| The Yinkeng porphyry-Mo deposit, in west of Zhejiang Province, locates in eastern part of Qinhang orogenic belt,which is a new important metallogenic belt founded by China Geological Survey and the geological prospecting has continuously achieved new breakthrough these years. Study of the genesis of this deposit means a lot to realization of metallogenic process and the sources of metallogenic materials, as to provide a guide to the prospecting job. Comprehensive lithology, lithogeochemistry, isotopic geochemistry and dating of ore-bearing porphyry provides an important theoretical and pratical meanings to the disclosure of the process and evolution and discuss on geotectonic setting of granite in this district.On the basis of field work and investigaton, this essay conducts a systematical summary of geologaical characteristics of mine lot and ore body, using various modern testing methods and then systematically analysizes and investigates the granite in Yinkeng deposit, finally receiving some achievements as follows:①This essay brings forward that the rock type of Yinkeng ore-deposite is A-type granite, and the source of magma is mainly from lower crust, Probably with a small dye of mental material.②This essay also presents that the diagenesis age of granite porphyry is separately about110±1.1Ma by zircon SHRIMP dating, which represent Late yanshanian, the Cretaceous period.③After a study on systematical investigation of geologaical characteristics of this deposit,this essay conducts a test on H-O isotopes and S isotopes of ore and granite,with the results revealing that the metallogenic fluid is mainly magma water, still mixed with little atmospheric water, and S comes from magma.④According to the study above, the diagenetic metallogenic model of Yinkeng Porphyry molybdenum deposit is that lithospheric thinning and thermal material from upper mantle gushing up give rise to melting of lower crust rocks in the double condition of raising temperature and reduced pressure, Late yanshanian, Eastern China, in the wake of crust-mantle material exchanging and mixing. Then Mantle material and new form of the melt gush up along Jiangshan-Shaoxing deep faults. The melt of highly differentiation with metallogenic material invaded in the Yinkeng and mineralized. |
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