The age,palaeoclimate, palaeovegetation,coal seam architecture/mire types,paleodepositional environments and thermal maturity of syn-collision paralic coal from Mukah,Sarawak, Malaysia |
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| Institution: | 1. School of Science and the Environment, Manchester Metropolitan University, John Dalton Extension Building, Chester Street, Manchester M1 5GD UK;2. Geography, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4RJ, UK;3. School of Earth & Environmental Sciences, James Cook University, Queensland 4811, Australia;1. Academy of Scientific and Innovative Research (AcSIR), CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, India;2. CSIR- National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, India;1. Department of Palynology and Climate Dynamics, Albrecht-von-Haller-Institute for Plant Sciences, Georg-August-University of Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany;2. J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August-University of Göttingen, Berliner Straße 28, 37073 Göttingen, Germany;3. Department of Soil Science, University of Jambi, Jalan Raya Jambi Muara Bulian KM 15 Mandalo Darat, 36361 Jambi, Sumatra, Indonesia;4. Department of Soil Science and Land Resource, Bogor Agriculture University (IPB), Jalan Meranti, IPB Campus, Darmaga, Bogor, Java, Indonesia;1. Laboratoire GET, CNRS UMR 5563, Université Paul Sabatier, OMP, 14 Avenue Edouard Belin, 31400 Toulouse, France;2. Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2207 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada;3. Geological Survey of Canada, 1500-605 Robson Street, Vancouver, British Columbia V6B 5J3, Canada;4. Department of Palaeontology, Geological Faculty, Saratov State University, 83 Astrakhanskaya Str., 400012 Saratov, Russia;5. Paleontological Institute, Russian Academy of Sciences, 123 Profsoyuznaya Ul., 117997 Moscow, Russia;6. Geological Institute, Russian Academy of Sciences, 7 Pyzhevsky Lane, 119017 Moscow, Russia;7. Muséum National d''Histoire Naturelle, 25 Rue Munster, 2160 Luxembourg, Luxembourg;8. Institut für Geologie, Leibniz Universität Hannover, Callinstr. 30, D-30167 Hannover, Germany;9. The Natural History Museum of Denmark, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark;10. Laboratoire Biogéosciences, CNRS UMR 6282, Université de Bourgogne, 6 Bd Gabriel, 21000 Dijon, France;11. Laboratoire IDES, CNRS UMR 8148, Université Paris Sud XI, 91405 Orsay, France;12. Ifremer, Unité de Recherche Géosciences Marines, 29280 Plouzané, France |
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| Abstract: | The Mukah coal accumulated in the Balingian Formation where the time-stratigraphic position is poorly defined by fauna, though a probable Late Miocene age has always been assigned to this formation. Samples collected in the present study that yielded an abundance of Casuarina pollen associated with occurrences of Dacrydium, Stenochlaena palustris, Florschuetzia levipoli and also Stenochlaena areolaris spores, compare closely to zone PR9 of the palynological zonation of the Malay Basin, and can be tied to depositional sequences of Malay Basin Seismic sequences I2000/I3000, indicating an Early Miocene age for the studied coal. The Early Miocene age shows that the Mukah coal was formed during the collision between Luconia Block–Dangerous Grounds with the Borneo that lasted from Late Eocene to late Early Miocene. The rapid increase of deposition base-level caused by the collision is clearly reflected by the architecture of the Mukah coal seams that were generally thin, and also by the reverse order of the paleo-peat bodies.The studied coal samples contained large amounts of detrohuminite without the enrichment of liptinite group macerals, usually explained by the dominance of herbaceous plants in the paleomires. However, the pollen assemblages recovered in the present study provide no support for a ‘herbaceous’ swamp, instead the peats were likely formed mainly from forest vegetation based on the recovery of dominant arboreal pollen assemblages in the present study. Palynomorph assemblages recovered in the present study, with abundance of Casuarina pollen associated with common occurrences of Dacrydium, strongly suggest Kerangas vegetation and Kerapah type peat swamps, indicating a very wet climate. The occurrence of rattan and Pandanus pollens shows that the kerapah type peat swamps were locally bordered by rattan and Pandanus swamps. This shows that the prevailing use of coal petrography to discern the type of vegetation that was present in the peat-forming mires may lead to wrong conclusions. Therefore, a multi-disciplinary approach must be applied for a more accurate and reliable spatial interpretation of the type of vegetation that was present in the peat-forming mires.Consistent with the low sulphur content, evidence from the palynomorph assemblages recovered from the coal seams shows that the coal-forming peat was deposited in freshwater mires with little or no marine influence, despite the fact that the accumulation of the Mukah coal-forming peat took place within a coastal plain setting. Moreover, the fauna present in the host rock formation also suggested a brackish-water environment of deposition. |
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| Keywords: | Kerapah swamps Ombrotrophic Rheotrophic |
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