C.4. Executive Summary
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C.4. Executive Summary Lasarda-Pacheri manganese ore block is located in the north western part of the Horse- shoe shaped Precambrian Bonai-Kendujhar belt (Plate - II). The belt, extending for 60 km length in NNE-SSW trend with width of 25 km, occupying parts of Sundargarh and Kendujhar districts (73 F/8, 73 G/1 and G/5) in North Odisha has a unique position in the mineral resources map accounting for huge resources of iron and manganese. Exploration for manganese in the block was carried out by Geological Survey of India, Eastern Region, State unit: Odisha, Bhubaneswar for assessment of resource potential during the FS 2001-02 to 2004-05. The exploration work includes detailed geological mapping on 1:2000 scale, pitting/trenching followed by exploratory drilling. The exploration block is enclosed by Lat 2203’26” Long: 8517’34”(bottom SW corner), 2203’7.2”: 8518’28.9” (bottom SE corner), 2203’44.7”:8518’51.8” &2203’41.5”:8518’58.4” (Central eastern corner), 2204’11.5”:8519’16” (north eastern corner), 2204’26.3”:8518’46.9” (north western corner), 2203’57”:8518’27.5” & 2204’3”:8518’15.5” (Central western corner) in Survey of India toposheet no. 73 F/8. The total block area is 2.57 sq km and out of 2.57 sq km area, the total mineralised area covers 1.679 sq km and non-mineralised area occupies 0.891 sq km. The rock types in the area include BHJ / BHQ, chert, shale of different colouration, tuff, dolomite, mafic volcanics and laterite, both ferruginous and manganiferous varieties. All these lithounits belong to the Koira Group of the Iron ore Super Group. Manganese mineralisation is confined to the brecciated chert, manganiferous shale and laterite. The area forms part of a NNE plunging synclinorium having southerly closure. The mapped area has imprints of two pervasive planer fabrics, one conforming to the regional fold axis (NNE – SSW) and the other in NW - SE direction. The explored area constitutes a part of the western inverted limb of the “horse-shoe synclinorium”, the inverted nature being manifested by the reverse order of superposition of the lithounits. The chief planar structural elements are bedding and axial plane cleavage while minor fold axes and bedding – cleavage intersections are the main linear structures observed in the area. Development of weak foliation in shale is quite conspicuous. Manganese ore bodies occur as conformable but discontinuous bands and/or lensoidal bodies within shale and brecciated chert horizons, extending along the regional strike of the lithounits. In the top laterite, ore bodies occur in form of discreet isolated pockets. The width of ore bodies vary from 1m to 8m. The ore bands are mostly affected by weathering to a considerable depth along with the enclosing rocks. Localisation of ore lenses / pockets within the chert – shale – laterite zone / horizon may be attributed to the geochemical segregation associated with the process of deep chemical weathering and subsequent lateritisation. Further, occurrences 1 of manganese ore zones associated with brecciated chert and along weak foliation planes of shale point to the process of shearing and brecciation undergone in the area. The ore is lateritoid type at most of the places and is of low to medium grade. The chief manganese minerals are pyrolusite, psilomelane, lithiophorite, and cryptomelane. Botryoidal, box work and colloform structures are commonly observed within the ore. The ore is, in general steel grey to dull grey in colour and is soft and powdery in nature. Phosphorous content in the Mn ores does not show much variation lying in the range of 0.1% to 0.23% which is well within the permissible limit of different end use specifications for various industries. A total of 85 vertical boreholes were drilled on a square grid of 100m X 100m in the Lasarda-Pacheri block for a total drilling meterage of 4852.2m (37 in Lasarda sub-block and 48 in Pacheri sub-block), with collection of 634 drill core samples from the ore zones for chemical analysis. A resource of 7.86 million tonnes of saleable grade Mn ore with average content of 26.16% Mn has been estimated at 20% Mn cut-off, based on the exploration works carried out in Lasarda and Pacheri blocks. In addition, resources of 1.59 million tonnes of marginal (15% - 20% Mn) grade ores have also been estimated. In addition, resources of 1.71million tonnes of marginal (10% - 15% Mn) grade ores have also been estimated. Thus, the total resources of Lasarda-Pacheri block is 11.16 million tonnes with average grade of 22.72 % Mn at 10% Mn cut-off. The block wise ore:overburden ratio as calculated comes to 1:8.33 and 1:4.16 respectively for Lasarda and Pacheri sub-blocks for the +20% Mn ore zones.. The manganese ore of the explored blocks is found to be suitable as blast furnace feed of Iron and Steel industry. This report pertains to G3 stage exploration and the exploration work is coming under 333 in UNFC Classification. C.5. INTRODUCTION Exploration for manganese in Lasarda-Pacheri block in the north western part of the horse-shoe Bonai-Kendujhar belt was carried out by Geological Survey of India, Eastern Region, State unit: Odisha, Bhubaneswar for assessment of resource potential. The exploration work includes detailed geological mapping on 1:2000 scale, pitting/trenching followed by exploratory drilling. Different segments of this well known mineral belt were systematically mapped at various times by eminent geologists namely H. C. Jones (F.S. 1918–19), M.S. Krishnan, (F.S. 1925–27), B.C. Gupta (F.S. 1939–41), B. Gupta, (F.S. 1939–40) and B.K. Seth, (F.S. 1957– 59). 2 Large Scale Mapping, pitting & trenching, geochemical sampling carried out during FS 1999-2000 in the north western part of the belt brought to light several promising area of manganese mineralisation. Subsequently, one drill rig was deployed during F.S. 2000 - 2001 to carry out test drilling in these demarcated areas. Following the favourable exploration results obtained during this field season, detailed exploration by means of detailed geological mapping (1:2000 scale), pitting/trenching and drilling on grid pattern was taken up in Lasarda-Pacheri block for resource assessment during the F.S. 2001-02 to FS 2004-05. The quantum of exploration work accomplished in this block includes 2.57 sq. km. of detailed mapping on 1: 2000 scale, 18 cu. m. pitting & trenching with collection of 31 nos. pit/trench samples, 4852.20 m exploratory drilling with collection of 634 nos. of drill core samples, chemical analysis of pit, trench and core samples, identification of ore zones and resource estimation at cut-off grade of 20% Mn and 15% Mn. C.6. BLOCK DESCRIPTION C.6.1. Location The proposed block to be auctioned occupies an area of 2.57 sq km, out of which the mineralised area covers 1.679 sq km and non-mineralised area occupies 0.891 sq km. It falls in parts of Survey of India Toposheet Nos. 73 F/8, as per Survey of India Open Series Map and is bounded by Lat 2203’26” Long: 8517’34”(bottom SW corner), 2203’7.2”: 8518’28.9” (bottom SE corner), 2203’44.7”:8518’51.8” &2203’41.5”:8518’58.4” (Central eastern corner), 2204’11.5”:8519’16” (north eastern corner), 2204’26.3”:8518’46.9” (north western corner), 2203’57”:8518’27.5” & 2204’3”:8518’15.5” (Central western corner) . It forms north western part of Bonai - Kendujhar belt, in the northern part of Odisha bordering Jharkhand. The belt extends for about 60 km in a NNE – SSW direction with a width of about 25 km and is well known as “Horse-Shoe Synclinorium” in the geological literature. Being one of the most important iron and manganese mining centers of Odisha, the area is well communicated with other parts of the State as well as with the neighbouring State of Jharkhand both by rail and road. C.6.2. Accessibility Lasarda is situated at a distance of about 8 km south of Barbil, a Tehsil and Industrial town of Kendujhar district. Barbil is situated at a distance of 300 km from State Capital Bhubaneswar and lies on National Highway 215 connecting Panikoili with Rajamunda and further beyond with the industrial town of Rourkela at a distance of 150 km from Barbil. Panikoili in turn is situated on National Highway - 5 connecting Kolkata with Chennai. 3 Barbil is the Railway terminus of the Tatanagar - Barbil section of the South Eastern Railway. C.6.3. Physiography and Drainage The area exhibits a rugged topography and is dissected by first, second and third order streams. Karo river flowing from south to north serves as the main drainage channel of the area. The influence of lithology on the evolution of topography is well exemplified. The Banded Iron Formation being more resistant stand out conspicuously forming high ridges, thereby defining the Horse Shoe configuration of the belt whereas the flanking volcanics and shale, in most parts are lateritised and form low plateaus and valleys occupying the central part of the belt in the elevation range of 450m to 600m with an average altitude of around 550m. The topography in and around Lasarda-Pacheri block represents the intervening valley lying between the western NNE-SSW trending BIF ridges and the eastern conspicuously rising Siddhamath Pahar. C.6.4. Climate The climate of this belt is sub-tropical with temperature rising to a maximum of 45C in summer and falling down to a low of 5C in the winter, the average day temperature being 23C during the months of December to February.