Geology and Geochemical Investigation for Structurally Controlled Gold Mineralization in Mariga, North-Western Nigeria

Abstract

Aeromagnetic and geochemical investigations were undertaken as a reconnaissance an important component in enhancing the geologic information of Mariga area as it pertains a potential for the extraction of economic gold, gemstones and associated structurally controlled mineralization. This is done with an aim of understanding the structural setting, delineating lithological contacts and possible alteration zones as well as identification of prospective zones for structurally controlled mineralization. The area is bounded between Latitude 9° 50' to 9° 55' and Longitude 5Q 55' to 6° 00'. The study area falls within the Schist Belt of north-western Nigeria. The lithological variations include coarse to fine grained, clastics pelitic schists, phyllites, banded iron formation and mafic metavolcanics (amphibolites). For the enhancement and general understanding of the structural geology of the area, the original TMI grid was processed, filtered and transformed to other grids using Oasis montaj software with associated extensions of the package such as MAGMAP, SPI and CET. First Vertical and Second Vertical Derivatives, Analytic Signal, Tilt Derivative and Horizontal Gradient were produced. These were done in order to extract the magnetic lineaments of the area. Density heat map was produced by employing image analysis techniques such as texture analysis and symmetric feature detection algorithms to identify the magnetic anomalies and vector analysis on their line segments to identify structural complexity. Geochemical analysis was done on soil samples and analysed for elements such as gold, silver, manganese, copper, zinc and iron. ArcGIS 10.8.1 was used for weighted overlay thematic maps such as geology, lineaments, feature orientation and geochemical anomaly. Results of aeromagnetic interpretation show that the magnetic signatures vary from -142 nT to 145 nT in the area which is quite appreciable contrasting signature for magnetic anomaly delineation. Several lineaments with major NE - SV trend was identified in the area. Also, major regional faults trending NE-SW and E-W delineated around the north-western part cross-cuts some of the lineaments and lithologic contacts. Feature intersection orientation density heat map showed areas associated contact aureoles and other deposits along with hot spot edges seem to be closely associated with structural complexity, identifiable in the aeromagnetic map. Prospective areas have been identified after the weighted overlay analysis and indicate that the north-western portion of the study area is deemed more prospective. This area recommended for further ground geophysics detailed investigations follow up.