Geochemical Characteristics and Genetic Analysis of Lead-zinc Deposits of the Mohailaheng Area in the Northern Section of Lancang River, Nujiang River, Jinsha River, Qinghai

Mohailaheng lead-zinc mineralization is located in Jieduo back-arc foreland basin in the northern margin of metallogenic belt in the northern section of Lancang River, Nujiang River and Jinsha River. It mainly contains carbonate seam of Zaduo group in Lower Carboniferous. Ore-bearing formation and the NWW fracture are important ore-controlling factors in the Mohailaheng area. Ore minerals are mostly galena, sphalerite, limonite, etc. In the studied area, major element Mg/Ca value is less than 0.6, the average LREE/HREE value is 5.59, the (La/Yb)N average is of 0.73, showing that there is LREE/HREE fractionation, and there is a weak HREE enrichment characteristic; Trace elements Sr and Ba are slightly enriched, Rb, Th, Ta, Nb and other elements show a slight loss characteristic. These data indicate that ore body and surrounding rock have the same or similar material sources. In conclusion, lead-zinc deposits originated in shallow shore-paralic depositional environment, and ore deposit genesis possesses the characteristics of the Mississippi Valley-type(MVT) deposit.