PRECAMBRIAN RARE EARTH MINERALIZATION LAYER OF PALEOWEATHERING CRUST TYPE DISCOVERED IN NORTHERN HEBEI PROVINCE

• ZHANG Yun-qiang, 
• YUN Jie, 
• LI Guang-dong, 
• GAO Shang, 
• ZHOU Ming-xing, 
• HE li, 
• ZHANG Ya-guang, 
• ZHAO Li-ying