Formação ferrífera associada à sedimentação glaciogênica da Formação Puga (Marinoano) na Serra da Bodoquena, MS
Year: 2007
Type: article
Abstract: Iron formation associated with diamictite interpreted as belonging to the Puga Formation (Marinoan) is reported here in a different context from the already known deposits of the Jacadigo Group, at the Urucum´s Massif. The iron formation occurs as a bed about 2 m thick, oriented NS and dipping 45º to East, confined in a massive foliated diamictite with ferruginous matrix presenting low metamorphism. It’s composed of centimetric hematite and magnetite layers alternated with submilimetric layers of silica, sometimes stretched due to the tectonic deformation of the Paraguay Mobile Belt. Fe 2 O 3 vary from 75% in the borders, to 52% in the center of the body. The iron concentration in the borders is due to the remobilization of silica to the center of the body, probably because of the tectonic events. Chemical analyses show that Al 2 O 3 concentrations are high (2,89 – 3,45%), and the strong linear correlation with TiO 2 and Zr indicate terrigenous contribution during chemical deposition. Isolated blocks of granite occur within the BIF, but tectonic overprinting makes it difficult to have a clear observation of the relationship between the clasts and original lamination. Despite the Puga Formation has its origin related to glaciogenic events, there are no clear evidence to link this iron formation origin to the glacial processes.
Institution: Universidade de São Paulo
Language: Portuguese
Subfield: Geochemistry and Petrology
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W4252420646