Integrated Geophysical Investigation for Shallow-Scale Massive (Pb-Zn) Sulphide and Barite Exploration in the Abakaliki
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Integrated Geophysical Investigation for Shallow-Scale Massive (Pb-Zn) Sulphide and Barite Exploration in the Abakaliki and Obubra Mining Districts (AOMD), Southeastern Nigeria Innocent John Arinze 1 & Chidubem Okwudiri Emedo 1 Received: 25 May 2020 / Accepted: 14 October 2020 # Society for Mining, Metallurgy & Exploration Inc. 2020
Abstract This contribution presents the first multi-scale geophysical investigation conducted in the Abakaliki and Obubra mining districts (AOMD), southeastern Nigeria, for the exploration of shallowly emplaced (< 50 m) massive sulfide and barite mineral deposits. Raw airborne magnetic data covering the AOMD was acquired and subjected to diverse enhancement routines to facilitate the identification of areas of subtle magnetic anomalies for subsequent ground truthing. The mineralization is mainly made up of galena, sphalerite, and barite. The contrasting physical properties between these minerals and their host rocks make resistivity, induced polarization (IP), spontaneous potential (SP), and magnetic methods ideal to study and delineate the mineralization and possibly locate the ore bodies. Wenner DC resistivity and IP data acquired along the same parallel traverses are inverted using Res2dinv to produce 2D tomography models of resistivity and chargeability. The resistivity and IP models were successful in delineating zones of sulfide and barite mineralization. The ground SP data collected along the same traverses as the resistivity and IP data were interpreted as line graphs. The 1D SP models show a number of central negative anomalies that could be related to sulfide mineralization. These anomalies show fair-to-good spatial continuity and are in close agreement with the result obtained in the resistivity and chargeability model. This study suggests the presence of exploitable mineral deposits in the AOMD and demonstrates the superior interpretative ability of combined geophysical methods over a single geophysical approach. Keywords Abakaliki . Obubra . Anomaly . Resistivity . Chargeability . Self-potential
1 Introduction The Abakaliki and Obubra mining districts (AOMD) are regarded as major metallogenic ore provinces in southeastern Nigeria. These districts are underlain by geological formations that play host to a variety of underexplored and underexploited mineral deposits that consists mainly of galena (PbS), sphalerite (ZnS), and barite (BaSO4) in association with other accessory minerals such as quartz (SiO2), pyrite (FeS2), and chalcopyrite (CuFeS2). The significance of the solid mineral sector in the country’s present economic framework coupled with the increase in demand for industrial minerals has led to a surge in exploration activities in the AOMD in recent years (2013 until date). Exploration programs, including geological, * Chidubem Okwudiri Emedo [email protected]; [email protected] 1
Department of Geology, Faculty of Physical Sciences, University of Nigeria, Nsukka 410001, Nigeria
geochemical, and geophysical surveys were initiated and execut
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