Metallogeny Of The Lizhu Skarn Iron Deposit Of Zhejiang

Lizhu iron deposit is located in the north part of Jiangshan-Shaoxing suture zone between the Yangtze Block and Cathaysia Block,. In this area, there are lots of faults and igneous activities occurred. The skarn and hornstone are found in contact metamorphic zone, and the iron-molybdenum-zinc deposit is related to the metamorphic zone. The study of ore characteristics, mineralization stage division and the metallogenic mechanism in the Lizhu iron deposit can provide a good foundation to find new ore deposits around Lizhu area.Through the study of mineragraphy, petrography, zircon U-Pb geochronology and fluid conclusions analyses, the metallogenic model can be made. Main conclusions are as follows.(1) The age of 147.3±1.1Ma in the Guangshan granite was obtained. Combined with the previous study, at least 3 intrusive stages from the Guangshan granite are recognized, and the Guangshan granite and Shanxi diorite belong to the an intrusive complex. The age of the diorite porphyry which cuts through ore body is 97.2±1.2 Ma. The age of the Yujiashan granite is 98.1±0.8 Ma. They are formed in the same magmatism in the Late Yanshanian.(2) Based on the field observation, mineragraphy and petrography, the mineralizing periods of the Lizhu iron deposit can be divided into 3 stages:prograde stage, retrograde stage and sulfide stage, which the retrograde stage is regarded as the main metallogenic period.(3) The study of fluid conclusions shows that the Guangshan granite and retrograde stage of the Lizhu deposit have the same characteristics of fluid conclusions. Zircon U-Pb geochronology and fluid conclusions confirmed that Guangshan granite and Shanxi diorite have a close genetic relationship with the Lizhu iron deposit.(4) The Lizhu iron deposit is formed in 4 metallogenic stages of (a) the Neoproterozoic-early Paleozoic stage (stratum sedimentary stage), (b) the Caledonian movement and Indosinian movement stage (tectogenesis stage), (c) the Early Yanshanian stage (mineralization stage), and (d) the Late Yanshanian stage (ore body damage stage).