By Abdi Suprayitno

Coal is a complex solid object, consisting of various elements representing many chemical components, most of them are derived from the remains of plants, consisting of various fibers which consists of multiple cells. By Thiessen (1947)

Coal is a solid object is composed by carbonaceous macerals. This definition include all the coal from various degrees of coal (coal rank) that begins from peat, lignite, sub-bituminous coal, bituminous coal, semi-anthracite, anthracite and meta-anthracite. By Spackman (1958)

Coal is a combustible sedimentary rock, formed by the remains of plants in varying levels of preservation, followed by the process of compacting and buried in the shallow basins. As soon as the barrier layer down constantly, the buried remain plant is influenced by temperature and pressure process. By The International Hand Book of Coal Petrography (1963)

Coal is a combustible sedimentary rock, derived from plants (mainly contain of carbon, hydrogen, and oxygen), brown to black, since depositional exposed to chemical and physical processes result the enrichment of carbon content. Wolf (1984)

Coal is sediment, organoclastic in nature, composed of lithified plant remains, which has distinction as combustible material. By Thomas (2002)

Geotectonic Position

Paleotopografi

Geographical Position

Climate

Flora / Plants

Decomposition

Basin Subsidence

Geological Time

Post-Depositional Process

Organics Changing

Geotectonic Position

Climate

Basin geometry

Sediment supply

Accommodation space

Flora type

Paleotopografi

Basin geometry

Swampy area are formed

Geographical Position

Climate

Groundwater surface

Sea water abration

Climate

Plants growing

Tropical wet climate can build bright coal

Neither in the pole earth

Flora

Specify the kind of flora/plants

Decomposition

Determine bacteria decompose the plants

Basin Subsidence

Subsidence and plant accumulation are in balance,

produce thick coal

If Subsidence < accumulation : plant will decompose

with air

Id Subsidence > accumulation : thin coal, plants are

not grown up well

Geological Time

Produce good coal, if buried with thick sediment

Except coal is intruded by intrusions, high rank coal

Post-Depositional Process

Effect the quality of coal, such as structure, intrusion,

erotion

Organic Changing

Biochemistry

Geochemistry

Biochemical Process

Present aerobe and anaerobe bacteria

Plants (cellulose) Glucose Gas and Water

Aerobe bac.

Water

Aerobe bac.

Air

Pea

t

Anaerobe

bac.

Deeper

Biochemical Process

Vitrinisation

Fusinitisation

Peat characteristic :

Brown to black

> 75 % water content

< 60 % carbon content

Shown the origin plants

Can cut by a knife

Porous like sponge

Geochemical Process (physicochemical stage)

Peat LigniteBituminous Anthracite

Pressure + temperature + time

Peat accumulation (coal 1 ft) :Lignite : 160 years

Bituminous : 260 years

Anthracite : 490 years

Temperature :200 deg C : > 10 million years

150 deg C : > 50 million years

100 deg C : > 200 million years

50 – 60 deg C : Never be formed

Coal Rank control factors :

Original coal rank

Intrusion and structure

Pressure

Temperature

Disturbing type and its period

Autochthonous Coal (In situ)Seat earth presentRoot is perpendicular with

beds or seamClean coal (low ash)Steady swampWide spread coalHomogenous thicknessPresent fine grained quartz

sandstoneGood forming macerals

Allochthonous Coal (Drift)No seat earthNo perpendicular rootVary quality and thicknessDeltaic formationSharp contact with above

sedimentMarine environmentPresent Coal ballsSpotting coal spreadingHigh ashPresent macerals and

minerals

• Continental• Fluvial• Desert• Lacustrine• Glacial

• Marginal-marine / shoreline• beach / barrier island• estuarine / lagoonal• tidal flat

• Marine• neritic• oceanic

Lacustrine system

It can be formed by fault, rifting; landslide; crater

explosion then collapse; fluvial activity.

Insitu and drift coal

River

Fluvial Flood Basin

Fluvial Flood Basin

Deltaic system

River enter the ocean

Sediment supply rapid than distribution to basin

Insitu and drift coal

Lagoonal and barrier island system

Consist of sandy barrier island; the lagoon; channel

crossed the barrier to the open sea

Insitu and drift coal

Regressive marine

TPI (Tissue

Preservation

Indices) & GI

(Gelification)

TPI indicates

where the peat

was decomposed

GI indicates wetter

condition

Most of coal is formed in coastal area (Diessel,

1984)

Refer to Horne (1978) in coastal area :

Back Barrier : thin coal, spread along the strike, layering, high S.

Lower delta plain : thin coal, vary in S content , along the channel, splitting

Transitional lower delta plain : thick coal, low S, splitting, washout

Upper delta plain - fluvial : thick coal, low S, pod shaped, splitting

First period

Lower Carbon to Permian

North America and Europe

Second Period

Lower Cretaceous to Tertiary

Coal

Third Period

Quaternary

Peat

Paleogene

Ombilin (West

Sumatera)

Bayah (West java)

Pasir (East Kalimantan)

Sebuku (South

Kalimantan)

Melawai (West

Kalimantan)

Neogene

Warukin and Dohor

(South Kalimantan)

Pamaluan, Pulaubalang,

Balikpapan dan

Kampung Baru (East

Kalimantan)