Recognition of boulder in granite deposit using integrated borehole and 2D electrical resistivity imaging for efective mine planning and development Muhammad Junaid 1 , Rini Asnida Abdullah 1,* , Radzuan Saa’ri 1 , M. Alel 1 , Wahid Ali 1,2 , Arshad Ullah 1 1 Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310, Skudai, Johor Bahru, Malaysia 2 Department of Mining Engineering, Balochistan University of Information Technology, Engineering and Management Sciences (BUITEMS), Airport Road, Quetta, Pakistan *Corresponding author email address: asnida@utm.my Abstract: Evaluations of a mineral resource are necessary for mineral rights, owners and investors alike. However, for resource evaluation the detail documentation of subsurface geological spatial distribution such as lateral and vertical extent of bedrock and topsoil, hydrogeological investigation and boulder characterisation is mandatory. Boulder is hard and crystalline compact rock block, which substantial presence in a deposit highly infuence the drilling equipment selection. A traditional exploration technique particularly for granite resource evaluation is drilling. But even fnite number of drilling sample fails in the accurate delineation of boulders because drilling is limited to small point and rock mass is heterogenous and thus immense portion of the deposit via drilling method remain discern. 2D electrical resistivity imaging (2D ERT) technique of the study area over an area of 3.5 km 2 was accomplished by six resistivity lines using a Schlumberger protocol with inner and outer electrode spacing of 5 m and 10 m respectively. Inverted resistivity images successfully identify the existence of boulders in the area of investigation in the topsoil region; characterized by high resistivity values more than 2400 Ω.m. Whereas, only one core log (BH3) out of three reported presence of boulders. Thus, the research study presented in this paper enables us to conclude that the combined application of borehole and ERT allows us to derive that 2D ERT enhances the resource evaluation efciency and reduces the cost considerably for underlying subsurface geological characterization. Keywords: Electrical resistivity imaging, boulders, granite, borehole, mine planning Abstrak: Penilaian sumber mineral diperlukan untuk hak-hak mineral, pemilik dan pelabur. Walau bagaimanapun, bagi penilaian sumber mineral, dokumentasi terperinci geologi permukaan bawah seperti rentangan tegak dan sisi batu dasar, penyiasatan hidrogeologi dan pencirian batu tongkol adalah mandatori. Batu tongkol adalah blok batuan kompak keras dan berhablur, di mana kewujudannya di dalam deposit sangat mempengaruhi pemilihan peralatan penggerudian. Teknik penerokaan tradisional terutamanya untuk penilaian sumber granit ialah melalui kaedah penggerudian. Walau bagaimanapun, dengan bilangan sampel penggerudian yang banyak, masih belum dapat mengenalpasti kehadiran batu tongkol secara tepat, ini adalah kerana, kaedah penggerudian adalah terhad kepada titik kecil dan massa batuan adalah heterogen dan sebahagian besar deposit melalui kaedah penggerudian masih dapat dilihat. Pengimejan resistensi elektrik 2D (2D ERT) dari kawasan kajian sepanjang 3.5 km 2 dicapai oleh enam garis resistivity menggunakan protocol Shlumberger dengan jarak elektrod dalam dan luar masing-masing 5 m dan 10 m. Imej kerintangan terbalik berjaya mengenalpasti kewujudan batu tongkol di kawasan penyiasatan di kawasan tanah atas yang dicirikan oleh nilai resistivity melebihi daripada 2400 Ω.m. Manakala, satu log teras (BH3) daripada tiga laporan menemukan kehadiran batu tongkol. Oleh itu, kajian penyelidikan yang dibentangkan dalam makalah ini membolehkan kita menyimpulkan bahawa gabungan aplikasi lubang jara dan 2D ERT membolehkan kita membuat kesimpulan bahawa 2D ERT meningkatkan kecekapan penilaian sumber dan mengurangkan kos dengan ketara untuk pencirian geologi bawah permukaan asas. INTRODUCTION Mineral exploration is the initial and essential stage of a mining cycle (Figure 1), which covers prospecting, mapping and surveying of a mineral deposit (Haldar, 2012). In simple words, mineral exploration is the systematic evaluation of the mineral deposit with a view to mine it proftably and efciently. This shows that efcient evaluation of the mineral repository is the key to successful mine planning and development. However, for successful mine planning and development the efcient delineation of numerous subsurface geological features such as determination of lateral and vertical extent of topsoil and bedrock, hydrogeological Figure 1: Mining operation stages. investigation and recognition of boulders is prerequisite. Boulder is a block of hard rock present in rock reserve, which immense quantity highly infuence mine planning, particularly selection of drilling equipment. DOI : https://doi.org/10.7186/bgsm67201912 Bulletin of the Geological Society of Malaysia, Volume 67, June 2019, pp. 99 – 104 0126-6187; 2637-109X / © 2019 Geological Society of Malaysia. All rights reserved.