Lanthanide tetrad effect observed in leucogranites from China

Some leucogranites from China have been found to display the tetrad effect (Masuda et. al., 1987). Abundances of all rare earth elements (REE) in leucogranites from Hunan Province, China, were studied for the first time by inductively coupled plasma mass spectrometry (ICP-MS) in order to investigate the shape of the tetrad effect. The chondrite normalized REE pattern consisting of all members except Eu revealed a clear M-type tetrad effect, according to the classification by Masuda et. al. (1987). Eu shows a strong negative anomaly. These features may reflect a long history of contact with water. Mathematical analyses of the REE patterns suggest also an octad effect behind the patterns and symmetry between the first (La-Ce-Pr-Nd) and fourth tetrads (Er-Tm-Yb-Lu).