2D Electrical Resistivity Imaging survey to delineate sub-surface granitic body in an asset near Deeri Village, Rajasthan
Country: India Region: Pali, Rajasthan Period: 2014-16 Commodity: Pink Granite
Finding blockable pink granite deposit in areas where the body in hidden under soil cover often pose a risk until the extensions of the deposit is known. Drilling verification shall not always suffice for a tangible understanding of the sub-surface behaviour of the granitic body & influence of fractures affecting blockability of the body. Such notions of risk can be avoided if an 2D image of the sub-surface section could be generated which would be helpful is discerning in-crop depth, availability of hard rock & fractures affecting the body.
2D Electrical Resistivity Imaging was undertaken to cover an area of about 40 hectare of land surface in as many as 08 different alignments with a cumulative of 1400 Line meters. Interpretations of the resistivity sections could then be utilised to create a surface map indicating extensions of the hard rock at moderate & shallow depth, so are the gully portions within the hard rock profile.
The program resulted in successfully delineating extension of the deposit to high accuracy levels resulting in opening up of several pits in the area which would earlier have scanty information on the sub-surface behaviour of the deposit; also assisted in planning opening of the pits avoiding the gully area and weak rock. 2D ERI emerged out to be a powerful prospecting tool to generate images of the sub-surface based on which efficient & quick decisions could be taken.
Geophysical prospecting to delineate granite body behaviour & physical state in sub-surface in prospects around Pali, Rajasthan
Country: India Region: Pali, Rajasthan Period: 2019 Commodity: Granite
The program was aimed at deciphering physical state of the granitic body at sub-surface indicative of blockability of dimensional stone to be recovered from the deposit.
- 2D Electrical Resistivity Imaging to assess physical condition of the intrusive rocks in the sub-surface up to a depth of 65 m.
- Interpretation of weathering profile & structural regime prevalent on the intrusive body based on 2D resistivity results.
- Assess blockability of the rock based on diamond core drill recovery.
- Assess resource area available for economic exploitation of the deposit.
2D ERI investigation was conducted across 04 pre-identified profile lines with a cumulative of 720 m in two adjacent localities. 2D resistivity results indicated absence of sizable hard rock profile in the sub-surface in one location owing to dense network of fractures & soil infillings. In the other location, Resistivity sections indicated presence of hard rock at shallow depth in one portion, however the in-crop outline steeply declined to a greater depth in the other part of the section indicating a huge pile of soil cover to reach the hard rock. The results helped investors to take an informed decision on further development of the property since the volume of soil cover would impact on the overall economics of extraction of blockable material from the deposit.
2D Electrical Resistivity Imaging survey in delineating Dolerite Intrusive (Black Granite) body in a prospect near Warangal, Telangana State, India
Country: India Region: Warangal District, Telangana Period: 2020 Commodity: Dolerite (Black Granite)
The prospect is spread across 03-hectare area near Warangal city in Telangana, India. The prospect lies within Proterozoic Age Peninsular gneissic complex (PGC) represented by grey coloured Hornblende Biotite Gneiss. Exposure of dolerite could be seen for a surface length of about 400 meters with an average of 15 m width. Scope of work included the following.
- 2D Electrical Resistivity Imaging to assess sub-surface extension of the dolerite body to a depth of 40 m below surface with an electrode spacing of 05 m.
- Outline boundary between the host & intrusive body, depth of occurrence, weathering profile & fracture zones.
- Identify zones that are rendered blockable based on interpretation of resistivity data.
- Assess resource area available for economic exploitation of the deposit.
03 ERI Lines totalling 645 metres were planned parallel to each other across the known trend of intrusive such that the dolerite appears in the resistivity cross-section as a distinctive body. In one of the 2D ERI sections presence of high resistivity zone that correlated well with the ground exposure could be observed. Based on the results an area of 0.15 hectare of possible black granite body with a width of 20 m & average depth of 20 m could be assessed. With limited area of resources, about 12,000 cubic meters of blockable resource material could be assessed.
Geophysical prospection & drilling assessment to delineate granite in-crop and assess blockability of the body in a lease area near Jeevana, Rajasthan
Country: India Region: Beawar, Rajasthan Period: 2021 Commodity: Granite
The Malani volcanics series within the Sandmata Complex comprising of Archean Sillimanite-Staurolite-Biotite gneisses has left several episodes of magmatic intrusions leading to interesting pattern both in the intrusive & the host supra-crustal rocks. The prospect is one such area which exposes the granite, gneisses & dolerite intrusions which invites to prospection for blockability of the recovered material. Scope of work in the program included,
- 2D Electrical Resistivity Imaging to assess physical condition of the intrusive rocks in the sub-surface up to a depth of 50 m.
- Interpretation of weathering profile & structural disturbances experience by the intrusive body in the 2D resistivity section.
- Assess blockability of the rock based on diamond core drill recovery.
- Assess resource area available for economic exploitation of the deposit.
2D ERI investigation was conducted across 04 pre-identified profile lines with a cumulative of 600 m at 02 location planned as a pair of cross cutting lines. Resistivity sections indicated presence of hard rock profile at a depth of 20 m; several factures were also identified based on pattern of the resistivity changes. A total of 05 diamond core holes were sunk in various locations and variable length between 60 feet & 120 feet. Presence of abundant fractures rendered expected recovery of material to be low thus reducing the volume of expected resources.