coal (0.62-4.69 %) are higher compared to the Bayah coal (0.53-1.23 %), this suggests that the heat source to the thermally affected coals is closer in the Ombilin coal than that of in the Bayah coal.
References
Cook, A.C., 1975. The spatial and temporal varia- tion of the type and rank of Australian coals. In: Cook, A.C. (ed.), Australian black coal-its occurrence, mining, preparation and use. Australasian Institute of Mineral and Metal- lurgy, Illawara Branch.
Cook, A.C. and Johnson, R.D., 1975. Seam thick- ness, quality and structure variations in the Bulli coal, Sydney Basin, NSW. Australasian Institute of Metallurgical Conference. South Australia.
De Coster, G.L., 1974. The geology of the Central and South Sumatera Basins. Proceedings of Indonesian Petroleum Association, 3rd Annual Convention. Jakarta.
Darman, H. and Sidi, F.H., 2000. An outline of the geology of Indonesia. Indonesian Association of Geologists. Jakarta.
Eubank, R.T. and Makki, C.A., 1981. Structural geology of the Central Sumatera back-arc basin. Indonesian Petroleum Association, 10th Annual Convention. Jakarta.
Harsa, E., 1975. Some of the factors which influ- ence oil occurrence in the South and Central Sumatera Basins. Regional Conference on the geology and mineral resources of Southeast Asia. Jakarta (unpublished).
Hutton, A.C. and Cook, A.C., 1980. Influence of alginite on the reflectance of vitrinite from Joadja NSW and some other coals and oil shales containing alginite. Fuel, 59.
Jones, J.M., Davis, A., Cook, A.C. and Murchison, D.G., 1984. Provincialism and correlation be- tween some properties of vitrinite. International Journal of Coal Geology, 3.
Katili, J.A. and Koesoemadinata, R.P., 1962. Structural pattern of South Banten and its re- lation to the ore-bearing veins. Department of Geology, University of Indonesia, Bandung.
Koesoemadinata, R.P., 1978. Sedimentary frame- work of Tertiary coal basins of Indonesia. 3rd Regional Conference on geology and mineral resources of Southeast Asia. Bangkok.
Koesoemadinata, R.P. and Matasak, T., 1981. Penelitian endapan batubara di sekitar Bayah- Jawa Barat. Institut Teknologi Bandung. Bandung.
Koning, T., 1985. Petroleum geology of the Ombilin intermontane basin, West Sumatera, IPA 14th Annual Meeting Conference.
Marubeni Iida and Kaiser Steel, 1971. Ombilin coalfield, West Sumatera, Indonesia. Techni- cal report of investigation and exploration, Marubeni Iida Co.Ltd. and Kaiser Steel Inter- national Mining Corp. (unpublished).
Santoso, B and Daulay, B, 2005. Vitrinite reflec- tance of Ombilin coal according to its petro- graphic analysis. Indonesian Mining Journal, 8 no.01
Santoso, B and Daulay, B, 2007. Maceral and mineral analysis of Lebak coals regarding their utilisation. Indonesian Mining Journal, 10 no.08
Shibaoka, M. and Smyth, M., 1975. Coal petro- logy and the formation of coal seams in some Australian sedimentary basins. Economic Geology, 70.
Standards Association of Australia, 1964. Aus- tralian standard code of recommended prac- tice for taking samples from coal seams in situ. AS CK5.
Standards Association of Australia, 1966. Glos- sary of terms for coal and coke. ASK 149.
Standards Association of Australia, 1975. Meth- ods for the analysis and testing of coal and coke: reporting of results. AS 1038 (16).
Standards Association of Australia, 1977. Code of practice for preparation of hard coal samples for microscopical examination by reflected light. AS 2061.
Standards Association of Australia, 1981a. De- termination of the maceral group composition of bituminous coal and anthracite (hard coal) AS 2515.
Standards Association of Australia, 1981b. Micro- scopical determination of the reflectance of coal macerals. AS 2486.
Standards Association of Australia, 1983. Guide for the taking of samples from hard coal seams in situ. AS 2617.
Standards Association of Australia, 1986. Coal maceral analysis. AS 2856.
Teichmuller, M. and Teichmuller, R., 1982. The geological basis of coal formation. In: Stach,
E. et al. (editors), Stach’s textbook of coal petrology. Stuttgart.
Downloads
Issue
Section
License
Indonesian Mining Journal provides immediate open access to its content on the principle that making research freely available to the public to supports a greater global exchange of knowledge.
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
