Paleoenvironmental, paleoecological and thermal metamorphism implications on the organic petrography and organic geochemistry of Tertiary Tanjung Enim coal, South Sumatra Basin, Indonesia [Elektronische Ressource] / vorgelegt von Donatus Hendra Amijaya

Hendra

Informations

• Publié par: rheinisch-westfalischen_technischen_hochschule_-rwth-_aachen
• Publié le: 01 janvier 2005
• Nombre de lectures: 17
• Langue: English
• Poids de l'ouvrage: 4 Mo

Extrait

Paleoenvironmental, paleoecological and
thermal metamorphism implications on
the organic petrography and organic geochemistry
of Tertiary Tanjung Enim coal,
South Sumatra Basin, Indonesia





Von der Fakultät für Georessourcen und Materialtechnik
der Rheinisch-Westfälischen Technischen Hochschule Aachen

zur Erlangung des akademischen Grades eines

Doktors der Naturwissenschaften

genehmigte Dissertation


vorgelegt von M. Tech.


Donatus Hendra Amijaya

aus Yogyakarta




Berichter: Univ.-Prof. Dr.rer.nat. Ralf Littke
Univ.-Prof. (em) Dr.rer.nat. Detlev Leythaeuser

Tag der mündlichen Prüfung: 23. September 2005

Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar.



















































untuk Indonesia… Acknowledgement

The scholarship to pursue the PhD degree at Aachen University and the German language
course at Goethe Institute, Mannheim was granted by the German Academic Exchange
Service (DAAD) to which first of all a grateful acknowledgement is made.

I would like to express tremendous gratitude to Prof. Dr. Ralf Littke, Head of the Institute of
Geology and Geochemistry of Petroleum and Coal (LEK), Aachen University, for his interest
in the research topic and his supervision during my work at LEK. His understanding and
patience as he was confronted with my “way of work” deserves great respect. I also extend
sincere regards to Prof. Dr. Detlev Leythaeuser for his willingness to be the co-supervisor and
his advice for the final version of my dissertation.

I equally thank PD Dr. Jan Schwarzbauer, Head of the Organic Geochemistry Laboratory at
LEK, and Dr. Bernd Krooss, Head of the Petrophysics Laboratory at LEK, who granted me
unlimited access to the laboratory facilities. They introduced various aspects of organic
geochemistry to me, a very exciting subject that never got my attention before. They also
delivered a lot of important suggestions for my research.

My knowledge on coal petrography was improved by fruitful discussions with Prof. Dr.
Marco Ercegovac (Serbian Academy of Sciences and Arts, Belgrade) and Prof. Dr. Ali
Karayigit (Haceteppe University, Turkey) during their visit as guest scientist at LEK, to
whom my regards are addressed. I also thank to Dr. Achim Bechtel (Bonn University) for the
discussion on organic geochemistry. My gratitudes are addressed to Dr. Jim Hower, Dr. Janet
Dehmer, Dr. Sandra Neuzil, Dr. Tim Moore and an anonymous reviewer (International
Journal of Coal Geology), also to Dr. Clifford Walters, Dr. Henrik Petersen and Dr. Michael
Kruge (Organic Geochemistry) for numerous helpful comments, which enormously improved
earlier versions of part of this work.

Kind support from Prof. Peter Kukla and PD Dr. Harald Stollhofen (Institute of Geology,
Aachen University) by issuing the letter of recommendation for the prolongation of my
scholarship was crucial for the continuity of my work.
iv Acknowledgement
I am indebted to PT. Tambang Batubara Bukit Asam (PTBA) Management at Tanjung Enim,
Sumatra, Indonesia for the permission to take coal samples in PTBA concession area and also
for lodging support during field work. I would like to acknowledge the coal geologists of
PTBA, especially Ir. Suhedi and Ir. Pajar Hariadi from Exploration and Development
Department and Ir. Roberth Bunga, Head of the Geological Section at Tambang Air Laya
mine, for their enormous help and discussions during field work.

Valuable suggestions and support from Ir. Djoko Wintolo, DEA and Ir. Marno Datun (Gadjah
Mada University, Yogyakarta) and Dr. Ir. Komang Anggayana (Bandung Institute of
Technology, Bandung) are highly appreciated. Assistance on coal sampling at PTBA and
preliminary sample preparation at Gadjah Mada University were provided by Pentatok
Kuncoro, Lalu Winaran, Rimbun Nainggolan, Tiastomo Ardian and Harry Nugraha.

The electron microscopy analysis was conducted at the Central Facility for Electron
Microscopy, Aachen University and the XRD analysis was done at the Institute of
Mineralogy, Aachen University. I thank all staff members from both institutions who assisted
in these analyses.

Co-operation and technical assistance from my fellow-colleagues at LEK, Dipl. Geol. Ralf
Meier, Emmannuel Eseme, M.Sc., Ina Blumenstein, M.Sc., Dipl. Geol. Alex Kronimus,
Phillip Weniger and Jens Köster on organic geochemistry analysis, as well as Rolf
Mildenberger's assistance to prepare the polished sections for microscopic analysis and his
teaching on technical aspects of microscopy, are gratefully acknowledged. I thank Dipl. Geol.
Danny Schwarzer, Dipl. Geol. Sabine Rodon, Dipl. Geol. Yvonne Senglaub and Dipl. Geow.
Susanne Nelskamp for the German language correction on my annual reports to DAAD and
Dr. Dirk Prinz for correcting the “Zusammenfassung” of this dissertation. I was also helped
by LEK-secretariat staff, Mrs. Dorit Kanellis and Mrs. Renate Wuropoulos, to handle the
administrative subjects.

Special thanks are due to my wife, Sita Yuliastuti Amijaya, for the encouragement she gave
between her own activities to finish her study in Cologne and to my parents, for their support
and understanding.

Abstract

Organic petrography and organic geochemistry studies have been conducted on Tertiary
age coals from Tanjung Enim, South Sumatra Basin. The South Sumatra basin is among
the most important coal producing basins in Indonesia since the coal resources represent
one third of Indonesian coal resources. The coals are of subbituminous rank and
characterized by low vitrinite (huminite) reflectance (VR = 0.35 - 0.46%). In this area, r
the coals were also locally intruded by andesitic sills. The thermally metamorphosed
coals are of medium-volatile bituminous to meta-anthracite rank (high vitrinite
reflectance, VR up to 5.18%). r

The studied low rank coals are dominated by huminite (34.6 - 94.6 vol. %). Less
abundant are liptinite (4.0 - 61.4 vol. %) and inertinite (0.2 - 43.9 vol. %). Minerals are
found only in small amounts (0 - 2 vol. %); mostly as iron sulfide. In the high rank coal,
the thermally altered vitrinite composes 82.4 – 93.8 vol.%. Liptinite and inertinite are
observed only in very minor amount. Mosaic structures can be recognized as
groundmass and crack fillings. The most common minerals found are carbonates, pyrite
or marcasite and clay minerals. The latter consist of kaolinite in low rank coal and illite
and rectorite in high rank coal.

The coals outside the metamorphism area are characterized by high moisture content (4
- 11 wt.%) and volatile matter content (> 40 wt.%, daf), as well as less than 80 wt.%
(daf) carbon content. In contrast, the thermally metamorphosed coals are characterized
by low moisture content (only < 3 wt.%) and volatile matter content (< 24 wt.%, daf), as
well as high carbon content (>80 wt.%, daf).

Based on maceral assemblages, the low rank coals can be grouped into five classes: (1)
humotelinite-rich group, (2) humodetrinite-rich group, (3) humocollinite-rich group, (4)
inertinite-rich group and (5) humodetrinite-liptinite-rich group. Comparing the
distribution of maceral assemblages to the maceral or pre-maceral assemblages in
modern tropical domed peat in Indonesia reveals many similarities. The basal section of
the studied coal seams is represented typically by the humodetrinite-liptinite-rich group.
This section might be derived from sapric or fine hemic peat often occurring at the base vi Abstract
of modern peats. The middle section of the seams is characterized by humotelinite-rich
and humocollinite-rich groups. The precursors of these groups were hemic and fine
hemic peats. The top section of the coal seams is typically represented by the
humodetrinite-rich or inertinite-rich group. These groups are the counterparts of fibric
peat at the top of the modern peats. The sequence of maceral assemblages thus
represents the change of topogenous to ombrogenous peat and the development of a
raised peat bog.

A comparison between the result of detailed maceral assemblage analysis and the
paleodepositional environment as established from coal maceral ratio calculation
indicates that the use of coal maceral ratio diagrams developed for other coal deposits
fails to deduce paleo-peat development for these young tropical coals. In particular,
mineral distribution and composition should not be neglected in coal facies
interpretations.

The coalification path of each maceral shows that vitrinite, liptinite and inertinite
reflectance converge in a transition zone at VR of around 1.5%. Significant decrease max
of volatile matter occurs in the zone between 0.5 – 2.0% VR . A sharp bend occurs at max
VR between 2