Identification and origins of iron sulfides in Czech loess

Multiple rock-magnetic and non-magnetic techniques were employed to identif y iron sulfides in late Pleistocene Czech loess deposits. The results indic ate that iron sulfides in the loess at Znojmo section are mainly pyrrhotite and pyrite, with stoichiometry ranging from Fe10S11 to FeS2. Although earl y pedogenic origin of fine sulfide fraction can not be ruled out, scanning electron microscopy (SEM) of individual grains and microscopic observations of magnetic extracts show that iron sulfide grains are probably of detrita l origin. Potential sources of these sulfides may have been eluvium loams a bove hypothetical ore deposits in the vicinity of the section or glacifluvi al sediments from nearby glacial margins. Framboidal pyrite forms, now comp letely replaced by iron oxides, suggest that some particles of biogenic sul fides may have also been transported into loess from presumably fluvial sed iments.