Journal of Geosciences, 57 (2012), 65–85 DOI: 10.3190/jgeosci.115 Original paper Petrophysical and geochemical characteristics of late Variscan granites in the Karlovy Vary Massif (Czech Republic) – implications for gravity and magnetic interpretation at shallow depths Vratislav Blecha1,*, Miroslav ŠteMprOk2 1 Institute of Hydrogeology, Engineering Geology and Applied Geophysics, Charles University, Albertov 6, 128 43 Prague 2, Czech Republic;
[email protected] 2 Institute of Petrology and Structural Geology, Charles University, Albertov 6, 128 43 Prague 2, Czech Republic * Corresponding author The Karlovy Vary Massif (KVM) in northern Bohemia is a composite granite body built up of Late Variscan biotite, two-mica and lithium mica granites. We summarize the available whole-rock geochemical and petrological data and correlate them with similar information from three boreholes in the northern and southwestern parts of the Massif. The aim of the study was to determine whether various types of granites differ in their physical and chemical properties, and whether any differences in physical characteristics affect the accuracy of geophysical interpretation. In accord with the earlier studies, we distinguish two geochemically and petrophysically contrasting granite suites – the Older Intrusive Complex (OIC) and Younger Intrusive Complex (YIC). The geochemical data show that the OIC and YIC granites differ significantly in the content of most major-element oxides (like SiO2, TiO2, FeO, Fe2O3 tot, MgO and CaO). As to physi- cal parameters, the granites differ markedly in magnetic susceptibilities and in the contents of radioactive elements (U and Th). From gravity and magnetic data we compiled a 22 km long geophysical profile, which crosses two of the three studied boreholes.