MAKUM COAL FIELDPresented byMridusmita Borah Shalini Barua. Tarangini Sonowal INTRODUCTION: The Makum Coal field is the best developed coal field in Assam. The coal measures extend over as length of 29 km and nearly 4.8 kms in width,over an area of nearly 30 sq kms. The field lies between the latitudes 27 15 and 27 25 N and longitudes 95 40 to 95 55 E towards the northeastern fringe of Dibrugarh District adjacent to Margherita town. Though the coal measures run from the Dirak river in the West upto the hair-pin bend of the Tirap river in the east and biyond,the productive parts lie between the Namdang and the Tipongpani rivers containing the Namdang,Baragolai ,Ledo,Tirap and Tipong collieries owned by Assam Railway and Trading Company. The massive Tipam Sandstone is well exposed in the area and the Dihing boulder and pebble bed is found in the Dihing river bed at Margherita.Geology of the Area: The area is mainly composed of Tertiary to Quarternary rocks. Surmas are almost absent in the area. Barail sediments in Upper Assam show maximum development with thick coal seams which is within the Tikak Parbat Formation and overlies conformably the Disang Group of Eocene age. The Dihing Group rests unconformably over the Tipam Sandstone and Alluvium and high level terraces also found in this area . .alluviums and thick highly carbonaceous sediments. Eocene Barail Group Tikak Parbat(475m) Boragolai(300m) Nagaon(2400m) FORMATION Pliocene Eocene Disang Group(over 3000m thick) .The stratigraphic subdivision of the coalfield area are given below: AGE Recent and Pleistocene GROUP Alluvium and high level terrace UNCONFORMITY Dihing Group UNCONFORMITY Middle Miocene Tipam Sandstone UNCONFORMITY Oligocene to U. . The contact between this Group and the overlying Barail Group is Gradational. The beds are highly folded and the sedimentary structures are seldom seen here.The members of this group are seen in the sections of the Khasi Hills and Tirap rivers and in the southern part of the coalfield. .NAOGAON SANDSTONE FORMATION: Mallet (1876) included this in the Disang Group.grey and well bedded sandstone and the thickness is about 2400 metres.but now its believed to be the oldest formation of the Barail Group which rests conformably over the Disang Shales.against which override the rocks of the Baragolai and Tikak Parbat Formations. The formation is consisting of hard. The quartzitic sandstone are well exposed towards the south east of the Namdang Colliery and the outcrops are confined to the south of the HaflongDisang thrust. BARAGOLAI FORMATION: This.5 m to 0.but nowhere in the area under investigation the seams attain workable thickness. A number of coal seams.varying in thickness from 0.along with the Upper Tikak Parbat Formation.8 m has been traced in the Baragolai Formation. . The Baragolai Formation consists of alternating sandstone and shales which sometimes may be of carbonaceous nature.was grouped originally into µthe Coal Measure Sub-series¶by Mallet which later designated by Evans as µCoal Measures¶. . The basal part of the formation contains all the five workable coal seams. It comprises medium to fine grained tough quartzose sandstone.mudstone and carbonaceous shales.clays. This formation shows maximum development of coal seams in Upper Assam.well bedded sandy shales. The sandstones are pink in colour and shales are highly carbonaceous which exhibit very good leaf impressions and also rich in pyrite.TIKAK PARBAT FORMATION: Thinest formation of the Barail Group and rests over the Baragolai Formation which is the main coal bearing formation. TIPAM GROUP: In this area only the lowermost part of Tipam Group is exposed and the beds cover a wide area in the central and south-eastern part of the coalfield. Bluish-green and greenish coloured sandy shales. Silicified and semi-carbonised wood and lignitic material are also seen at places in the sandstones. . The sandstones and conglomerate beds consist of numerous rounded pebbles of quartz and jasper. Pebbly sandstones and thin conglomerate beds .shaly sandstones and clays occur at places which attributed to the presence of chlorite. The sandstones are current bedded and sometimes form high cliffs and water falls.coarse grained feldspathic sandstones constitute the sequence found here. The group consists of alternate pebble beds and loose. . The sandstones.coarse.which are at places ferruginous. In most of the places the rocks are concealed under alluvium and high level terraces.on weathering turn brownish and the pebbles are mostly of quartzitic sandstones.greyish to greenish feldspathic sandstones.DIHING GROUP: Outcrops of the Dihing Group are small and isolated along the base of the foot-hills in between the eastern extremity of the abandoned Tirap quarry and Lekhapani to the west and Tirap river in the north. . Twenty-seven particulate pellets were prepared and studied on Leitz MPV-1 and MPV-3 units under normal reflected light and reflected blue light excitation. Additional samples were used wherever a thick clean coal section was encountered . .Material And Method of Makum Coal Field: Twenty seven representative samples were prepared after crushing all the 112 samples collected from freshly exposed mine and quarry faces in Namdang. Baragolai. Ledo-Tirap and Tipong collieries. Individual samples thus prepared represent a seam section. This type of coal is taken as good coking coal and high swelling index. . So. for manufacturing metallurgical coke 10-15% . Makum coal is mixed with coking coals of Tharria.Chemical Characteristics: The coal seams of Makum Coalfield show a lower rank by their high volatile matter & fixed carbon contents whereas on the basis of their low moisture content and high calorific value a higher rank can be assigned. The Makum coals are low in ash content but sulphur content is higher . 5%) . Seam no. higher fixed carbon and calorific value.seam no.1 differs from seam no.3 has highest total sulphur content amongst five main coal seams in the coalfield.3-5. On the basis of overall proximate chemical data of coal seam 1 and 3 appear to be identical.3 in having lower ash and sulphur contents. The abnormality in rank in relation to chemical properties of these coals has been attributed to their high sulphur content. On analysis they show 81.9%) and low oxygen (8. Total sulphur content in all the five coal seams vary widely without any trend both laterally and vertically. relatively high hydrogen (5.6 to 83.0 per cent carbon. The coal is blocky in nature. Tiny pyrites specks are frequent in the coal. . It breaks with subconchoidal to conchoidal fracture. devoid of any perceptible lithotype banding and are entirely made up of vitrain ( Mishra.Megascopic Character: The Tertiary coal seams of Assam. in general those of the Makum coalfield are jet black in color with vitreous lustre. because of two sets of fracture planes and crumbles easily on separation from the seam.1981) . Microscopic Character: under normal incident light: The Makum coal seam is rich in collinite. They show spongy or granular texture.6%) & semifusinite plus fusinite (0. Desmocollinite and telocollinite are highly gelified. The liptinite macerals are in subordinate amount (5.3%) & sporinite (0.1%) & telocollinite plus minor amount of telinite (20.5-9. The associated inorganics (4.0-9. inertodetrinite (1. concretionary calcite (0.6-9.5%) mainly consisting of resinite (2.8%) .4%).49. The coal seam nos.0-32.1-7.5%) are chiefly formed by sclerotinite (2.4 %).8%).1 & 3 are rich in desmocollinite (30.1-20. Low to moderate proportion of inertinite macerals (9.4%).0%) and clastic minerals-clay and quartz (1.4-12.5-6.2.0-47.0%).9.9-6. 8-63.9-22.0%) are low to moderate in amount in both the seams.Under blue light excitation: Coal seams nos.6%) of which 41. . The Makum coal field of tertiary coals of northeast India have fluorescence properties of various macerals.5 per cent is formed by per hydrous vitrinite. Non-fluorescing vitrinite and inertinite macerals together (10. 1 & 3 of Makum coalfield have high productions of fluorescing macerals (78.4-88. The closure of the syncline being at Namdang.plunging towards north-east. known as ³Ledo Anticline´ .the rocks of Barail and Tipam have overridden the younger Dihing Group. At Ledo the limb is again folded into an anticline.is referred to as the ³Namdang Syncline´. The Namdang Syncline is bounded on the north and south by two large thrusts-the northern one being the ³Margherita Thrust´ and Southern being the ³Halflong-Disang Thrust´ In Northern part of the coalfield. The northern limit of the syncline extends in a North-easterly direction from Namdang to Ledo.STRUCTURE The Makum coalfield area represents a well defined asymmetrical syncline. In the Southern part of the area the beds of Nagaon sandstone override the rocks of the Barail Group along Halflong-Disang thrust. . In its adjoining tikak colliery area the seams have a maximum thickness of20.there are 5 regionally persistent coal seams.58 . This seam is exposed in the bed of the Namdang river near the Namdang mines and is folded into a syncline with a plunge towards ENE.while further west in the Boragolai mines area it is 11. The thickness of the seam is 10.8m.COAL SEAMS From Namdang colliery in the west to the Tipong colliery in the east. 60 ft seam : This is the thickeast and most important seam of the Makum coalfield and serves as datum for correlation of other coal seams. 1. These are confined to basal 200m section of the Tikak Parbat Formation. All these seams contain bands of clays or shales.8m. 53m It has been worked only in the Boragolai colliery and an equivalent has been met in the Ledo colliery area. Exposures are not continuous.16-2. .5m Outcrops rare. Has variable thickness-thickening and thinning within short distances in Tipong area.2. Thickness varies from-1. 4.Ledo and old Tirap mines. Crops out in Ledo and Tirap collieries.3 to 1.Tikak. 20ft seam: This seam has been worked in all collieries. 5ft seam: Worked in the Boragolai. New seam: Thickness-2. 3. . QUALITY: Makum coal is of good quality with low ash content and high C. . Outcrops not found Recognised in abandoned seams.5.I Coal being subjected to tectonic disturbances is pulverised at places. 8ft seam: Worked in Boragolai. 8ft seam being impersistent is not considered for calculation of reserves. Tikak and old Tirap collieries. initiated deltaic sedimentation in Nagaland. Isolated backwater bodies or lagoons paralleling the shoreline on the prograding delta complex served as sites for peat accumulation.lagoonal and fluviatile.swampy. . coinciding with regression of sea during Oligocene epoch. Eastern parts of Assam and South-Eastern Arunachal Pradesh.GENESIS Geological informations on the coal bearing sediments of Tikak Parbat and Boragolai Formations of Barail Group indicates that rising of Himalayas. DEPOSITIONAL ENVIRONMENT: The wide spectrum of lithofacies and their frequent lateral and vertical variations reflect a sequence of depositional environments varying from shallow marine. GSI . References: Basant K.Misra Coal fields of North eastern India. Presence of arenaceous foraminifera and formation water salinity indicate that the sediments of Barail Group were deposited under brackish water mileau.