This PhD project will investigate a variety of high-grade BIF-hosted iron ore deposit in the Iron Quadrangle (IQ) which is located at the southern border of the Sao Francisco Craton, Minas Gerais, Brazil. Despite over 100 years of mining and exploration of iron ore in the IQ, there is still a distinct dearth of information on the exact geological and geochemical environment in which the different hypogene iron ore types (e.g. massive magnetite, martite, granoblastic hematite, microplaty hematite, specularite) formed.
Even though most of the iron ore deposits within the IQ appear to be related to regional fold zones and different strain domains at a larger scale, it is still not known, which genetic role play smaller scale folds and/or shear zones in the control of the high-grade iron ore bodies. Furthermore, the question about the importance of igneous intrusions and their associated magmatic hydrothermal fluids with regards to the upgrade from BIF (~35 % Fe) to high-grade iron ore is still not well constrained. The main high-grade (> 63% Fe) iron ore deposits are hosted by the Caue-Formation, a Paleoproterozoic Banded Iron Formation of Lake-Superior Type. Besides basic petrographical and mineralogical studies, new analytical technology, such as Laser ICPMS for trace element mineral chemistry, in-situ SIMS for oxygen and iron isotope chemistry and infra-red geothermometry for fluid inclusion studies in iron oxides will be used to better constrain the paleohydrothermal fluid sources and iron ore forming processes. This will contribute a new genetic model, which can be used to explore for deep extension of existing and/or new concealed high-grade iron ore bodies.