A Magnetic Geothermometer in Moderately Buried Shales

Shales contain magnetic minerals generally at very low concentrations. In the early stages of diagenesis, inherited are altered, while nanominerals formed. this study, we proposed a study shales over stratigraphic thickness 1.3 km from borehole in Paris basin (Borehole EST 433, France), and same formation (Opalinus Clay) collected seven boreholes Jura molasse (Swiss). Magnetic measurements experimental temperatures <30 K allowed proxy magnetite nanograins named PM. We showed that some these formed around pyrite grains, probably under action temperature organic matter. PM was then compared to maturity values found correlation between percentage reflectance vitrinite. The both molassic Swiss basins comparable characteristics for given level. therefore provided constraints on level oil window area. Our can be used as geothermometer which CaCO3 is lower than 60%.