Huhn, et al., (2019) report that new interpretations of IOCG mineral systems in Brazil are proposed based on integration of geophysical, geological and geochemical data. At a continental scale, the Riacho do Pontal and Vale do Curaçá Districts flanking high-speed tomography images control on a broad scale as well as the Carajas IOCG Province in Brazil. On the northern edge of the São Francisco Craton, two copper districts were studied in Brazil and represent two new frontiers in mineral exploration. The Vale do Curaçá Copper District is situated in the interior of the craton, whereas the Riacho do Pontal Copper District is situated along its border. The Caraíba Mine and associated mineralization at the Vale do Curaçá District are related to Paleoproterozoic hydrothermal processes. However, the mineralization located in the Riacho do Pontal has been identified as dominantly Neoproterozoic.
More recently, new papers have been published regarding both districts that increased knowledge of copper mineralization and led to their characterization as IOCG deposits. Regional magnetic and gravimetric surveys were analyzed to interpret the geological, structural and metallogenetic characteristics of the Riacho do Pontal and Vale do Curaçá Copper Districts. The Vale do Curaçá Copper District is located in a high gravimetric NS domain. It is 110 km in length and 22 km in width and shows a strong wavelength gravity high (up to -40 mGal).The ore in the Caraíba mine has a density greater than 3.13 g/cm3 in contrast to the sterile rocks with a density of less than 2.98 g/cm3. The gravimetric signature of the Riacho do Pontal Copper District is mainly characterized by a NW-SE Bouguer anomaly low (down to -45 mGal).
Geologically, these areas are related to the gneiss outcrops of Sobradinho Remanso and the southern portion of the Riacho Seco Complex. The Ria4 occurrences of the Riacho do Pontal Copper District are situated on these regional low-gravity domains. 3D models obtained with Geosoft VOXI Earth Modeling inversion show that the Caraiba mine is intrinsically related to the high magnetics associated with gravity anomaly highs. The ore bodies are subvertical and probably controlled by a stretching lineation. MVI magnetic and gravity inversion shows two main NNW prospective trends. Trends I and II have a sigmoidal shear shape. These trends are positioned in the contact zone between domains with high magnetic (SI>0.005) and gravimetric anomalies (>-10.000 mGal) and show a contrast in density and magnetite content. Trend I is 60 km in length and 7 km in width; hosts the Caraíba, Surubim and Vermelho mines and other deposits; and is the most important trend for hosting IOCG deposits in the Vale do Curaçá District.
The results obtained from the magnetic inversions conducted in the region of the Pontal do Pontal show weak magnetic anomalies along a NW-SE trend. The magnetic linear discrete features are related to shear zones. These NW-SE features overlap older and deeper NE-SW features of the São Francisco cratonic root.
Managed & Built by I2M Consulting, LLC | © 2010-
