Mapping Geochemical Anomalies Through Principal Components Analysis in BIF Mines: An Approach Referring to the Bonito Mine, Northeastern Brazil

Given the subtle complexity associated with the geochemical composition of iron ore deposits, a full understanding of their behavior appears to entail a well-structured geochemical database. In this context, the Principal Components Analysis (PCA) approach has been applied to map geochemical anomalies throughout an exhaustive database concerning the banded iron formation (BIF) deposit of the Bonito Mine, as sited in Rio Grande do Norte State in Northeastern Brazil. The BIF deposit is related to the Serra dos Quintos Formation, Serido Group, considered as a Neoproterozoic metasedimentary sequence, deposited and metamorphosed during the Brasiliano-Pan African orogeny. The ore typology scheme comprises hematitic itabirites, magnetitic itabirites, martitic itabirites and amphibolitic itabirites. The PCA drawn data appear to reveal that two first principal components prove to explain almost 73% of the cloud information and, as expected, the Fe2O3 and SiO2 contents turn out to have the highest factorial loads on PC1. In addition, the geochemical anomalies, as projected on the factorial plane, appear to reveal some relevant information regarding the geological processes occurring during the iron ore formation. The qualitative correlation between Mn and P-Al2O3 contents indicate that an important sedimentary input have taken place, culminating in the development of the Bonito Mine BIF deposit.