Development of Funginite on Muaraenim and Lower Members of Telisa Formations at Central Sumatra Basin - Indonesia

Petrography analysis of coal is the study organic and inorganic components of coal bearing formations. This research conducted observation method under microscopic of thin incision to identify organic maseral group. The organic composition of coal from Muaraenim Formation is known to average for vitrinite maseral group 79.30%, inertinite 10%, liptinite 3.4%, and non-organic 7.3%. While the composition of coal from the Bottom Members of Telisa Formation for the average of vitrinite maseral group 66.4%, mineral matter 30.32%, inertinite 3.26%. The liptinite maseral group is not present as a coal component in the study area. The funginite development of the Muaraenim Formation is quite abundant 2.8% indicating peat swamp ecosystem in wet-dry conditions in ph 3 -5. In contrast, the development of funginite Lower Members of Telisa Formation is known to be absent which is replaced by the presence of frambiodal pyrite and indicates peat ecosystem in wet conditions at ph 6 - 7.

Funginite / Sclerotinite as coal component influenced many geological characteristics including sw am p forest ecosystems during the decomposition of organic matter takes place.. Funginite / Sclerotinite is an organic component of coal origin (Tertiary) Sclorentinite (Paleogene). In Tertiary coals, a variety of forms are present as sclerotinite; sclerotia (resting spores), teleutospores, mycorrhizomes (symbiotic associations of fungal tissue w ith higher plant roots) and stromata/fungal fruiting bodies - Ruiz et al., 2012).
This study w ill be discussed in more detail w ith respect to the developm ent funginite /Sclorentinite on tertiary coal deposits (M ember of the Low er Telisa and M uaraenim Formation).

Geologi cal Set t i ng
The research area has the tect onic fram ew ork of Sumatra w hich located at the Central Sumatra Basin. Regional Geology of research area is based on the Geological Research and Developm ent Cent er, Bandung detail at the Geological M ap of Rengat sheets (Suw arna, Budhitrisna, 1994) and Geological M ap of Solok Sheet of Low er M embers of Telisa Formation (Silitonga, PH & Kastow o, 1994). The M uara Enim Formation as a coal carrier formation has characteristic ripple structure composed of clastic sedimentary material in the form of fine clays of lignite coal insertion w hich precipitated the phase of regresion at the end of the M iocene. Whereas the Low er M embers of the Telisa Formation have characteristic of intercalation betw een the shale and very fine sand of subbituminous coal type A lenses deposited on maximum transgression phase at t he Beginning to M id Miocene (Barber and Crow , 2005) Regional Geological M aps on research location are show n in Fig. 1.  The method for this research, starting w ith crushed the coal sam ples int o a maximum size of 1 mm and placed in resin blocks. The sam ple blocks w ere polished w ith a specified polisher. M icroscopic investigation w as carried out w ith a Carl Zeiss M icroscope and Point Counter M odel F w as conduct ed to determine the micro-organic components of coal ( fig. 2). During maceral analysis, 500 points w ith a minimum distance of huminite particles under oil immersion. Fifty points of huminite reflectance w ere made on each sam ple.

Fig 2. Carl Zeiss M icroscope and Point Counter M odel F w ith 500 x magnification
The sam ple selection in this research uses "channel sam pling" method from selected ideal coal sam ples as w ell as represent ing research area. The sam ple selection also bases on quality and quantity to meet the standard of test fixation. Treat sam ples from coal bodies, less likely to avoid direct oxidation in a long time to keep capillary moisture as w ell as coal surface. The sam ple sampling preparation for microscopic observation w as taken from the sam ple to be analyzed, then crushed until it passed the 1 mm filter and carried out the division so as to obtain 15 gram representative sam ples for petrographic analysis. The 1 mm sam ple is mixed w ith epoxy / transsoptic pow der resin, printed in rectangular or rounded mold. After hard the surface is rubbed w ith a 600, 800 and 1200 emery paper, then polished to obtain a smooth coal surface for petrographic analysis. The maseral analysis is performed under a microscope using the immersion oil on the surface of the sam ple. This analysis uses 25x, 32x, 50x or even 60x lenses and an automatic 0.4 mm transverse counting machine and 0.5 mm vertical. Approximately 500 points w ere observed excluding visible resins and minerals. M aseral can be observed or counted as a group of maseral or as sub-maseral. In performing a duplicate analysis of 3% difference for each accepted maseral. The reflection measurements are performed on the surface of vitrinite particles, in monochromatic green light, w avelength 546 mm. All equipm ent should be lit at least half an hour before calibration. To measure maximum reflection, the polarizzer is set in position 45O. Next turn the 360O microscope and do the reading. To measure this reflection the lens used is high magnification (50 or 60x) and should be placed right in the middle. The readings are r epeated from 50 to 100 readings (Petrology, 2011).

Result and Di scussi on
In general, the main organic composition of coal is dominated by vitrinite group w hich is the main ingredient of w ood and bark tissue. While inertinite, liptinite and mineral matter groups may be higher or low er than others.
The composition of the coal mine The M uaraenim formation is know n to average for vitrinite maseral group 79.30%, inertinite 10%, liptinite 3.4%, and non-organic 7.3%. While the composition of coal Coal M embers Bottom Line Telisa for the average of vitrinite maseral group 66.4%, mineral matter 30.32%, inertinite 3.26%. The liptinite maseral group is not present as a coal component in the study area. The coal coal composition is given in tables 1 and 2. The developm ent of funginite maseral from the inertinite maseral group, is know n to spread quite abundantly and is colonial am ong fusinite thin w all cells berkw ok turm eric w hite to yellow ish.
The developm ent of funginite from M uaraenim Formation coal is given in 3a and 3b. In general, the developm ent of funginite can be caused by surface moisture or capillary of a material betw een w et and dry or ph 3 -5. Coal Formation M uaraenim based on the calculation of maseral composition obtained facies of limnic deposits that turn into limnotelmatic in the atm osphere of the sw am p ecosystem is poor w ill supply w ater / Ombrhotropic mires (Prayitno, 2016a) Such a condition allow s the w at er supply or surface line to the peat layer to vary according to the supply or rainfall during peat decomposition.
The condition of peat sw am ps that rely solely on w ater supply from rainfed can ultimately lead t o the developm ent of bacterial as an important component responsible for the decomposition process of organic matter to be disrupted, in this case w ill have an effect on the effectiveness of decomposition of organic matter. M oreover, the topographic changes from the limnine to the limnotelmatic conditions influence the groundw ater level limit to be low er than t he surface layer or peat layer, so that the peat layer is more w et to dry (Anggayana et al., 2014).
The developm ent of funginite maseral is not only influenced by local factors such as w ater supply, ph value, depth of peat layer to w ater surface, also determined by more global tectonic motion such as basal decline and sea level change, in this case succession of sedimentation Sediment materials are affected by transgression or regression conditions. In contrast to the M uaraenim Formation deposited in the regression phase, w hich causes the ineffectiveness of the decomposition and gelification process of peat materials, the Low er M embers of Telisa Formation are precipitated at the peak phase of transgression. Coal on Low er M embers Telisa Formation based on calculation of organic maseral composition obtained facies of limnic deposition in an atm osphere rich in w ater supply / rheotrophic mire (Prayitno, 2016b) Table 2. Rheotrophic M ires is a peat sw am p that has a w ater supply from tw o sources. First supali w ater that comes from rain-fed, usually the volume increases w ith the rainy season. Both come from ground w ater w hich is a process of infiltration through rock pores or rock fractures. During the dry season, this type of peat sw am p is possible still in w et conditions. Developm ent of funginite Low er M embers Telisa Formation based on microscopic observation is know n not present as a coal-forming component.
Peat sw am ps in the rheotropic mire atmosphere allow the peat layer t o be alw ays w ell below t he w ater surface and in ph 6 -8 This causes the developm ent of funginite can not develop properly. How ever, the mineral matter content of mineral pyrite is quite abundant to form the fram biodal pyrite structure w hich indicates the average surface w ater far above the peat surface. Abundance of mineral matter Coal M embers Bottom Line of Telisa Formation is given in the Fig 4.a.b.c.
Thus the relationship betw een funginite developm ent and mineral matter abundance may be inversely proportional. The formation of pyrite minerals can be as syngenetic pyrite or epigenetic pyrite. The abundance of mineral matter in the form of syngenetic pyrite and funginite developm ent can be attributed to the basic active basin motion in a certain period so that local and regional tectonic factors can be an important factor for the developm ent of both.

Conclusi ons
The developm ent of funginite locally can be influenced by chemical, biological and chemical conditions of settling environment. While the global factor is more determined by the basin motion. The developm ent of funginite and mineral matter in a deposition period can indicate certain climatic conditions at the time of deposition.
funder. And also PPPTekmira-Bandung, w hich also supports parties involved in this research.