余石山变粒岩型铌钽矿是近年在中祁连西段发现大型铌钽矿，但对铌钽矿含矿地层归属厘定不清，在梳理前人研究成果基础上，通过野外精细调研和区域对比，重新厘定了这套地层，建议将其从长城纪熬油沟组中解体出来，建立新的岩石地层单位，即新元古代余石山岩组；同时，分析余石山岩组原始层序，总结其形成过程。研究成果为中祁连地块西段地层对比和研究提供了新材料，也为中祁连西段变粒岩型铌钽矿找矿和成矿研究提供了基础。

Yushishan Leptynite type Nb-Ta Deposit is a large Nb-Ta ore deposit discovered in western Central Qilian in recent years. However, the attribution of Nb-Ta ore bearing strata is unclear. On the basis of combing previous research results, through fine field research and regional comparison, this suit of strata has been redefined. It was disassembled from the Changcheng period Aoyougou Formation to establish a new lithostratigraphic unit, named the Neoproterozoic Yushishan Formation. The original sequence of Yusishan Formation was analyzed, and the formation process was also summarized. The research results not only provide new materials for stratigraphic contrast and research in the western section of the Central Qilian massif, but also provide a basis for prospecting and metallogenic research of Yusishan Leptynite type Nb-Ta deposit in the western section of the central Qilian massif.