Singhbhum Nucleus - Chiria, Joda, Malangtoli, Bolani, Thakurani, Khandadhar, Tildah, Gandhamardan
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Major iron ore deposits are distributed over a 200 x 100 km area of the Meso- to Neoarchaen Singbhum Nucleus in the northern part the state of Orissa and southern Jharkhand, north-eastern India, approximately 250 km WSW of Kolkata (Calcutta). These deposits are clustered in a number of districts (as described below), specifically the largest in the Keonjhar-Sundergarh-Monoharpur area in both Orissa and Jharkhand (including the deposits at Keonjhar - Joda East, Noamundi, Bolani, Thakurani, Bhadrasahi, Seremnda, Katamati, Khandbandh, Jilling, Joribahal, Jajang, Malangtoli, Mankarnacha, Balda, Palsa, Sakradihi; Sundergarh - Barsua, Kalta, Tildah, Badamgarhpahar, Baliapathar, Dandrahar, Khandadhar, Basada, Diringburu, Mithurda, Patraposi; Monoharpur - Chiria, Kiriburu, Megahatuburu/Meghtaburu, Balkundi, Langlota, Kasia, Gua, Noamundi, Barapada, Koira, Roida, Khandabour, Jindal, Orghat, San-Indupur, Jorrudi, Deojhar, Gonua, Nuagoan, Patabeda, Raikela, Jorani.) and the less extensive Mayurbhanj (the Gorumahisani, Sulaipat, Badampahar deposits), Gandhamardhan (the Gandhamardan deposit) and Nausahi-Nilgiri (the Daitari, Tomka deposits) districts in Orissa.
The 280 x 200 km, east-west elongated Singbhum Nucleus occupies the southern corner of the approximately 600 x 600 km Singhbhum Craton in north-eastern India. The Singhbhum Craton is bounded to the south-west by the Sukinda Thrust and coincident margin of the NW-SE trending Mahanadi graben; to the north-west by the Namada-Son lineament; to the north and east by the alluvial cover of the Indo-Gangetic and the Garo-Rajmahal plateau basalts; and the Bay of Bengal coast to the south-east.
The northern two thirds of the craton is occupied by the Chotanagpur Terrane of gneisses and granites, comrising an upward sequence of Meso-to Neoarchaean orthogneiss, late Paleoproterozoic gabbro and anorthosite and Mesoproterozoic syn- to late- and post-tectonic granites and gneisses.
The Chotanagpur terrane is separated from the Singbhum Nucleus by the 50 km wide, curvilinear Singbhum-Dhalbhum Mobile Belt which, from west to east changes trend from NE to east to ESE. Its southern margin is defined by the major, 200 km long, 1 to 25 km wide, north-dipping Singhbhum Thrust, while the less intense Dalma Thrust zone forms its northern margin. The Singhbhum thrust contains mafic and ultramafic intrusives and is beleived to have been active intermittently from 2.3 Ga, with the major activity at around 1.6 Ga. The sequence within the mobile belt compsises the Neoarchaean Singhbhum Group, composed of mica schists, quartzose schists and granulites, chloritic schists and orth- and para-amphibolites, the latter after mafic and ultramafic volcanics. This group is unconformably overlain by the Dalma volcanic suite of mafic to ultramafic rocks of ophiolitic association, grading from tholeiitic, alkaline basalts, andesites and komatiites interbedded with tuffs and sediments in the lower sections to high-Mg vitric tuffs and komatiitic pyroclastics and an upper succession of high-Fe, low-K pillowed tholeiite. The Dalma volcanic suite is overlain by the Gangpur Formation, noted for its manganese silicate (gondites) units. It was followed by the 1.6 Ma Chakradharpur granite.
The Singbhum Nucleus was largely stabilised by 2.9 Ga and comprises that section of the Singbhum craton south of the Singbhum thrust and north of the major, south dipping Sukinda thrust. It is composed of a series of supracrustal rocks which have been intruded by the large Singbhum granite batholith (2.9 to 3.0 Ga) which is around 80 km wide and extends from the Sukinda thrust in the south to the Singbhum thrust in the north. The Singhbhum Granite Complex comprises 12 separate domal or sheet like, arcuate magmatic bodies emplaced in three successive, but closely related phases is composed of quartz monzonites to granites. Several smaller satellite granites are found to the east and west, although some of these are believed to be younger. The whole granite complex covers an area of 10 000 sq. km and contains relics of the oldest gniesses in the nucleus - the 'Older Metamorphic Group' (OMG) which have been dated at 3.8 Ga. The OMG comprises medium grained mica schists, quartzites, calc-silicates and para- and ortho-amphibolites, and were last heated at 3.4 Ga. These rocks appear to have been metasomatically modified to migmatites and tonalite/trondhjemite gneisses as enclaves within, and locally adjacent to the Singhbhum granite.
The OMG is unconformably followed by the 'Iron Ore Group' (IOG) which hosts all of the iron deposits of the nucleus. It is found in four main areas or structural remnants (corresponding to the districts listed above), namely the:
i). Naumandi Basin, which comprises a major NNE plunging synclinorium with steeply dipping limbs which covers an area of approximately 125 x 30 km. This structure is truncated by the Singhbhum Thrust to the north, and is terminated by the Bonai granite batholith to the south-west which is possibly younger than the main Singhbhum granite. Iron deposits are distributed along both limbs of this structure, forming ridges that are up to 750 to 900 m asl. The eastern limb is known as the Keonjhar district, the western limb the Sundergarh district, while Monoharpur is in the northen part of the structure in Jharkhand State and includes the continuation of both limbs. The iron formations within this basin have been subjected to three deformations. D1 folding is generally inclined to reclined with axes plunging 20° N to NNE. These axes are in turn deforemed by upright, asymmetric open F2 folds along axes parallel to F1, plunging NNE to NE. The third pulse, F3, trends E-W producing a series of canoe faults through their interaction with F2.
The IOG sequence in the Naumandi Basin can be summarised as follows, from the base:
- Unconformity with the underlying Older Gneiss Group;
- Sandstones and conglomerates;
- Mafic lavas with interbedded tuffs and minor siliciclastic sediments;
- Lower shales;
- Banded hematite jasper (BHJ) or banded hematite quartzite (BHQ) and ferruginous shales that hosts main ore deposits;
- Upper shales and volcanics.
ii). Gandhamardhan area where a sliver of IOG occurs along the western margin of the Singhbhum granite, around 30 to 40 km SSE of the Naumandi Basin, hosts the deposit of the same name. The IOG is represented by a greenschist facies sequence of basal meta-pelites, followed by meta-volcanics, banded iron formation, upper meta-pelites and volcanic rocks and conglomeratic quartzite.
iii). Nausahi-Nilgiri Basin which occurs in an embayment on the south-western margin of the Singhbhum granite, another 30 km further south than the Gandhamardhan area. The IOG sequence is more complicated in this area, where it comprises six sequences. The lower sequence resembles the IOG succession, commencing with mica and chlorite schists, quartzites with interbedded hornblende schists and amphibolites interpreted to be meta-volcanics. The second sequence contains ferruginous meta-sediments (mainly after shales) with a siliceous upper section, including black banded chert, jasper and quartzite. The third has an unconformity at its base and comprises conglomerates, sandstones, shales and slates with mafic volcanic flows and tuffs in the upper part. The fourth is composed of shales and banded hematite jasper rock unconformably overlying the third sequence. The fifth is made up of clastics rocks and the sixth lies unconformably above with clastics and a transition to calcareous schists and siliceous limestone at the top.
iv). Mayurbhanj (or Gorumahisani) basin on northern half of the eastern margin of the Singhbhum granite where lenticular bodies of hematite with subordinate magnetite/grunerite are common, as are quartz vein iron occurrences between intrusive masses of granite and charnockite rocks, although banded iron formations are also present. This basin is intruded by both the Singhbhum Batholith on its western margin, and by the 1000 sq. km, 1.2 Ga, Mayurbhanj Granite which intrudes the Singhbhum Granite and is composed of three phase, a fine grained granophyric granite, coarse grained granite and a small biotitic aplogranite.
Correlation between these areas is uncertain, based only on stratigraphic similarities. The interpreted IOG occurs as a narrow, sinuous band of metavolcanics and ferruginous quartzites and includes some massive-magnetite mineralisation with 47 to 57% Fe and 14 to 25% TiO2 and 0.59 to 4.8% V2O5 at Kumhardhobi.
Over the northern quarter of the nucleus, extensive developments of dominantly metavolcanic lavas, the 1.7 to 1.6 Ga Dhanjori suite/Jagannathpura lavas, overlie the IOG. These have been correlated with the Dalma volcanic suite of the Singbhum-Dhalbhum Mobile Belt and are overlain in the same area by the little deformed Kolhan suite composed of basal conglomerate, followed by mature quartzites, limestone and shale deposited between 1.6 and 1.5 Ga.
The IOG has also been invaded by a number of ultramafic complexes of varying sizes, particularly in association with the Sukinda and Singhbhum thrusts. The widespread 1.5 to 1.0 Ga New Dolerite dykes cut almost all rocks of the nucleus.
To the east of the Singhbhum Granite complex and south of the Mayurbhanj Basin, a circular development of 2.1 Ga aged tuffs, lavas and sediments (quartzites, arkoses and ferruginous shales) overlies older supracrustal rocks, with alkaline and related intrusions near the margins, including gabbro, anorthosite, granophyres, riebeckite granite and pyroxene granites, while a thick differentiated sill (base of dunite grading up to dolerite) occurs in the centre of the structure.
The principal ores of the IOG are associated with banded hematite quartzite (BHQ), banded hematite jasper (BHJ) and banded & ferruginous shales. with grades ranging from 55 to 69% Fe. The ores commonly contain steel grey hematite as hard, compact, fine grained ores as well as soft and powdery varieties.
Three erosional surfaces have been recognised in the region, namely: i). Upper Jurassic to Lower Cretaceous; ii). Upper Eocene; and iii). Upper Miocene.
Lateritic ore is dominant in some mines, while massive supergene, canga, brecciated hematite and blue dust are all worked. Hematite is the principal ore mineral.
Manganese is also produced from supergene enriched manganiferous shales that occur within the IOG
Published reserve and resource figures include:
5.428 Gt @ >60% Fe (Total reserves in Orissa, 2005, Govt of Orissa);
3.5 Gt @ >60% Fe (Total reserves in Jharkand, 2005, Govt of Jharkand);
1.7 Gt @ >60% Fe (Total reserves in the Chiria deposit, 2005, Govt of Jharkand);
2.33 Gt @ >60% Fe (Total reserves in the Keonjhar district, 2000, Govt of Orissa);
0.74 Gt @ >60% Fe (Total reserves in the Sundergarh district, 2000, Govt of Orissa);
42 Mt @ >60% Fe (Total reserves Daitiri & Tomka deposits, 2000, Govt of Orissa);
250 Mt @ >60% Fe (Total reserves Gandhamardan, 2000, Govt of Orissa);
553 Mt @ 60% Fe (Proved reserve, Malangtoli, Krishnaswamy & Sinha, 1988);
355 Mt @ 61% Fe (Reserve, Bolani, Krishnaswamy & Sinha, 1988);
250 Mt @ 64% Fe (Reserve, Thakurani, Krishnaswamy & Sinha, 1988);
120 Mt @ 62% Fe (Proved reserve, Kiriburu, Krishnaswamy & Sinha, 1988);
100 Mt @ 64% Fe (Reserve, Joda East, Krishnaswamy & Sinha, 1988);
65 Mt @ 65% Fe (Reserve, Jilling & Longlata, Krishnaswamy & Sinha, 1988);
116 Mt @ 58 to 60% Fe (Reserve, Barsua, Krishnaswamy & Sinha, 1988);
200 Mt @ 61 to 62% Fe (Reserve, Khandadhar deposits, Krishnaswamy & Sinha, 1988);
322 Mt @ 63% Fe, 0.03% S, 0.09%P (Total reserve, Naomundi, 1973);
116 Mt @ 59% Fe (Proved reserve, Dandrahar deposits, Krishnaswamy & Sinha, 1988);
227 Mt @ 61% Fe (Reserve, Tildah, Krishnaswamy & Sinha, 1988);
50 Mt @ 62% Fe (Reserve, Kalta, Krishnaswamy & Sinha, 1988);
50 Mt @ 61.5% Fe (Reserve, Daitari, Krishnaswamy & Sinha, 1988);
44 Mt @ >60% Fe (Remaining reserve, Kiriburu, SAIL, 2006);
26 Mt @ >60% Fe (Remaining reserve, Megahatuburu, SAIL, 2006);
Production from Orissa in 2004-05 amounted to 46 Mt of ore.
The most recent source geological information used to prepare this summary was dated: 2006.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
Beukes N J, Mukhopadhyay J and Gutzmer J, 2008 - Genesis of High-Grade Iron Ores of the Archean Iron Ore Group around Noamundi, India: in Econ. Geol. v.103 pp. 365-386|
Bhattacharya, H.N., Chakraborty, I. and Ghosh, K.K., 2007 - Geochemistry of some banded iron-formations of the Archean supracrustals, Jharkhand-Orissa region, India: in Journal of Earth System Sciences v.116 pp. 245-259|
Ghosh G and Mukhopadhyay J, 2007 - Reappraisal of the structure of the Western Iron Ore Group, Singhbhum craton, eastern India: Implications for the exploration of BIF-hosted iron ore deposits: in Gondwana Research v12 pp 525-532|
Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.
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