The Proterozoic sequences in the North of Distrito Federal (Brazil) and in Bezerra and Vila Boa regions (Goiás) comprise carbonates, pelites and sandstones from Bambuí and Paranoá Groups. In Distrito Federal, such units are tectonically overlapped by metasediments of green schist facies of Canastra Group. Among the mineral constituents of the pelitic terms of all these units, phyllosilicates, particularly illite and muscovite, are predominant and are identified using X-ray diffraction with the help of reflection d(001) decomposition. The Kübler Index (Illite Crystallinity Index) complements the interpretation of local diagenesis and the possible bulk tectonic influence on the diagenesis/metamorphism that is a result of the overlap by the thrust fault of Canastra Group on Paranoá and Bambuí groups, in the Distrito Federal region. Results indicate epizone conditions for the samples analyzed from Canastra Group and anchizone for samples from Bambuí and Paranoá Groups. In the rocks at the North of Distrito Federal, the Kübler Index values are lower than in Bezerra - Vila Boa region. Moreover, the contents of Bambuí Group rocks are smaller than Paranoá's in the entire study area; therefore, the influence of tectonic bulk occurs gradually, starting from the highest load point.
Paranoá Group; Bambuí Group; Decomposition; Diagenesis-anchizone
