Introduction:Bhalukona – Jamnidih Block (BJB) is situated in the state of Chhattisgarh. BJB is part of NeoArchaean Sonakhan Greenstone Belt of Bastar Craton. Geological Survey of India has carried out preliminary exploration in this block and identified sulphide bearing mafic-ultamafic intrusive rock with anomalous Ni, Pt and Pd values. This block is considered to have very high potential for Ni-PGE-Cr-Cu.
License: DGM Chattisgarh has placed BJB for auction, which covers an area of 30 sq.km. Deccan Gold Mines Limited (DGML), in an effort to diversify into battery / multimetal deposit exploration and mining, has participated in the bidding. DGML had received the official intimation from the Government of Chhattisgarh that the has been selected as the “Preferred Bidder” in respect of Bhalukona-Jamnidih Ni, Cr and Associated PGE Block in Chhattisgarh on the basis of the eauction conducted by MSTC on March 6, 2023. DGML is anticipating to receive the composite block soon. The ‘Composite License’, once granted provides seamless transition from exploration to mining.
Geology and Mineralization: The Bhalukona-Jamnidih block forms a part of Neo-archean Sonakhan Schist Belt in the NE fringe of Bastar Craton. The Sonakhan Belt contains wide spectrum of volcano-volcanoclastic rocks of Sonakhan and Bilari Group, mafic- ultramafic intrusives, undeformed granitoids, younger dykes and quartz veins. The rocks of Sonakhan Group are represented by talc-Cholrite schist, chlorite schist, tremolite schist, meta-olivine websterite and meta-agglomerate. These rocks are disconformably overlain by acidic rocks of Bilari Groups.
The rocks of Bilari Group represent mostly porphyritic/non-porphyritic rhyolite and rhyolitic breccias. These volcano-volcanoclastic sequences have been intruded by large mafic-ultramafic magma of largely gabbro, anorthositic gabbro and pyroxenitic composition. The mafic ultramafic suites have been further intruded by undeformed granitoids of Dongargarh Group and subsequently by younger dykes, quartz and epidote veins. In the study area the mineralization is very irregular and disseminated in nature.
Primary sulphides occurring in the form of disseminated pyrite, arsenopyrite and chalcopyrite observed in freshly broken surface of pyroxenite and gabbro and in meta ultramafites. Mineralisation is occurring mainly in the form of blebs and dissemination of sulphides in pyroxenite and gabbro variants. Mineralology/ petrography from the block need to be explore further as the mineralization is disseminated.
Disseminated submicroscopic and microscopic sulphide grains are present in quartzo-feldspathic veins, acid volcanic, gabbros, pyroxinite and metapelitic schist mainly of chalcopyrite, pyrrhotite and pyrite.
Exploration: GSI has carried out preliminary exploration including, geological mapping, geochemical surveys and trenching. These surveys has shown the presence of intrusive mafic ultamafic complex with sulphides. Geochemical sampling has shown anomalous Ni and PGE values. Samples collected from Chiprikona area seems to be encouraging for Ni –PGE mineralization as one highly altered pyroxenite body of nearly 400m in strike length and 50m in width have yielded high Pd (1174ppb), Pt (241ppb) and Ni (0.16%) values. Also sample SBJ/PGE-23 shows high Pd (123ppb), Pt (42ppb) and Au (67ppb) values in the southern part of Chiprikona.
In Bhalukona-Jamnidih block, total 26 cu. m. of pitting/trenching was carried out to understand the subsurface behaviour of rock under the soil cover and the contact relationship between the Pyroxenite and Gabbroic and metabasic rock. Trenching was done across the regional strike of the rock. Total 6 number of trenches were prepared in Bhalukona-Jamnidih block namely SBJ/T/1, 2, 3, 6, 9 and 10.
The average length, breadth and depth of the individual trench was taken as SBJ/T/1: 5x1x1, SBJ/T/2: 5x1x1, SBJ/T/3: 5x1x1, SBJ/T/6: 5x1x1, SBJ/T/9: 4x1x1, SBJ/T/10: 2x1x1 and a total of 26 no. of pitting/trenching samples were collected. The average value of Cu is 528ppm and Co is 94ppm in trench SBJ/T/1. The average value of Ni is 392ppm in SBJ/T/2, 655ppm in SBJ/T/10 and 372ppm in SBJ/T/6. The average value of Cr is 264ppm in SBJ/T/2, 520ppm in SBJ/T/10 and 502ppm in SBJ/T/6.
Summary: Available data shows that BJB block has very high potential for sulphide – bearing Ni-Cu-PGE mineralization. DGML plans to carryout detailed geophysical surveys and drilling.