Umrer Area is operated by Western Coalfields Limited (WCL), a Mini Ratna (Category-1) company and a wholly owned subsidiary of Coal India Limited (CIL), which is a Government of India undertaking.
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Summary:
Umrer Coalfield is one of the most prominent Coalfields located in Vidarbha region of Maharashtra. Occurrence of coal in this area was discovered in the late fifties.
For the convenience of exploration, the Makardhokra block was sub – divided into Makardhokra - I, II & III blocks. The eastern most part adjacent to Amb river was named as Makardhokra-II block and an underground mine namely Makardhokra-II UG was opened in this block.
Umrer-Butibori railway line passes through this block and the UG property in the south side of the railway line was subsequently converted into opencast mine and renamed as Makardhokra-II OC.
The proposed Mining Plan for Makardhokra-I Expansion OC mine has been envisaged in Makardhokra Mine-I geological block upto the floor of bottom-most Seam-I. This geological block lies in the western side of Makardhokra Mine-II block where Makardhokra-II OC Project has exhausted. A major fault separates Makardhokra Mine-I block from Makardhokra Mine-II block.
The details of the various formations encountered are as follows:
• Metamorphic Formation The Metamorphic Formation has been intersected in only one borehole (MUM59) drilled in the block where it is overlain by Kamthi Formation and is represented by mica schist. A maximum thickness of 2.47m of mica schist has been intersected in this borehole which is mainly composed of biotite & muscovite.
• Talchir Formation Talchir formation is represented by fine grained greenish sandstones and green splintery shales. It has been intersected in 8 boreholes drilled in this block. The greenish shales are arenaceous, micaceous or calcareous. The sandstones generally contain grains of undecomposed feldspar.
• Barakar Formation Exposures of Barakar formation have not been seen in this block. The Barakar formation overlies the Talchir formation with a graditional contact. The maximum thickness of this formation as intersected in borehole MR-9 is 217.35m.
Based on borehole data, the Barakar sequence has been divided into three characteristic lithounits. The Barakar formation occurring from Kamthi/Barakar contact to roof of Seam-VI and from floor of Seam-I to Barakar/Talchir contact have been named as Upper and Lower member respectively, whereas, the coal bearing strata occurring from Seam-VI to Seam-I is named as Middle member.
The Upper member comprises of mainly medium to coarse grained, grey to greenish white sandstones with subordinate carbonaceous and grey shales. The Middle member of the Barakar Formation shows development of coal seams and is characterized by an alternation of shales, sandstones and coal seams. The Lower member of the Barakar Formation is represented by fine to coarse grained greyish sandstones with interbands of grey and carbonaceous shales and a few thin coal bands. This unit is devoid of any workable coal seam.
The mineral composition of Barakar sandstones, as observed in borehole cores, constitute mainly of Quartz, Feldspar and Mica with occasional disseminations of Garnet and Pyrite. The cementing material is mainly kaolinised Feldspar and clay.
• Kamthi Formation The Kamthi formation rests over Barakar beds with distinct unconformity. The Kamthi rocks are represented by ferruginous sandstones and shales/clay. The sandstones display a reddish brown colour due to iron stains. The Kamthi formation is generally loose and friable. It is rich in quartz and kaolinised feldspar. In three boreholes (MR-39, 40 & 66) Kamthi Formation has not been intersected.
• Lameta Formation Lameta Formation occurs in the entire block overlapping Barakar/Kamthi formation. It is represented by calcareous sandstones and clays. Calcareous sandstones are generally arenaceous, gritty and cherty type, containing lumps of chert and jasper. Earthly greenish sandstones are common, whereas, clays which are usually sandy and red or green in colour. Occasionally, the rocks underlying the Deccan traps are found to be calcified. Associated minerals are calcite, aragonite, chert, jasper, quartz and feldspar. These sandstones are hard & compact in nature.
• Deccan Trap The Deccan Trap formation occupies the north-western part of the block. It is comprised of massive greenish to greyish black basalt. It is occasionally vesicular, filled with secondary materials. It has been intersected in 46 boreholes drilled in the block.
• Soil Almost the entire area of the block is covered by black cotton soil and occasionally by sandy & clayey, brown to reddish brown soil.
In Umrer Coalfield, three coal seams, designated as Top, Middle and Bottom, have been established in the coal column. The Bottom seam is split into 5 sections viz Sections A, B, C, D and E from bottom upwards. The Top and middle seams which attain good workable thickness have no split sections. In Makardhokra area, the same set of coal seams has developed but with increased parting between the seams. The seams in the block under report have been designated as Seam I, IIB, IIT, III, IV, V, VI from bottom upwards.
The thickness of coal seams along with their intervening partings is given in the following table. The thickness figures mentioned below pertain to only those boreholes where the seams and parting are not affected by fault /subcrop.