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Peat deposits of the Muara Siran, East Kalimantan area, were investigated for their vertical and lateral succession, to examine the characteristic variability, particularly its macro- and microtextures. The deposits are situated in the Kutai Basin, in the vicinity of several Cenozoic coal deposits. Peat samples were taken from twenty-seven coring sites in the area, using a MacCaulay peat corer. The Muara Siran peatlands lie between the Kedang Kepala and Belayan Rivers. Siran Lake lies between these rivers and within the peat system. The peat thickness varied from 0.5 m to 12 m. Decomposed sapric peat formed the basal and margins of the deposit, overlain by moderatelydecomposed hemic peat in the central part of the peatlands, though both sapric and hemic peat types are interbedded at the margins of the mire. The fibric peat types were found mostly at the top of the mire and only distal from any active streams. Twenty-four samples of peat were freeze-dried for petrographic analyses of both plant part and maceral analyses using a reflected microscope. On the average, the dominant plant parts were stems and wood (i.e. secondary xylem). Maceral composition was mostly from the huminite group (on the average 89%), particularly the macerals humodetrinite and textinite. Macroscopic peat type and microscopic composition are linked. Fibric peat was found to be rich in wood and textinite. Hemic was mostly composed of stems and wood with textinite and humodetrinite as the most abundant macerals. Sapric peat has near equal proportions of stems, wood, and macerated tissue. Humodetrinite is the most abundant maceral in sapric. The average ash and sulfur content were low, 1.29 wt.% and 0.11 wt.%, respectively. Understanding the physical characteristics of inland peat as in Muara Siran peatland is essential to build knowledge of how inland peat is formed and what makes it different from coastal peat. Muara Siran is a unique, relatively small peatland in the central eastern Kalimantan which is still considerably pristine, hence may serve the aim of this study well. [ABSTRACT FROM AUTHOR]

Fifteen samples were taken ply by ply from a 33 m thick drill core of Muara Wahau coal seams for interpretation of depositional environments. Generally, lithotype variation in the bottom part of the coal seams has a lower frequency than in the upper part. Petrographical analysis was performed to determine the maceral composition, groundwater index (GWI), and gelification index (GI). The samples from lower sections show much higher GWI-GI values and lower variation frequency than from the upper section. This characteristic is interpreted as the result of development of mesotrophic to ombrotrophic peats during the deposition of lower to upper parts of the section, respectively. During the development of the mesotrophic peat, water was more abundant and relatively stable in budget. However, during the development of ombrotrophic peat, water was less abundant and relatively not stable in budget. The latter is related to the water supply depending only on rain, resulted in the more sensitive water table in the ombrotrophic peat. The unstable water table is thought as the reason of higher variation frequency of lithotype, GWI, GI, as well as maceral composition in the upper part of the core. Unstable water table would lead to moist condition in the uppermost layer of the ombrotrophic peat, favoring fungi to grow. This is confirmed by the higher abundance of sclerotinite maceral in samples from the upper part of the coal core. [ABSTRACT FROM AUTHOR]

Abstract: The present study describes vertical variations in lithotypeand petrographic composition of a Miocene lignite bearing succescion from the Upper Kutai Basin, East Kalimantan. Twenty four lignite samples from two drill holes at Ritan area were callected. Ritan''s lignite have been analyzed Based on the lithotype analysis, the Ritan''s lignite show variations in the predominance of some macerals that macroscopically and microscopically to asses the characteristics and depositional environment of the lignite present. indicating succesion of inveronmental changes. Macroscopically the dominanlithotype are banded dull, followed by dull, and parting impregnated within the lignite seam. Microscopically the dominant maceral group are huminite present in moderate to high value (27,9-78,7%) while the minor one is inertinite group showing a low value (6,5 12,2%), followed by low to moderate value of liptinite (19,9 31,5%). Reflectance measured on the maceralhuminite range from 0,235 to 0,354% placing the Ritan coals into a transition stage from peat to lignite. Examiniation of lihotype variation and the distribution macerals constituent suggest a Miocene lignite as marsh to upper delta plain depositional setting. [Copyright &y& Elsevier]

Abstract: The present paper entails the petrographic characterization on limited coal samples drawn from the Tarakan basin, Eastern Kalimantan, Indonesia. These coals contain a high concentration of huminite which, in turn, is dominated by telohuminite. As a result of telohuminite content they have high GI and TPI values. They contain, low concentrations of liptinite and inertinite macerals. The dominant microlithotype is vitrite. Based on the macerals and microlithotypes of these coals, their paleodepositional environment has been reconstructed. Accordingly it is deciphered that these coals have originated under telmatic condition. There was predominance of wood derived tissues and increased subsidence rate prevailed in the basin. Moreover, during the time of their evolution, there were alternate phases of oxic and anoxic moor conditions with intermittent moderate to high flooding in the basin. [Copyright &y& Elsevier]