Characteristics of Rare Earth Elements in Volcanic Rocks from Changbai Mountain

Changbai Mountain is located in the circum-pacific Cenozoic volcanic region, where basalt is widely distributed over nearly 20000 km², and in which, high contents of rare earth elements (REEs) have been reported. As it is known, the value for utilization of such REE resources depends not only on their contents but also on their existing characteristics, however, no related reports have been made in this respect about the REEs in the Changbai Mountain area so far. In this work, using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), the main component elements and rare earth elements in the volcanic rocks from Changbai Mountain were both accurately determined, the results revealing that the composition of the rocks is similar to lithofacies of basalt and trachyte, and the amount of the REEs was as high as 211-893 μg/g, with REEs enrichment being more easily found in the latter. Furthermore, negative europium anomalies (δEu) of 0.06-0.69 were observed, and the ratios of light rare earth elements and heavy rare earth elements (∑LREEs/∑HREEs) had a range of 3.80-5.61, which meant that the LREEs were prone to be more enriched. Finally, a grade extraction procedure was carried out to study the REEs existing phases, the results show that the REEs mainly exist as phosphate phase (52.9%-88.5%), carbonate phase (14.6%-43.8%) and oxides (6.04%-18.4%), while those of silicate phase and ion adsorption phase were the least. The grade extraction procedure was proven to be accurate, with recovery yields of 91.1%-108%, providing a feasible strategy for similar analytical purposes.