E-ISSN : 2541-5794 P-ISSN :2503-216X
Journal of Geoscience,
Engineering, Environm ent , and Technology
Vol 03 No 02 2018
94 Rajagukguk, Y.M & Nalendra, S. / JGEET Vol 03 No 02/2018
M acerals Analysis
Seam
M 2 M uaraenim Form ation, : Im plicat ion
t ow ard Coal Facies and Coal Rank In Kendi Hill , Sout h Sum at ra
Y.M Rajagukguk
1,*, S. Nalendra
11
Sriw ijaya University, Jl. Srijaya Negara, Bukit Besar, Ilir Barat I Kot a Palembang 30139
* Corresponding aut hor: yonat hanm angatur @yahoo.com
Received: 29 Apr 2018. Revi sed: 25 M ay 2018, Accept ed: 29 M ay 2018, Published: 1 June 2018 DOI: 10.24273/jgeet .2018.3.2.670
Abst ract
The M uaraenim Form at ion is a coal bearing form at ion in Sout h Sumat ra Basin of t he Lat e M iocene Pliocene. M uaraenim Form at ion based on coal seam cont ent is divided int o four seam , are: M 1, M 2, M 3 and M 4. Coal seam in t his area include in seam M 2 m em ber, w it h t he general charact erist ics of t he presence of sili cified coal on t he roof and floor of coal seam s as a m arker. The adm inist rat ion of t he research area is locat ed in east Kendi Hill, Sout h Sumat ra. The Kendi Hill is com posed of adesit e igneous rocks t hat int ruded M uaraenim Form at ion in unconform it y at t he t im e of Pleist ocene. This st udy aim s t o det erm ine t he environm ent of coal deposit ional based on m aceral analysis and det erm ine t he fact ors influence t he physical charact erist ics of coal seam s in Kendi Hill. Dat a t hat has been obt ained from t he field, t hen conduct ed a select ion pr ocess.The num ber of sam ples analyzed w ere nine sam ple based on near and far t o t he Kendi Hill spread from t he sout hern, cent r al , and nort hern of t he locat ion. The result of t he analysis w ill display t he m aceral diagram . M egascopically, coal seam in t he Kendi Hill are black, dull w it h bright , uneven subchoncoidal, blackish brow n in st reak, have a pyrit e and resin. The t hickness of t he coal seam s ranges from 0,45 t o 14 m et ers. Based on t he m aceral analysis, t he coal seam i n t he M uaraeni m Form at ion is com posed dom inat ed by vit rinit e, t hen lipt init e, inert init e and m ineral m at t er pyrit e (1,6-6,6%). Vit rinit e reflect ance of coal in t he research area ranges from (0,37-0,48%) t hat included t o t he Sub-bit um inous High Volat ile Bit um inous C. From t he result s of Tissue Preservat ion Index and Gelifi cat ion Index value indicat ed t hat t he coal facies in t he research area w as a lim nic t o w et forest sw am p. W hereas t he deposit ion of t he M uaraenim Form at ion in delt aic environm ent (Transit ional low er delt a plain).
Keyw ords: Coal, M aceral, M uaraenim Form at ion, Sout h Sumat ra Basin
1. Int r oduct i on
Indonesia is a count ry t hat has a lot of nat ural resources, one of w hich is a nat ural w ealt h in the field of energy is coal. In t he current st at e of coal in Indonesia has a variet y of physical charact erist ics of form at ion. According t o Horne (1978) the and Gelificat ion Index (GI). The role of t he m aceral is based on t he propert ies t hey possess, including t he nat ure of t he at t ribut e and scalar nat ure. Furt herm ore used t he W ard (1986) classificat ion t o know coal rank of t he research area based on t he vit rinit e reflect ance value (Rv) obt ained from t he laborat ory t est . The environm ent of coal deposit ional based on Horne (1978) and coal facies det erm ination t heory Diessel (1986) still used by
Prat am a and Am ijaya (2015) as reference for
det erm ining t he depositional environm ent and coal facies based on organic pet rographic analysis.
This research aim s t o det ermine t he environm ent of coal depositional based on m aceral analysis, det erm ine t he coal facies and coal rank in Kendi Hill and det erm ine t he factors influence physical charact erist ics of coal seam s in t he research area.
Rajagukguk, Y.M & Nalendra, S. / JGEET Vol 03 No 02/2018 95 Fig. 1. Locat ion m ap of research area.
The M uaraenim Form at ion conform ably overlaying w it h Airbenakat Form at ion t hat com posed of sandst one, sandy claystone, t uffaceous sandstone and m udst one w it h coal int ercalat ion (Heryant o, 2006). M uaraenim Form ation is a coal bearing form at ion in Sout h Sum at ra Basin of t he Lat e M iocene Pliocene. According t o Shell (1978), in ideal condit ion M uaraenim Form at ion is divided int o several m em bers, nam ely M 1, M 2, M 3, and M 4 (Fig. 2). M em ber of M 2 consist s of clay, carbonaceous clay, silt st one, clayst one, and coal. M 2 m em ber have t hree m ain layers; seam C (pet ai seam ), seam B (suban seam ), and seam A2 (M angus seam ). Pet ai seam is t he low er lim it on seam M 2 w hich has t he charact erist ics of t he availabilit y of silicified coal on t he floor. Suban seam bet w een t he pet ai seam and m angus seam , w hich has a t hi ck enough silicified coal on t he floor. M angus seam is t he upper lim it on seam M 2 w hich has t he charact erist ics of t he availabilit y of silicified coal on t he t op seam .
The unit of t he young volcano (Kendi Hill) is one of t he int rusions of igneous rocks locat ed in t he research area of Pleist ocene. The int rusion is formed on t he surface because of t he flow of m agm a derived from shallow dome t hat causes uplift, fault , and fold (Fig. 3) (Amijaya and Lit t ke, 2006).
96 Rajagukguk, Y.M & Nalendra, S. / JGEET Vol 03 No 02/2018 Fig. 3. Geological m ap and geological sect ion of t he
M uaraenim area (M odified from Bam co, 1983; Gafoer et all., 1986 on Am i jaya and Lit t le 2006).
3. M et hods
The research used descript ive-observat ive m et hods, used consist ed of lit erat ure st udy, field observat ion in t he from of m easured section t o know geom et ry, lit hology, sediment st ruct ure and physical description coal seam . The m et hod used in sam pling is channel sam pling, t aking represent at ive of coal seam from floor t o roof t hen mixed int o one research area w ere t hree sam ples represent ing each coal seam . The sam ple of coal t aken is distinguished by near and far from Kendi Hill. Sam ples locat ed near Kendi Hill are nort h coal sam ples and t hose far from Kendi Hill are sout hern coal sam ples.
The m et hod of m aceral analysis on coal, t ool used is point counter t o ident ify and calculat e the num ber of m acerals, t hen ray reflect ion m icroscope funct ion t o know t he t ype of m aceral and m ineral Based on t he result s of t he analysis, t he deposit ional environm ent , coal facies, and coal rank of the research area can be det erm ined by t he consist ing of m aceral cont ent and vit rinit e reflect ance.
4. Resul t and Di scussi on
4.1 Deposi t i onal Envi r onm ent Seam M 2, M uar aeni m For m at i on i n Kendi Hi l l
Based on environm ent analysis of coal deposit ion, M uaraenim Form at ion is included int o t he Transit ional Low er Delt a Plain (Fig. 4). According t o t his model, t he Transit ional Low er Delt a Plain depositional environm ent is com posed of repet it ion lit hology (from bot tom t o t op) from roof seam C (pet ai) t o floor seam A2 (M angus) is coal, clayst one, sandst one layer, silt st one, sandst one, clayst one, and coal seam .
Lit hology on research area consist ing of clayst one, silt st one, and sandst one w it h parallel lam inae carbonaceous, indicat ed sediment ary coal bearing on seam M 2 found vert ically in t he
Fig. 4. Coal deposit ional environm ent on Seam M2 based on Horne (1978).
Rajagukguk, Y.M & Nalendra, S. / JGEET Vol 03 No 02/2018 97 Telocolinit e + Desmocollinit e), Ti (Telocollinit e: Fusinit e + Semifusinite + Sclerotinite).
The recalculat ion result s are plot ed int o t he facies diagram Tissue Preservat ion Index (TPI) versus Gelificat ion Index (GI). The coal seam M 2 in t he research area ot t he sout hern, cent ral, and varying prices of Tissue Preservat ion Index (TPI) in indicated changes in plant com posit ion and peat t ype in t he research area likely due t o changes in deposit ion environm ent . Tissue Preservat ion Index (TPI) value >1indicat es t he high percent age of the presence of w ood plant s show n by t he presence of abundant t elocollinit e m aceral, w hile t he Tissue Preservat ion Index (TPI) value <1 indicat es m aceral derived from herbaceous plant s. Based on Gelificat ion Index (GI) on seam M 2 show s relat ively high value ranges from (3,31-8,42%) indicating t hat t he oxidat ion process does not t ake place predom inant ly, w hich is show n by t he low inert inite cont ent (Table 2). Diessel diagram result s show t hat coal seam M 2 in M uaraeni m Form at ion is form ed in t he range Low er Delt a Plain t o Upper Delt a Plain. The Low er Delt a Plain environm ent is spread in lim nic st ages dom inat ed by shrubs. W hile t he Upper Delt a Plain environm ent is form ed at t he w et forest sw am p st age, it has a relat ively high Tissue Preservat ion Index (TPI) value and is dom inat ed by t elocollinite. For Low er Delt a Plain environm ent show ed low Tissue Preservat ion Index value and Gelificat ion value w it h predom inant ly desm ocoli nit e m aceral st ill affect ed by seaw at er (Fig. 7). This is evident from t he presence of pyrit e m inerals (1,6-6,6%) in t he seam M 2 M uaraeni m Form at ion indicat ing t hat t he deposit ion of coal in t he research area is influenced by rising sea levels (Fig. 8).
Table 1. Result and descript ion of coal seam M2, M uaraenim Form at ion, in Kendi Hill based on m aceral analysis
Not e : BB = Coal V = Vit rinit e F=Fusinit e
Telovit rinit e + Teloinert init e
Det rovit rinit e + Gelovit rinit e + Inert odit rinit e + Geloinert init e
GI =
Vit rinit e + Geloinert init e
98 Rajagukguk, Y.M & Nalendra, S. / JGEET Vol 03 No 02/2018
Fig. 5. Seam M 2 st rat igraphy colum n (no scale) w it h coal deposit ed on Transit ional Low er Delt a Plain based on Horne, 1978.
SEAM C
SEAM B
SEAM A2
Rajagukguk, Y.M & Nalendra, S. / JGEET Vol 03 No 02/2018 99 M eanw hile, t he value of vit rinit e reflect ance of
coal in t he research area ranges from (0,37-0,48%) t hat included t o t he Sub-bit um inous High Volat ile Bit um inous C (Table 3). High percent age of vit rinit e reflect ance value in seam M 2 is inseparable from t he influence of int rusion igneous rocks in Kendi Hill, w hich caused t he coal seam s in t he nort hern part higher t han t he coal seam s in t he cent ral and sout hern part ranged from (0,44-0,48%), w hile the average value of vit rinit e reflect ance at t he cent er is (0,37-0,47%) and in t he sout hern is (0,42-0,45%) (Table 2).
4.2 Coal char act er i st ics, seam M 2 M uar aenim For m at ion i n Kendi Hi l
The coal out crop in t he research area is found around Kendi Hill, in M uaraenim Form at ion, Sout h Sum at ra as coal-bearing form at ion in t he research area. Coal geom et ry at t he research area is influenced by t he int rusion of kendi Hill, so t hat the coal seam has a st rike t hat follow s kendi Hill shape and dip a relat ively erect. Coal dist ribut ion at the research area is relat ive Nort h W est t o Sout h East and Nort h t o Sout h (Fig. 9).
Fig. 6. The presence of pyrit e and resin in coal seam M2 Coal charact erist ics in Kendi Hill m egascopically are black, dull w it h bright , uneven subchoncoidal, blackish brow n in st reak, have a pyrit e and resin. The t hickness of t he coal seam s ranges from 0,45 t o 14 m et ers, w hich consist s of seam C = 5-8m eters, seam B = 11-14m et ers, and seam A2 = 6-7m et ers. The m ain charact erist ics of t he m ain seam is seen from t he presence of im purit y coating on each seam in t he form of silicified coal. Charact erist ics of seam C is t he exist ence of silicified coal on t he floor, on
seam b t he exist ence of silicified coal on t he floor, and seam A2 t he exist ence of silicified coal on t he roof (Table 4). Physically t he seam C is m ore com pact t han seam B and seam A2. That because seam C is in a zone closer t o t he int rusion of andesit e in Kendi Hill so t hat t he seam C coal layer has bet t er qualit y and rank t han seam B and seam A2.
Fig. 7. TPI and GI Diagram s in research area.
Fig. 8. Pyrit e associat ed w it h t elocollinit e and sem ifusinit e associat ed w it h desm ocollinit e, reflect ance w hit e li ght 500x.
Pyrite
100 Rajagukguk, Y.M & Nalendra, S. / JGEET Vol 03 No 02/2018 Table 2. Coal rank classificat ion according t o vit rinit e reflect ance m axim um
NO ZONE SAM PLE
CODE
Ti ssue Preservat i on Index (TPI)
Gel i fi cat i on Index (GI)
M ean Refl et an ce Vi t ri ni t e (Rv %) 1
NORTH
YR-AU 0,35 5,13 0,44
2 YR-BU 0,56 5,38 0,46
3 YR-CU 0,52 4,02 0,48
4
CENTER
YR-AM 0,4 8,42 0,41
5 YR-BM 0,99 3,31 0,37
6 YR-CM 1,27 4,62 0,47
7
SOUTH
YR-AS 1,07 4,36 0,43
8 YR-BS 0,82 3,97 0,42
9 YR-CS 1,43 3,65 0,45
Table 3. Coal rank classificat ion according t o vit rinit e reflect ance m axim um .
RANK M AXIM UM REFLECTANCE
(%Rv m ax)
Subbit om inous <0.47
High Volat ile Bit um inous C <0.47 <0.51
High Volat ile Bit um inous B 0.51 0.71
High Volat ile Bit um inous A 0.71 1.10
M edium Volat ile Bit um inous 1.10 1.50
Low Vilat ile Bit um inous 1.50 2.05
Sem i - ant rachit e 2.05 3.0 (approx)
Ant rachit e > 3.0
Table 4. Descript ion of coal charact erist ics seam M2.
Param et er l ayer Seam A2 Seam B Seam C
St rike/Dip N3350
E/670
N3340 E/700
N3250 E/750
Thickness 6 7 m 11 14 m 5 8 m
Colour Black Black Black
Lust er Vit rain Vit rain Vit rain
Cleavage Uneven - Subchoncoidal Uneven - Subchoncoidal Uneven - Subchoncoidal
St reak Black his brow n Blackish brow n Black
Roof Silicified coal - -
Rajagukguk, Y.M & Nalendra, S. / JGEET Vol 03 No 02/2018 101 Fig. 9. M ap of dist ribut ion pat t ern of coal layer of research area
5. Concl usi ons
Based on t his research, it can be concluded as follow s:
1. The sediment ary environm ent and coal bearing form at ion in Seam M 2 M uaraenim Form ation in Kendi Hill, Sout h Sum at ra based on m easured st rat igraphic cross sect ion are Transit ional Low er Delt a Plain w it h sub-environm ent crevasse spays, sw am p,and dist ribut ary channel.
2. Based on t he result of m aceral analysis and diagram s Tissue Preservat ion Index and Gelificat ion Index Diessel conduct ed on nine sam ples of coal, it is suggest ed t hat t he deposit ion environm ent of coal in t he research area is t ranst ion of Lim nic (Low er Delt a Plain) t o w et forest sw am p (Upper Delt a Plain), w it h m aceral com position consist s of vit rinit e (69-82,6%), liptinite (0,6-5,6%), inert inite (9,8-20,8%) and m ineral m at t er pyrit e (1,6-6,6%). Organic m at erials t hat develop in research area dom inat ed by plant s of shrubs and w ood plant s w it h t ype m aceral t elocollinite and desm ocolinit e.
3. The value of vit rinit e reflect ance coal in research area ranged from (0,37-0,48%) t hat included to t he Sub-bit uminous High Volat ile Bit um inous C. The closer t o int rusion andesite Kendi Hill t he vit rinit e refl ect ance is higher
(nort hern, 0,44-0,48%) t han t hat of coal aw ay from t he int rusion zone (cent er, 0,37-0,47% and sout hern, 0,42-0,45).
4. Coal charact erist ics Kendi Hill, seam M 2 M uaraenim Form at ion are black, dull w it h bright , uneven subchoncoidal, blackish brow n in st reak, have a pyrit e and resin w it h The t hickness of t he coal seam s ranges from 0,45 t o 14 m et ers.
Acknow l edgm ent
Acknow ledgment t ribut e t o PT. Prim a M ulia Sarana Sejaht era w ho has perm it t ed researcher, t hen t hanks t o t he aut hors addressed t o t he field supervisor M r. Lulu Sishandi and M r. Fat hulah Hayyan Assy Ari w ho have provided input and inform at ion.
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