The State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China;
East China Institute of Technology, Fuzhou 344000, China;
The State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China;
The State Key Laboratory for Mineral Deposits Research, Nanjing University, Nanjing 210093, China;
East China Institute of Technology, Fuzhou 344000, China;
black rock series; Early Cambrian; trace elements; northwestern Hunan; China;