Discovery of scandium enrichment and its geological significance in the Dawanshan Neoproterozoic metamorphic basalts from the Mouding area in Central Yunnan Province, China

Scandium ( Sc) is one of the critical mineral resources that countries around the world are competing for. The Dawanshan metamorphic basalt in Mouding County, central Yunnan, has a thickness of more than 36. 5m, an exposed area of 0. 5km(2), and a formation age (781. 3 +/- 1. 9Mo) of Neoproterozoic Nanhua Period. In this paper, the whole rocks geochemical analysis, full automatic mineral analysis ( TESCAN TIMA) observation, NPPM thin section regional surface scanning and single mineral in -situ LA-ICPMS analysis were carried out for the metamorphic basalt. The results show that the Sc contents of the metamorphic basalts range from 47. 0 x 10(-6) to 97. 9 x 10(-6), with an average content of 69. 1 x 10(-6), and with an average scandium oxide (Sc2O3) content of 10(6) x 10(-6). As the Sc mineralization has stable spatial distribution characteristics, so it has the potential to form Sc deposit. At the same time, the metamorphic basalts are accompanied by Ti and Fe mineralization, with the TiO2 contents of 2. 57% -6. 13% ( average 4. 25%); The TFe contents range from 13. 3% to 23. 7%, with an average content of 17. 7%. There are two types of Sc existence state: ionic phase and isomorphism phase. The Sc in the form of isomorphism mainly exists in ilmenite and rutile minerals, and the contents of Sc in ilmenite range from 70. 0 x 10(-6) to 168 x 10(-6), with an average value of 108 x 10(-6); Sc contents in rutile can up to 297 x 10(-6). However, the contents of Sc in magnetite, biotite and other minerals are lower than that of the whole rocks, which makes little