Gravity signature and physical properties of copper deposit in the Curaçá Valley, northern Bahia/Brazil – case study

Abstract

This paper aims at analysing the application of the gravimetric method in the search for copper ore in the Valley of Curaçá River in northern Bahia, Brazil. The area where this study was carried out is known as Angico Farm, one of the claims of Caraíba S.A., a copper producer in the northern Bahia, Brazil. There are 18 drill holes at the Angico Farm target, drilled in order to investigate the mineralizations in depth. We have obtained information such as geographic coordinates and chemical results from the company in order to test the geophysical response and the correlation with geology. A 3D inverse gravimetric model was generated in order to verify the validity of the method in exploring for copper ore associated with hydrothermally altered mafic and ultramafic. Both mafic/ultramafic rocks and copper ore present high density, therefore the gravity method may not be effective for identification. We have shown, however, that copper ore from the Curaçá Valley presents a fairly good gravity response, and 3D inverse mathematical model pointed out a well‐delimited copper orebody in the regions where drill holes intersect the ore and coincide with the positive gravity anomaly. The ore contents were overlapped on cross‐sections of density extracted from the inverse model and such information helped us to check out the consistency of the gravimetric method in mapping and modelling mineralized bodies associated with mineral occurrence. Additionally, magnetic susceptibility and gammaspectrometric data were acquired along 18 drillcores to investigate their possible correlation with orebodies.

Magnetic modelling and physical properties of magnesite deposits and regional sequences of Serra das Éguas, Brumado, Brazil

“…Furthermore, the use of physical properties in‐depth has key meaning to use the information as constraints to perform forward/inversion modelling. The joint application was employed to model, for instance, Au–Ag deposits in Canada (Abbassi et al., 2018), for IOCG deposits (Leao‐Santos et al., 2015), for cooper deposits in Brazil (Vasconcelos et al., 2018). Additionally, Baltosser and Lawrence (1970) have described the relationship between radiometric, resistivity and magnetic susceptibility data collected in drill holes and the magnetite per cent for metallic mineral exploitation.…”