Metallogenic Epoch Characteristics and Geochemical Features of Granitic Pegmatite Rare Earth Ore in Tabutou Area, Shandong Province

Based on the field investigation and the division of pegmatite belts, through the analysis of petrography, isotope chronology, and geochemistry, the authors determined the diagenetic and metallogenic age and discussed the source of ore-forming material and the relationship between pegmatite and rare earth ore to establish a metallogenetic model of the deposit.The geochemical characteristics show that the rare earth-bearing pegmatite is low silicon, low alkali and iron peraluminous-rich. potassium chang-plagioclase granite pegmatite, potash feldspathic granite pegmatite and potash feldspar granite all have the characteristics of high silicon and alkali and low iron peraluminous. There is a clear differentiation of light and heavy rare earth element, a loss of high field-strength elements such as Ta, Ti, Nb and P, and an enrichment of large ion lithophiles elements as K and Rb. The LA ICP-MS isotope dating shows that the Th-Pb dating of the bastnasite was(128.5±2.0) Ma and (134.4±1.2) Ma, indicating that the mineralization of rare earth occurred in Mesozoic Cretaceous.