REE in the upper soil developed on granodiorite

摘要

In humid conditions rocks weather rapidly and intensively, so fresh samples are not always available. Therefore in this study we try to find if petrological interpretations of Pohorje granodiorite is possible from the soils developed on it. The chondrite-normalised REP pattern of bedrock remains similar in so I samples. Obvious differences are in a depletion in REP (especially MREE) in the soil. After Ti normalisation mass balance showed REP mobilization during weathering. REE could be released by weathering of rock-forming silicate minerals such as hornblende, weathering of some accessory minerals such as epidote, allanite, titantite or because of clay minerals weathering in which they are secondarily bonded. It is possible that depletion in MREE was a consequence of advanced releasing of plagioclases and apatite during weathering. Vermiculite, and remains of hornblende and biotite might preferably bound HREE. X-ray diffraction results mostly confirm conclusions of mass balance. Matching of rock and soil samples is confirmed also by statistical analysis (t-test). We found out that REP are mobilised during rock weathering and soil formation, but their fractionation patterns are not significantly influenced by these processes.