Integration of induced polarization, resistivity, and magnetic data of IOA occurrences in Ararenda, western of the Santa Quiteria magmatic arc, Ceará Brazil

Abstract

The Neoproterozoic Santa-Quitéria Magmatic Arc (SQMA) hosts significant IOA occurrences that were recently documented in their geological, petrographic, geochemical, and geochronological aspects. To advance the understanding of the geologic framework and metallogenetic potential beneath the SQMA, we used an integrated geophysical approach. In this context, this study is the first geophysical evaluation of these occurrences and provides valuable insights into the ore mineralization of this under-researched region. Seven profiles (E-W direction) were acquired using magnetic, resistivity, and induced polarization methods. The results allowed us to integrate the geological map information with the geophysical anomalies at the subsurface. According to the resistivity and IP inversions there are resistive and chargeable bodies at depths ranging from the surface to up to 180 m, and it is possible to associate the IP anomalies in shallow depths to deep magnetic 3D anomalies modeled. Most 3D magnetic anomalies are located on or very close to the IOA occurrences identified on the surface. The positive anomalies on the IP-chargeability map are related with the sites of alterations, shears, and contact zones. In addition, based on geological mapping, there is a correlation between high chargeability values and high magnetic values with iron formations (iron ore). In contrast, the correlation between high chargeability and low magnetic values indicates metal sulfides (including copper). The results presented here is a start point to further exploration work for this mineral system and we can suggest the future development of more dense geophysical data to better characterize it. An exploratory drilling holes campaign should be used in a second stage as a basis for the 3D geological model of this area. These two approaches will be crucial to improve the mineral knowledge of the SQMA.