The role of airborne geophysics in the investigation of gold occurrences in the Itapetim Region, Borborema Province, Northeast Brazil

Abstract

We present a combined analysis of airborne geophysical data (magnetics and gamma-ray spectrometry) and field aspects of Itapetim lode gold district region, aiming to identify structurally deformed and hydrothermally altered zones, which are suggestive of gold mineralized sectors. The main geophysical lineaments are oriented in the NE-SW and E-W directions and display a clear correlation with the major gold-bearing structures in the region. In the magnetic maps, the key pathfinder for gold occurrences is their association with strongly magnetized areas positioned along the Itapetim Shear Zone and outer contour of Teixeira Batholith. In the field, such structures are materialized in protomylonitic and mylonitic rocks that present evidence of ductile and brittle deformation, whereas kinematic criteria are suggestive of a transpressional tectonic regime. In addition, the main radiometric pattern is characterized by K enrichment, which is correlated with a hydrothermal mineral assemblage dominated by quartz, potassium feldspar, and tourmaline. Based on the obtained data integration, we produced an integrative map and located ten new target areas of possible gold mineralization, which is correlative to other well-known lode deposits in Northeast Brazil and Africa.

Mapping geological configuration using geophysics data: an investigative approach in targeting iron ore, gold mineralization and other commodities, a case study of Toko-Nlokeng area (Nyong Greenstone Belt, SW Cameroon)

“…Similar main geophysical lineaments are oriented in the NE-SW and E-W directions and display a clear correlation with the major gold-bearing structures in this paper has been speculated within the Alto Moxotó Terrane NE Brazil (e.g. Leite et al 2019;Santos et al 2023), but links between early arc formation and later compression were missing (Santos et al 2017;Santos et al 2021). Herein, we have revealed the former products, the tholeiitic Toko-Nlokeng host rocks, to be the result of early subduction, which is coeval to other poorly understood maficultramafic sequences within basement units of the Central Subprovince (e.g.…”

“…The TNF8 attractive iron ore target is a complexly folded zone in the southwest of the area as shown in Figure 11(c). This has an amplitude of over 25,000 nT which is structurally comparable to several iron ore and gold deposits in West Africa and NE Brazil (Santos et al 2017;Fabricio-Silva et al 2019;El-Shazly et al 2019;Leite et al 2019;Santos et al 2021). At the TNF12 anomaly, the far southeast of the TNF11 prospect, IFs outcrops were found to be continuous up to 50 m along the strike.…”

“…The proposed workflow for mapping structural and lithology was performed using two inputs, field sheet measurements and auto-detected aeromagnetic-radiometric data. Techniques relating to preprocessing and lineament extraction from aeromagnetic grids as well as methods of calculating structural trends are described by Santos et al (2017), Leite et al (2019) and Montsion et al (2021). Parameter sensitivity testing was also performed as part of the workflow to determine optimal parameters and the effect each has on results.…”

“…The integration of geological and geophysical datasets is useful in tropical and equatorial regions where deposits are generally covered by heavy vegetation and thick laterite profiles and can provide in-depth information on ore genesis. Such an interdisciplinary approach has provided successful results in Precambrian terrains in Australia (Aitken and Betts 2009; Holden et al 2012; Hronsky and Kreuzer 2019; Hronsky 2020), in Brazil (Leite et al 2019; Santos et al 2017, 2022) West and Central Africa (Metelka et al 2011; Jessell et al 2016; Chardon et al 2020 Sepwouo et al 2022), the south Eastern Desert of Egypt (Zoheir 2012; Eldosouky et al 2017; Karmel et al 2022), the Guiana Shield in South America (Combes et al 2022) and Canada (Montsion et al 2021). Among the wide range of geophysical methods, the aeromagnetic method is considered to be one of the most rapid, cost-effective and versatile geophysical tools that can help reveal large- and small-scale features, including differences between basement rock types, magmatic intrusions, volcanic rocks and fault structures (Feumoe et al 2012; Holden et al 2012; Combes et al 2022).…”

Geologia e aspectos genéticos de depósitos de esmeralda em zonas de cisalhamento: um olhar sobre os depósitos esmeraldíferos da Província Borborema, Nordeste do Brasil

“…A estruturação final da Província Borborema ao fim da era Neoproterozoica e início do período Cambriano favoreceu a formação de diversos depósitos e/ou ocorrências minerais (e.g. Araújo et al, 2005;Pereira et al, 2019), incluindo ocorrências de esmeralda confinadas ao longo de zonas de cisalhamento transcorrentes, cujo pico metamórfico foi estimado em 566 ± 6 Ma (Viegas et al, 2014).…”